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Day 11: Worden's EVA Day Journal Home Page Splashdown Day

Apollo 15

Science and a Press Conference

Corrected Transcript and Commentary Copyright © 2000 by W. David Woods and Frank O'Brien. All rights reserved.
Last updated 2013-10-18
[This section primarily covers the twelfth day of the mission, 6 August, 1971.]

[This is perhaps the quietest day of the mission. The main objective, i.e. exploration of the Hadley/Apennine region of the Moon, has been achieved as well as a huge clutch of secondary aims and there is little remaining to do except to ensure they return safely in a healthy and well-aimed spacecraft. Al Worden will continue to make navigation sightings of the Earth and Moon against the stars in case communication with Earth is lost, when he would be forced to manually bring Endeavour home. In the interests of science the crew of Al, Dave Scott and Jim Irwin will continue to operate the SIM bay, take photographs of the approaching Earth and conduct another experiment to help characterise the light flash phenomenon experienced by many other crews.]

[During their rest period, the Mass Spectrometer and the Gamma-ray Spectrometer, both mounted at the end of separate, retractable 7-metre booms, have been operating, as has the Alpha Particle Spectrometer, though the covers for the latter instrument are closed.]

Public Affairs Officer - "This is Apollo Control at 254 hours, 29 minutes. And the crew has now been asleep for about an hour and a half. We have about 7 hours remaining in their sleep period. And just a few minutes ago, Flight Director Glynn Lunney checked with his flight control team on the status. The reports from around the room are generally about the same. All looks quiet and everything is looking good. Apollo 15 at the present time is 147,745 nautical miles [273,623 kilometres] from the Earth, and the spacecraft is traveling at a speed of 3,591 feet per second [1,094 m/s]. We will continue to provide status reports hourly. The air-to-ground lines are down but we do have tape recorders running, and should we get any unexpected calls from the crew, we'll play those back for you shortly afterwards. At 254 hours, 30 minutes, this is Apollo Control."

Public Affairs Officer - "This is Apollo Control 256 hours, 34 minutes Ground Elapsed Time in the mission of Apollo 15. Heading homeward at 3,714 feet per second [1,132 m/s]. Still 143,341 nautical miles [265,468 km] out from Earth. Splashdown is in the North Central Pacific; 38 hours, 36 minutes away. Crew is still asleep at this time. No recent communications. They have 4 hours and 54 minutes of their scheduled sleep period remaining. Milton Windler's Maroon Team has taken over for the graveyard shift here in the Control Center. The spacecraft slowly rotating in the Passive Thermal Control mode; which for the people here in the Control Center, is rather like watching the grass grow. At 256 hours, 35 minutes Ground Elapsed Time, this is Apollo Control."

Public Affairs Officer - "This is Apollo Control at 258 hours, 26 minutes. Some other times, 3 hours and 3 minutes remaining in the Apollo 15 crew rest period. Splashdown some 36 hours, 45 minutes away. Apollo 15 spacecraft Endeavour now 139,283 nautical miles [257,952 km] out from Earth. Velocity building up very gradually, now 3,831 feet per second [1,168 m/s]. Current vector shows the Ground Elapsed Time of Entry Interface, Saturday, of 294:58:06; velocity at the Entry Interface would be 36,097 feet per second [11,002 m/s]. All these numbers concerned with entry and splashdown will change back and forth over the next day and a half. Crew apparently in fairly deep sleep at the present time according to Flight Surgeon. Spacecraft rotating about the longitudinal axis in the barbecue roll - Passive Thermal Control mode. All spacecraft systems are in excellent shape, operating nominally. No problems with spacecraft or crew. At 258 hours, 28 minutes, this is Apollo Control."

[Flight Plan pages 3-367, 3-368, 3-369, 3-370 and the current page, 3-371.]
Public Affairs Officer - "This is Apollo Control, 261 hours, 29 minutes Ground Elapsed Time. Should be coming up on crew wakening here momentarily. Spacecraft communicator Joe Allen will be giving the crew a call followed by some wake-up music. The spacecraft, meanwhile, is 132,367 nautical miles [245,144 km] out from Earth. Velocity: 4,038 feet per second [1,231 m/s]. The spacecraft communicator is checking the weather room display for a forecast for the landing area which calls for scattered clouds and good visibility. And looks like he's getting all see to wake the crew up."

261:30:07 [Music - "Anchors Aweigh"]

261:30:20 Allen: Good morning, Endeavour. This is Houston.

[Comm break.]
261:31:34 Worden: Hello, you guys.

261:31:35 Scott: Good morning.

261:31:37 Allen: Good morning, Dave. A little something special for your LMP from your lunar lift-off Flight Director with young Ed Fendell on the cymbal.

261:31:50 Worden: Oh, man; he's standing at attention right now.

261:32:00 Allen: Roger. We copy that. [Long pause.]

261:33:00 Allen: Endeavour, this is Houston, with our first request of the day. We'd like the X-ray Spectrometer, On, please.

[The early morning tasks for the crew include going through the post-sleep checklist, stopping the PTC rotation and aiming the SIM bay so that the X-ray Spectrometer can get a look at another astronomical target. The Flight Plan omitted to include the instruction to switch the instrument on so Allen is prompting them. Since the spacecraft will be at a stable attitude, Mission Control will advise the crew of what angle they can set the steerable High Gain Antenna to, thereby maintaining a high quality link to Earth.]
261:33:08 Scott: Roger. Coming on.

261:33:12 Allen: Okay, Dave. And I've got High Gain Antenna angles for you when you exit PTC.

261:33:25 Scott: Okay. Stand by one, Joe. [Long pause.]

261:34:25 Scott: Okay. Go with your High Gain angles.

261:34:31 Allen: Roger. High Gain pitch, plus 24; yaw, 264. And, Dave, I've got CSM consumables if you're interested in copying those.

261:34:53 Scott: Okay. Go, Joe.

261:34:55 Allen: Roger. GET 261 plus 00. RCS total, 38. Quad A, 42; 39, 32, 38. H2 tanks: 34, 32, 33. O2 tanks: 49, 50, 40. And there's a note on that which reads, "Fat City." Over.

[With only one day left in the mission, they have over a third of their original consumables load remaining. Thus the comment "Fat City". However, the reader ought not to think that the mission planners miscalculated their load. Given any one of a vast number of entirely conceivable scenarios and their apparently generous margin would be quickly used up. For example, a rescue rendezvous on a stricken Lunar Module in the wrong orbit around the Moon would have cut deeply into their RCS margin. American spacecraft were designed with acceptable leak rates from their cabins and it is entirely possible that Endeavour's hull could have developed a greater leak rate than it did, increasing the flow of oxygen from the tanks. Power and cooling requirements could have changed, affecting usage of their hydrogen and oxygen stocks. It is a measure of the mission's highly nominal nature and the careful husbanding by the crew and ground controllers of the spacecraft's systems that they have these excellent reserves at this stage of the flight.]
261:35:42 Scott: Yes, man. I guess so. That's pretty even, isn't it?

261:35:45 Allen: Yes, sir. And, Dave, a comment...

261:35:52 Scott: What a machine.

261:35:54 Allen: Roger. A comment: you're being served now by the MOCR shift that witnessed a new endurance record for Apollo flights, being set during the night.

261:36:10 Scott: Ohh, that's interesting. We'd forgotten about that. [Pause.]

[Joe Allen is careful to qualify this endurance record by applying it to Apollo. Other American and Soviet flights have been in space longer. For example, the Gemini VII flight of Frank Borman and Jim Lovell stayed up for 14 days and the ill-fated visit of Soyuz 11 to the Salyut 1 space station lasted nearly a month.]
261:36:32 Allen: And, Endeavour, I'll be standing by for when you're ready to copy down the few changes in your Flight Plan for today. I can bring you up to date over the next 7 hours or so and get all that out of the way. I'm also curious to know if you've had time to listen to any sea shanties from the HMS Endeavour up there. Over.

261:37:02 Scott: No. We haven't had a chance to, Joe. Stand by and I'll get my trusty pen out, after we get through with this - coming out of PTC, and we'll do the Flight Plan.

261:37:13 Allen: Okay, fine. You should ask your trusty record librarian, Al, where the sea shanties are, if you have time today.

261:37:25 Scott: Okay. We were talking about that last night, and came to the realization that we brought all these neat things along, and we hadn't had time to listen to a single one of them.

261:37:35 Allen: Not at all surprised to hear it.

261:37:41 Scott: I'll tell you, yesterday, we finally got to catch our breath.

261:37:53 Allen: You always said the hours are long.

261:38:01 Scott: Roger. [Long pause.]

261:38:16 Scott: The hours are long but the accommodations are palatial.

261:38:23 Allen: Was that the way it went, Dave?

261:38:33 Scott: Sounds like you've recovered from all that - the other - couple of last few days, too.

261:38:40 Allen: Very nearly.

[Very long comm break.]

[Within the next minute, the X-ray Spectrometer will begin a 55-minute period of data collection while pointed at the galactic south pole. This is a point in the celestial sphere which is between the constellations of Cetus and Sculptor and is chosen to exclude as much galactic-sourced x-ray flux as possible, essentially providing a control measurement with which to compare other readings.]

261:49:00 Irwin: Houston, this is 15. Standing by to copy Flight Plan update.

261:49:06 Allen: Roger, Jim. Good morning. The first...

261:49:10 Irwin: Good morning, Joe.

261:49:11 Allen: ...entry should be at 261:42. And it is a - a change in the first register of the DAP load - the time column. We want that to read, 11101. Over.

[The five digits read to Jim set the status of a register in the computer which controls how the Digital Auto Pilot operates. In this case, the fourth digit is being changed from a "1" to a "0" which narrows the deadband from ±5.0° to ±0.5°. The attitude of the spacecraft will therefore be maintained within this tolerance. These tighter limits require more use of the RCS thrusters to maintain. However, at this late stage of the mission, they have generous reserves and little reason not to use them.]
261:49:44 Irwin: Give me the time again on that, Joe.

261:49:49 Allen: Roger. 261 plus 42.

261:50:04 Irwin: Okay. At 261:42, I don't see any DAP information. I see one on 261:35.

261:50:15 Allen: I may have done it again, Jim. Let me see. [Pause.]

[The version of the Flight Plan used in the compilation of this Journal does indeed have this DAP load at 261:44.]
261:50:29 Allen: Stand by on that. Let's - let's continue on with some of the easier steps. At 262...

261:50:36 Irwin: Roger. [Laughter.]

261:50:37 Allen: ...plus 05, it should - that - that - that's 262 plus 05 add "Gamma-ray Gain Step, two steps."

261:51:08 Irwin: Understand. At 262:05, Gamma-ray, two steps.

261:51:13 Allen: Roger. And at 263:55, under the line "Noun 70," et cetera, add "X-ray to Standby." And at 263:59 delete the Verb 48 line and the DAP load over in the time column.

261:51:55 Irwin: Okay; at 263:55, we'll add a step there after Noun 70, X-ray to Standby; and then, at 263:59, we'll delete the Verb 48 and also delete the DAP load that's in the time column.

261:52:18 Allen: Roger. Turning the page to 264:02, the DAP - load in the time column should read, 11101. And at 265...

261:52:44 Irwin: Okay; understand.

261:52:45 Allen: ...the DAP load status in the notes column should read, 11101, X1111, and this continues through for 2 hours. Over.

261:53:16 Irwin: Okay. Understand that 264:00, in time column, changed the DAP load there from all ones to 11101; and then, at 265, the DAP load will be changed the same way to continue for 2 hours.

261:53:43 Allen: That's correct, Jim. And moving on to 266:30, delete the "Gamma-ray Gain Step to Shield, On" line.

261:54:02 Irwin: Okay. 266:30, to - eliminate the Gamma-ray Gain Step.

261:54:10 Allen: Roger. Moving to 267 plus 20, add the two steps: "Gamma-ray boom, Retract, talkback barber pole for about 2½ minutes, then gray, and then Off." And the second step, "Gamma-ray Gain Step to Shield, On."

261:55:01 Irwin: Okay. Understand, there are two steps there. The first one is Gamma-ray Retract, barber pole for about 2½ minutes, then gray, and then turn it Off. Second one is Gamma-ray Gain Step to Shield, On.

261:55:17 Allen: That's correct. Moving to 267 plus 42, change the DAP load in the time column to read 11101, X1111. Over.

261:55:38 Irwin: Understand, from all ones to 11101.

261:55:43 Allen: That's correct. Turning the page to 268:02, the DAP load in the time column, the same change.

261:56:02 Irwin: Okay. I copy. [Pause.]

261:56:15 Allen: Okay. On the same page, 268:30, Gamma-ray Gain Step, five steps.

261:56:35 Irwin: Understand, Gamma-ray Gain Step to five steps.

261:56:46 Allen: That's correct, Jim. Now looking at page 3-378, the "UV photos - Trans-Earth Coast," A couple of changes there. About halfway down the page where it reads "two frames, filter 2, exposure time 20 seconds," delete that line, and add the line - the two lines, "one frame, filter 2, exposure time 20 seconds; one frame, filter 2, exposure time 2 seconds."

261:57:45 Irwin: Okay. I have that. Joe. It's kind of our standard change in the UV procedures.

261:57:49 Allen: That's correct, Jim. And the mag Metro under the "configure camera" section should be changed to read mag Papa.

261:58:13 Irwin: Okay. Understand mag Papa.

261:58:18 Allen: Okay, Jim. And the last one for you, a biggie, turning over four pages to the "Sextant Photo Test", strike the line "PCM Cable".

261:58:39 Irwin: Okay. Eliminate PCM cable on - on the Sextant Photo Test.

261:58:43 Allen: Roger. [Pause.]

261:58:52 Irwin: Can we go back now to the very first one?

261:58:58 Allen: Jim, I knew you were going to ask that. The first one, I guess, was a small typographical error, and there's no change required there. And, please don't tell Dave about it. He's keeping score against me.

261:59:17 Irwin: Okay [chuckle].

[Of course, Dave can hear everything that's being said.]

[The PCM cable was found to be missing early in the mission. It was intended to electronically indicate to Mission Control when a camera was being operated for the purposes of accurate data collection. Joe is referring to procedures detailed on page 3-382 of the Flight Plan for the Sextant Photography Test]

[Long comm break.]

[Flight Plan page 3-372.]

262:05:21 Allen: Endeavour, this is Houston with a forecast weather report for your landing area. They're calling for high scattered - 2,000 [feet altitude] scattered, 10 miles vis[ibility], winds about 15 knots out of the east-northeast, waves going to 4 feet, and we're predicting no midcourse 6 correction for trajectory reasons. And from the weather report none is required for weather reasons. Over.
[Had the weather at the planned landing site been unsuitable, the trajectory of the spacecraft could be altered within limits to move splashdown to a more suitable site. The near limit is set by the ability of the spacecraft and crew to withstand a steeper, hotter, higher-g re-entry. The far limit is constrained by the fact that if the spacecraft enters at too shallow an angle, it will not lose enough velocity before flying out of the atmosphere again, only to re-enter a second time, long after the Command Module's limited reserves have run out.]
262:06:04 Scott: Gee, that sounds pretty good, Joe. Except we saw a movie about that weather stuff once.

262:06:22 Allen: Roger. We copy that. And, Dave, we do have one question. Is it true that nothing can stop the Army Air Corps?

262:06:35 Scott: That's true, Joe. That's true.

262:06:41 Allen: I'm beginning to believe it.

262:06:49 Scott: Well, that means you're just about qualified.

262:06:58 Allen: I'm glad you still have reservations, though. Your Gamma, by the way, is right on 6.5 as close we can tell right now.

[Based on their current trajectory, Mission Control expect the spacecraft to intercept the atmosphere at an angle of 6.5° to the Earth's local horizontal. This is in the middle of the prescribed range of angles and indicates that their navigation is spot on.]
262:07:12 Scott: Well, that's pretty good. Must be compensating errors along the way somewhere.
[Comm break.]
262:09:33 Scott: Say, Houston; 15.

262:09:37 Allen: Go ahead.

262:09:41 Scott: We reviewed our entry stowage last night. We're going to do the stowing this morning. And in the process, why, we came up with one extra little bag up here, which we're labeling LM return items, which is essentially the same thing as 14 brought back. And I wonder if you might check with our good FIDO and see if he wants the details of that, or whether maybe Ed Mitchell can give you the general kind of items, and that would be acceptable. But we have one - one bag, which I'm sure you're aware of, and we'll stow it and tell him exactly where we stowed it. And if he wants the details, well, we'll give it to him.

262:10:22 Allen: Okay, fine, Dave. We copy that, and pass that information along. I have the morning news report if you're interested in listening.

262:10:33 Scott: Roger. Everybody's hooked up and listening. Go.

262:10:38 Allen: Roger. This is the news for 6 August, 1971. In the first round in the American Classic at Firestone Country Club, Akron, Ohio, the leaders are Jerry Heard and Mike Hill, both with 3 under par 67s. Arnie Palmer shot a 70 and Nicklaus a 73. The U.S. built its gold medal total to 50 in the Pan Am Games, and they're entering their second week now. Cuba is a distant second with 17 gold medals, but a Cuban set a world record yesterday in the hop, skip, and jump. The record was 57 feet, 1 inch. We're coming up on the first full weekend of national football exhibition games, and New Orleans Saints play the Buffalo Bills; Dallas Cowboys play the L.A. Rams. And these two games are the beginning of an 11-game weekend. I've got the baseball scores. American League East: Yankee's beat Baltimore, 5 to 0; Boston over Detroit, 5 to 4, American League West: Kansas City over Minnesota, 7 to 4; and Oakland edged out Milwaukee, 2 to 1. The National League: Chicago over San Diego, 3 to 0; Pittsburgh beat Montréal, 7 to 2; and Houston 0, the Dodgers 3. The government reports today the latest figures in the nation's unemployment problem, and one private economist predicts the jobless rates probably will show still another rise. Five days after the steel industry and Union agreed on a new contract without a strike, tens of thousands of steel workers have been laid off, and the hearths are cold as users consume steel-strike-preparedness stock piles. William Martin, Jr., who reorganized the New York Stock Exchange 33 years ago, proposes an overhaul of the entire securities industry.

262:13:00 Allen: We want to interrupt here. If we could have Accept, please, we'll provide you with a new state vector.

[Placing the Up Telemetry switch to Accept allows the computer to accept information radioed digitally from Earth, in this case to upload revised numbers that define their best estimate of the spacecraft's position and velocity in three dimensions.]
Allen (continuing with the news): The Senate shelves, until September 13, that compromise draft-extension bill, which Nix - President Nixon wants now, and when it comes up, it will, quite possibly, face a filibuster. The U.S./Middle East expert Joseph Sisco concludes "practical and concrete," and those are in quotes, talks in Israel. He says no decisive breakthrough was achieved, and he didn't expect any. The Middle East cease-fire, which went into effect last August 7, hasn't ushered in peace, but it has suspended Israeli-Arab fighting. The last 12 months have been the best year for Israel since 1967 and the euphoria induced by results of the Six-day War. A government study says Americans will spend more than 105 billion for medical care in 1974, and even the most ambitious Federal health insurance proposal would add less than 12 billion to the tab. Congress is set to embark on a month-long summer vacation after the Senate completes action on a measure keeping Federal agencies in business until October 15. That's good news. And - a - an added word which could be a science update; you may have heard yesterday, but let me repeat it anyway. We've had very clean laser returns off the LR cubed, which is located at Hadley Base; In fact, very good and immediate returns from that. Also, as you know, we have a good subsatellite orbiting the Moon, and are getting data from all the experiments onboard that. Over.

262:15:06 Scott: Oh, that's very good news, Joe. Thank you. We hadn't heard about the LR cubed, but we were hoping it was super-clean.

[The LR cubed, or LR3 or LRRR is the Laser Ranging Retro-Reflector. It is an array of glass cube-corners which have the property of reflecting a light beam back in the same direction from whence it came, similar to reflectors placed on bicycles to improve their visibility in car headlights. Dave and Jim placed the third LR3 on the Moon (see the Apollo 15 Lunar Surface Journal starting at 124:19:13), forming a network with reflectors set up by the Apollo 11 and 14 crews. By sending laser pulses from Earth to these reflectors and timing how long it takes for a return reflection, it is possible to measure the intervening distance to great accuracy and to monitor changes in that distance over time. During training and while actually deploying it, it had been made clear to Dave and Jim that it ought to be kept "super-clean", something that could be very difficult to achieve in the dusty, low-g environment of the Moon.]
262:15:19 Allen: Roger; and it's your computer.

262:15:25 Scott: Rog.

262:15:27 Allen: And, an added a note for Al. Alfredo, I'm not sure if you got a report on your bistatic radar experiment. Taylor Howard got very, very clean echoes on both the S-band and the VHF frequencies, and he's busy analysing that data right now.

[During some near-side passes of the Moon, the spacecraft's antennae were aimed at the lunar surface for the Bistatic Radar Experiment. The echoes received by antenna on Earth yield information about the electrical properties of the surface and can reveal some structure in the subsurface.]
262:15:51 Worden: Very good, Joe. [Long pause.]

262:16:48 Allen: Endeavour, this is Houston with a final update concerning the trusty LCRU on the lunar surface. We turned it on yesterday, and it worked beautifully for about 13 minutes. We w - we were panning around, zooming in and out, got a few more good pictures of the - the surrounding mountains, and suddenly we lost the TM [telemetry] downlink. In fact, we lost everything in a very short time, about 1/60th of a second, almost as though someone had turned it off. We tried - we waited awhile and tried to reactivate it, and did such things as send signals back to it to pan around, while we looked carefully on the passive seismometer for evidence of motion. Apparently it was not responding to the signals. The temperatures were completely normal right before it went off the air. We're not exactly sure what happened. Over.

[The LCRU (Lunar Communications Relay Unit) is a suitcase-sized box mounted on the Rover which integrated all the communications requirements of the crew on the surface into one package, being an interface between their VHF communications and the S-band links to Earth. It also handled the remote control function for the Rover's TV camera.]
262:17:59 Scott: Gee, that's interesting, Joe. It's - you sh - I guess it completely went off, and just didn't get hung up somewhere.

262:18:06 Allen: That's right, Dave. It wasn't a mechanical problem. We most likely popped a circuit breaker or something like that. It's a little difficult to sort out.

262:18:18 Scott: Would you like us to go back up and check it for you?

262:18:23 Allen: Knew you were going to ask. Stand - stand by. [Long pause.]

262:18:51 Scott: Joe, I'm - I'm in - I'm interested in hearing you say that the temperatures were normal. One of the things that - Of course, we'll debrief them on when we get back, but Jim and I both noticed that each successive day was warmer than the preceding day. And, on the last day, if you left your hand or something in one position for any period of time, it would really - the suit would really heat up on that particular surface. And I'm surprised that the system ran this long with that temperature up there, because I suspect it really got pretty hot.

262:19:30 Allen: Dave, that's interesting comment. By normal, I guess I mean within limits. It apparently was about 90 degrees [Fahrenheit] on the LCRU and about 90 de - 92 degrees on the camera when it gave up the ghost. However, that's well within its limits, and we don't think that circuit breakers, or whatever, let go because of the temperature. The one thing we did not have sensored, as I understand it, were the - the batt[ery] temperatures of the Rover that was - that was feeding the power into the TV, however.

262:20:11 Scott: Gee, 92 sounds pretty cool to us. I - I would have guessed much - much hotter than that. That's a pretty good thermal system on it, if it kept the temperatures down that low.

[Thermal blankets, solar radiators and the melt-freeze cycle of a number of wax packages on top of the LCRU were designed to keep the internal temperature stabilised.]
262:20:23 Allen: That's correct. [Pause.]

262:20:27 Scott: Or maybe [laughter] Jim mentioned maybe that's centigrade, huh?

262:20:36 Allen: Negative on the centigrade, Dave. However, when we turned the camera off at the end of EVA 3, the temperature was up around 122 degrees.

262:20:52 Scott: Yeah, I'd believe that, easily.

[Long comm break.]

[ As with all anomalies during a mission, the loss of the radio link with the Rover was extensively researched to try and determine its cause. The main clue to the problem was the rate of decay of the signal received on Earth from the LCRU as it died. While the crew was on the surface, the unit was powered from its own batteries. Before they left the Rover for the last time, the power was switched to the Rover's batteries via a capacitor so the lift-off could be watched from Earth and the progress of the lunar day and the changes in lighting could be monitored. In tests with a duplicate unit, the observed rate of decay could only be duplicated by disconnecting this external power supply.]

[Despite Allen's comment, suspicion does eventually fall on a 7.5-amp circuit breaker which, in tests, did open at high temperature when the heatsink effect of its connecting wire altered it characteristics. In subsequent missions a 10-amp breaker was substituted.]

262:26:02 Allen: Endeavour, this is Houston. The Surgeon reports that we have good respiratory data from your biomed volunteer, but we have evidence that one of the three EKG leads is open-circuited, either not attached or broken somewhere. And, sometime over the next few hours, we'd like - we'd like you to troubleshoot this for us, please; and, if need be, there is an extra biomed harness in the medicine kit. Over.

262:26:37 Scott: Roger. Okay. We'll check into that.

[Very long comm break.]

[As the crew finish their breakfast, the current period of X-ray data collection comes to an end. Al has a few tasks before the PTC roll is re-established and he proceeds with a realignment of the spacecraft's IMU (Inertial Measurement Unit) platform using program 52. For this realignment, Al sights on the stars Menkent (computer code 30) and Alphecca (code 43) to derive the torquing angles for the platform. As the spacecraft is stable and the HGA (High Gain Antenna) is in use, Mission Control can directly view these angles as Al brings them up on the DSKY. The platform is being realigned to the PTC REFSMMAT, an orientation that makes it easier for Al to set up the PTC roll.]

262:56:52 Allen: Endeavour, we have the angles.

262:56:58 Scott: Roger, Houston.

[Long comm break.]

[Flight Plan page 3-373.]

[Meanwhile, to keep the cabin atmosphere cleansed of exhaled carbon dioxide, the crew change a lithium hydroxide canister, number 20 in receptacle A, for a fresh one, number 22.]

263:05:39 Allen: Good Ship Endeavour, this is Houston. We'd like a crew status report at your convenience, please.

263:05:48 Irwin: Roger. Stand by.

[Comm break.]
263:08:27 Irwin: Okay, Joe, I have the crew status. We all got 8 hours sleep. PRD readings were: Al was 25031, and mine was 08042. Consumables at 261:00; RCS total, 38. Quads: 42, 32, 39 and 38. H2: 34, 32 and 33. O2: 49, 50 and 40. Over.

263:09:07 Allen: Okay, Jim. Thank you.

[As Jim will report the next day, at 287:56:16, Dave's PRD is out of business.]

[Very long comm break.]

Public Affairs Officer - "This is Apollo Control at 263 hours, 25 minutes Ground Elapsed Time. Shift change underway here in the Control Center. Spacecraft now 127,788 nautical miles [236,663 km] inbound toward Earth at a velocity of 4,181 feet per second [1,274 metres per second]."
[Al's next task is to prepare the optical system for another set of cislunar navigation sightings as part of the their backup ability to navigate themselves to a successful splashdown in the Pacific Ocean tomorrow. Once the optics have been calibrated and the spacecraft maneuvered to the required attitude for the exercise, Al measures angles between three stars and Earth's horizon on the opposite side of Earth from the star using P23 in the computer. The three stars are Zeta Tauri, Alpha Tauri (Aldebaran) and Alpha Aurigae (Capella). The positional information derived from this fix combined with the time of the measurement and a knowledge of where their current state vector ought to place them allows the computer to update the state vector as required and thus allow the entry angle, or gamma, to be calculated.]
263:25:58 Worden: Houston, 15.

263:26:04 Henize: Go ahead, 15.

263:26:09 Worden: Roger. We've resensored the EKG and appreciate a checkout from the docs down there.

263:26:16 Henize: Roger. Stand by.

263:26:22 Worden: Good morning, Karl.

263:26:24 Henize: Good morning, Al. How are you doing?

263:26:29 Worden: Just fine.

263:26:32 Henize: Says the EKG looks good down here. Hold one.

263:26:38 Worden: Okay.

[Comm break.]
263:29:27 Henize: Al, your new CapCom is just coming up to speed this morning. I understand that there has been a problem with the biomed harness, and they want to know if the one you have on right now is the one that gave trouble shortly before.

263:29:41 Worden: That's affirmative. And I did find the loose one.

263:29:47 Henize: Okay; we're getting a good signal on you, and I guess that information makes everybody happy down here. Thank you.

263:29:55 Worden: Okay.

[Very long comm break.]

[Worden, from the 1971 Technical Debrief - [To Scott.]"I think both you and I got a reaction from the paste or whatever was used on the disk on the biomed sensors. Now, I've still got some welts, some lesions, that I got off those biomed sensors."]

[Scott, from the 1971 Technical Debrief - "I'm not sure it was the paste or just the pressure of the sensor being on that same spot on my skin."]

[Worden, from the 1971 Technical Debrief - "Well, that could be. I'm just wondering if maybe there isn't something that could be looked into to see if there's a different kind of adhesive or something that would alleviate that problem"]

[Slayton, from the 1971 Technical Debrief - "Did they test you for allergy to that paste preflight as they are supposed to?"]

[Scott, from the 1971 Technical Debrief - "Yes."]

[Worden, from the 1971 Technical Debrief - "Yes."]

[Scott, from the 1971 Technical Debrief - "We wore it all preflight."]

[Worden, from the 1971 Technical Debrief - "Maybe you're right, Dave"]

[Scott, from the 1971 Technical Debrief - "We tried to put them exactly in the same spot on launch morning. Dr. Teegan painted a circle on us where they had put those things. I redrew mine every once in a while, and it was very helpful. You just stuck them right where the mark was. And it was real easy to locate them there. But I think that doing it over and over sort of made you a little sensitive in that area. Al and I both have little rings there where the thing sort of cut in. But it was far better than wearing them all the time. I know that we could hardly wait to get ours off after we came up off the surface, because it was really getting irritable. I think it was very beneficial to be able to take those things off and let your skin dry out."]

[Woods - "After you've come back up from the surface, and they've asked Jim to wear his biomeds again and again, and you're wanting to give Jim a bit of a break because you don't realise there's a problem with Jim's heart rhythm. You talk about how they are really quite sore things to wear."]

[Scott - "Yeah, quite sore. That goes back to just having [them on] a long, long time. We got ready to go on 15 before the flight and we knew it was a twelve-day flight. We said, 'Can't wear sensors the whole time.' And the doctors said, 'Well, you have to because there's nobody up there to put them on.' We said, 'We can put them on.' They said, 'No you can't.' 'Yes, we can put them on.' They said, 'Well, it won't be in the right place.' We said, 'Oh, it'll be in the right place.' The doctors said, 'No, we're going to have to tattoo you to make sure you put them in the right place.' We said, 'No, you're not going to tattoo us. We'll put them in the right place. Just show us how to do it.' And they finally condescended and putting the sensors on was really no big deal. But some of the other guys came back. I remember, I think 12 came back and they had some real sores. Those things - just - I don't think it's because necessarily what's under them, it's just you cover up the skin, put a plaster on your hand, you cover up the skin for that long and it gets itchy and sore. So we said let's rotate and take them off. So that's what we did."]

Public Affairs Officer - "This is Apollo Control at 263 hours, 52 minutes. The crew is performing a series of cislunar navigation star sightings and Apollo 15 is 126,706 nautical miles [234,659 km] away from Earth. Velocity: 4,215 feet per second [1,285 metres per second]."

263:58:43 Henize: 15, this is Houston. We still have a concern about your OPS pressure and would appreciate it, if it's at all accessible, to have a reading at the present time.

[The OPS (Oxygen Purge System) package that Dave and Jim brought up from the lunar surface, and which Al used during his EVA as an emergency backup, contains a highly pressurised tank which Mission Control want to bleed into the cabin before re-entry.]
263:59:01 Worden: Okay; it's - it's pretty well buried right now, Karl. What's your concern on it?

263:59:07 Henize: Well, first of all, they're anxious that the OPS pressure be down close to zero at - at entry, and they'd like to figure out how much they're going to use tonight and how much tomorrow night in order to bring that down. I guess we don't have it tomorrow night. They're - they're anxious to know whether or not it's - we're going to be able to bring down it's pressure in using it tonight.

263:59:34 Worden: Okay. I guess it came down to 800 [psi, 5,500 kPa] from 2,000 [psi, 13,800 kPa] last night, but probably came back up. As soon as we get a chance to do some shuffling around here, why, we'll check it and give you a call.

263:59:46 Henize: Good enough. Thank you.

263:59:51 Worden: Rog. It's sort of down in the bottom of the pile right now; and we're getting ready to start reentry stowage, so we'll be able to - to get to it in a little while.

264:00:01 Henize: We understand.

[Comm break.]

[Flight Plan page 3-374.]

264:02:48 Henize: Al, the way people talk down here, they're going to give you a medal for good sightings up - up there. They say that the - the gamma [this is the re-entry angle] from this last series of sightings was 6.55 [degrees], whereas the value we have down here is 6.50.

264:03:09 Worden: Roger, Karl.

[Comm break.]

[Now that all the tasks requiring a stable spacecraft orientation are out of the way, Al can get the PTC roll going again. The first part of this is to maneuver the spacecraft to the PTC attitude, essentially broadside on to the Sun. To do this, he enters the three angles for required attitude, with respect the current platform orientation, into the three registers required for Verb 49, collectively called Noun 22. The first angle, for roll, is not defined so the current roll angle, called up by Noun 20, is used instead. The pitch and yaw angles are 90° and 0°, as defined in the Flight Plan. At this point, Al hits a problem.]

264:04:33 Worden: Houston, 15. You may have seen an - an excursion there as we started the Verb 49 maneuver to PTC, and we're trying to figure it out, too.
[The spacecraft has begin pitching down unexpectedly.]
264:04:43 Henize: We copy.

264:04:46 Voice in Mission Control: What was that?

[Comm break.]
264:05:49 Henize: 15, Houston. We didn't see any obvious glitches down here, but we're going to go back and look at the data.

264:05:58 Worden: Okay. What happened was, we were loading Noun 22 to the Verb 49; and, apparently on the - the last entry, on the third register, we got about a 1-degree-per-second pitchdown pitch rate, and went to SCS, and then back to ch - to CMC, and tried it again, and it worked just fine.

264:06:25 Henize: Roger. [Long pause.]

264:07:03 Worden: Houston, it looks like we might have got that old 22 degree glitch in the CDU.

264:07:16 Henize: We copy. [Long pause.]

264:08:15 Worden: And, Houston, right now, we're reading about: 93, 93 and 334 on the ball.

264:08:38 Henize: Roger. [Long pause.]

264:09:27 Henize: 15, this is Houston. We feel that we can get rid of that discrepancy if you'll do a Verb 40, Noun 20.

264:09:36 Scott: Okay, we'll do one of those. [Long pause.]

[Verb 40, Noun 20 translates as "Zero ICDU" and "Present ICDU angles"; essentially zeroing out any confusion in the ICDU.]

[The CDU (Coupling Data Unit) is an electronics box, in the lower equipment bay, right next to the CMC. There are two parts to it: The ICDU (Inertial CDU) and the OCDU (Optics CDU), The ICDU and OCDU seem to be quite independent systems, but share a common box simply because of their similar tasks. The CDU's inputs are the "resolvers" which are fitted on the gimbal pivots on the IMU (for the ICDU) and also on the shaft and trunnion axis of the optics systems (for the OCDU). The resolvers take angular data from the gimbals and sends pulsed signals to the CDU. One positive pulse, the CDU adds one increment to the gimbal angle; one negative pulse, it subtracts one increment to the gimbal. It is possible that these "pulses" are a nasty source of error if, for whatever reason, they get out of sync and we speculate that's what happened, and why the CDU's had to be zeroed out. The system will reset itself after the zeroing is completed.]

[Now, we might think that zeroing the CDU's would be done only in unusual cases. Interestingly, the "Zero Optics" switch on the sextant/telescope panel not only moves the optics to the zero shaft/trunnion position, it also sends a "zero OCDU" command to make sure that the OCDU is truly reset.]

264:10:13 Scott: Yep. Looks like that's what it was. [Long pause.]

264:11:18 Henize: Dave, we suspect the cause of that glitch back there was probably due to the fact that you might have loaded a Noun 20 instead of the Noun 22. Is that possible?

[One possibility is that since Noun 20 forms part of Noun 22, the two have been mixed up in some way.]
264:11:35 Scott: We're thinking. Stand by. [Long pause.]

264:12:17 Scott: Karl, I guess it's a possibility, but we were both looking at it, and I guess we don't think so, but that's a distinct possibility. [Long pause.]

264:12:52 Henize: 15, Houston. About all we can say is that everything's looking fine at the moment, and we'll go back and look over the data. We haven't had a chance to do that yet.

264:13:01 Scott: Okay. Yes. Roger. Understand. It - it looks fine up here and that - that could have been the problem.

[Comm break.]

[Once the spacecraft has been properly maneuvered, Al can continue with the PTC roll which requires him to use P20, the tracking program.]

264:14:19 Scott: Houston, 15. Talking it over, I guess that must have been a - a Noun 20 load because, I guess as I remember it, the CDU glitches occur in increments of 11. And 11 plus 11 doesn't equal 26, I don't think.

264:15:06 Henize: Okay; we copy.

[Comm break.]
264:16:11 Scott: And, Houston, in our present attitude, a yaw CDU change would be converted to a pitch rate, so that sort of all adds up.

264:16:22 Henize: Very good.

[Comm break.]
264:18:04 Henize: 15, Houston. When you have some time to listen, I have a couple of sentences of comments on the procedure for the - the light flash experiment.
[The crew's third light flash experiment continues their probing into the properties of the visual flashes seen by many crewmembers and thought to be due to high energy cosmic rays interacting with their visual system.]
264:18:17 Scott: Okay. Why don't you stand by 'til we get our trusty crew all lined up and ready to go.

264:18:23 Henize: Very good. [Long pause.]

264:18:44 Henize: Incidentally, Dave, as we line them up, one of the changes is that we'd like to keep the cabin lights bright this time.

264:18:53 Scott: Oh, you like the lights bright? Okay.

[During the first light flash experiment, it seems the cabin lights were dimmed though the crew wore eyeshades to help them become dark-adapted. This change to the procedure is intended to check whether dark-adaptation affects the visibility of the flashes, perhaps indicating whether they are caused by stimulus of the retina or of the brain's visual cortex. As Karl Henize is about to explain, one of the crew will expose their eyes to the cabin lights for one minute in the middle of the test to see if the count is affected.]

[Comm break.]

264:21:04 Henize: 15, Houston. We see indications that the optics aren't zeroed, and we'd recommend that you zero them, with the reminder, of course, to bring the angles down to 10 degrees - less than 10 degrees before you zero them.
[On the third day of the flight, ground controllers noticed that when the optics were motor driven to their zero position, a slight bias was being introduced into their reading. The message went up for the crew to bring the trunnion angle (similar to the tilt axis of a camera tripod) to less than 10° prior to zeroing them.]
264:21:18 Scott: Okay; that's - that's standard procedure. We'll get it. Thank you. It's even been written up on the panel for about 8 days now, or so.

264:21:32 Henize: Very good.

[Long comm break.]
264:26:11 Scott: Okay, Houston. Go ahead with your procedures on the light flash.

264:26:15 Henize: Roger. We'd like to have you put the window shades on, as usual, but leave the cabin lights bright. And what we're going to do is to sort of calibrate one crewman in terms of the degree of a dark adaption required to see the flashes. That would be interesting to know. After you don the eyeshades and give us a mark and go ahead and count things, after a while, you - one of you - and we prefer you, Dave, just to be specific - can expect for us to call up to you to take off the eyeshade for 1 minute. And after a minute we'll do the timing for you, if you like. We'll tell you to put it back on and, in this minute time look around at the lights, get back to sort of - your eyes normally adjusted, then put on the eyeshade again, and - and give us marks as you start seeing things. And that's - that's the only difference from the normal procedure. We would - we would prefer to have all - all the data on the voice downlink, if possible.

264:27:25 Scott: Okay. Understand the - open the eyes, and - Stand by one. [Pause.]

264:27:40 Scott: And, Houston, we talked over the - the downlink bit, and it's just impractical if we're all going to try and keep up with the comments on where and what we see. It would just be too confusing for you. And I think - if - if you cannot get your data from the tape, we'll do that; but, I think it is much more practical to go ahead and put it on the tape and just inform you of when we get the marks.

264:28:05 Henize: Okay, we've had - we've had - we've had some trouble with the tape in the last couple of times around, is the reason the people are sort of saying "Hey, if we could possibly get it down in real time we'd feel happier."

264:28:24 Scott: Oh, you - you mean you - you cannot get the data off the tape, huh?

264:28:43 Henize: I guess we've been having trouble with voice quality on the DSE [Data Storage Equipment], and Gerry just now says, "Hey, let's check it right now. See how it's doing." And we'll let you know in the next few minutes as to what's pref - preferable.

264:28:58 Scott: Okay. That's a good idea. [Long pause.]

264:29:57 Henize: 15, this is Houston. It looks as though the DSE voice downlink is acceptable, now; and we'll do it your way.

264:30:11 Scott: Okay. Let us get squared away here and make sure we get all the shades up and all. [Long pause.]

264:30:42 Henize: 15, one more comment on that DSE voice problem. This is, to some extent, dependent on how well your mikes are adjusted. So make sure that they're in a good position.

264:30:54 Scott: Rog. I guess a downlink would probably be the same problem. We'll get them all squared away.

[Comm break.]

[ Similar to a simple tape recorder, the DSE stores data and voice on narrow parallel tracks without using the helical scan techniques seen in later tape machines. The machine onboard Endeavour has a much higher data packing density than the models used on previous missions, to cope with the upgraded J-mission spacecraft and the data coming from the SIM bay, and it has to work for longer. Over the past day, Mission Control have been having some problems with its first few feet of tape which have been contaminated with flaking silver oxide from the leader tape. Tiny scratches on the recording heads, much higher data densities and a longer mission duration are taking their toll on the recorder's efficiency. This problem, though, might not be directly linked with the quality of the voice track.]

264:32:19 Scott: Houston, 15.

264:32:21 Henize: Go ahead, 15.

264:32:25 Scott: How do the rates look for PTC now?

264:32:28 Henize: Just got the word that they look good for spin-up.

264:32:33 Scott: Okay.

264:32:37 Henize: I think that's another great example of ESP at work.

[The previous Apollo mission, Apollo 14, gained notoriety in the news media when it was revealed that Ed Mitchell, the Lunar Module Pilot, had independently carried out experiments in ESP (Extra Sensory Perception) during the flight. Though a deeply serious and intellectual man, Mitchell's foray into the fringes of accepted science seemed out of place in the hard science and engineering realm of America's most prestigious agency and, to some extent, was a source of some mirth among his colleagues, therefore the humour from Henize. Joe Allen made a couple of similar quips while Dave and Jim were on the Moon.]

[Comm break.]

Public Affairs Officer - "This is Apollo Control; 264 hours, 34 minutes. Apollo 15 now establishing a 3/10th's per second rotation, 3/10ths of a degree per second rotation, for Passive Thermal Control. Shortly, the crew will begin the light flash experiments again. The marks on this experiment will be put on the onboard tape recorder. It will not be on the air to ground."

264:35:28 Worden: Okay, Houston; 15. We're experimenting [for light flashes].

264:35:37 Henize: Roger.

[Very long comm break.]

[The crew are somewhat surprised to find that they are not seeing any flashes and discuss their attitude relative to possible sources, especially the Sun.]

264:37:17 Worden (onboard): It's a quiet morning.

264:37:19 Scott (onboard): Say again?

264:37:20 Worden (onboard): It's a quiet morning.

264:37:21 Scott (onboard): Yes.

264:38:47 Worden (onboard): Maybe that means that they come from the Sun. Huh?

264:38:51 Scott (onboard): Hmm.

264:38:57 Worden (onboard): Very interesting. Or that the window shield's cutting them off.

264:39:02 Scott (onboard): No, we had the window shields up before.

264:39:04 Worden (onboard): Did we?

264:39:05 Scott (onboard): Yes.

264:39:06 Worden (onboard): Um hum.

264:39:07 Scott (onboard): Because we had them - the cockpit all dark.

264:39:08 Worden (onboard): Be dark. Yes.

264:39:09 Scott (onboard): Yes, that's right. We did. The only difference now is that the Sun's behind...

264:39:13 Worden (onboard): We're not - we're not pointed at the Sun - Yes. And the Moon's behind us. Some place behind the Sun. Isn't it?

264:39:23 Scott (onboard): No. No, nobody's behind the Sun to us.

264:39:27 Worden (onboard): Hey, we - You know, we're not shielded - we're not - Gee, I don't know.

264:39:44 Worden (onboard): We may not be in orientation in PTC to be looking at the Sun either. Well, that shouldn't make any difference yet. Were we in PTC when we did it before?

264:39:59 Scott (onboard): ...

264:40:00 Worden (onboard): Huh?

264:40:02 Scott (onboard): I think so. Because I remember thinking, "How are they going to figure the attitude?" They'd have to get it off the - the data.

264:40:11 Worden (onboard): Yes.

264:40:19 Scott (onboard): Yes, I see. The - the Sun - will soon be behind the Earth, right?

264:40:25 Worden (onboard): Yes, should be.

264:40:27 Scott (onboard): So, if the Sun is close to being behind the Earth right now, maybe the Earth will shield it.

264:40:32 Worden (onboard): Oh, you mean warpage in the pausal tail?

264:40:37 Scott (onboard): Yes.

264:40:38 Worden (onboard): That could be. It comes out in a - in a pinwheel fashion.

264:40:56 Worden (onboard): Although I saw some last night when I went to sleep.

264:41:00 Scott (onboard): Yes, I did, too.

264:41:01 Irwin (onboard): Yes.

264:41:09 Scott (onboard): That's good, Jim. Is that an hour? (Laughter)

264:41:14 Worden (onboard): (Laughter) Change the sheet.

264:41:15 Scott (onboard): Wake up, Jim (laughter).

264:41:16 Worden (onboard): (Laughter) ... Houston (laughter). You're ...

264:41:22 Scott (onboard): ...

264:41:23 Worden (onboard): ...for minutes.

264:41:24 Scott (onboard): All you got to do is repeat that 10 times now, Jim.

264:41:36 Irwin (onboard): Boy, that was fast.

264:46:04 Scott (onboard): Maybe we've been desensitized to them.

264:46:06 Worden (onboard): (Laughter)

Public Affairs Officer - "Distance is 124,934 nautical miles [231,377 km]. Velocity; 4,272 feet per second [1,302 metres/second]."

264:46:19 Scott: Houston, 15. We're still here; it just looks like a quiet morning.

264:46:24 Henize: Roger. Glad to know that you're still awake. Keep on looking for the cosmic rays.

264:46:33 Scott: Looking as hard as we can.

[Long comm break.]
264:52:23 Scott (onboard): Absolutely nothing. Very amazing.

264:52:28 Worden (onboard): Yes.

[Finally, nearly 20 minutes into the experiment, Dave sees a flash.]
264:52:44 Scott: Mark CDR.
[Long comm break.]
264:52:45 Scott (onboard): Yes, down on the left eye at about 7 o'clock; intensity about 2. Point source of light.

264:52:57 Worden (onboard): I guess we can get ready then. They're starting to come.

[Flight Plan page 3-375.]
265:01:33 Irwin: Mark LMP.
[Comm break.]
265:01:34 Irwin (onboard): Flash at 8 o'clock on the periphery; intensity 2.

265:04:02 Scott: Mark CDR. [Long pause.]

265:04:01 Scott (onboard): It was in the left eye at 6 o'clock at about a third of the way from the center out; intensity 3; point source of light.

265:04:23 Worden (onboard): You two guys must be shielding me.

265:04:27 Scott: Mark CDR.

[Comm break.]

[Al is beginning to wonder whether the other two are shielding him from whatever is producing the flashes and starts some gentle banter with Dave by suggesting that his Commander is making up the results.]

265:04:28 Scott (onboard): It was in the left eye about 2 o'clock; a quarter of the way in; intensity 1; point source. Yes, we're taking it all for you, Al.

265:04:41 Worden (onboard): You must be.

265:04:42 Irwin (onboard): I think Dave's imagining all these.

265:04:45 Scott (onboard): Got to do something for the ...

265:04:46 Worden (onboard): ... he's gotten to the point where he's conjuring them up on me.

265:04:51 Scott (onboard): Dedicating my imagination to science.

265:04:53 Worden (onboard): Right. Protecting all those who go after you.

265:04:59 Scott (onboard): Wait until you see how many I'm going to see in the last minute (laughter).

265:05:04 Worden (onboard): Confound that curve.

[Then, after half an hour, Al sees what he has been waiting for.]
265:05:49 Worden: Mark CMP.
[Comm break.]
265:05:47 Worden (onboard): Mark CMP.

265:05:48 Scott (onboard): Yay!

265:05:49 Worden (onboard): Left eye; dead center; intensity 2; point source. Only ones I can see are the ones that hit me right between the eyes like a ...

265:08:02 Worden: Mark CMP.

[Comm break.]
265:08:03 Worden (onboard): Right eye; about 1 o'clock; 2/3rds of the way out; intensity 2; and a little streaking - some towards the center of the eye - about another third of the way down.

265:09:03 Irwin (onboard): Do you have your eyelids closed?

265:09:06 Worden: Mark CMP.

[Comm break.]
265:09:07 Worden (onboard): Two flashes: one at 9 o'clock in the left eye and one at 6 o'clock in the left eye; both intensity 3. Yes, my eyes are closed, Jim.

265:09:17 Irwin (onboard): Your eyelids are closed.

265:09:18 Scott (onboard): Yes. Me, too.

265:09:24 Worden (onboard): Your eyelids aren't going to stop anything.

265:09:27 Irwin (onboard): Don't think so. Just want to get consistent data.

Public Affairs Officer - "This is Apollo Control at 265 hours, 10 minutes. The Apollo 15 crew has about another 10 minutes left in the light-flash experiment. They're recording this data on the onboard tape recorder. Although obviously every once in a while the Command Module pilot keys the air to ground when he takes a mark; you can hear that. Apollo 15 now 123,490 nautical miles from Earth. Velocity: 4,320 feet per second. We're 30 hours away from landing."

[In fact, the crew are keying their mike on every count, then allowing their description of it to be recorded on the DSE. On the next mark, Jim keeps his mike keyed.]
265:10:34 Irwin: Mark LMP. Flash. One at 4 o'clock, halfway out. Another one at 2 o'clock on the periphery. Intensity 3. [Long pause.]

265:11:18 Worden: Mark CMP. [Long pause.]

265:11:19 Worden (onboard): Two o'clock; almost on the periphery; and intensity between 3 and 4. Bright one.

265:11:53 Worden: Mark CMP.

[Comm break.]
265:11:54 Worden (onboard): Two o'clock; streak from right to left; centered about the 2 o'clock radial; about halfway out; intensity 2.

265:13:53 Irwin: Mark LMP.

265:13:51 Irwin (onboard): It was a streak; right eye; moving from the top down toward the bottom, intensity 4.

[The crew discuss among themselves whether the paucity of marks might be due to them becoming adapted to their environment.]

[Long comm break.]

265:19:50 Scott (onboard): Maybe we get adapted to it.

265:19:52 Worden (onboard): Hmm! I suppose so.

265:19:55 Scott (onboard): You build up an immunity.

265:19:56 Worden (onboard): Mm-hmm.

265:19:57 Scott (onboard): Or maybe it's destroyed so many brain cells we don't have any ... left for it.

265:20:00 Worden (onboard): You know, that's right. Maybe that's it. Mmm. Our sensitivity is so dulled...

265:20:05 Scott (onboard): Yes.

265:20:06 Worden (onboard): ...that we just don't see them anymore.

265:20:07 Scott (onboard): A lot of people would probably agree with that.

265:20:09 Worden (onboard): Yes (laughter).

265:20:10 Irwin (onboard): Mmm-hmm.

265:20:12 Scott (onboard): That's why we're doing them to begin with. Because people are worried about that, I guess.

265:20:19 Irwin (onboard): Well, I wonder if we're the same distance on the trajectory as we were when we did it on the way out?

265:20:24 Scott (onboard): (Yawn) I don't know.

265:20:25 Irwin (onboard): Is that the idea - to be in the same spatial relation? Yes, we could look...

265:20:30 Worden: Mark CMP. [Long pause.]

265:20:29 Worden (onboard): Right eye; dead center; point source; intensity B.

265:20:38 Irwin (onboard): We could look at the Flight Plan when we get through. The distances are in there.

265:20:44 Worden (onboard): Mm-hmm. Yes. We could always figure it out.

265:21:11 Irwin: Mark LMP. [Long pause.]

265:21:13 Irwin (onboard): It was a streak; left eye; top to bottom; intensity 2; it was right at the periphery.

265:22:04 Irwin: Mark LMP. [Long pause.]

265:22:05 Irwin (onboard): Again it was a streak; it was - appeared to be in both eyes; moving from 1 o'clock toward the center; intensity 3.

265:22:28 Irwin: Mark LMP. [Long pause.]

265:22:27 Irwin (onboard): A flash; 2 o'clock; periphery; intensity 2.

265:23:29 Worden: Mark CMP.

[Comm break.]
265:23:30 Worden (onboard): Right eye; 11 o'clock; about halfway out; point source; intensity 3.

265:26:08 Worden: Mark CMP.

[Comm break.]
265:26:09 Worden (onboard): Left eye; about 10 o'clock, 2/3rds of the way out; point source; intensity 3.

265:28:50 Irwin: Mark LMP. [Pause.]

265:28:51 Irwin (onboard): Flash; position 2 on the periphery; right eye; intensity 2.

265:29:00 Irwin: Mark LMP. [Long pause.]

265:28:58 Irwin (onboard): Same position; intensity 4; flash.

[At this point the recording on the DSE stops.]
265:29:54 Henize: 15, Houston. Be advised the DSE just ran out tape. If there's anything significant to be said from here on in, say it on the air to ground, please.

265:30:04 Scott: Okay. Will do.

[Comm break.]
265:31:19 Irwin: Mark LMP. Flash. Four o'clock, about a quarter of the way out. Intensity 3. [Long pause.]

265:31:48 Scott: Mark CDR. Right eye; a streak about 3 o'clock to 6 o'clock. Intensity 2. [Long pause.]

265:32:31 Scott: Mark CDR. Point source; right eye, 12 o'clock, halfway out. Intensity 2. [Long pause.]

265:33:31 Scott: Mark CDR. Right eye; point source; 7 o'clock about half way out; intensity 2.

[Comm break.]

[One hour assigned to the experiment passes at 265:35:28. Readers might note that one of the crew does not appear to have exposed their eyes to the cabin lighting in the middle of the experiment as was requested at the start of the experiment.]

265:36:48 Henize: 15, this is Houston. We find an hour's passed now, and we thank you very much for the data, and there's a general question. Since the counting rate was less than previously, is there - is there any impression that you have that the intensity may have been less than previously. Also, the intensity of the individual flashes.

265:37:13 Scott: Roger. I think that'd be a general comment that all three of us experienced. [Long pause.]

265:37:35 Scott: And, Houston, also, you might note that we all saw flashes last night when we went to sleep - just before we went to sleep, and I guess - we feel like there's a surprising decrease in number and intensity today.

265:37:53 Henize: Roger. We copy that you feel today's frequency is less than last night's and also that the intensity is less today.

265:38:09 Scott: Roger. That's correct.

265:38:17 Henize: Thank you very much for the free information.

265:38:24 Scott: Okay.

[Comm break.]

[The crew is scheduled to begin a 1-hour exercise period followed by a 1-hour mealbreak.]

265:40:46 Scott: Houston, this is 15.

265:40:49 Henize: Go ahead, 15.

265:40:53 Scott: Looking back at 264:16, there's a callout there to close the Mapping Camera cover. We did not do that because [of] the extension of the Mapping Camera.

265:41:16 Henize: Roger. We concur with you that that was the right action; the one that you took.

265:41:27 Scott: Okay.

[Very long comm break.]
265:55:36 Henize: 15, this is Houston. We'd like to set your mind at ease about that attitude glitch [at 264:04:33]. It was indeed due to loading a Noun 20 in place of a Noun 22.

265:55:48 Scott: Okay. Thank you.

[Long comm break.]
Public Affairs Officer - "This is Apollo Control at 265 hours, 57 minutes. Apollo 15 now 121,548 nautical miles [225,106 km] from Earth. Velocity has increased to 4,385 feet per second [1,337 m/s]."
[Flight Plan page 3-376.]
266:04:13 Scott: Houston, Apollo 15. The OPS pressure is 1,000 [psi, 6,900 kPa].

266:04:18 Henize: Roger, 15. We copy 1,000 on the OPS pressure. And we have a suggestion down here that may make the OPS - simpler to handle. We'd like to put the hose over its connector there and simply turn the OPS on to bleed down gradually and simply replenish the cabin pressure and then you don't have to bother with you - operating it tonight.

266:04:48 Scott: Roger. That's sounds like a pretty good idea. Okay; we'll do that.

266:04:51 Henize: Roger. And then everybody will be completely satisfied that it's bled out by the time you reenter.

[Very long comm break.]
Public Affairs Officer - "This is Apollo Control at 266 hours, 17 minutes; and at 28 hours, 54 minutes away from landing. Apollo 15 is 119,694 nautical miles [221,673 km] from Earth. Velocity: 4,413 feet per second [1,345 m/s]."

Public Affairs Officer - "This is Apollo Control at 266 hours, 50 minutes. Apollo 15 will reach the halfway point, in distance, from the Moon to the Earth at 271 hours, 30 minutes, 34 seconds Elapsed Time. At that time the distance will be 106,662.7 nautical miles [197,538.9 km]. Earth referenced velocity will be 4,920 feet per second [1,500 m/s]. The Moon reference to velocity: 4,077 feet per second [1,243 m/s]. At this time Apollo 15 is 119,243 nautical miles [220,838 km] from Earth, and the velocity is 4,462 feet per second [1,360 m/s]."

[Flight Plan page 3-377.]
267:08:33 Henize: 15, this is Houston with a couple of comments about the SIM bay experiments if you're willing to listen.

267:08:46 Scott: Roger Houston. Go ahead.

267:08:50 Henize: First of all, on the Gamma-ray experiment, Dr. Arnold reports that Al Worden probably performed the first recorded repair of a scientific instrument in space, because earlier in that day he'd begun to experience some problem with excess noise in the Gamma-ray experiment. And when Al went out in the EVA - we don't know what happened there - but at the end of the EVA, the Gamma-ray cleared up and has been doing beautifully ever since. You must have given it a pretty good kick there, Al.

267:09:29 Scott: Well, not - not only is he a plumber, he's an electrician as well.

267:09:32 Henize: Roger. On the X-ray Spectrometer, the work you've been doing on the galactic sources of x-radiation has - is already showing considerable interest. And, in particular, the Scorpius X-ray I data gives us a longer continuous observation of this source than we've ever had before and shows a fairly long period variation, whi - which - I with - I should put in a word of caution - which still might be instrumental, but looks real, and was previously unrecorded and has the - has Dr. Adler rather excited. And I'm sure the other as - astronomers will be much interested also. Indeed, we may go back to that source later today, although I don't think that's clearly decided yet.

[The Apollo 15 Preliminary Science Report reveals that these variations in the x-ray measurements from Scorpius X-1 might be due to wobbles in the spacecraft's attitude. As has been regularly discussed in this journal, the spacecraft can never adopt a precise attitude. Rather, it constantly tends to drift, being brought back within an acceptable range of attitude limits called the deadband. Outside of this deadband, the computer takes active measures using the RCS jets to bring the attitude back in.]

[Even though the deadband was 1° wide (±0.5°) during the measurement, this amount of variation in the pointing accuracy of the X-ray Spectrometer is enough to cause variations of up to 1.5%. However, superimposed on this were larger, long-term variations in the x-ray flux from Scorpius X-1 which were believed, at the time to be statistically significant.]

267:10:32 Scott: Rog. That sounds interesting.

267:10:34 Henize: And otherwise, I guess - that - that's about the most exciting news from the SIM bay.

267:10:46 Scott: Okay. Very good. We're ready to talk about entry stowage, if you'll get out your - your map and your little legend there...

267:10:55 Henize: Okay.

267:10:56 Scott: ...on where things go and we'll run down the line here.

267:10:59 Henize: Okay. We've - incidentally - one more comment, the Mass Spectrometer, on the retraction sequence yesterday, showed us no increase in contamination, which was something of a surprise. And it's probable that we might try that once more today to make sure that that wasn't some sort of instrumental difficulty there. Maybe we just have a cleaner spacecraft atmosphere than we thought, though.

267:11:25 Scott: Yes, from what Al said when he was looking around out there, it sounded to me like things were pretty clean.

267:11:30 Henize: Roger. [Long pause.]

[This conversation refers to an experiment carried out yesterday which tested the degree of gaseous contamination around the spacecraft. The Mass Spectrometer was operated on its boom at varying distances from the spacecraft and the science team hoped to characterise the gases at different distances from the hull. These contaminants could include oxygen leakage from the cabin, water and urine dumps, RCS propellant, water from the cooling evaporators.]
267:11:51 Henize: Okay, 15. If you will turn off your squelch it will help, because we may occasionally have periods in - when comm is rather weak. And, otherwise, go ahead.

267:12:04 Scott: Okay. What - what we use as a reference is the Entry Stowage Map, spacecraft 112, 26 July 1971, which is in the front of our Flight Plan. And, if you have that in front of you, why, I'll just go through that and give you the additions, deletions, and changes, of which there are very few.

[Endeavour is returning a substantial amount of cargo to Earth including 76.8 kilograms of rock. The placement of all this material within the cabin cannot be left to whim. Rather, it is important that the spacecraft's centre-of-gravity, and therefore the distribution of mass inside, be carefully controlled for its flying characteristics depend on it. Since the centre-of-gravity is displaced away from the physical centre, the spacecraft's shape provides it with a small, but important degree of lift as it re-enters the atmosphere. This will be used to fly the spacecraft to the landing site in the Pacific Ocean. Ground controllers will check the placing of items in the cabin to keep the position of the centre-of-gravity within limits.]
267:12:30 Henize: Okay. We're - Stand by one moment.

267:12:40 Scott: Okay. [Long pause.]

267:13:16 Henize: Okay. Go ahead.

267:13:23 Scott: Okay. A-1 is stowed as prescribed there. Top of A-1 has a bag - a decontam bag in which we have sample container number 2, for 23 pounds, and the LM return items.

267:13:50 Henize: Roger.

267:13:53 Scott: A-2 is as you have listed. [Long pause.]

267:14:10 Henize: Roger.

267:14:13 Scott: And, on top of A-2, we have the ISA decontam bag, for 64 pounds.

267:14:22 Henize: We copy.

267:14:27 Scott: Okay. A-3, A-4, A-5 and A-6 are as you have on your list right now.

267:14:33 Henize: We copy.

267:14:37 Scott: A-7 is as you have on your list, with the addition of the LM DAC and the LM - 70 millimeter camera that failed on the surface, which we thought you might like to take a look at.

[While at Hadley, the crew had two failures with their cameras. By returning both, engineers can determine the cause of the problems and rectify them before the next flight.]

[The DAC (Data Acquisition Camera) is a small 16-mm movie camera, one of which was taken to the lunar surface. Five of the eight magazines taken with it jammed in use. Post-flight analysis found that the problems were due to procedural errors and training was improved for subsequent flights.]

[Jim's 70-mm Hasselblad stills camera failed during their second and third lunar EVA, only to resume functioning once returned to the spacecraft. It was used successfully on the trip home. Post-flight analysis found that two set screws on the motor drive spindle were slipping and steps were taken to prevent this on subsequent cameras.]

267:14:51 Henize: Right. Both of those are - are added items, I take it.

267:14:56 Scott: That's correct. [Pause.]

267:15:04 Henize: We copy.

267:15:08 Scott: Side of A-7 is the EVA umbilical and bag, as per - prescribed.

267:15:13 Henize: Roger.

267:15:16 Scott: Top of A-7 is sample collection bag - Oh, stand by. [Long pause.]

267:15:39 Scott: Okay. Let me - let me go back and make a correction here, Karl. Look over in the left-hand column where it says top of A-1, and scratch "Sample collection bag number 2."

267:15:53 Henize: Okay.

267:15:56 Scott: And then go back to your right-hand column there. On top of A-7, we have decontam bag with sample collection bag number 2 and the BSLSS bag, for a total of 48 pounds.

267:16:16 Henize: We copy.

267:16:21 Scott: Okay.

267:16:19 Scott (onboard): The 35-millimeter bracket in the bag, we're going to put that in the...

267:16:24 Henize: Could I clarify that - both of those bags together were 48 pounds, or do I also put over the 20 - the 33 pounds we had on A-1?

267:16:26 Irwin (onboard): That's going to go in there.

267:16:35 Scott: No, the total of collection bag number 2 plus the BSLSS is 48 pounds.

267:16:40 Henize: I understand.

267:16:45 Scott: And you can scratch the collection bag number 2 for 23 off of A-1.

267:16:49 Henize: Roger. [Pause.]

267:16:58 Scott: Okay. And then in A-8, it's stowed as prescribed, with the exception of one less lightweight headset, which is some - somewhere on the Moon.

267:17:18 Henize: Roger.

267:17:24 Scott: Okay. On the side of the next page in the left column, on the side of A-8 in the bag, as you have there, with the addition of the core tube pole.

267:17:43 Henize: Say again.

267:17:48 Scott: Okay. I - I figured that would be a strange one. On the side of A-8 in bag, there are four items there, and one additional item has been added. The drill core-stem, which we just labelled as a core tube pole, because it looks like a pole.

267:18:05 Henize: Roger. That's the three-foot core stem.

267:18:09 Scott: That's correct.

267:18:15 Henize: Okay.

267:18:18 Scott: And A-9 is collection bag number 3, for 30 pounds.

267:18:27 Henize: We copy.

267:18:31 Scott: B-1, B-2 and B-3 are as you have them listed.

267:18:38 Henize: Okay.

267:18:41 Scott: B-5 is rock box number 1, for 36 pounds; and B-6 is rock box number 2, for 40 pounds.

267:18:51 Henize: Okay. We copy.

267:18:57 Scott: And then B-5 and 6, B-8, L-2 and L-3 are as you had them listed.

267:19:06 Henize: Okay.

267:19:11 Scott: And R-1 is the Flight Data File and LM PPK.

267:19:21 Henize: We copy.

267:19:26 Scott: And then, on the next column, they are all as you have listed. For the top R-2, R-3, and in R-3 we have the entire LM data file. And we've taken R-12 out of R-3 and put it in another spot.

267:19:47 Henize: Okay.

267:19:51 Scott: R - far - R-4 is as you have it, as is R-5, R-6, R-8, R-11, R-13.

267:20:02 Henize: We copy.

267:20:06 Scott: Okay. U-1 will only have one temporary stowage bag in it.

267:20:12 Henize: We copy.

267:20:16 Scott: U-2 will have the items listed, plus the accessory bag, in which we have - the contaminated gloves. And I'll read you a list of those items, if you are ready to copy.

267:20:29 Henize: Okay. Go ahead.

267:20:33 Scott: Have one set of EV gloves and one set of IV gloves, the tethers - the - the waist tethers, paper towels. And I guess that's about it.

267:20:47 Henize: Roger.

267:20:51 Scott: U-3, it's as you have prescribed there.

267:20:56 Henize: Roger.

267:21:02 Scott: Stand by one, Karl. [Long pause.]

267:21:46 Scott: Okay, Houston. Ready to go with the right-hand column. U-4 is as prescribed, and R-2 is as prescribed.

267:21:54 Henize: Roger.

267:21:59 Scott: Okay. The PGA bag is as prescribed with the following additions. First we have - in - in the bag where we'll put the lunar sample - we'll have R-12, with the CSM Malfunction Procedures and Systems Book.

267:22:26 Henize: We copy.

267:22:29 Scott: And the lunar sample is bag number 7, for 24 pounds.

267:22:40 Henize: Roger.

267:22:47 Scott: Okay. And then, everything else is as prescribed. And the CMP PGA will be in the sleep restraint under the right-hand couch with two TSBs, which are now acting as waste containers.

267:23:10 Henize: Roger. And that - that location was where again?

267:23:17 Scott: Underneath the right-hand couch, strap down as - as it's prescribed. We just wanted to note that, within that sleep restraint with the PGA, will also be two TSBs.

267:23:29 Henize: Roger. We copy.

267:23:34 Scott: And that's just light waste material in those TSBs. And I guess that pretty much takes care of it, unless you have any questions.

267:23:54 Henize: Thank you, Dave. We copy all of that.

267:23:59 Scott: Okay. And, as you go through it and look it over, if you have any questions or anything you would like us to shuffle around, why, let us know.

267:24:09 Henize: Okay. We sure will. Thanks.

[Prior to making another set of P23 navigation sightings, Al will realign the IMU to the PTC REFSMMAT. For this he sights on Polaris (code 05 in the computer), also known as the North Star and as Alpha Ursae Minoris, and Aldebaran (code 11) or Alpha Tauri. As the spacecraft's systems' are being relayed to Earth by the High Gain Antenna (HGA), Mission Control note the three platform torquing angles as Al brings them up on the DSKY.]

[Very long comm break.]

267:25:44 Irwin (onboard): ...to have some wet packs. I think I'll finish what I have, and then I still - Yes, I'll hit the wet packs.

267:25:49 Scott (onboard): You got 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 wet packs. Hey, we're in...

267:25:59 Worden (onboard): That's enough to keep us alive.

267:26:01 Scott (onboard): Oh, yes.

267:26:02 Worden (onboard): Do we have - How many deals do we have to mark? Two?

267:26:05 Scott (onboard): Just two. Let me stick that in there, too.

267:26:08 Worden (onboard): Great. I think, Just to clean this place out a little bit, I'm going to take some of these bacon squares and throw them.

267:26:23 Scott (onboard): Yes (laughter). It's probably a good idea.

267:26:46 Worden (onboard): As a matter of fact, we could consolidate a lot of this stuff.

267:26:48 Scott (onboard): Yes.

267:26:50 Worden (onboard): We could use these bags for garbage bags.

267:26:53 Scott (onboard): Yes.

267:27:00 Irwin (onboard): You dropped yours.

267:27:06 Scott (onboard): God damn! Dropped it on the floor. Lord a'mighty.

267:27:32 Scott (onboard): Get what you want?

267:27:35 Worden (onboard): Yes.

267:27:41 Irwin (onboard): Oh, a little spaghetti. I had some for breakfast; it wasn't bad. A vast spectrum.

267:27:54 Scott (onboard): Two meals tomorrow, breakfast, and two more meals today...

267:28:05 Irwin (onboard): One - two - Uh-oh, we'll have to eat - to eat fast, to eat it all up.

267:28:13 Worden (onboard): No, I don't think so (laughter). I think we're going to be there.

267:98 17 Scott (onboard): Do you guys think...

267:28:18 Worden (onboard): We've got 10 wet packs.

267:28:19 Scott (onboard): Ten wet packs, huh?

267:28:22 Worden (onboard): Yes, one for lunch, one for dinner, and - one for tomorrow.

267:28:50 Scott (onboard): Want a wet pack, Jimmy?

267:28:52 Irwin (onboard): Yes, I'll probably take one as long as you got them out.

267:28:54 Scott (onboard): Anybody tried the beef stew?

267:28:55 Irwin (onboard): Yes, I have a beef stew here.

267:28:57 Scott (onboard): Mine was pretty good.

267:28:58 Scott (onboard): I'll try one.

267:28:59 Scott (onboard): You want to try one?

267:29:00 Worden (onboard): Yes.

267:29:03 Scott (onboard): Pretty interesting.

267:29:06 Worden (onboard): Have a wet pack.

267:29:10 Scott (onboard): Okay.

267:29:14 Worden (onboard): ... get the drinks out here.

267:29:18 Scott (onboard): And right now you got a P52.

267:29:21 Worden (onboard): Oh, really.

267:29:22 Scott (onboard): Just to stir you up a little bit.

267:29:25 Worden (onboard): Okay. Here's the beverage.

267:29:27 Irwin (onboard): Okay. What kind of beverage do you want here, Dave?

267:29:33 Scott (onboard): I can't take anything but water, grape, and cocoa. I'm through with that other stuff. Somebody ought to...

267:29:37 Irwin (onboard): There's one grape left.

267:29:38 Scott (onboard): Well, you can have it.

267:29:39 Irwin (onboard): Getting lucky.

267:29:40 Scott (onboard): I don't care. I'll just drink water.

267:29:41 Irwin (onboard): Oh, I - I'd like the grape, too.

267:29:43 Scott (onboard): I can't take anymore. I've had 21 days of those juices, and that's all I can handle.

267:29:51 Irwin (onboard): Yes. I'm with you, pal. I feel that way about a lot of this stuff. Well, what do you want to drink, Al? Did you get your drink?

267:29:59 Worden (onboard): No, not yet.

267:BO 00 Irwin (onboard): Do you want an orange?

267:30:02 Worden (onboard): Yes, I don't guess there's any pineapple left, is there?

267:30:05 Irwin (onboard): There's a pineapple-orange.

267:30:07 Scott (onboard): Is there a pineapple-orange in there?

267:30:08 Irwin (onboard): Yes.

267:30:09 Worden (onboard): Yes, that's what I'd like.

267:30:17 Irwin (onboard): No, I take that back. There's an orange-grapefruit. There's no - no pineapple. What's your choice?

267:30:24 Worden (onboard): Oh, I'll have an orange.

267:30:25 Irwin (onboard): Okay.

267:30:48 Scott (onboard): Is that P52 due now?

267:30:50 Worden (onboard): Yes.

267:30:51 Scott (onboard): Okay. Jim, put these back.

Public Affairs Officer - "This is Apollo Control at 267 hours, 35 minutes. Apollo 15 is 117,343 nautical miles [217,319 km] away from Earth. Velocity: 4,528 feet per second [1,380 m/s]. All systems performing normally, and the back up Command Module Pilot Vance Brand has joined CapCom Karl Henize."

267:35:44 Henize: 15, we have your torquing angles.

267:35:54 Scott: Ro - Roger.

[Very long comm break.]

[Al stops the PTC rotation and maneuvers Endeavour to an attitude, given in the Flight Plan, from which he can calibrate the spacecraft's optics prior to another period of cislunar navigation. This is the first in a series of tasks, including photography of the Earth and of an upcoming lunar eclipse, which will have the spacecraft being maneuvered to various attitudes. For the P23 sightings, angles are given in the Flight Plan to point the HGA at Earth.]

[Al's three sightings for the cislunar navigation are to measure the angles between the following: Elnath (Beta Tauri) and Earth's horizon furthest from the star, Capella (Alpha Aurigae) and Earth's horizon furthest from the star, Alphard (Alpha Hydrae) and Earth's horizon nearest the star. Note that at this point of the flight, Endeavour is poised almost equidistant from the Moon and Earth while, in a couple of hours, Earth's shadow will sweep over the Moon.]

diagram showing the current geometry of the spacecraft with respect to the Earth and Moon, prior to the eclipse.

[This diagram, though simplified and not to scale, shows the current geometry of the spacecraft with respect to the Earth and Moon. The two planets are almost in line with the Sun, but by virtue of the motion of Moon in its orbit (upwards on the diagram) and the direction of Endeavour's initial motion away from the Moon at Trans-Earth Injection (downwards on the diagram), the crew are well to one side of the Earth/Moon line and see Earth as a thin crescent.]

Crescent Earth displayed along with the nearly full Moon, as would be seen from the spacecraft.

[These two images are reproduced from the Flight Plan at around this time (page 3-377 and 3-379). The crescent Earth is displayed along with the nearly full Moon. Al must take his P23 marks on the outside edge of the Earth's crescent, finding the point within it's hazy atmosphere where he believes the solid edge of the planet begins, a skill he has practised in a simulator at MIT and during the early stages of the flight.]

267:53:48 Henize: 15, this is Houston. The next several attitudes are going to require us to use Omni Delta, and we suggest that you go Manual and Wide and stow the High Gain Antenna.

267:54:03 Worden: Okay. We'll do that and go to Omni Delta.

[Flight Plan page 3-379.]

[Once the P23s are out of the way, the UV photos of the Earth are their next task. The procedures detailed on page 3-378 of the Flight Plan call for omni-directional antenna D for this. The instructions for subsequent tasks do give HGA angles relevant to the attitudes used for those tasks so it is unclear at the time of writing why the HGA is being folded away.]

[Very long comm break.]

268:13:49 Henize: Apollo 15, this is Houston. We'd like to have you retract the Mass Spectrometer boom for 85 seconds.

268:14:00 Worden: Understand. Retract the Mass Spec. Boom for 85 seconds.

268:14:08 Irwin (onboard): Yes, I will. Soon as I get the door closed here.

268:14:10 Worden (onboard): Roger. Get you then.

268:14:11 Henize: That's affirm, and then we'll leave it there for about 5 minutes. We'll cue you when to extend it again.

268:14:18 Worden: Okay.

[Long comm break.]
268:14:19 Irwin (onboard): Okay, retracting now.

268:15:47 Irwin (onboard): ...

268:15:50 Scott (onboard): Huh?

268:15:52 Irwin (onboard): Screwed up.

268:16:36 Worden (onboard): Your stuff.

268:17:07 Irwin (onboard): This the way it goes in?

268:17:08 Scott (onboard): Yes, it's getting a little tricky. Ought to get that thing in there, though.

268:17:12 Irwin (onboard): Does it go in all the way?

268:17:13 Scott (onboard): Yes, put it in.

268:17:16 Worden (onboard): Yes.

268:17:22 Scott (onboard): ...

268:17:28 Irwin (onboard): That's funny. Looks like it fits in there pretty well. Oh, what's in - Okay. You're going to put the camera on anyway.

268:18:11 Scott (onboard): Got ... we can start.

268:18:13 Irwin (onboard): Yes.

268:18:15 Scott (onboard): Okay.

268:18:17 Worden (onboard): Okay, we're starting. Noun 35. Starting now.

268:18:50 Scott (onboard): Guess we might as well maneuver, huh?

268:18:54 Irwin (onboard): I don't know. Why do you want to go early?

268:18:57 Scott (onboard): Why not? There's nothing in - the Flight Plan ... Nothing in here ... that I can see.

268:19:08 Irwin (onboard): Well, how about - explain this.

268:19:12 Scott (onboard): Gamma-ray gain. Got to be there by...

268:19:17 Irwin (onboard): Not until 50 - 30 minutes from now.

268:19:37 Scott (onboard): Yes, that's right.

[The boom carrying the Mass Spectrometer has been fully extended since yesterday.]
Public Affairs Officer - "This is Apollo Contral at 268 hours, 20 minutes. Apollo 15 is 115,361 nautical miles [213,648 km] from Earth. Velocity: 4,598 feet per second [1,401 m/s]. We're 26 hours, 50 minutes from landing."

268:20:04 Irwin (onboard): I guess we're going to dim the lights and do all this on time. Rather sit for - we can get a flashlight out.

268:20:14 Scott (onboard): ...

268:20:18 Irwin (onboard): Well, we'll see. One minute. Let's see. I don't know why - cabin lights are not going to affect it anyway with that cover over it.

268:20:28 Scott (onboard): ...

268:20:40 Irwin (onboard): Says we're supposed to use the PCM cable. How can we shoot - that PCM cable for the 250? The EL? It won't reach this window, will it? And we'll have the Nikon in the other window.

268:20:55 Scott (onboard): Didn't we have that this morning?

268:20:57 Irwin (onboard): Well, it's ruined the other things, Dave. That's for the sextant photos.

268:21:22 SC (onboard): (Sneeze)

268:21:36 Irwin (onboard): Solid 24 minutes of activity, isn't it?

268:21:59 Irwin (onboard): We got MAG N on there. And I still have a MAG way back here with a - color - Q. They suggested T, but -

268:22:24 SC (onboard): (Yawn)

268:22:26 Scott (onboard): ... Q ...

268:22:28 Irwin (onboard): Might as well.

268:22:56 Scott (onboard): ...

268:23:04 Irwin (onboard): I'll look in this TSB over here.

268:23:06 Worden (onboard): Look in - in U-1 back there.

268:23:58 Irwin (onboard): ...

268:24:00 Worden (onboard): Roger. You messed up 190 ...

268:24:02 Henize: 15, this is Houston. Would you please extend the Mass Spec. boom all the way out again.

268:24:08 Scott (onboard): Tell him yes.

268:24:11 Worden: Roger. In work.

[The controls for the boom, as well as the rest of the SIM bay, are mounted on the right hand side of the spacecraft on panel 230.]
268:24:13 Henize: And I have a T-start for the lunar eclipse photo's when you're ready to copy.

268:24:20 Worden: Okay. Go ahead with the T-start.

268:24:31 Henize: T-start for lunar eclipse photo's. 268:59:47.

268:24:43 Worden: Understand, 268:59:47.

268:24:48 Henize: That's correct, Al. [Long pause.]

[This is the time reference used to start the Mission Timer from which subsequent photographic events are coordinated.]
268:24:53 Irwin (onboard): Yes, my camera's still up here, Dave.

268:24:55 Scott (onboard): Okay, good.

268:25:00 Worden (onboard): Hey, we're going to have to rush.

268:25:01 Scott (onboard): Huh? I know it. Why - logical.

268:25:04 Worden (onboard): Okay, 59, 47, ...

268:25:07 Scott (onboard): How long is that from now?

268:25:10 Worden (onboard): Three minutes.

268:25:11 Irwin (onboard): Well, why don't we go ahead to U - Why don't you go...

268:25:13 Henize: Al, we had a question on the Mass Spectrometer and it may be too late. Was it possible to confirm by visual look through the window that it was retracted?

268:25:27 Worden: Negative, Karl. You can't determine that it's retracted. All you can determine is that it's full out.

[Al discovered during his solo mission that he could just make out the boom-mounted instruments from window 5, the right-hand window, by peering through it obliquely, but only when the boom was fully extended. Therefore, he can inform them that it is no longer fully extended but cannot tell by how far it has come in.]
268:25:33 Henize: Roger. Well, when it was retracted, you wouldn't be able to see it. That's what I'm asking. Is it possible for you to take a look now and see if it slowly comes in to view.

268:25:44 Worden (onboard): You want...

268:25:45 Scott (onboard): Okay, he wants you to watch and see if it does come full out.

268:25:50 Worden: Roger. In other words, you're asking to a confirm that it does come full out.

268:25:54 Scott (onboard): All right. ...

268:25:54 Henize: That's correct.

268:25:56 Scott (onboard): ...look down...

268:25:57 Worden: Okay.

[Comm break.]
268:25:58 Scott (onboard): ...and if you can't see it, it was retracted. If you can see - You can't see it then.

268:26:02 Irwin (onboard): Yes.

268:26:06 Scott (onboard): ...

268:26:08 Worden (onboard): Sure I can. Okay, Jim, I'll go ahead maneuver you. You're the act again.

268:26:17 Irwin (onboard): Okay.

268:26:19 Scott (onboard): Let's see a Flight Plan.

268:26:53 Irwin (onboard): Well, if we can't find that other mag, Al, we might have to use this one. Got the one MAG here of black and white from the LM. It has got to be...

268:27:02 Henize: Just to clarify...

268:27:03 Irwin (onboard): ...very high speed.

268:27:04 Henize: ...our question, Al, the main question was just to confirm whether or not it did go out of your field of view. Did it actually move from the full - from the full-extended position? Since we saw no change in the data when we retracted it during the test yesterday, there is a suspicion that, even though you actuated the switch, that for some reason it didn't retract.

268:27:26 Worden: Understand. [Pause.]

268:27:26 Irwin (onboard): I see - there's one boom extended.

268:27:31 Worden: Okay. It's fully extended now, Karl. But it may be too late. It may have already been out by the time we looked.

268:27:43 Henize: Roger.

[Long comm break.]
268:27:44 Worden (onboard): Is that talkback barber pole or gray?

268:27:46 Irwin (onboard): Gray.

268:27:46 Worden (onboard): Yes.

[Al's sighting of the Mass Spectrometer here doesn't help answer the question from the back room. To prove that the instrument is indeed being retracted, they need Al to confirm it has left his field on view.]
268:27:50 Scott (onboard): It kind of oscillates back and forth, doesn't it?

268:28:08 Worden (onboard): Karl doesn't realize we don't want to get too much UV. He must think we watch out that window every time we extend and retract it.

268:28:20 Irwin (onboard): Hmm.

268:28:21 Scott (onboard): Yes, no kidding.

268:36:53 Henize: 15, this is Houston. We have a rather extensive update to the Flight Plan. And also, a change to the procedure for the contamination of photos, which we can read up to you at your convenience.

268:37:09 Worden: Okay. Does it involve the things going on here in the next couple of hours?

268:37:17 Henize: It's pertinent beginning at 271. We probably ought to get it in before the press conference at 270.

268:37:35 Worden: Okay. Stand by one. [Long pause.]

[The crew are busy with the UV photos of the Earth at the moment, and at the top of the hour, will continue with photography of the lunar eclipse.]

[Worden, from the 1971 Technical Debrief - "Most of the UV photography was done when all three of us were on board. Jim handled all of that. I read the checklist, and it worked very well.]

["Window number 5 was covered with a Lexan shield, which acted as an ultraviolet filter for those portions of the flight when we weren't taking ultraviolet pictures out that window. Because of the distortion and the poor optical quality of the Lexan, pictures would have been greatly degraded if they had been taken through the Lexan shield. There were some portions in the Flight Plan where it called for the Lexan shield to be removed for visual or for orbital-science photography, which was not ultraviolet photography. At some portions in the Flight Plan, where some of that photography was being done, the Lexan shield was left off the window for periods greater than the time prescribed in the Flight Plan. I observed no effects from any ultraviolet radiation. I don't believe there's anything that was observed after flight either."]

268:37:56 Worden: Okay. Go ahead, Karl

268:38:02 Henize: Okay. If you've got the Flight Plan out, we'll go over to 271 hours. And at 271:20, just under S-Band AUX TV Science, we add Verb 49, maneuver to contamination photo attitude. The attitude is 014, 195, 016; High Gain [Antenna], pitch, minus 23; yaw, 252.

268:38:53 Worden: Okay. At 171:20 [means 271:20] just after S-band AUX TV Science, Verb 49 to 014, 195, 016; High Gain, pitch, minus 25 - 23; and the yaw, 252.

268:39:09 Henize: Roger. Just after that, we delete "Mass Spectrometer, Ion Source, Off", and in the space there, add "Configure for urine dump."

268:39:25 Worden: Roger. Delete the Mass Spec. and Ion Source, Off, and configure for urine dump.

268:39:32 Henize: Okay. Delete the next one, two, three, four lines, but we - and that brings us to Gamma - Gamma-ray Gain Step, Shield, Off, which we leave in.

268:39:44 Worden: Roger. Delete four and leave in the Gamma-ray Gain Step, Shield, Off. Go.

268:39:48 Henize: Delete all of the rest of that page. And add at 271:40, Verb 48, 11101, 01111, and P52, option 3.

268:40:22 Worden: Okay. 271:40, Verb 48, 11101, 01111, and a P52, option 3.

268:40:32 Henize: Roger. And at 271:45, we add Gamma-ray Boom Deploy, 41 seconds, then Off. Gamma-ray Gain Step, Center, and start contamination photos.

268:41:16 Worden: Okay. 271:45, Gamma-ray Boom Deploy, 41 seconds, then Off. Gamma-ray Gain Step to Center. Start the contamination photos.

268:41:26 Henize: And there's a note on the photos that you begin to dump according to the photo procedures, which are - I have an update to that I'll give you later. And that we dump the water to 40 percent, in order to have the right weight at entry. Roger. It's important that we don't go below 40 percent on the water dump.

268:42:01 Worden: Okay. Understand. Dump according to photo procedures and the water dump to no less than 40 percent for entry.

268:42:08 Henize: That's affirmative. On the next page, 272 hours and zero minutes, we - I - I presume you know that we're not doing the midcourse correction 6. We cancelled the P52 there. And we keep the H2 purge line heater on, but we cancel the P30 external Delta-V. We cancel the Verb 49 maneuver, we cancel the next one, two, three, four, five, all the way down to the H2 and O2 fuel cell purge, which we keep.

268:42:48 Worden: Okay. Understand. Keep the H2 purge line heater, cancel the P52, and the set of lines below H2 line heater on, and keep the H2/O2 fuel cell purge.

268:43:03 Henize: Roger. And at 272:28, a note that you should be ending the contamination photos at that point.

268:43:13 Worden: Say again.

268:43:14 Henize: 2 - 272:38. [Pause.]

268:43:31 Worden: Okay. 272:38, end contamination photos. Go ahead.

268:43:35 Henize: Right. At 42 we cancel - we delete the waste water dump, since we've already done it. And at 42 we add: "Start the Mass Spec. boom test." and the procedures are to be read up in real time. At 58 we cancel the midcourse 6.

268:44:09 Henize: At 273:01 we...

268:44:11 Worden: Okay. At 272:47, that's the - hold on. Let me read it back. 272:42 the Mass Spec. boom test procedures in real time, and cancel MCC-6. Go ahead.

268:44:25 Henize: Roger. At 273:01, we cancel the burn status report and we add: "X-ray experiment, On. Alpha/X-ray Covers, Open, and record the GET."

268:44:58 Worden: Okay. 273:01, X-ray experiment, On, Alpha/X-ray Covers, Open, and record the GET. Go ahead.

268:45:05 Henize: Roger. At 03, we delete the Gamma-ray, X-ray, alpha particle, MSO, On. And down at 273:47, we add Gamma-ray Boom, Deploy.

268:45:34 Worden: Okay. A deletion at 273:00 - or 03, the four items there and then Gamma-ray Boom, Deploy, at 273:47. Go ahead.

268:45:47 Henize: Roger. And one final item on 274:05, in the Mass Spectrometer instructions there, the discriminator should be Low instead of High.

268:46:03 Worden: Okay. 272:04 [sic] Mass Spec. discriminator, Low versus High.

268:46:09 Henize: Roger. And if you have the time, I can give you the update on the contamination photography, which is on photo 25 and 26 in the back of volume 1 of the Flight Plan.

268:46:21 Worden: Stand by one, please. [Long pause.]

268:46:54 Worden: Okay, Houston. Let's hold off on the updates of those other photos, so we can get squared away for the eclipse photos.

268:47:00 Henize: Roger.

[Very long comm break.]

[Just now, the crew are in the middle of a sequence of taking photographs of the Earth using film and equipment which can work in ultraviolet light. The procedures for this can be found on page 3-378 of the Flight Plan.]

[The spacecraft is maneuvered to face window 5 towards Earth. This window has panes made from quartz rather than glass because of this material's transparency to UV light. A Hasselblad camera is fitted with a specialised 105-mm UV capable lens and magazine N, which is loaded with IIa-o UV sensitive film. The RCS is configured in an minimum impulse mode where single jets rather than pairs of jets are used to control the spacecraft's attitude. The motion rates of the spacecraft are allowed to settle down until they are less than 0.2°/sec in all axes. This is to minimise smearing of the images due to the long exposure times (up to 20 seconds) called for.]

[Eight images, AS15-99-13483 to AS15-99-13490 are planned in this sequence; two each through four filters. In the pair taken through filter 1, the crescent Earth is virtually invisible. AS15-99-13487 does show Earth well but a streak of flare, probably caused by the Sun reflecting off wipe marks on the window. With the Earth presenting such a thin crescent, the Sun is very near the camera's field of view.]

[Next, by the Flight Plan, the magazine is changed to colour film and a reference shot taken through the same camera/lens combination. An earlier change in the Flight Plan asked for magazine P to be used instead of M. However, this magazine was finished three orbits before Endeavour left the Moon. Magazine Q does have seven shots taken through the 105-mm UV lens but it is apparent from the angular size of Earth's image that these were not taken until later in the mission, perhaps just before or just after the crew's rest period. Frame AS15-96-13135 is typical from this set.]

[Flight Plan page 3-381.]

[At 268:59:47 GET, the Mission Timer is started from zero, leading up to photography of the starting phase of the lunar eclipse. Procedures for this are given on page 3-380 of the Flight Plan. Two cameras are used; a Hasselblad loaded with colour film is mounted in the left-hand rendezvous window (number 2) and the Nikon 35-mm camera with very high speed black and white film goes in the right-hand rendezvous window (number 4). Since these windows face along the spacecraft's longitudinal axis, Endeavour is maneuvered to point at the Moon. As we will see later, once the spacecraft is in the required attitude, the CMC switch is placed in Free (no active attitude correction) and the spacecraft will begin to drift away.]

Geometry of Earth, Moon and spacecraft during eclipse.

[A lunar eclipse occurs when the Moon's orbit takes it through the Earth's shadow. If the plane of the Moon's orbit around the Earth were perfectly matched to the plane of the Earth's orbit around the Sun then this phenomena would occur monthly at each full Moon. However, a 3° tilt between these two planes cause it to occur less often, never more than twice per year. Though of little scientific interest nowadays, it is an interesting and beautiful sight and the Apollo 15 crew are fortunate to be able witness it from directly between the two planets. It takes a period of hours for the Moon to fully enter the umbra (the full shadow) and leave again. Both events will be photographed from the Command Module.]

[At 5, 8, 11, 14, 17 and 19 minutes into the sequence, frames are taken on the Hasselblad with gradually increasing exposure times. The photographic record shows that four images are taken using the 250-mm lens and a further 6 using the 80-mm lens. With the long exposure times, and the fact that the Hasselblad images are being taken handheld, these images are somewhat blurred but AS15-96-13108 and AS15-96-13115 are representative examples of both. At 19, 20, 21, 22, 23 and 24 minutes, with the Moon now deep into the umbra, exposures are made with the Nikon, again with increasing exposure times up to one minute for the final shot. These are currently not available to the AFJ.]

[One interesting point to note in these photographs is the apparent shape of the shadow as it crosses the Moon. As seen from Earth, the effect of the Moon's spherical shape on the shadow can be ignored because it is being viewed from the same vantage point as the source of the shadow. Indeed, the apparent curvature of Earth's shadow is a very simple proof that the Earth is round. Endeavour, however, is providing a new vantage point for this event, well off to the side of the Earth/Moon line. The shape of the Moon alters the apparent line of the Earth's shadow such that at the start of the eclipse, the curve of the Earth is more than cancelled out. In two hours time, when the exiting Moon is photographed again, the shape of the moon will reinforce the curve of the Earth and produce a very strong crescent effect. Note also that the shaded part of the Moon has a reddish hue.]

[Once the Moon has completely entered the umbra, it is no longer lit directly by the Sun. However, if Dave and Jim were to be standing at Hadley Base at this time (and thankfully, they aren't) they could look up at the Earth/Sun position and see a truly awe-inspiring sight of 40,000 kilometres of sunset/sunrise all around the Earth forming a ring of gold in the sky. During this moment, and depending on atmospheric conditions on Earth, this golden ring is often seen to turn the eclipsed Moon a dark, copper brown colour.]

[Instruments left behind at Hadley Base are also being subjected to the changes on the surface brought about by the eclipse but the only change noted by them is a drop in the surface temperature of approximately 185 Kelvins.]

Public Affairs Officer - "This is Apollo Control at 269 hours, 03 minutes. Apollo 15 now 113,437 nautical miles [210,085 km] from Earth. Velocity: 4,667 feet per second [1,423 m/s]. The televised news conference from the spacecraft is scheduled for 270 hours, 20 minutes, or 2:54 pm Central Daylight Time."

269:13:08 Henize: 15, this is Houston. Your astronomer CapCom is getting curious to know whether you are seeing anything of the lunar eclipse. Anything visible?

269:13:20 Irwin: Oh, sure, we've seen it come down to about half to about a fifth illumination at the present time, relative to the Sun's illumination.

269:13:29 Henize: Roger. And what percent of the disk is covered now?

269:13:35 Irwin: Stand by.

[Comm break.]
269:15:47 Irwin: Okay, Karl. Looks like about 9/10ths of the disk is covered at the present time, and we've been taking the pictures all along. It's a very pretty sight out there.

269:16:00 Henize: Roger. Sounds like you are getting close to total eclipse there. Hey, we note down here that in your Free mode you are drifting somewhat in pitch and you are about 5 degrees off now. The recommendation is to go Auto and stop the drift if you can and cycle back to Free before you take your next photo. If there is anything you can do to correct the pointing it might be a good idea.

269:16:25 Irwin: Okay. Right now those photos are handheld, so we'll get to it when we get to the Nikon.

269:16:29 Henize: Okay.

[Long comm break.]
269:22:04 Irwin: Houston, 15. The Moon's in the shadow now and we have a variation in color from a almost a light gray to a burnt orange from one side of the Moon to the other. Almost like the old harvest Moon, except that I'm not sure there's any atmosphere up here yet.

269:22:23 Henize: Roger. We copy.

[Comm break.]
269:25:17 Irwin: Houston, 15. We've finished the photos, and Al had the Moon in the reflex part of the Nikon all the way, so I'm sure the pointing was okay.

269:25:25 Henize: Very good.

269:25:26 Irwin: Right now the Moon is sort of - varies from sort of a very pale orange to a good deep burnt orange on one side and a very gradual change. And I hope the - the photos come out because it - it certainly is pretty.

269:25:45 Henize: Very good. It sounds like a beautiful view from up there. You've seen a lunar eclipse of the Moon twice as big as anyone else has ever seen such an eclipse.

269:25:56 Irwin: That was very interesting, and it certainly is a - a pretty view. It'd be a - a great place for somebody like you to come up and use your trained eye to interpret all this and understand it.

269:26:09 Henize: Sounds like it would be fun, someday. [Long pause.]

269:26:29 Henize: I see you have your EMS entry check coming up. If there is any chance of my slipping in this change of procedure on contamination cloud photography I'd be pleased to - at this point.

[The EMS (Entry Monitor System) is crucial to helping the crew guide the Command Module through re-entry to splashdown. Throughout the flight, the velocity measuring section of it has been regularly checked. Soon Al will carry out a test of the scroll section of the instrument.]
269:26:42 Irwin: Okay, give us a couple of minutes to reconfigure here. We'll have time to do that.

269:26:45 Henize: Okay, fine. I'll stand by for your word.

[Long comm break.]
269:31:08 Scott: Okay, Houston. Go with the contamination cloud photography update.

269:31:13 Henize: Roger, Dave. Are we on photo 25?

269:31:19 Scott: Photo 25. Go.

269:31:23 Henize: Okay, the reason for this change is that we have to use the DAC, instead of the Nikon, since we've run out of Nikon film. The first change is under procedure - one, configure camera; we go down to the second line in the CM4, et cetera, we X that out, and we substitute - CM4...

[The DAC, as well as being a movie camera, can be pressed into service as a stills camera by setting its frame rate to Time. A magazine of very high speed film is also available for it.]
269:31:48 Scott: Stand by one, Karl. We want to find out if we have any more Nikon film. We may have some.

269:31:58 Henize: Okay. [Long pause.]

269:32:15 Henize: 15, Houston. Our records show that you will be out of Nikon film when you finish the lunar eclipse photography, and we'd prefer that you use it for the lunar eclipse.

269:32:32 Scott: Does that include mag W.

269:32:37 Henize: Stand by.

269:32:43 Scott: Oh, disregard that. We just found a - a little note on mag W. It says "Do not load in camera." I guess that takes care of that. Go ahead with your update.

[This author's guess is that magazine W is identical to the other 35-mm roll for the Nikon except it will remain in its case. This would allow post mission determination of the degree of fogging caused by cosmic ray exposure to these very sensitive films.]
269:32:55 Henize: Okay, fine. The basic specs there in - are - We're using window 4/DAC - D-A-C/18 [-mm lens]/VHBW [Very High-speed Black and White film]-bracket, M-I-R for mirror, PCM pic cable. T1, 1/1,000, infinity, 24 feet [frames?] per second.

269:33:43 Scott: Okay. DAC/18/VHBW-bracket, mirror, PCM cable, T1 1/1,000, infinity, and 24 frames per second.

269:33:53 Henize: Correct. The next line, it's magazine H, magazine Hotel, and magazine - and instead of frame number, it's magazine percent to be filled in there.

269:34:06 Scott: Roger. Hotel and percent. Go.

269:34:08 Henize: Okay. Completely delete number 2, and substitute instead the following. "Utility Power, On; cover lens; DAC, On, 2 seconds." Change shutter to "1/60;" change frame rate to "Time."

269:34:45 Scott: Okay. "Utility Power, On; cover lens; DAC, On, 2 seconds," change shutter to "1/60th," frame rate to "Time," in place of the number 2 you have. Go ahead.

269:34:54 Henize: Roger. In step 3, we delete "Inhibit all jets," and, at the end, we add "CMC Mode, Free."

269:35:08 Scott: Roger. Delete "Inhibit all jets," and add "CMC Mode, Free" at the end. Go ahead.

269:35:14 Henize: Roger. At the - at the end of step 4, before, "Repeat 4-frame sequence," we write "CMC Mode, Auto." And we delete "Repeat 4-frame"...

269:35:33 Scott: Okay. Say again.

269:35:35 Henize: We - we - we - we delete the "Repeat 4-frame sequence."

269:35:42 Scott: Okay, step 4. Add "CMC Auto" and delete "Repeat 4-frame sequence." Go ahead.

269:35:47 Henize: Roger. Step 5. Instead of T plus 6 plus 6:30, we - it's T plus 3:30, 3 plus 30. Dump waste water...

269:36:02 Scott: Roger. T plus 3:30 vice T plus 6:30.

269:36:06 Henize: Roger. And it says "Waste water or urine," it's really "Waste water and urine." The - and we dump...

269:36:16 Scott: And vice or.

269:36:18 Henize: Go ahead, and - Okay, and we dump to 40 percent as you've been previously advised. Also a part of 5, add "Repeat step 4 [damp rates]."

269:36:42 Scott: Okay. In step 5, add "Repeat step 4 and damp rates." Go.

269:36:48 Henize: Step 6, the time there is not 26 plus 30, but it's 28 plus 30. Also...

269:36:57 Scott: Roger; 28 plus 30 vice 26 plus 30.

269:37:00 Henize: Roger. At the bottom, we delete "Repeat 4-frame sequence," and we add the following: "T plus 32 plus 0; CMC Mode, Auto," and below that "Repeat step 4 [damp rates]."

269:37:29 Scott: Okay. At the end of step 6, can - cancel "Repeat 4-frame sequence," and add "T plus 32 plus 0, CMC, Auto," and then "Repeat step 4 and damp rates."

269:37:42 Henize: Roger. On step 7, it's "T plus 43" instead of 48; and, at the end, delete "Repeat 4-frame sequence," and add "CMC Mode, Auto."

269:38:01 Scott: Okay. Step 7 is "T plus 43" and delete the "Repeat 4-frame" and add "CMC, Auto." Go.

269:38:08 Henize: Roger. Step 8. We delete "Enable all jets," and what we record is the magazine percent. And that's the end of the correction.

269:38:18 Scott: Okay. Step 8, delete "Enable all jets," and add percent instead of frames.

269:38:23 Henize: Roger. That's got it.

269:38:27 Scott: Alrighty we'll do all those.

[Comm break.]
269:40:35 Henize: 15, this is Houston. Sorry to tell you, but I made a couple of errors in that read-up. Can we make it two corrections?

269:40:46 Scott: Okay. Stand by one, please, Karl. [Long pause.]

269:41:07 Scott: Okay, Karl; where are the corrections?

269:41:10 Henize: It's photo 25. [Long pause.]

269:41:40 Scott: Okay. I'm on photo 25.

269:41:42 Henize: Right. At the end of step 5 and step 6, I put in a little statement saying "Repeat step 4, damp rates." That's really meant to say, "Repeat step 3," which is "damp rates," in both cases.

269:42:00 Scott: Okay, understand.

[Long comm break.]
269:45:43 Henize: 15, Houston.

269:45:50 Worden: Go ahead, Karl.

269:45:53 Henize: Guys, at the end of photo 26, when you get through with this sequence, requesting 2 seconds of protect frame, also.

269:46:05 Worden: Okay. I...

269:46:06 Scott: Okay, got you.

[Comm break.]

[Richard Gordon, the backup Commander for Apollo 15 takes over the CapCom position for a short time.]

269:48:34 Gordon: 15, Houston. [I] have a lunar eclipse photo PAD [as required] on your Flight Plan, page 384, when you're ready.

269:48:47 Worden: Stand by, Dick. [Long pause.]

269:49:17 Worden: Okay. I'm ready to copy the photo PAD on the lunar eclipse.

269:49:21 Gordon: Okay. 270:49:53.

269:49:32 Worden: Roger. 270:49:53.

269:49:36 Gordon: Roger.

[Long comm break.]
Public Affairs Officer - "This is Apollo Control at 269 hours 51 minutes. Those last couple of transmissions have been by the backup crew Commander, Dick Gordon, who has joined CapCom Karl Henize at the console. Apollo 15 now 111,271 nautical [206,073 km] miles from Earth. Velocity: 4,746 feet per second [1,447 m/s]."

269:58:37 Henize: 15, we'd like to have Omni Charlie.

269:58:42 Worden: Omni Charlie.

[While working through these sighting and photographic tasks, Endeavour has been communicating with Earth via omni-directional antenna D, one of four distributed around the periphery of the CM.]

[Very long comm break.]

[Flight Plan page 3-383.]

270:08:35 Worden (onboard): Percentage on the mag?

270:08:39 Irwin (onboard): Okay.

270:08:40 Scott (onboard): Trim and call it 75.

270:08:44 Irwin (onboard): Okay, we're moving. Stable DAC. G&N Power coming back to AC 1. CMC Mode, Auto, Dave? A Verb 49 maneuver to the lunar-eclipse attitude. I wonder - I guess we better be in that attitude - for the press conference. Okay. You ready?

270:09:09 Henize: 15, Houston. We'd like to get the High Gain [Antenna] up. Pitch, 22; Yaw, 261.

270:09:17 Irwin (onboard): Say, buddy!

270:09:22 Scott: Stand by; we're maneuvering. [Long pause.]

270:09:21 Worden (onboard): Stand by; we're maneuvering.

270:09:25 Scott (onboard): The numbers, Jim.

270:09:26 Irwin (onboard): Okay; 040, plus 011, plus 041.

270:09:42 Scott (onboard): Forty, ll, and 41. Right?

270:09:44 Irwin (onboard): That's right.

270:09:54 Scott (onboard): What time's the chronometer say?

270:09:55 Irwin (onboard): Twenty after.

270:09:58 Worden (onboard): Yes.

270:10:05 Scott: Okay, Houston. Are your High Gain angles for the sextant photos or for the lunar eclipse photo attitudes?

270:10:13 Henize: Sorry about that, Dave. When you complete this maneuver, they're in your Flight Plan. Pitch, minus 22; Yaw, 227.

270:10:22 Scott: Rog.

[These last HGA figures are those for the second period of lunar eclipse photography.]

[Comm break.]

270:12:03 Scott (onboard): Oh, yes. That's not bad. Not a bad picture. Oops!

270:12:18 Henize: 15, we'd like to have Omni Bravo.

270:12:28 Scott: Omni Bravo.

[Long comm break.]
270:12:23 Scott (onboard): Can you get that for him, Jim? Omni Bravo?

270:12:26 Irwin (onboard): Oh.

270:12:27 Worden (onboard): I'll get it...

270:12:28 Irwin (onboard): Omni Bravo.

270:12:29 Worden (onboard): ... Okay.

270:12:40 Scott (onboard): It's looking up.

270:12:46 Worden (onboard): Let's see...

270:12:47 Scott (onboard): Wait.

270:12:49 Worden (onboard): Yes, let me get it.

270:12:53 Scott (onboard): What say to open all the windows and get a little light in here, huh?

270:12:58 Worden (onboard): Yes.

270:13:Og Scott (onboard): There seem to be - Ah, there won't be any at the lunar-eclipse attitude, though.

270:13:32 Irwin (onboard): Turn all the floods up all the way.

270:13:34 Scott (onboard): Yes.

270:13:52 Worden (onboard): What time's ...?

270:13 54 Scott (onboard): In a few minutes.

270:13 59 Irwin (onboard): Yes, at 20 after.

270:14:00 Scott (onboard): Yes.

270:14:11 Scott (onboard): One guy here.

270:14:13 Irwin (onboard): Let's see if this controller wants to take up.

270:14:17 Scott (onboard): One guy here. Here, I got it, Jim. Why don't you come on down?

270:14:25 Irwin (onboard): Come down now?

270:14:26 Worden (onboard): Yes. Sit on my urine hose. Keep the...

270:14:28 Scott (onboard): Sit on urine hose and keep it down. The controller, we can stick under the couch - for now. This moose is in the way.

270:14:47 Worden (onboard): (Laughter) Too much gravity.

270:14:50 Scott (onboard): Get over in the - put your feet'on the couch and sit down.

270:14:53 Worden (onboard): Well, someone's going to have to get up and get the switch.

270:14:54 Scott (onboard): What switch?

270:14:55 Worden (onboard): Science...

270:14:56 Scott (onboard): I'll get it.

270:14:57 Worden (onboard): ...TV switch.

270:14:58 Scott (onboard): Yes, it's got to go Transmit on the TV.

270:15:00 Worden (onboard): Yes.

270:15:02 Scott (onboard): Let's see if this all is going to work. No, we've got to shift it over - away from the corner. Yes, okay. Hold on to that.

270:15:27 Irwin (onboard): Okay, it looks like we're in attitude. Al?

270:15:30 Worden (onboard): Right.

270:15:31 Irwin (onboard): And we got to get the high gain going there.

270:15:33 Scott (onboard): Okay. It's not in the press con - shoo - it's not in here.

270:15:45 Worden (onboard): It's in there for the - the maneuver to the - yes, the eclipse attitude.

270:16:00 Scott (onboard): Let's see, you ought to try and move those hoses somewhere, Jim. Because you're going to end up having to be further back in the corner, I think. This thing needs to come - Great. I don't - Why don't you come - You get down...

270:16:18 Irwin (onboard): What's wrong?

270:16:20 Scott (onboard): Taped right now, but I think...

270:16:21 Worden (onboard): Yes.

270:16:22 Scott (onboard): Yes, it needs to come over this way more. It's not going to go any further on the other side of the bulkhead there.

270:16:35 Irwin (onboard): Yes.

270:16:36 Scott (onboard): See, because I'm - I'm in the far - no. Jim, can you get down? And let's see how it's going to work.

270:16:40 Henize: 15, Houston. Give us Auto and Narrow on the High Gain, please.

270:16:44 Scott (onboard): Whew!

270:16:46 Scott: Roger. Auto and Narrow.

[Long comm break.]
270:16:48 Worden (onboard): You want the front end to come this way a little? You want the front end to come this way?

270:16:56 Scott (onboard): No, I guess it's all right, if I can - It - it - There.

Public Affairs Officer - "This is Apollo Control at 270 hours, 17 minutes. We should be getting television in a few minutes now. Apollo 15's distance from Earth 110,080 [nautical] miles [203,868 km]. Velocity: 4,790 feet per second [1,460 m/s]."

270:20:00 Scott (onboard): It's reflected. I mean there's not...

270:20:01 Worden (onboard): Yes, that's what I made it for. Pick up behind here. No, right behind here.

270:20:08 Scott (onboard): Tell you one thing. I hope we can turn the lights up.

270:20:10 Worden (onboard): Yes. Might help.

270:20:12 Scott (onboard): Lights all up?

270:20:13 Worden (onboard): Yes. Oh, put it up it.

270:20:18 Scott (onboard): Al, you take that little bit and we'll put it on the patch.

270:20:21 Worden (onboard): Okay.

270:20:22 Scott (onboard): Okay. Yes, that's fine. How's that?

270:20:26 Worden (onboard): You got it, Jim. Fix it (laughter).

270:20:33 Scott (onboard): You see a patch, Al?

270:20:34 Worden (onboard): Yes.

270:20:35 Scott (onboard): Okay.

270:20:37 Irwin (onboard): Okay, there you go.

270:20:38 Worden (onboard): No, I don't want it.

270:20:39 Irwin (onboard): See there? It's going to be hitting it. By gads, I'll Just hold it on the patch.

270:20:54 Worden (onboard): (Laughter) Maybe.

270:20:58 Irwin (onboard): I'm in charge of light - light - light effect there...

270:21:00 Worden (onboard): Light, yes.

270:21:01 Irwin (onboard): ...on the patch.

270:21:02 Worden (onboard): Light my own.

270:21:04 Irwin (onboard): You want me to turn it on at the right time, Bob?

270:21:06 Worden (onboard): (Laughter)

270:21:07 Irwin (onboard): Huh?

270:21:08 Worden (onboard): (Laughter)

270:21:09 Scott (onboard): No, I think that's all right. There. Maybe you ought to come over this way a little bit. You're up there, like you're hiding in a corner.

270:21:20 Irwin (onboard): There you go.

270:21:21 Scott (onboard): There. No, I don't think you need that on the patch, do you?

270:21:24 Worden (onboard): No.

270:21:26 Scott (onboard): You still got to look at the stupid camera.

270:21:27 Worden (onboard): No, it doesn't - shows my face up there.

270:21:31 Irwin (onboard): What do you mean?

270:21:32 Scott (onboard): Okay.

270:21:34 Worden (onboard): We'll keep it available in case somebody wants to look at my face (laughter).

270:21:42 Scott: Houston, 15. You ready down there?

270:21:50 Irwin (onboard): Well, it's in TV already. Who put it in TV?

270:21:53 Henize: Roger, 15. ...

270:21:54 Worden (onboard): I put it in TV.

270:21:55 Henize: We're close to ready. Are you ready for the big press conference?

270:21:57 Worden (onboard): That goes Transmit.

270:21:59 Scott: Roger. We're ready. Anytime you want to go to transmit, let us know.

270:22:05 Henize: Okay. You can go ahead to transmit.

270:22:10 Irwin (may be Scott): Roger. [Long pause.]

270:22:11 Scott (onboard): Roger. We are. I got 3 seconds, 2 seconds, 1 second. How's that? There.

270:22:19 Worden (onboard): Except for - move your wire, Jim.

270:22:22 Scott (onboard): That a boy, now. See? They get it all. Okay, Houston, talk to us. We're all here. Except how does it...

Real Video file (887K)

270:22:31 Henize: Hey, 15, we're getting a beautiful picture coming through.

270:22:34 Scott (onboard): Yes.

270:22:36 Worden (onboard): Very good.

270:22:37 Scott: Roger. Go ahead with your questions.

270:22:45 Scott (onboard): It's probably blank as hell.

270:22:46 Henize: Roger. We'll - we'll admire the beautiful picture for - for a few minutes here.

270:22:50 Scott (onboard): ... this one.

270:22:51 Worden (onboard): ... lens?

270:22:54 Scott (onboard): Yes, that's been done.

270:22:56 Henize: Deke just passed out from the shock, incidentally.

[The crew appear in a row, facing the camera. Dave is camera-left, Al in the centre and Jim to camera-right. Dave has a noticeable beard after 12 days in space.]
270:23:01 Irwin (onboard): Do we look that scroungy? (Laughter)

270:23:03 Scott (onboard): Yes - yes. No, we look so good.

270:23:05 SC (onboard): (Laughter)

270:23:07 Worden (onboard): Mmm!

270:23:08 Scott (onboard): He probably can't believe it.

270:23:09 Worden (onboard): Yes.

270:23:12 Irwin (onboard): It's just because we haven't shaved in 2 weeks.

270:23:14 Worden (onboard): Is that a fact?

270:23:15 Irwin (onboard): Yes.

270:23:15 Henize: Okay, fellas. I have a preliminary statement to make here. The questions you will be asked in this news conference have been submitted by newsmen here at the Manned Spacecraft Center who've been covering the flight. Some of the questions they raised have been answered in your communications with - with Mission Control, but the public-at-large has not necessarily heard them. The questions are being read to you exactly as submitted by the newsmen, and in an order of priority specified by them.

270:23:45 Scott (onboard): Hmm.

270:23:46 Henize: Question number 1. This last week, we have shared scores of exciting moments with you. Which single moment would you most like to live again, and is there any moment which you would never like to repeat?

270:24:03 Scott: Well, I guess we all probably have a different idea of which would be the single most exciting moment of the flight, and maybe we'll just run through it one at a time. I guess the most impressive moment I can remember is standing up on Hadley mountain - Hadley Delta, and looking back at the plain and seeing the LM and the rille and Mount Hadley, and the whole big picture in one - one swoop. And I think we've got some pictures for you from up there, and I believe the TV was running at the same time, and I think that was probably the most impressive sight that I've ever seen. Al?

270:24:40 Worden: I guess I'd have to say - sort of, two events occurred which were exciting, for different reasons, and I guess they were really kind of the highlights of - of the flight for me. One was, right after LOI, when we got our first look at the Moon, and it was a fantastic, spectacular sight. And the other, I guess, was when TEI burned so beautifully, and right after TEI, that was an awfully good feeling.

270:25:12 Irwin: Okay. Well, I guess there were a great many new thrills for me, and the one that was most impressive though, was the lift-off. It began the flight, and I knew that I was going into space after a few years of waiting and training. And then, as far as the event that I would not like to - to repeat again, was probably the time when I fell down in front of the TV, when we were deploying the Rover.

270:25:42 Scott (onboard): Let me get your mike.

Real Video file (539K)

270:25:45 Henize: Question number 2. Near Spur crater, you found what may be "genesis" rock, the oldest yet collected on the Moon. Tell us more about it.

270:25:59 Scott: Well, I think the one you're referring to was what we felt was almost entirely plagioclase or perhaps anorthosite. And it was a small fragment sitting on top of a - a dark brown larger fragment, almost like on a pedestal. And Jim and I were both quite impressed with the fact that it was there, apparently waiting for us. And we had hoped to find more of it, and, I'm sure, had we more time at that site, we would have been able to find more. But I think that this one rock, if it is, in fact, the beginning of the Moon, will tell us an awful lot. And we'll leave it up to the experts to analyse it when we get back, to determine its origin.

270:26:48 Henize: Question number 3. Apollo 15 is already being described as one of the great events in the history of science. Aside from the crystalline rock, what other findings at Hadley-Apennine seem most important to you?

270:27:02 Scott (onboard): Jim? Why don't you answer that?

270:27:06 Irwin: I guess, immediately, I think of the orientation, or organization that was revealed in the side of Mount Hadley. There's 14,000 feet vertical relief of vast mountain face exposed to us. And there was layering in there that was most impressive for the total 14,000 feet, and we commented on the number of beds we could see. That really impressed me, that you could have that much organization in - on a large mountain on the Moon.

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270:27:45 Henize: Question number 4. This is the toughest landing area we have attempted to - to reach on the Moon. Describe what it was like, flying into it.

270:27:59 Scott: Well, I think, to begin with, we had every confidence that we could get to the landing site. The trajectory had been modified such that we had adequate clearance over the mountains. And the first sight I had out the window was somewhere around probably 9 or 10,000 feet, as we passed down below the upper elevations of Mount Hadley. And I could see Mount Hadley to my left before we pitch - pitched over and saw the plain at Hadley, and that was probably as impressive sight - a sight as I've seen. The landing itself, once we pitched over, was somewhat of a surprise in that the - the cratering was much more subtle than we had expected. There was a great lack of any large fragments or boulders on the surface. It was apparently quite smooth, and those rather deep craters, which we had anticipated using as landmarks - because of their subtlety - did not appear quite as readily as we had hoped. I think we did recognize our relative position east-west of the rille because of the size of the rille itself. I think we were a little off on the north-south, but close enough to handle the traverses in the Rover. And, I think that having a vehicle such as that - as that enables us to go into more complicated, difficult landing areas, because it's not necessary to land on an exact point. We can take advantage of our mobility and land anywhere within a certain prescribed area which was initially our goal on this flight.

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270:29:39 Henize: Question number 5 for Al Worden. In lunar orbit, you too carried out geologic observations; for example, you reported cinder cones. Could you discuss this and other observations from 60 miles up?

270:29:54 Worden: Yes, the comment on the cinder cones was one of color, but we noticed particularly on - on some of the lighter part of the back side that many, many of the craters that we flew over were filled with what appeared to be lava. There seemed to be a great number of lava flows in the mare area, particularly Mare Imbrium. Mare Imbrium seems to be a - just a - countless numbers of - of lava flows, which were all apparently very thin and very fluid. And you can see - you can just count number - numbers of flow fronts covering Mare Imbrium. So, we got, I think, quite a distinct impression of a - of a - of a great deal of volcanism around the Moon. And, in some particular isolated area such as the Littrow area and such as areas like probably the Aristarchus plateau, there's a great deal of volcanism and some cinder cones and - and certainly a lot of lava flows.

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270:31:06 Henize: Question number 6. Do you feel that the workload during your three lunar surface excursions was too demanding? You appeared at times to be reaching the limit of your endurance. Any recommendations for Apollo 16?

270:31:24 Scott: I think any time you set out on a task such as the one we had, you're bound to, at certain times, get a little tired, which I think we probably did. However, I think we came back and I don't think we ever reached anywhere near the limit of our physical endurance. I think Apollo 16 probably has everything in hand; It's just a matter of conditioning yourself. Jim and I have discussed it since we got back on board the Endeavour and concluded that our training is what really prepared us, and the many hours we spent during geology field trips and in simulations at the Cape in our suits, we feel was the factor which really contributed to being able to proceed with those duration EVA's. I see no problem in the future with conducting three successive 7-hour EVAs. Neither one of us were particularly physically tired. I think the fatigue is really in the - the mental regime, in which you're concentrating very intensely for 7 hours, and you're pressing to do your best all the way through and - and keep your eyes open to make the appropriate observations and gather the samples. And I think its really more of a mental factor than a physical factor.

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270:32:50 Henize: Question number 7. You described the Lunar Rover as a bucking bronco on the Moon. Would you elaborate and assess the Rover's performance and tell us what changes you recommend for the 1972 model?

270:33:04 Scott (onboard): (Laughter) Jim, you want to talk about that? Why don't you go ahead? Not too hard, though (laughter).

270:33:13 Irwin: Well, there were several times there when we were riding along where we'd hit on a sizable bump and you could - you could see the - the wheels come off the ground and then float through the air and - but Dave should comment more as far as the - the driving. And it was really like a bucking bronco, that's true, because I was strapped in. As you know, Dave had to strap me in because I had some trouble with my seatbelt, but I - I really did feel like I was on a - a bucking bronco.

270:33:42 Scott: I think I might add that it's a - it's a very stable machine, but because of the - the 1/6th gravity, it tends to float. In - in the simulations that we ran in Houston, we saw the same amplitude or same degree of bouncing but a different damping. In other words, the - the vehicle would come off the ground, or one wheel normally would come off the ground, and it would take somewhat longer to return to the ground than in one g. And I think it's just a matter of being - becoming accustomed to the - to driving. It's a very stable vehicle; the suspension system - system is excellent. We had to make some rather sharp avoidance turns periodically, and in - in these turns, we could tell the vehicle was quite stable; no tendency to turn over whatsoever. I think the only recommendation we'd really have would be to come up with a new idea on the seatbelt-type arrangement, and we - we've discussed that also. I think we have some suggestions we could make when we get back to ensure that you can have both crewmen securely in their seats in a short period of time. Other than that, I think the vehicle is about as optimum as you can build.

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270:35:02 Henize: Question number 8 for Dave Scott. The drill seemed to drive you up the crater walls. What was the problem, and was it worth the time?

270:35:14 Scott: I guess I'd anticipated that question. I think the problem was a - a striking discovery. When we went to Hadley Rille, we expected to find a regolith, or the soil, about 5 meters thick. And with that in mind, like 25 feet, I expected to have no trouble putting the heat flow probes in or drilling the - the core stem because of the expected soft soil. After about 1 meter, I ran into hard rock, and my first thought was it was an isolated rock somewhere within the - the soil. But that was not the case. Apparently, what we have is a very thin regolith, or a thin soil layer above solid rock. And with this in mind, I think we brought back a core stem or a deep drill-core of the Moon of basic bedrock or foundation rock on Hadley Plain. I think that's a very significant find. I think it will be very meaningful to the scientists when they analyze it.

[After being taken to Earth, the core stem will be found to have gone through regolith, as expected preflight. Dave had been deceived as had others before him by the very compact nature of lunar soil below the first few centimetres. X-ray examination of the contents reveals 58 separate layers along with various pebbles and an increasing density down to the bottom of the core.]
Scott (continued): The perplexing problem was doing the actual drilling and extracting the core stem. If you put a drill into solid rock, it's very difficult to get it out. And there at the end, it took both Jim and I with our shoulders pushing, as hard as we could, up - to extract the drill stem. But in the final analysis, as I look back on it, I think it is indeed worthwhile. At the - at the time it occurred, we were both interested in moving out to the northern complex and further geology, which Jim and I are both quite interested in. And the mechanical task of doing the drill at that time seemed what - somewhat less important than seeking new - new finds in a new geological area. But, in retrospect, I think we have, in fact, brought back one of the most significant samples of the whole trip.

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270:37:14 Henize: Question number 9 for Dave Scott.

270:37:17 Scott (onboard): Gee, I don't want them all.

Henize (continued): In view of your comment to geologist Leon Silver about the need for trained scientists on the Moon, do you think that Scientist-Astronaut Jack Schmitt should be included in the crew of Apollo 17, the last of the Apollos.

270:37:34 Scott: Well, since I really have very little say-so as to which - which people get selected for which crews, I might sort of bypass it with a - with one comment that the more qualified a man is on the Moon, the more results you're going to get. And I think that's one of the reasons that we put as much time as we did into the geological aspects, in hopes of - of learning enough to bring back some significant data. I think that in any situation such as this, in any scientific endeavor, that you want the most qualified people possible. You must also remember that this is a - a highly complex operational mission. It requires a great deal of - of training and skill in order to fly these machines. I think, in particular, Jack Schmitt is a very highly qualified individual in both aspects. And I believe it's up to the - the management, that when they select the crews, to select the best people for the flight.

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270:38:40 Henize: Question number 10 for Al Worden. What runs through the mind of a man orbiting the Moon alone?

270:38:51 Worden: Well, I guess - I guess the - the thing foremost in my mind during those three days was how I was going to keep up with the time line and the Flight Plan, and how I was going to keep track of all the experiments we had going and where they were, and - and whether they were operating or not. And I guess that was a very, very fast three days for me. When I wasn't looking at the SIM bay experiments, I was looking out a window and taking pictures, and it was a pretty crammed three days. As a matter of fact, I - I guess I didn't really have - have much time to give any thoughts to being alone up there.

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270:39:30 Henize: Question number 11, again for Al. You said, after your spacewalk, you wish you'd stayed out longer. What was it like out there between the Earth and the Moon, and why did you come in so soon?

270:39:45 Worden: Well, let me answer the last one first. I - I guess I didn't come in soon; I came in when the job was done. And, as a matter of fact, I made an extra trip back out to take a look at the Mapping Camera. Now as - as far as what I felt like when I was out there, we talked a little bit about it after - after the EVA and decided it was sort of like walking on stage at your high school - dinner dance or something. We opened the hatch and it was pitch black, and as soon as we got out, the Sun was beating down on everything, and it looked like a very large floodlight on a stage. And then putting the TV camera out on the door just added a little bit more to that sort of unreal feeling that it was time to get out on the stage and do something. I think, as far as the EVA went, we did it just almost exactly as we'd practised it. It took almost exactly the same amount of time; we did it the same way. And, of course, we had practised that with pan - with the Mapping Camera in the extended position, and so that - that really posed no difficulty to us.

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270:40:55 Henize: Question number 12 for Dave and Jim. You - you didn't have time to get to North Complex, craters which may have been formed volcanically and where you thought some surprises might be found. Was this a significant loss?

270:41:12 Irwin (onboard): Why don't you?

270:41:13 Scott: Well, I'll start out and - and throw an answer there. I think if you look back at the original requirements for the landing at the Hadley-Apennines, they were primarily to inspect the front and the rille. It was only after a - a considerable amount of study had been done and some rearrangement in the Flight Plan - the timing on the surface, that we found we had enough time to plan to go to the Northern Complex. So the Northern Complex was, in fact, an addition to the original requirement; it was a bonus. And I think because Jim and I have spent so much time with volcanics in our terrestrial geology work, that we were quite interested in getting to the Northern Complex to see if, in fact, it was a volcanic area. But I don't believe we lost anything from the lunar surface by not going there; only we would have had an extra bonus had we been able to reach that point. And, with that in mind, I hope that some day somebody gets a chance to go back and take a look at the Northern Complex. Jim, do you want to answer?

270:42:19 Irwin: No, I agree with everything you said. It was just a little personal disappointment that we couldn't get up there, because we - we thought we'd have another beautiful view of the - the plains there and the LM, a view almost...

270:42:29 SC (onboard): (Sneeze)

270:42:30 Irwin: ...as beautiful as it - as it was from the side of Hadley Delta.

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270:42:37 Henize: Question number 13 for each of you. Would you, please, in your own words, tell us what you gave the American taxpayers besides a few hours of good television?

270:42:53 Scott: Oh, I think - the magnitude of the scientific data we return will speak for the taxpayers' money. The small amount of time they had for television, I think, is rather insignificant relative to the amount of return we've gathered in the SIM bay and in the lunar samples we have aboard right now. I think these data will not only en - enhance the progress of science, but it will reach the common man on the street directly by the - the byproducts of what we learn. I think man must extend himself, the new frontiers must be open in order for us to - to propagate mankind, and I think this is one way in which we do it. I - I feel that the taxpayers got, probably - as a matter of fact, I hope they got more than their money's worth out of the flight. And, if you could see the size of the film magazines that Al brought in yesterday from those cameras, why, you'd see that we have indeed at least a great deal of data on film alone.

270:44:00 Worden: Well, I really guess that there's not much to add to what Dave said. He - he expressed my sentiments exactly, and that the - the knowledge that, hopefully, we've - we've added to our store of information about the Moon and about ourselves will be increased in an extent which is greater than - than the - than the capital that was - spent on the flight itself. And, I would certainly think that - that the full theory adds significantly to - to man's knowledge about himself primarily and about himself in those areas where it will help future generations maybe.

270:44:46 Irwin: I can only add that we're bringing back just a lot of - lot of data and a lot of material, and it's going to take many years for people to really appreciate how much was gained from - from this flight.

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270:45:05 Henize: Question number 14. It seemed this flight had as many problems as some of the old Gemini missions. Which of these gave you the most concern; and, for Dave, did you ever feel you were back on Gemini VIII?

270:45:23 Scott: Well, I guess we weren't aware we had that many problems. I thought this was a rather trouble-free flight, myself. We went a long way, we spent a long time doing the job, and I think, relative to the number of systems we have in all the spacecraft, that we had very few problems. I can think of none that were significant that would enable me to compare it with Gemini VIII at all. We had a - I guess the first little problem we had was a - a leak in our water system, which was cleared up rather rapidly by somebody having already done some investigation and having a procedure at hand. I believe our system is such that people have all the anticipated problems understood, and, when they have them understood, they come up with solutions which are quite meaningful and successful. And I feel like the spacecraft and the life support systems on the Moon and everything worked exceedingly well. I - I guess really I couldn't ask for much more. [To Jim.] How about you?

270:46:37 Worden (onboard): Well, I really don't...

270:46:38 Scott (onboard): No, go ahead.

270:46:40 Irwin: You know really, we had very few problems. It seemed like a very tame simulation, as far as I was concerned.

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270:46:47 Worden: Certainly, there were - there were - there were irritating things that happened like some circuit breakers in the spacecraft here that gave us some trouble, and some lights that aren't working exactly right. But certainly none of the important aspects of the flight or - or none of the essential pieces of equipment have malfunctioned, and I think it's been just great.

Worden (onboard):Okay, Karl, you take it from there, baby.

270:47:18 Henize: Gentlemen, we'd like to continue the press conference in a few minutes. But, in the meantime, we'd be anxious to get - start - get one of you started on the lunar eclipse photos. We have three more questions.

270:47:28 Irwin (onboard): Yes, turn...

270:47:29 Scott (onboard): We got to try to do both?

270:47:31 Henize: Question...

270:47:34 Scott: Okay...

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270:47:40 Henize: Question number 15...

270:47:35 Irwin (onboard): Why don't we show them the lunar eclipse?

270:47:37 Scott (onboard): (Laughter)

270:47:39 Irwin (onboard): There's a lunar rock to show them.

Henize (continued): ...for Dave and Jim. How many times did each of you fall down on the lunar surface. Did any of these falls hurt you or give you any problems?

270:47:54 Scott (onboard): Let's think, how many times?

270:47:57 Irwin: Well, I fell down twice...

270:47:57 Scott (onboard): Yes.

Irwin (continued): ...and it was never any real problem. Actually, I could have got up very well by myself without any help.

270:48:06 Scott: Yeah, I guess I fell down twice, too, and as Jim said, it was never any real problem. It's a matter of if you start to go - and, of course, the terrain there, I guess you could see the television, was quite rough and irregular with occasionally rocks around, and we were pressing to try and get things done. And it was just a matter if you just start losing your balance, to go ahead and go easy, and accept somewhat of a - a light fall. Because of the one sixth gravity, there was never any impact when we hit. Take it easy and get up slow. And I don't think either one of us ever came anywhere near the point of being hurt, in that sense of the matter, it's just a matter of slowing you up for a minute, enabling you to regain your balance, and go ahead. And I - I have a question. Do you want to have the photos of lunar eclipse with the television now, or do you want us to get on with the - the camera photos? Because if that's the case, we have to turn the lights out in here.

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270:49:13 Henize: Rog. We're going to skip down to the last question, Dave, which says your cabin must be jammed with Moon rocks, core samples, suits and assorted hardware. Can you show us what it's like in there? And, as you show us around, you can get set up for the Moon photos and dim the lights when you like.

270:49:28 Worden (onboard): Oh, man.

270:49:29 Irwin (onboard): (Laughter) Ohh!

270:49:30 Scott: Okay. I guess...

270:49:31 Worden (onboard): (Laughter)

Scott (continued): ...to show you around, we have to unstow everything. We're - we're pretty well stowed for reentry right now. We have all the samples stowed, the suits are all stowed, and I guess, in order to show you around, we'd have to do some unstowing because under - beneath the couches right now, it's jammed full. And I guess we'd like to do that for you, but it's some - somewhat impractical, in that all you're going to see would be some edges of some white bags, and that's why we have the room in the cabin here. Every - everything's pretty well squared away. But, when we get back, I'm sure you'll have an opportunity to see the many things we have, and there's really a lot of it.

[Since all three crewmembers are seated in front of the camera, it seems they have missed the T-start time of 270:49:53 for the second tranche of lunar eclipse photos. However, the eclipse is a slow event and it is not too much of a concern if the timings are out slightly.]
270:50:12 Henize: O - okay, Dave. That's fine. And I guess one last request is when you get over to that window to - and before you take the photos, could you give us a quick picture of the Moon with the TV camera?

270:50:25 Scott: Sure will. [Long pause.]

270:50:26 Scott (onboard): Can try it.

270:50:31 Worden (onboard): (Humming)

270:50:37 Scott (onboard): Have I got any pictures? I'll cut this thing down.

270:50:40 Worden (onboard): (Humming)

270:50:42 Scott (onboard): See any magazines?

270:50:43 Worden (onboard): Yes...

270:50:44 Irwin (onboard): Right here's some, Dave. I got Al's. You got some? Procedures, cameras...

270:50:55 Worden (onboard): You ought to get over here.

270:50:56 Scott (onboard): Let me get over there.

270:50:56 Henize: 15, the word here is to proceed; give your photography first priority there, and maybe we can see the - the Moon out of the other window.

270:51:09 Worden (onboard): That's ...

270:51:11 Scott: Okay. We're working on it. [Long pause.]

270:51:10 Scott (onboard): Okay, we're working on it.

270:51:14 Worden (onboard): Oh, ...

270:51:17 Irwin (onboard): Got enough?

270:51:27 Irwin (onboard): Hold it, Al. It's still going...

270:51:29 Scott (onboard): Monitor? Yes, I can get it from here. I think.

270:51:56 Henize: 15, Houston. We hear that your attitude is very good right now; there's no need to trim the maneuver.

Real Video file (657K)

270:52:03 Scott: Okay. Thank you.

[Comm break.]
270:52:05 Irwin (onboard): Okay, Al, you got the camera all set up over there, huh?

270:52:08 Worden (onboard): Yes.

270:52:09 Irwin (onboard): Do you want me to read the settings to you, just in case?

270:52:10 Worden (onboard): Yes.

270:52:11 Irwin (onboard): There's a change.

270:52:12 Worden (onboard): Yes.

270:52:14 Scott (onboard): If you'll grab those ...

270:52:18 Irwin (onboard): What do you want me to get, Dave? Get the lights? Yes, I can get them.

270:52:24 Worden (onboard): If you can get the lights -

270:52:38 Irwin (onboard): Turn this up a little bit. Okay, Al, when you're ready for me, I'll read to you.

270:52:50 Scott (onboard): Could that be it?

270:52:53 Worden (onboard): Need anything down there, Dave?

270:52:55 Scott (onboard): No, I don't think so. See what it looks like.

270:53:01 Irwin (onboard): Well, it's completely dark now. Just the lower part is orange.

270:53:04 Scott (onboard): Yes.

270:53:07 Irwin (onboard): The top part's almost a red, a dark red, and the bottom is an orange.

270:53:11 Worden (onboard): Here.

270:53:12 Scott (onboard): There you go. Yes, you got her. 270:53:16 Scott: Okay, Houston. I think you have a picture of her now. There she is.

270:53:19 Worden (onboard): Okay.

270:53:20 Irwin (onboard): Okay. Let's check it; f/1.2?

270:53:23 Worden (onboard): Yes.

270:53:24 Irwin (onboard): 1/500th?

270:53:25 Worden (onboard): Right.

270:53:26 Irwin (onboard): Take eight frames? Okay, I guess we'll give priority to you, huh, Al?

270:53:30 Scott (onboard): Okay, we - we got to get the...

270:53:31 Henize: 15, so far we have a blank screen down here.

270:53:37 Scott: Oh, really? I've got a good picture on the monitor.

270:53:41 Worden (onboard): Okay, Jim, while...

270:53:42 Henize: Hang on for a moment, please. [Pause.]

270:53:43 Irwin (onboard): Okay, we're coming up on 6 minutes here at 55...

270:53:47 Worden (onboard): Besides, we're Free here.

270:53:49 Scott (onboard): Boy, every time those - the jet fires ...

270:53:52 Irwin (onboard): Okay, go - we're Free.

270:53:54 Worden (onboard): Okay, Jim.

270:53:55 Henize: It's coming through now. [Pause.]

270:53:57 Worden (onboard): Okay, Jim.

270:53:58 Irwin (onboard): Okay, stand by. Your first one'll be a 60-second exposure time and I'll - it'll be at 55:53.

270:54:06 Worden (onboard): Well, that's kind of - not ...

270:54:07 Henize: That's a beautiful picture with just an edge of the Moon coming out of the eclipse.

270:54:11 Worden (onboard): I can do it anyhow.

270:54:12 Irwin (onboard): Can you?

270:54:14 Scott: Rog. That's right.

270:54:17 Irwin (onboard): Okay. Suit yourself then. I'm...

[Comm break.]

[The TV picture shows a copper-coloured Moon which is steadily brightening on one side.]

270:55:18 Henize: 15, Houston. We'd like to ask if you got full zoom there?

270:55:26 Scott: Roger. It's all the way out.

270:55:38 Henize: Could you please give us ALC [Automatic Level Control] to Peak [to try and give the picture more contrast]?

Real Video file (1,076K)

270:55:43 Scott: All right. I think we are - stand by one.

[Long comm break.]

[Flight Plan page 3-385.]

Real Video file (838K)

270:59:51 Gordon: Hello, Endeavour; this is Yankee Clipper. Over.

270:59:57 Scott: Hello, Yankee Clipper. How are you?

[Dick Gordon was the Command Module Pilot of the Apollo 12 CSM, Yankee Clipper.]
270:59:59 Gordon: Roger, I've got a naval tradition to pass on to you.

271:00:03 Scott: Go ahead.

271:00:05 Gordon: Roger. When ships of the line have completed a mission such as yours and they return to home port, they always have a broom flying from the yardarm. Over.

271:00:19 Scott: Rog. Well, we'll do that.

271:00:22 Gordon: Thank you.

271:00:25 Scott: We wouldn't want to break any traditions, Dickie.

271:00:33 Gordon: Dave, I'm watching you; I wouldn't let you.

271:00:37 Scott: Atta boy, and I'm glad.

271:00:54 Scott: Okay, Houston. We're going to switch windows here with the TV camera, so we can switch windows with the camera cameras.

271:01:08 Gordon: Roger, Dave. [Long pause.]

271:01:49 Parker: 15, Houston. When somebody gets a free hand up there, could we start the charge on battery A? We're afraid that might keep us from going to bed if we don't get it started soon.

[Comm break.]
271:03:40 Scott: Houston, the Moon is an orange ball, now - a dull orange ball with a sort of a gray area in the center on - on one side opposing the side that's slowly coming into illumination at the present time, and you'll possibly get more and more of the lunar surface exposed to sunlight as we go along here. The picture you have is really pretty good for what we see, because there's very little illumination on the Moon. And only when we get the cockpit lights down reasonably low and get our face up in the window can we see the definition. So it's really not a bad picture.

271:04:23 Parker: Roger, 15. Thanks for the description, and the picture we're getting down here is quite good also.

Real Video file (1,426K)

271:04:31 Scott: Okay, I'm sure you'll have a much better one here in a few minutes.

[Long comm break.]

[The second period of lunar eclipse photography essentially reverses the procedure used first time around. See page 3-384 of the Flight Plan for details. Coordinating the sequence with the Mission timer, a series of photos are taken using the Nikon with the exposure time decreasing at 6, 7, 8, 9, 10 and 11 minutes on the timer. They then change to the Hasselblad and take images at 11, 13, 16, 19, 22 and 25 minutes. The Hasselblad photographic record shows 5 frames taken using the 80-mm lens and 4 taken with the 250-mm lens. AS15-96-13122 shows an example from the former, AS15-96-13125 is a somewhat smeared example from the latter.]

271:12:02 Parker: Apollo 15, Houston. Over.

271:12:07 Scott: Houston, 15. Go.

271:12:09 Parker: Roger. It looks like you've had enough of the pho - [TV] photography for right now. It's beginning to get pretty bright on the tube. I guess we can go ahead and power it down.

271:12:22 Scott: Okay. [Pause.]

271:12:33 Scott: That's interesting, Houston, because it looks like only about - oh, maybe 1/20th or so, maybe, of the Moon is illuminated at this time; just a thin sliver, but very bright.

271:12:46 Parker: Roger. Copy, Dave.

[Long comm break.]
Public Affairs Officer - "CapCom is Bob Parker, now. And as the camera was powered down, Apollo 15 was 107,495 nautical miles [199,080 km] from Earth. Velocity: 4,888 feet per second [1,490 m/s]."

271:15:49 Worden: Roger.

[Comm break.]
271:17:32 Parker: Apollo 15, Houston. Request S-band Aux to Science, please.
[Two switches on panel 3 allow the auxiliary channel on the S-band radio system to be switched to carry information from 4 different sources. They are: Mission Control want to receive data from the SIM bay at this time.]
271:17:41 Scott: Roger.
[Very long comm break.]
Public Affairs Officer - "This is Apollo Control at 271 hours, 20 minutes. Shift change is underway in the Control Center. ..."

271:39:11 Scott: Houston, Apollo 15.

271:39:16 Parker: Roger, Apollo 15; go ahead.

271:39:19 Scott: In getting ready for contamination photography, we find that we've got a - a certain number of exposures left in the Nikon. Namely, we're on exposure number 29 in mag Victor, and we think we have 45 total, which would enable us to complete the contamination photography with the Nikon, if you desire, rather than with the DAC, as you changed.

271:39:52 Parker: 15, they plan on using those last 15 frames or so on Victor for postmission calibration, so we still intend to press on with the DAC, please, Dave.

271:40:04 Scott: All right, understand. Thank you.

271:40:08 Parker: And, Dave, if you'll give us start time on that, I'll give you a call at the end, because we want you to cycle some extra film through the DAC to give them a little leader there at the end to protect their film or something.

271:40:22 Scott: Okay, we'll do that. Stand by.

[Long comm break.]
271:47:23 Parker: Apollo 15, Houston. Over.

271:47:28 Scott: Go ahead, Bob.

271:47:29 Parker: Roger. We were seeing the Optics tripped around against the hard stops. We'd like to have you bring them back and then zero them in, per the usual procedure. We kind of guess your getting ready for [a P]52 anyway, aren't you?

271:47:42 Irwin: Pretty soon.

[This is the P52 platform realignment which was read up to the crew at 268:39:48.]

[Long comm break.]

271:54:22 Parker: And, 15, we have your torquing angles. You go to torque.

271:54:27 Scott: Roger; in 30 seconds.

[Very long comm break.]

[Flight Plan page 3-387.]

272:07:49 Parker: Apollo 15, Houston. If one of you guys is free, we've got some updates we could read to you.

272:08:06 Scott: Okay, Houston; 15. Stand by one.

272:08:12 Parker: Okay, understand you're ready. What - the first thing is an entry PAD. So you might whip out your Entry Checklist. [Long pause.]

272:09:26 Worden: Okay, Houston; 15. Go ahead and [garble] from that.

272:09:30 Parker: Roger. Would you believe it, we're going to land in mid-Pacific? And after that, it's 000, 153, 000; 294:41:37, 267, plus 26.12, minus 158.10; 06.2; 36097, 6.50; 1084.8, 36179; 294:58:37; 00:29; Noun 69s are NA; 4.00, 02:13; 00:18, 03:38, 07:44; 04, 140.3, 37.5; 213, down, 09.6, right, 4.7; lift vector, up. Comments: 1. Use nonexit EMS pattern, 2. RET of 90K, 6 plus 06, RET of mains, 8 plus 32; landing, 13 plus 29; constant g, roll right; Moon set time, 294:56:20. Over.

[The data passed up for this entry PAD is interpreted as follows:

Purpose: This is a very preliminary entry PAD, intended to give the crew something to get them home should communications be lost. Tomorrow, prior to re-entry in 22 hours time, another entry PAD will be read to them, then they will make a final correction to their trajectory before the final entry PAD is read to them.

Landing target: Mid-Pacific landing site.

IMU gimbal angles required for trim at 0.05g: Roll, 000°; pitch, 153°; yaw, 000°.

Time of the horizon check: 294:41:37.

Spacecraft pitch at horizon check: 267°. This is 17 minutes before time of entry.

Splashdown point: 26.12° north latitude, 158.10° west longitude.

Maximum number of g's during entry: 6.2.

Velocity at 400,000 feet altitude (about 66 nautical miles or 122 km): 36,097 feet/second (11,002 meters/second).

Entry flight path angle at 400,000 feet: 6.50°.

Range to go to splashdown point from 0.05g event: 1,084.8 nautical miles (2,006 km).

Predicted inertial velocity at 0.05g event: 36,179 feet/second (11,027 meters/second). This is required to set the starting condition of the EMS.

Time of Entry Interface (400,000 feet): 294:58:37.

Time from Entry Interface to 0.05g event: 0:29 (seconds).

Planned drag level (deceleration or g-force) during the constant-g phase: 4.00.

Time from Entry Interface until their velocity slows sufficiently to allow a circular orbit around the Earth: 2:13.

Time from Entry Interface that the communications blackout begins: 0:18.

Time from Entry Interface that the communications blackout ends: 3:38.

Time from Entry Interface that the drogue parachutes will deploy: 7:44.

Sextant star: 04 (Achernar, Alpha Eridani.)

Sextant shaft angle at Entry Interface minus 2 minutes: 140.3°.

Sextant trunnion angle at Entry Interface minus 2 minutes: 37.5°.

The next three items refer to an attitude check made using the COAS sighted on a star two minutes before Entry Interface.

Boresight star: 213. Since this is not a recognised star number from the Apollo list, we have yet to learn what it refers to.

Boresight Star pitch angle on COAS: Down 9.6°.

Boresight Star X position on COAS: Right 4.7°.

Lift vector at Entry Interface: Up.

Comments in addition to the PAD:

The non-exit EMS pattern is to be used, that is, the entry is not expected to skip off the atmosphere and re-enter.

90,000 feet (27.4 km) will be reached at 6:06 after Entry Interface.

Time of main parachute deployment: 8:32 after Entry Interface.

Time of landing: 13:29 after Entry Interface.

When maneuvering to ensure a constant g force (done after the max-g portion of the entry to assure a constant deceleration), the crew is to roll right.

Moonset (used to provide one more check of the entry progress): 294:56:20.]

272:12:11 Worden: Okay, Houston. Understand. Entry PAD, mid-Pac; 000, 153, 000; 294:41:37, 267; plus 26.12, minus 158.10; 06.2; 36097, 6.50; 1084.8, 36179; 294:58:37; 00:29; 4.00, 02:13; 00:18, 03:38, 07:44; 04, 140.3, 37.5; 213, down, 09.6, right, 4.7; lift vector, up. Comments: nonex - use nonexit EMS pattern; RET 90K is 6 plus 06; RET mains, 8 plus 32; RET landing, 13 plus 29; constant g is roll right, Moon set at 294:56:20.

272:13:27 Parker: Roger, Al. Good readback. And we'd be interested in knowing the status of the EMS check you ran 2 or 3 hours ago, if you have it.

272:13:36 Worden: Yes, sir. The EMS check was just fine.

[This check of the EMS was called for by the Flight Plan right after the first set of lunar eclipse photos. This is a range of test built into the EMS to check its performance and calibration, particularly of the scribe which will trace a line across a roll of paper during re-entry in response to the CM's velocity and the g-forces acting on it.]
272:13:39 Parker: Okay, that's good to know. At the end of your contamination experiment here, we'll be going into this Mass Spec. boom test. And, if you guys let me know when you're ready, we've got a procedure to read up to you for that - that we'll read up to you at that time. I assume you've been told that we aren't going to a midcourse 6, and right now mid-course 7 is looking like .09 [feet per second] which is - makes it kind of problematical as to whether we burn it or not. Weather in the recovery area is currently predicted to be, for your splashdown, 15-knot winds, 4-foot seas, 2,000 scattered, 10 miles - in other words, looking better and better all the time.

272:14:24 Worden: Roger, Bob; that sounds great.

[Very long comm break.]

[With the sixth midcourse correction burn cancelled, their workload is relaxed and they can carry out an extra experiment to try and photograph the cloud of gases generated when they make a water or urine dump. This information is helpful in understanding the results from the Mass Spectrometer.]

[Also, concerning the Mass Spectrometer's boom, Mission Control want to carry out a test that may determine the cause of the difficulties they have been having in deploying and retracting the boom. This test will occur in twenty minutes.]

272:26:56 Parker: Apollo 15, Houston. If you'll give us Accept, we'll give you a very slight clock update to sync you for entry. And be advised we will not be sending a state vector uplink at this time; your vector is still just as good as the one on the ground.

272:27:14 Scott: Roger; understand, and you've got Accept. [Long pause.]

[If the calculations made by the onboard computer are to be relevant, its clock must match those on Earth which are making the same calculations.]
272:28:18 Parker: 15, your computer.

272:28:22 Scott: Roger. Thank you.

[Long comm break.]
272:37:33 Parker: 15, Houston. Request you trim back to original attitude now.
[This is the attitude read up at 268:38:02 which they use for the contamination photography.]
272:37:40 Scott: Okay.

272:37:46 Parker: And again, if one of you has a couple of minutes, we can tell you a couple of other things.

272:37:53 Scott: Okay, in - in other words, you want us to maneuver back to the original attitude, rather than just damp rates, huh?

272:38:01 Parker: Roger; yes. We'd like to use the same star backgrounds; so that means going back to the original attitude in the Flight Plan around 271:20 or so...

272:38:15 Scott: Okay.

272:38:16 Parker: Which is what you got called up.

272:38:20 Scott: No, we don't have that called up. All we have is damp rates, but we'll do that. [Realises the Flight Plan has been updated.] Oh, what we have called up here? Yeah, okay.

[Comm break.]

[The fuel cell purge, due about now, is held off until 273 hours.]

272:40:31 Parker: And, 15; Houston. If one of you has some time, we'd like to talk about some stowage, please.

272:40:39 Scott: Okay, go ahead.

272:40:41 Parker: Okay, we've gone over the stowage which you read down this morning, and everything's shipshape, except we have one question on one item and that concerns the stowage of the core stems. The core stems should be stowed in the sleep restraint that has the CMP's PGA in it. We understand that it's now stowed in the bag on the side of A-8. I guess our first question is, how many - How long is the core stem at the present time? Did you break it down, or is it still three sections long, which we think it is on the ground.

[While on the surface, Dave was unable to break down the six sections of the three-metre-long core stem after he had removed it from the regolith. Three sections are still joined as a pole 1.5 metres long which is difficult to stow in a crammed place like Endeavour's cabin. Compartment A-8 is on the right-hand side of the aft bulkhead (against the heatshield) beneath what is normally Jim's couch position.]
272:41:16 Scott: No, it's still three sections long, and we could put it in the sleep restraint. It just seemed like a convenient place to stick it in the bag over there to keep it tied down well.

272:41:24 Parker: Okay. Next question is, how'd you get it in the A-8 bag, which according to our measurements on the ground is only 36 inches [92 cm] long and, therefore, apparently not long enough to hold the three lengths of core stem?

272:41:37 Scott: Well, it's sticking out a little bit, I guess we have to admit, but it's pretty well cinched down.

272:41:42 Parker: Okay, stand by.

272:41:47 Scott: But it's no problem; we can put it any place you like.

272:42:05 Parker: Okay, Dave, I guess we - I don't think it makes an awful lot of difference, but it'd probably make a lot of other people happy if we ended up putting it in the sleep restraint. They wouldn't worry about that loose end hanging out there - if it's not too much trouble.

272:42:20 Scott: Oh, it's no problem at all; be glad to do that.

272:42:23 Parker: Thank you.

272:42:24 Scott: You know, we know what number one priority on this spacecraft is.

[This is a humorous reminder from Dave of what the core stem cost to extract; in terms of time, effort and lost exploration of other regions at Hadley Base. To him, it is a very expensive sample and worth caring for.]
272:42:34 Scott: We wouldn't - we wouldn't lose that or misplace it or get it rattled around for anything, Bob.

272:42:44 Parker: No comment.

272:42:51 Scott: And you say everything else is okay, huh?

272:42:53 Parker: Roger. Everything else is A-okay.

272:42:58 Scott: Oh boy.

[Long comm break.]
272:46:21 Parker: And, 15, reminder or a question. Did you guys get the word that they like a pad of about 2 seconds worth of 24 frames per second at the end of those photos to protect these things?

272:46:25 Scott: Roger; we got that, Bob. Thank you.

272:46:47 Parker: And if you guys'll give me a call when you're ready to do the Mass Spec. boom test, I'll read it up to you.

272:46:54 Scott: All righty, Houston; stand by. [Long pause.]

272:47:36 Worden: Houston, 15.

272:47:37 Parker: Go ahead, 15.

272:47:41 Worden: Okay, you going to read up the procedures real time on the Mass Spec. boom?

272:47:44 Parker: Roger.

272:47:47 Worden: Okay, why don't we go ahead and do that, then, while we're finishing up the contamination photos?

272:47:52 Parker: Okay, stand by. Okay, 15, first step is Mass Spec. boom to Retract, talkback barber pole for 4 minutes or until gray. If talkback fully gray within 4 minutes, deploy boom and return to Flight Plan. Over.

[Before Apollo 15 took the first flight example to the Moon, it was expected that the boom carrying the Mass Spectrometer would take about 2 minutes, 40 seconds to deploy and retract. In use it has proved balky; sometimes working perfectly, sometimes stalling before reaching full retraction.]

[While operating the boom from panel 230, Al has a talkback indicator to inform him of the boom's status. It shows a striped pattern while the boom is on the move, changing to a gray flag once the limit of motion is reached. Stalling of the motor is indicated by a half gray flag.]

[There is a suspicion that the problem is associated with the temperature of the mechanism and the cable harness surrounding the boom. At their current attitude, the SIM bay is out of the Sun and is being chilled by facing deep space. Mission Control want to try and retract it while cold and are giving it plenty of time to make it.]

272:48:22 Worden: Roger. Understand you want retract on the Mass Spec. boom for 4 minutes, and, if it goes gray before then, go back to deploy and return to the Flight Plan.

272:48:32 Parker: That's affirm. And give - give us a call when you get done.

272:48:39 Worden: Roger.

[Long comm break.]
272:52:38 Worden: Come in, Houston; 15.

272:52:41 Parker: Go ahead, 15.

272:52:43 Worden: Okay, there's 4 minutes of Retract, and it's still barber pole.

[The motor that drives the boom has stalled.]
272:52:47 Parker: Okay, if the talkback is not fully gray in 4 minutes, let's go to Mass Spec. Boom, Off, center, for one minute. That's just to let the motor cool down.

272:52:57 Worden: Okay, it's off now.

272:52:59 Parker: Okay. [Pause.]

272:53:06 Worden: And what at the end of the one minute?

272:53:08 Parker: Okay, at the end of the one minute, we will deploy it for 20 seconds and then Off, center, and then we will retract for 40 seconds or until the talk back is one half barber pole [stalled] or fully gray [retracted] and then Off. Over.

272:53:25 Worden: Okay, got you. [Pause.]

272:53:37 Worden: Okay, going to extend.

272:53:39 Parker: Okay.

272:53:49 Worden: And do you want to pause it off between extend and retract?

272:53:53 Parker: Stand by. Not necessary to pause between Deploy and Retract on this.

272:54:03 Worden: Okay, it's in Retract now.

272:54:05 Parker: Copy. [Long pause.]

272:54:43 Worden: Okay, Houston, that's the 40 seconds of Retract, and it's at half barber pole, and I turned it off.

[The motor has stalled again.]
272:54:49 Parker: Okay. In that case, we'd like you to repeat the 20-second Deploy, 40-second Retract sequence twice more and, if gray talkback is still not obtained, we'll turn it off and wait until 275 hours, at which point we'll give you a call and we'll replay - we'll repeat that. Over.

272:55:08 Worden: Okay, fine. We'll cycle that whole thing twice more.

272:55:12 Parker: Roger.

[Comm break.]
272:57:16 Parker: 15, Houston. We'd like to proceed with the fuel cell purges now to get those out of the way before the P23s.

272:57:25 Worden: Roger, Houston. [Long pause.]

[About now, the fuel cells are to be purged to remove impurities in the H2 and O2 reactants by flowing these reactants through them. Earlier, a heater for the H2 purge line was switched on to ensure that when the purge occurs, only gaseous H2 at a high enough temperature reaches the fuel cell. The H2 is stored at temperatures near absolute zero and it is critical that the cells are not allowed to become too cold.]
272:58:19 Worden: Houston, Mass Spec. boom has been cycled three times. All I can get out of it is a half barber pole, and I've got it turned off right now.

272:58:28 Parker: Roger; copy, Al. We'll call you at 275 hours to repeat that, the reason for that is that presently we are sort of sitting in a cold-soak attitude. We're going to repeat it at 275 hours when we're sort of in a hot-soak attitude.

272:58:43 Worden: Okay.

[At that time, Endeavour will be carrying out some more x-ray astronomy in an attitude which will face the SIM bay towards the Sun.]

[Flight Plan page 3-389.]

[Very long comm break.]

273:09:41 Parker: Apollo 15, Houston. We'd like to go to Ion Source, Off, and Mass Spec. Experiment to Standby.

273:09:52 Worden: Ion Source, Off, and Mass Spec. to Standby.

273:09:55 Parker: Roger.

[Very long comm break.]

[Al continues with the third of four P23 cislunar navigation sightings he will complete today. As before, he first calibrates the pointing of the optics by sighting on Dnoces, a star, otherwise known as Iota Ursae Majoris but named by the Apollo 1 crew after Edward White II, the CMP of that crew. "Dnoces" is "second" spelled backwards.]

[For these navigation sightings, Al measures the angles between Elnath (Beta Tauri) and Earth's horizon furthest from the star, Capella (Alpha Aurigae) and Earth's horizon furthest from the star, and, finally, Alphard (Alpha Hydrae) and Earth's horizon nearest the star. Then, using P23, he can calculate if there needs to be any update to the current state vector, displaying that result as a change in position and a change in velocity.]

Public Affairs Officer - "This is Apollo Control. The crew has completed the program 23 midcourse navigation exercise, aboard the spacecraft, and should be beginning their eat period - or are already into it at this time. Before we put them to bed, they'll have one more set of navigation sightings to take on a series of stars. And we'll put the spacecraft in a Passive Thermal Control mode. The rest period is scheduled to begin at 277 hours, 30 minutes, or about 4 hours from now. Apollo 15 at the present time is 101,214 nautical miles [187,448 km] from the Earth, and traveling at a speed of almost 1 mile per second. We're reading 5,137 feet per second [1,566 m/s]."

273:28:48 Parker: 15, Houston. Al, we missed your last Noun 49 [change in position and change in velocity].

273:29:08 Worden: Okay, I'll show you this one.

273:29:10 Parker: Thanks.

[Very long comm break.]

[Endeavour has been holding attitude to a ±0.5° deadband all day. Now, with the P23s out of the way, the DAP can be reconfigured to change this to a ±5° deadband, which is less fuel hungry. This is done by entering all ones into the registers called up by Verb 48.]

273:39:30 Parker: 15, Houston. Looks like a good set of P23s again, Al. And your gamma, right now, on your vector, is 6.5.
[This means that the predicted re-entry angle, based on the current state vector, is 6.5°.]
273:39:48 Worden: It sounds like, after a while, we might get along without you, huh, Bob.
[Which, after all, is the object of the exercise.]
273:39:55 Parker: No comment.
[Al then rubs it in.]
273:39:59 Worden: As a matter of fact, if you guys keep working on your ground [calculated] vectors, they might even converge to the onboard vectors pretty soon.
[Very long comm break.]

[Flight Plan page 3-390.]

274:05:15 Parker: Apollo 15, Houston. Over.

274:05:19 Worden: Go ahead, Houston; 15.

274:05:21 Parker: Roger; 274:05, we'd like to delete the Mass Spec. line, where you turned on Multiplier, Low, et cetera. We'll delete that.

274:05:32 Worden: Okay. We'll delete that line, Robert. Thank you, sir.

274:05:35 Parker: Thank you. [Long pause.]

274:06:12 Worden: And, Houston; 15.

274:06:14 Parker: Go ahead, 15.

274:06:16 Worden: Roger; want us to - delete the Logic Power, two, if we're going to do the Mass Spec. at 275?

274:06:28 Parker: 15, that's affirm.

274:06:33 Worden: Okay. [Long pause.]

274:06:44 Parker: And, 15; Houston. You got any more updates to our Flight Plan?

274:06:51 Worden: No, but I'll scan it over; and, if I find any, I'll let you know.

[Very long comm break.]

[ At 274:15 GET, the SIM bay, and therefore the X-ray Spectrometer, are aimed at the north galactic pole for a 30-minute period of data gathering. As has been done twice before, the intention of aiming the instrument at this arbitrary direction, rather than at a specific known source of x-rays, is to measure the background x-ray flux, see how strong it is in comparison with the other arbitrary directions the instrument was pointed, and to look for any variability in these readings which gives a control reading against which any variability seen from the known sources can be compared.]

274:37:29 Parker: Apollo 15, Houston. Over.

274:37:33 Scott: Houston, 15. Go.

274:37:35 Parker: Roger; we have an update to the Flight Plan, if you guys are ready to copy.

274:37:41 Scott: Roger. We're ready to copy.

274:37:43 Parker: Okay. The attitude that we maneuver to at 274:46 there, for the second set of X-rays should be changed - that Verb 49 maneuver, should be changed to 196, 346, 012. Over.

274:38:14 Scott: Roger. Understand the Verb 49 maneuver to X-ray pointing attitude should be changed to 196, 346, 012.

274:38:25 Parker: Roger. And, before we start that Verb 49 maneuver at 274:45 or thereabouts, we'd like to cover the ex - We'd like to close the experiment covers, Alpha/X-ray, to Close. That's the one on panel 278. And then after we get to attitude at about 275:00, we'll go ahead and open those covers again, the Alpha/X-rays.

274:39:03 Scott: Roger. Understand, you want the Alpha/X-ray covers closed before the maneuver and opened after the maneuver.

274:39:09 Parker: Roger. These - the new position I sent you up on that - Those two steps there in the procedure are to keep from getting sunlight right in on some of the stuff to protect it. And...

274:39:19 Scott: Okay.

274:39:20 Parker: ...and, also at this time, you may terminate the battery A charge.

274:39:26 Scott: Okay, terminating the battery A charge. [Long pause.]

274:40:16 Scott: Houston, 15.

274:40:18 Parker: Go ahead, 15.

274:40:21 Scott: Roger, Bob. Do you want us to go to Standby on X-ray while the door is closed, or is it okay to leave it on?

274:40:29 Parker: Roger. You can leave it on - Dave.

274:40:34 Scott: Okay.

[Long comm break.]

[At 274:45, the spacecraft is maneuvered around to face the X-ray Spectrometer towards a point in space opposite the centre of the galaxy. As requested five minutes ago, the instrument's cover will be closed prior to the maneuver as there is a possibility that as the spacecraft is rotated around, sunlight might impinge on it. The change in attitude also affects which omni-directional antenna is best placed for communication with Earth.]

274:45:29 Parker: Apollo 15, Houston. Request Omni Charlie, please.

274:45:39 Irwin: Omni Charlie.

[Long comm break.]
274:49:33 Parker: Apollo 15, Omni Delta, please.

274:49:38 Irwin: Roger. Omni Delta.

[Very long comm break.]

[Flight Plan page 3-391.]

[Once the spacecraft is settled at its new attitude, a 1-hour period of measurement with the X-ray Spectrometer begins. Once again, this is a control reading rather than of a discrete, known source. Meanwhile, the crew begin the last meal of the day.]

275:07:09 Scott (onboard): Anybody else like chicken stew?

275:07:14 Irwin (onboard): Chicken stew, huh? Yes, I do. I didn't know we had any. Is that what you have up there?

275:07:31 Worden (onboard): Yes.

275:07:32 Scott (onboard): No, uh-uh.

275:07:44 Irwin (onboard): If you want to eat here, I'll be happy to come down the re.

275:08:31 Irwin (onboard): Hey, throw me some beef steak. Well, I guess some turkey and gravy.

275:08:50 Scott (onboard): ...

275:08:52 Irwin (onboard): Go back where? Yes, man, you aren't kidding.

275:08:58 Worden (onboard): Thought you wanted to go back to the Moon?

275:08:59 Irwin (onboard): Don't know why.

Public Affairs Officer - "This is Apollo Control at 275 hours. Apollo 15, at the present, time 96,347 nautical miles [178,434 km] from Earth, and traveling at a speed of 5,342 feet per second [1,628 m/s]. A short while ago, the recovery room here in the Control Center reported that the prime recovery ship is headed toward the target point in the Pacific Ocean - north of Hawaii. Seas in the predicted landing point are 4 feet, clouds are 2,000 broken, and we expect to have 15 knot winds at splash time tomorrow - generally very good weather predicted in the recovery area. The crew is scheduled to begin an eat period at this time. Following that, they have one more set of star sightings to take - mid-course navigation. Prior to putting the spacecraft in the Passive Thermal Control mode - after eating, rather, they'll put the spacecraft in the Passive Thermal Control mode prior to beginning their 9-hour rest period. And on the clock that's counting down towards splashdown, we show 20 hours, 9 minutes, 40 seconds now until splashdown."

275:09:26 Irwin (onboard): I'll trade with you, Dave.

275:09:27 Scott (onboard): All right.

275:09:28 Irwin (onboard): I'll go down there.

275:09:31 Scott (onboard): Down here?

275:09:32 Irwin (onboard): Yes.

275:10:37 Irwin (onboard): This is our new garbage can down here, huh? Good.

275:10:49 Irwin (onboard): You want to get those readings now, Al, or after supper?

275:10:52 Worden (onboard): I don't care.

275:10:54 Irwin (onboard): Get them now?

275:11:03 Worden (onboard): Okay. Start out with 5-C.

275:11:13 Irwin (onboard): 5-C reading 4 - 4.2.

275:11:19 Worden (onboard): All right; 5-D?

275:11:23 Irwin (onboard): 3.9.

275:11:25 Worden (onboard): 6-A?

275:11:26 Irwin (onboard): You writing them down?

275:11:28 Worden (onboard): Yes.

275:11:30 Irwin (onboard): 6-A is 4.1.

275:11:34 Worden (onboard): Okay; 6-B?

275:11:37 Irwin (onboard): 4.2.

275:11:42 Worden (onboard): 6-C?

275:11:45 Irwin (onboard): Greater than 5.

275:11:48 Worden (onboard): No kidding. Huh. Okay...

275:11:53 Parker: Apollo 15, Houston. Over.

275:11:54 Worden (onboard): ...6-D?

275:11:57 Scott (onboard transcript gives Worden): Houston, 15. Go ahead.

275:11:59 Parker: Roger. Remember back aways, we were talking about doing some more Mass Spec. boom tests at 275 hours, which is gone by. We're right now talking about delaying that until 276 hours, approximately, or at least until before you start your Verb 49 maneuvers for the next set of P23s. Over.

275:12:23 Scott (onboard transcript gives Worden): Okay, fine.

275:12:21 Worden (onboard): Okay, fine. 6-D.

[The final series of P23 navigation sightings is due at 276 hours, right after the current period of x-ray data collection and the crew's meal break is over.]
275:12:25 Parker: We're just letting it [the Mass Spectrometer's boom] heat-soak a little bit longer.

275:12:26 Irwin (onboard): Is that okay on 6-C, the fact that it's...

275:12:28 Worden (onboard): I don't know; we'll tell them.

275:12:30 Irwin (onboard): Okay, 6-D is 45.

275:12:36 Worden (onboard): Okay.

275:12:39 Scott (onboard transcript gives Worden): And, Houston; 15. I have some Command Module RCS injector temperatures for you.

275:12:45 Parker: Ready to copy.

275:12:48 Worden: Okay, these are readings off the Systems Test Meter. 5-A is 4. - or 5-C is 4.2; 5-D is 3.9; 6-A is 4.1; B is 4.2; C is greater than 5; and D is 4.5.

275:13:08 Parker: Roger. Copy 4.2, 3.9, 4.1, 4.2, greater than - and 4.5.

275:13:16 Worden: Roger.

[At 274:50 in the Flight Plan there is a call for the temperatures of the injector valves for four of the Command Modules RCS engines to be read, using the Systems Test Meter. While they need to be warm enough to accept propellant tomorrow during re-entry, it is unknown at the time of writing why they are being measured now. The Systems Test Meter is a simple way of allowing the crew to access many of the less important readings from the vast array of sensors that monitor the overall health of the spacecraft. The meter is mounted on panel 101, next to the spacecraft optics controls in the Lower Equipment Bay.

Panel 101 - the Systems Test Meter

The two rotary switches give access to a 'seven by four' matrix of signals allowing 28 different measurements to be available to the crew. The outputs of the spacecraft's sensors are normalised by the Signal Conditioning Equipment such that the required range of each sensor is expressed between zero volts and five volts. This preparation to a standard form makes it easy to telemeter the voltages to Earth, and it allows the crew to access a wide variety of readings using a single voltmeter without taking up precious space in the instrument panels. The drawback is that reference must be made to spacecraft handbooks to interpret the readings. To take the first reading, for example, at position 5-C, this setting gives the injector temperature of the secondary pitch-down thruster on the Command Module. The full range of 0V to 5V represents a temperature range of -50° to +50° Fahrenheit (-45.5° to +10° Celsius). The nominal value for this is greater than 28°F or a reading greater than 3.9V on the meter. In the event, all the readings read down by the crew are nominal.]

[Very long comm break.]

275:13:30 Irwin (onboard): Here, put it on there, I'll give you a squirt. How many do you want?

275:13:37 Scott (onboard): Is that the soup?

275:13:41 Worden (onboard): Chicken stew.

275:13:42 Irwin (onboard): How many do you want?

275:13:43 Scott (onboard): Three of them.

275:13:44 Irwin (onboard): Ready?

275:13:45 Scott (onboard): Yes.

275:14:01 Scott (onboard): Shit.

275:14:04 Irwin (onboard): Screw it in there?

275:14:05 Scott (onboard): Good.

275:14:06 Worden (onboard): ...

275:14:13 Scott (onboard): Yes. Roger.

275:14:16 Worden (onboard): ...

275:14:30 Irwin (onboard): Yes.

275:14:39 Scott (onboard): Well, we have a lot of drinks for breakfast.

275:14:42 Irwin (onboard): Okay, I ought to change the LiOH. Which one was it, Al?

275:14:48 Worden (onboard): Okay, 23 to B and 21 to A-5.

275:14:52 Irwin (onboard): Okay, going into B.

275:14:54 Worden (onboard): 23 into B.

275:14:56 Irwin (onboard): Okay.

275:16:22 Irwin (onboard): I wonder if any of this food is - the - the irradiated food.

275:16:26 Scott (onboard): Could be ....

275:16:33 Irwin (onboard): One way of preserving food these days is to...

275:16:37 Scott (onboard): ... radiation.

275:16:39 Irwin (onboard): And it preserves it. At certain times, radiation preserves it.

275:18:01 Irwin (onboard): Okay. Canister change is complete.

275:18:03 Scott (onboard): Okay. Very good.

275:19:22 Scott (onboard): ...

275:19:25 Irwin (onboard): That's wrong, Dave.

275:19:27 Scott (onboard): ...

[There is a break in the onboard recording.]
275:30:27 Scott (onboard): Al, you going to monitor comm? I'm going to get off the headset here.

275:30:29 Worden (onboard): ...

275:32:09 Scott (onboard): Come forward, Al. Thank you very much .... Just ruined the whole thing.

275:36:48 Worden (onboard): Oh - damn!

275:36:51 Scott (onboard): Oh, my God.

275:37:09 Worden (onboard): Freaking DAC won't come off.

275:37:15 Scott (onboard): You need one of these, too? That okay?

275:37:20 Worden (onboard): Okay. Okay.

275:37:27 Scott (onboard): There you go. Can I get that for you?

275:37:32 Worden (onboard): Thank you.

275:37:36 Scott (onboard): Ready for it now?

275:39:42 Scott (onboard): ... Move over some. ...

275:39:52 Worden (onboard): If I were you, I'd go over to the lab and pick one up out of there - a perfect sample.

275:39:58 Scott (onboard): They don't have them.

275:39:59 Worden (onboard): They don't?

275:40:O0 Scott (onboard): No.

275:40:08 Irwin (onboard): Dammit, why don't you buy a set of them? ...

275:40:14 Worden (onboard): I might buy them.

275:40:16 Irwin (onboard): Yes, but you'd be taking all that guff.

275:40:30 Irwin (onboard): Feast over his favorite rock.

275:40:34 Worden (onboard): Right.

275:40:39 Scott (onboard): ...

275:40:40 Irwin (onboard): How come?

275:40:41 Worden (onboard): ...

275:40:53 Worden (onboard): ...

275:41:05 Worden (onboard): On the ball.

275:41:12 Scott (onboard): ...

275:41:30 Worden (onboard): ... to surprise ...

275:41:40 Scott (onboard): ... 330 ...

275:41:49:Worden (onboard): (Clears throat) You going to do anything else down there? Are you going to do anything down there? All right.

275:41:58 Scott (onboard): ...

275:42:02 Worden (onboard): Well, I've got a P23 to do in 3 minutes, and then we got to ... the daytime. I got to clean up and change my long johns and take my biomed off, while I got the chance.

275:42:17 Scott (onboard): Okay.

275:42:58 Worden (onboard): Okay.

275:44:37 Irwin (onboard): Dave, I hope we're going to be able to see them unload all those rocks.

275:44:42 Scott (onboard): Yes, I think we should.

275:44:43 Irwin (onboard): Okay.

275:44:44 Scott (onboard): ... time ...

275:44:48 Irwin (onboard): I hope so. Yes. They'll just have to hold up the - the rocks until we're there.

275:44:58 Scott (onboard): ... going to have a ball ... Is that why you ...?

275:45:07 Irwin (onboard): Yes.

275:45:12 Scott (onboard): ...

275:45:15 Irwin (onboard): Yes.

275:45:19 Scott (onboard): ... mind working some long hours.

275:45:29 Irwin (onboard): How long does the medical take on the ship?

275:45:33 Scott (onboard): ...

275:45:34 Irwin (onboard): ... ship until about what - 6 o'clock tomorrow night? We'll be taking that physical until 10 tomorrow night ?

275:45:42 Scott (onboard): Ten their time is all I know.

275:45:48 Irwin (onboard): Oh, that's right. It's 4 our time, which is...

275:45:54 Scott (onboard): On board the ship.

275:45:56 Worden (onboard): Yes. ...

275:46:03 Irwin (onboard): Yes.

275:46:04 Scott (onboard): ...

275:46:24 Worden (onboard): ... we're laughing.

275:46:46 Scott (onboard): ...

275:46:59 Scott (onboard): I think we might look ...

275:47:35 Irwin (onboard): I had it under control. I had it under control.

275:47:41 Scott (onboard): ...

275:48:00 Worden (onboard): We're all having his.

275:48:05 Irwin (onboard): Man, we're down low. The cupboard's bare. Bacon squares.

275:48:27 Irwin (onboard): I don't know if we have enough in there for two more. Yes, I guess we do.

275:48:52 Scott (onboard): ...

275:48:57 Irwin (onboard): Yes, you need a reinfo - forced toe section.

275:50:55 Worden (onboard): I'll take that and get this - Going to use the camera.

275:51:26 Irwin (onboard): Have a 9-hour rest period.

275:51:42 Irwin (onboard): Make sure I'm turned on there, will you, Dave? My power on?

275:52:00 Worden (onboard): ...

275:52:02 Irwin (onboard): What? Yes, if you want to dig it out, it's in the - I put it in that bag. Dave, could you get - Dave, could you get - There's a bag in my TSB. One of the white towel bags that has all my gear it in.

275:52:38 Irwin (onboard): Thank you. It's in here, Al.

275:55:08 Parker: Apollo 15, Houston. Over.

275:55:13 Irwin: Go ahead, Bob.

275:55:14 Parker: Roger. If one of you fellows has the time, we might like to continue on with the Mass Spec. boom retract test.

[To recap, on occasion the Mass Spectrometer boom fails to retract. Mission Control suspect that this problem is temperature sensitive. Three hours ago, while the SIM bay was being chilled by being pointed towards deep space, a controlled attempt was made to retract it which was unsuccessful. This next attempt to retract it will be made with the boom's mechanism having been warning in the Sun for nearly an hour.]
275:55:23 Irwin: Okay. Is it something I should write down, or can I just do it real time?

275:55:27 Parker: I'll give it to you real time. It's not that complicated, Jim.

275:55:32 Irwin: Okay. Go ahead.

275:55:34 Parker: Okay. We need the Experiment switch to On down there in the Alpha - Excuse me, the Mass Spec. Experiment switch to On; and the Ion Source, On. Over.

275:55:49 Irwin: Okay. I understand Mass Spec. Experiment, On; and Ion Source, On. Stand by. [Pause.]

275:55:47 Irwin (onboard): David, can you get a couple of switches over there? The Mass Spec. Experiment, On; and the Ion Source, On.

275:56:10 Irwin: Okay, Bob. They're both On.

275:56:13 Parker: Okay. And then next, you go down to the other panel, and we go Deploy for 20 seconds on the Mass Spec. boom, and then Retract for 40 seconds, or until we get a gray indication. Over.

275:56:34 Irwin: Understand you want Deploy for 20 seconds and then - on the Mass Spec. boom, and then Retract, until we gray, for 40 seconds.

275:56:44 Parker: Roger. Whichever occurs first.

275:56:49 Irwin: Okay.

275:56:50 Irwin (onboard): Okay, Dave. On that Mass Spec. Boom, we go Deploy for 20 seconds. If you want, I can give you a mark.

275:56:59 Scott (onboard): That's okay.

275:57:21 Scott (onboard): They're Off.

275:57:23 Irwin (onboard): Go to Off and then I'll have you - and then Re - and then Retract it for 40 seconds...

[Comm break.]

[The mechanical problem, believed to be caused by the cable harness stiffening up when cold, has been stopping the boom retracting the final few centimetres where it would give a gray indication on the talkback. This time, it works flawlessly.]

275:58:17 Irwin: Okay, Bob. It [the talkback] went gray after thirty seconds.

275:58:20 Parker: Roger; copy. Stand by. [Long pause.]

275:58:46 Parker: Okay, 15. Looks like it's a cold soak problem, then, Jim. We'll just deploy it all the way out and leave it there.

275:58:56 Irwin: Okay. You want us to deploy it all the way, huh?

275:58:59 Parker: Right. After we did all that work and succeeded in retracting it, now we'll deploy it.

275:59:05 Irwin: Okay. We'll deploy it.

[Very long comm break.]

[Flight Plan page 3-392.]

Public Affairs Officer - "This is Apollo Control. Jim Irwin just reported that the Mass Spectrometer boom, on this attempt, retracted fully. And it was the indication of gray on the talkback, the indicator in the spacecraft. Previously, the indicator had gone half gray - half barber pole, indicating that the boom had not extracted fully. At that time, we suspected that it's possibly because the spacecraft was in an attitude where the boom was not exposed to solar heating. And, in the attitude at which it was attempted this last time, the Service Module bay was exposed to heating from the Sun. At which would seem to verify the theory that the problems in retracting that boom were due to cooling. At 276 hours, Apollo 15 is 93,232 nautical miles [172,665 km] from Earth and traveling at a speed of 5,480 feet per second [1,670 m/s]."

276:13:04 Parker: Apollo 15, Houston. Over.

276:13:09 Irwin: Go ahead, Bob.

276:13:10 Parker: Roger, Al. Recommendation from the ground here. They'd like to see - maybe as many as five optics calibration marks the next time, instead of the two. It's just to give them some data.

[When Al calibrates the spacecraft optics in preparation for his navigation duties, he has been taking only a couple of marks. For the upcoming P23, he should take five marks. However, Al misinterprets this request and give five marks for all the sightings rather than the three normally required.]
276:13:26 Irwin: Okay, I'll relay that information to our navigator.

276:13:29 Parker: Sorry about that, Jim. You sound like Al these days.

276:13:33 Irwin: Oh, we're getting so we all sound alike up here.

[Long comm break.]

[Now that Al has calibrated the optics, he continues with his final navigational exercise of the day. Once again, the angles are measured between Elnath (Beta Tauri) and Earth's horizon furthest from the star, Capella (Alpha Aurigae) and Earth's horizon furthest from the star, and, finally, Alphard (Alpha Hydrae) and Earth's horizon nearest the star. With the amount of change in his state vector calculated, Al can bring it up on the DSKY as Noun 49.]

276:21:08 Parker: Apollo 15, Houston. We're standing by ready to copy your Noun 49s.
[Comm break.]
276:24:16 Parker: 15, Houston. We'd like High Gain [Antenna], pitch at minus 30, yaw of 150.

276:24:29 Worden: Okay. Pitch, minus 30; and yaw, plus 5 - 150.

276:24:34 Parker: Roger.

276:24:37 Worden: And do you want us to go ahead and try and lock it up?

276:24:40 Parker: Please do.

[Very long comm break.]
276:41:31 Parker: Thank you, Al. [Long pause.]

276:42:39 Parker: Apollo 15, Houston. Over. [No answer.]

[Comm break.]
276:43:53 Parker: Apollo 15, Houston. Over.

276:43:58 Worden: Go ahead, Houston.

276:43:59 Parker: Roger. Guidance says thank you to Al [for the P23s]. And if - a couple of other things here, if one of you guys has a chance, we'd like a mag - magazine status read-out tonight, and we're seeing some noise on Dave's biosensors. He might want to check them or push them down a little bit or something.

276:44:23 Scott: Okay, I'll do that. And you want a magazine status read-out. What do - What do you mean by that exactly.

276:44:29 Parker: Roger. That means how many picture's been taken in some of the magazines there. I think Al's been doing it. He probably knows what's going on, if he can tell you.

276:44:56 Scott: Okay. I - I guess we don't have a good answer for you on that, Bob. They're all stowed away. And they've all been recorded as we've gone along. Is there any particular need for them before tomorrow sometime?

276:45:13 Parker: Negative, Dave. That's a good answer, it turns out.

276:45:18 Scott: Okay. I think you'll find them all neatly tucked away and recorded when - when you get them on the ship.

276:45:38 Worden: If you're wondering how many pictures we took, at last count, night before last, it was something like 1,840 some.

276:45:49 Parker: Understand, 1,847.

276:45:53 Worden: Or somewhere around the ball park.

276:45:56 Parker: Is that plus or minus one?

276:45:59 Scott: I think that was LM though, maybe yeah. Then you have to add that to the Command Module.

276:46:05 Parker: You mean like a mile of Pan Camera film, huh?

276:46:09 Scott: Something like that. It looks like it ought to hold a mile by the size of the thing.

[Comm break.]

[About now, the discrimination shield on the Gamma-ray Spectrometer is switched off for a 10-minute period to check its function.]

276:48:11 Scott: Houston, 15.

276:48:13 Parker: Go ahead, 15.

276:48:17 Scott: Well, I had - had the log out here, and I took a look at it, and at last count last night, we were 2,631 on Hasselblad pictures, total.

276:48:29 Parker: Copy.

[Comm break.]
276:51:06 Parker: Apollo 15, Houston. Over.

276:51:11 Scott: Go ahead, Houston; 15.

276:51:12 Parker: Roger, Dave. The interest in the mags was in reference to the UV - the mags for the UV photography tomorrow. So the interest was in the number of frames remaining on magazine Mike and magazine Papa, try - trying to determine which of those would be usable for tomorrow's UV photography.

276:51:35 Scott: Okay. I think we've got that log in the Flight Plan. Stand by 'til Al finishes his P23s, and we'll take a look.

276:51:41 Parker: Roger; understand. No big rush.

276:51:49 Scott: [I] think we'll use a mag that has some film in it.

276:51:53 Parker: Say again, Dave.

276:51:56 Scott: I said, at - at any rate, we'll use a mag that has some film in it tomorrow.

276:52:00 Parker: That's a good idea.

[Long comm break.]
276:57:06 Parker: Apollo 15, Houston. Requesting Gamma-ray Gain Step, Shield, Off, now, please.

276:57:14 Worden: Roger. Shield, Off, now. [Long pause.]

276:58:08 Parker: That was a good mark, Al.

276:58:17 Worden: Yes, and it didn't update the state vector very much.

[Very long comm break.]

[Flight Plan page 3-393.]

Public Affairs Officer - "This is Apollo Control at 277 hours, 7 minutes. Al Worden is presently completing a series of star sightings - midcourse navigation exercise, using program 23 in the onboard computer. This will be the last major activity before the crew begins it's 9-hour rest period. After completing this, they'll go through the presleep checklist, get the systems set up for the sleep period and put the spacecraft in it's Passive Thermal Control attitude, rotating at about the rate of 4 revolutions per hour. Apollo 15, at this time, is 89,626 nautical miles [165,987 km] from the Earth. The spacecraft velocity is 5,646 feet per second [1,721 m/s]. And we're now 18 hours, 3 minutes away from splashdown."

277:15:49 Parker: Apollo 15, Houston.

277:15:53 Worden: Go ahead.

277:15:55 Parker: Roger. Congratulations, Al. You've just been voted to receive a second Vasco da Gama award for that. We were afraid you were going to do them all the way through the rest period.

277:16:07 Worden: Well, they're fun enough. I wouldn't mind.

277:16:10 Irwin: So were we.

277:16:12 Parker: [Laughter.] Okay; and...

277:16:19 Worden: It wouldn't have taken nearly so long if you hadn't wanted five marks per each star.

277:16:31 Parker: Rog, Al. I'll tell you about that some time. And, 15, we're configured for the E-mod dump, if you fellows want to give it to us.

[A dump to Earth of the data in the Erasable Module (the 2-kwords of memory used by the computer) is part of the pre-sleep checklist. The crew status reports and read-outs from the onboard gauges are still to come. The fans in the H2 tank will be stirred and the crew's potable water supply will be chlorinated. Then, once a set of switch positions are verified, the communications system will be configured for the rest period.]

[Another task for the end of the day is to set Endeavour rotating in the PTC maneuver. Once the spacecraft gets to the PTC attitude, Al uses P20 in the computer to set the rotation going, essentially getting Endeavour to track a rotating vector. The rate of rotation is to be a little faster than previously. Al will enter 0.42° per second (entered as 04200) instead of 0.35° per second. Angles for dialling into the HGA controls are given. The antenna's control system will be operated overnight in the Reacq mode, whereby it tracks the Earth as long as its gimbal system can keep it pointing at it. When the spacecraft's rotation takes it out of range, it will move to preset angles which have been calculated to bring the Earth back into the antenna's beam as the PTC rotation continues.]

277:16:45 Scott: Okay, it[the E-mod dump]'s coming. Does the bio data look any better?

277:16:48 Parker: Rog. Yes, it does.

277:16:52 Scott: Okay.

277:16:56 Parker: And, as you get ready in the PTC, we'd like to do the PTC at 0.42 [degrees per second] there again tonight as last night, although it's changing the Noun 79 value there at 277:14.

277:17:16 Worden: Roger, Bob. I guess we use that as standard procedure now, the 4200.

277:17:21 Parker: Roger. You don't have to do it tomorrow night that way, though.

277:17:25 Scott: Okay. Use a different number tomorrow night.

[Of course, tomorrow night, they will not be in space.]

[Comm break.]

277:18:34 Parker: And, Apollo 15, be advised that tomorrow when you're taking your P23 marks, five marks on the cal[ibraton star] and 3 marks on the [other] stars with the P23 itself will be sufficient.

277:18:48 Worden: Okay, understand. 5 marks on the cal and 3 on each star.

277:18:52 Parker: Roger. Roger. [Long pause.]

277:19:26 Scott: Hey, Houston, 15. We've got presleep checklist ready, too.

277:19:30 Parker: Roger. We're standing by.

277:19:34 Scott: The crew's all ready for bed, no medications, and the onboard read-out: Battery C, 37; Pyro Bat A, 37.1; B, 37.1; RCS A, 55; B, 50; C, 48; D, 52. And I guess everything else is done. You've got your E-memory dump, and we're ready to power down as soon as we get the PTC going.

277:20:06 Parker: Roger, Dave. As far as we're concerned, we're all finished also. We will not be uplinking a state vector to you. We might have to do that sometime just for practice, but so far we haven't needed to uplink one to you. You guys are doing pretty super on those P23s.

277:20:24 Scott: Compensating errors. [Pause.]

277:20:35 Parker: I can't believe that was a unanimous vote, Dave.

277:20:41 Scott: No, it was only two to one.

[Long comm break.]
277:2x:xx [Unintentional key] Parker: Okay, G&C. Let me know when he's got his rate tab.

277:28:52 Parker: Apollo 15, Houston. You are Go to start to spinup for PTC.

277:28:57 Scott: Okay, Bobby. Thank you. [Long pause.]

277:29:30 Parker: And, Apollo 15, we'd like for you to check that the Potable Tank Inlet valve is open, please.

277:29:37 Scott: Roger; understand. Potable Tank Inlet valve, open. [Long pause.]

277:30:26 Scott: Houston, 15.

277:30:28 Parker: All right, go ahead, 15.

277:30:31 Scott: Okay. Listen, potable tank inlet valve is open and has been the whole flight. What prompted the question?

277:30:39 Parker: Stand by.

277:30:44 Scott: We're just curious. [Pause.]

277:30:56 Parker: 15, we saw a drop in the potable at the same time that the waste tank was staying stable, and we were - just concerned that it might have gotten out of configuration. We certainly expected it to be open; we just wanted to check it before you went to sleep, so we didn't have to wake you up.

277:31:11 Scott: Okay. Understand. Yeah - we're reading potable at 90%.

277:31:17 Parker: Roger. We're reading 94.

[Very long comm break.]
277:43:52 Parker: Apollo 15, Houston. No need to acknowledge, but we'd like to put the DSKY to sleep before you guys go to sleep.

[Very long comm break.]
277:38:18 Scott (onboard): Oh, 6:45 tomorrow.

277:38:22 Worden (onboard): Yes. ...

277:38:26 Irwin (onboard): He didn't.

277:38:33 Scott (onboard): Cabin temp, 67.

277:38:36 Worden (onboard): ...

277:44:01 Worden (onboard): Oh, shit.

Public Affairs Officer - "This is Apollo Control at 278 hours, 2 minutes. Flight Surgeon reports that Dave Scott, the only crewman on whom we have biomedical data tonight, appears to be nearing sleep, at least beginning to drop off, and we expect that he'll be sleeping shortly. During this sleep period, we don't expect any further conversation with the crew. The Passive Thermal Control mode appears to be stable. We're watching the attitude excursions, the movements that the spacecraft is making about its axis and it appears to be quite stable. It looks as if it will hold throughout the sleep period. At the present time, Apollo 15 is 86,650 nautical miles [160,475 km] from Earth. The spacecraft velocity is 5,789 feet per second [1,764 m/s]. Checking with the science support room, we have some statistics on the temperature excursions experienced by the lunar surface experiments packages at the Apollos 14 and Apollo 15 sites. The Apollo 14 station went through the largest temperature swing during the eclipse. It started at 173.9° above zero Fahrenheit [78.8°C], and during the maximum point of the eclipse, it was down to 150.6° below zero [-101.4°C], for a temperature swing of 324.5° [180.2°]. The Apollo 15 station measured a somewhat smaller swing. It started at 140° above Fahrenheit [60°C] and dropped down to 143.2° below Fahrenheit [-97.3°C]. These temperatures were measured on the top of the sun shield above the central station on both ALSEP packages. During the crew rest period we'll take the air to ground line down, keep the tape recorders running and play back any conversations that we might have with the crew, should any arise. At 278 hours, 4 minutes this is Apollo Control, Houston."

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