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Apollo 15

Solo Orbital Operations - 4

Corrected Transcript and Commentary Copyright © 1999-2008 by W. David Woods and Frank O'Brien. All rights reserved.
Last updated 2016-06-21

[Al Worden's final solitary rest period in lunar orbit began just prior to 154 hours GET (Ground Elapsed Time) during Endeavour's 39th revolution around the Moon. It is due to end eight hours later, at 162 hours GET, at the start of the eighth day on 2 August 1971.]

[During Al's sleep, the CSM (Command/Service Module) has been flying with the large main engine of the SPS (Service Propulsion System) facing the direction of flight. The experiments currently operating in the SIM (Scientific Instrument Module) bay are the Gamma-ray Spectrometer, the X-ray Spectrometer and the Alpha Particle Spectrometer. Mission Control cancelled the planned overnight operation of the Mass Spectrometer because of problems Al was having deploying and retracting the 7.3-metre boom which carries it.]

[Flight Plan pages 3-229, 3-231, 3-233, 3-235, 3-237, 3-239, 3-241, 3-243 and the current page, 3-245.]

[By the time he is contacted by Mission Control, halfway through Endeavour's 43rd orbit, his colleagues at Hadley Base on the lunar surface have been awake for 2 hours and are donning their suits and PLSS backpacks (PLSS, pronounced "pliss" stands for Portable Life Support System). Today will be a busy one for the crews of both spacecraft of Apollo 15. The surface crew of Dave Scott and Jim Irwin in Falcon not only have a punishing EVA (ExtraVehicular Activity) nearly five hours long, they must also be inside and packed away ready to lift-off in 9½ hours time. Then both crews will take part in the orbital dance called rendezvous, a difficult and demanding operation they have practised innumerable times in the simulators on Earth where the upper (ascent) stage of the Lunar Module finds and docks with Endeavour.]

161:59:36 Henize: Endeavour, this is the planet Earth calling. We'll start off the day this morning with a little bit of wake-up music for you. And if you appreciate our selection, you may respond with an E-memory dump, if you are able to hear me at the present time.

162:00:17 [Music: "Tijuana Taxi" by Tijuana Brass]

162:00:26 Henize: Endeavour, this is the planet Earth calling this morning. We'll start off with a little bit of wake-up music and then we'll get into the day's activities. If you are awake enough to hear this, you can express your appreciation for our fine music by sending us down an E-memory dump. [No answer.]

[2 kilobytes of the computer's 15 bit-per-word memory is of an erasable type which the computer can use as a scratchpad and to store values which may change throughout the mission. At regular intervals, Mission Control downloads the entire contents of this erasable memory to examine it and check that the computer is operating properly. This is usually done as part of the presleep checklist on page 1-26 of the CSM Systems Checklist, rather than postsleep.]
162:02:18 Henize: Endeavour, this is Houston. How do you read now? [Pause.]

162:02:31 Henize: Endeavour, this is Houston. If you are reading give us Accept and we'll send up a state vector.

162:02:46 Worden: Allo, Terre. Salute de l'Endeavour.

[In collusion with Farouk El-Baz, a geologist who trained him, Al has determined he will greet the Earth as often as possible with the same greeting, "Hello Earth; Greetings From Endeavour", spoken in a multitude of languages.]

[As well as downloading and examining the contents of the erasable memory, Mission Control wants to uplink a revised state vector into the computer's memory. The state vector is seven values which accurately describe the position and velocity of the spacecraft in three orthogonal axes at a particular time.]

162:02:51 Henize: Good morning, Al. How's the morning up there?

162:03:00 Worden: Well, I'll let you know when I wake up, Karl. I had another very peaceful evening.

162:03:07 Henize: Glad to hear it. [Long pause.]

162:03:34 Henize: We're ready for High Gain [Antenna to] Auto, Endeavour. And I have - and I have a Flight Plan update, the most important one being that, at 162:06, in about 3 minutes, we will delete - delete the "Gamma-ray [Spectrometer] Gain Step, Shield, Off."

162:04:10 Worden: Okay, Karl; understand. Let me get the Flight Plan out here.

162:04:25 Worden: Okay, "Gamma-ray Gain Step, Shield, Off" has been deleted.

162:04:28 Henize: Roger. And I have Mapping Camera photo PAD and some further Flight Plan updates when you are ready to copy.

162:04:38 Worden: Okay; go ahead.

162:04:41 Henize: Mapping Camera photo PAD down there at 162:55. T-start: 162:59:30, T-stop: 163:59:11.

162:05:02 Worden: Okay, understand. Mapping Camera photo PAD, T-start: 162:59:30, T-stop: 163:59:11.

162:05:13 Henize: That's correct, and further Flight Plan changes; we have very few today. At 162:16 we can delete the "Gamma-ray Gain Step, Shield, On."

162:05:28 Worden: Understand. 162:16; delete "Gamma-ray Gain Step, Shield, On."

162:05:33 Henize: Roger. Over on 163:10, we add "Map Camera, Image Motion, Increase" with appropriate barber pole comment. Increase, and then leave it on. "Increase/On" would be a better way of reading that to you.

162:06:02 Worden: Okay; understand. At 163:10, you want the "Image Motion, Increase to barber pole and On."

162:06:08 Henize: Roger. And at 163:40, we can add, "Mapping Camera, Image Motion, Increase/On." And also, "Gamma-ray Gain Step, Shield, Off."

162:06:40 Worden: Understand. At 163:40, you want the Image Motion, Increase to Increase/On. Do you want that - How many steps past barber pole do you want it?

162:06:59 Henize: Okay, Al. I - I missed the beat there. The one at 163:10 was "talkback barber pole plus 4 steps" at that time. And at 63:40, take it to "talkback barber pole" and leave it there.

162:07:34 Henize: Did that come through okay?

162:07:36 Worden: Okay; understand. The one at 163:10 is "Image Motion, Increase to barber pole plus 4, and then On". And then at 163:40 is "Increase to barber pole On", and "Gamma-ray Gain Step, Shield, On."

162:07:51 Henize: Roger. 163:40, that was Shield, Off; O-F-F. and at 163:50, the Gamma-ray Gain Step will go Shield, On; Shield O-N.

162:08:02 Worden: Okay. Understand 163:40, Shield is Off; and 163:50, the Shield goes On.

162:08:08 Henize: Roger. And that's the end of the Mapping Camera and the Flight Plan update.

162:08:16 Worden: Roger.

162:08:18 Henize: The computer is yours, Al. And I have [a] consumables update, if you would like it.

162:08:25 Worden: Okay; go ahead.

162:08:28 Henize: GET [Ground Elapsed Time] is 162 hours, 0 minutes; RCS total 60 [percent full]; Quad A: 60, [B] 60, [C] 59, [D] 61; hydrogen tanks: [1] 65, [2] 64, [3] 46; oxygen tanks: [1] 71, [2] 74, [3] 58.

162:08:59 Worden: Understand. RCS total is 60. That's with quads: 60, 60, 59, 61; H2 tanks: 65, 64, 46; and O2 tanks: 71, 74, 58.

162:09:12 Henize: That's correct.

162:09:18 Worden: And where do we stand on the RCS budget, Karl. Do you know?

162:09:34 Henize: Stand by on that, Al. We'll give you a good report in a few minutes.

[Comm break.]
162:10:41 Henize: Endeavour, this is Houston. On your RCS fuel, you are running roughly 6 percent below Flight Plan values, and you're still running roughly 15 percent above the red line. Quad Charlie is the lowest - the most critical quad. But, there's no big deal at the present time in any of them. Quad Charlie, incidentally, is 10 percent above the red.

162:11:10 Worden: Okay, Karl.

162:11:11 Henize: Quad Charlie, incidentally, is 10 percent above the red line.

162:11:18 Worden: Okay. Sounds fine.

[Comm break.]

[The flight controllers are keen to preserve as much RCS (Reaction Control System) propellant as possible. If an emergency situation should occur, like, for example, the LM has a problem rendezvousing with the CSM, much RCS reserve might be unexpectedly expended getting the CSM to rescue it.]

162:13:51 Henize: Endeavour, this is Houston. The latest information from Hadley Rille is that the crew is awake and about one hour from egress time. This EVA number 3 has been shortened in length somewhat to about 4½ hours in order to get our time line back on time for the nominal ascent. You can expect that you'll have some company later this afternoon.

162:14:33 Worden: Very good, Karl. And, let's see, I guess I can give you a crew status report if you want it.

162:14:40 Henize: Fire away.

162:14:42 Worden: Okay. I've got 7½ hours of sleep in one period. No medication. The PRD [Passive Radiation Dosimeter] is 23164.

162:14:54 Henize: We copy, Al.

[Long comm break.]

[Al is carrying out a routine realignment of the spacecraft's gyroscopically stabilised guidance platform. This is known as a "P52" after the computer program which aids the procedure. Prior to doing this, he switched the CMC (Command Module Computer) mode switch to "Free" which stops the RCS from continually trying to correct the spacecraft's attitude while he sights stars through the spacecraft's sextant. On this occasion, Al sights on star 01, Alpheratz, in Andromeda, and star 05, Polaris, the well known Pole Star. The platform is aligned to a predefined reference known as the landing site REFSMMAT and all attitude definitions in roll, pitch and yaw are with respect to this reference.]

162:18:35 Worden: Houston, Endeavour. If you're copying the DSKY, the gyro torquing angles are up [on it].
[When Al has finished realigning the platform, the angles by which the three gimbals must be rotated, or torqued, can be displayed on the DSKY (Display and Keyboard). The Flight Plan calls for Al to report these angles to Mission Control, but since the flight controllers can read the contents of the DSKY displays via telemetry, he simply allows them to copy them that way. The three angles were -0.014°, -0.044° and +0.016°, for the X, Y and Z gimbals respectively.]
162:18:41 Henize: Roger. We've copied them, thank you. [Long pause.]

162:19:26 Henize: Endeavour, this is Houston. [A] couple of quick questions. First of all, the Surgeons see something of a difference in your heart rate between the two nights sleep, and just out of medical curiosity, they'd like to have your subjective evaluation. Did you sleep better last night than the night before, or vice versa?

162:19:49 Worden: Gee, I guess subjectively, I slept pretty well both nights.

162:19:54 Henize: Just about equal in other words? Okay, and...

162:20:00 Worden: Yes, I think so, or maybe I slept a little better last night.

162:20:03 Unidentified speaker in Houston: Better last night?

162:20:04 Henize: Glad to hear that. You're con - confounding their theories.

162:20:xx Worden: On... [Long pause.]

162:20:34 Henize: Al, we'd like to have you verify tape motion at LOS; and if it isn't, start the tape running for us.

162:20:44 Worden: Roger.

162:20:46 Henize: And, on this P30 business; I see something of a - a long comment they made to you last night. Is everything on that clear?

162:21:03 Worden: Roger, Karl. I think so. I - I guess for the story there is we'll stay away from using the pocket P30 as much as possible, and when we do use it, especially when we're in deadband, we won't let it run more than 30 minutes.

[Since Al was using the P30 program as a timing device, he is probably referring to it as being a pocket watch.]
162:21:21 Henize: Okay. Everybody down here thinks that's a - a great philosophy. Good.

162:21:47 Worden: And, Houston; Endeavour. There were a couple of questions on the Flight Plan. I guess I'm wondering what we're going to do about the Mass Spec[trometer] today. We've got some things in here. Of course, we didn't use it last night, so there are, I guess, a few steps that you're to delete.

162:22:02 Henize: Righto. We don't intend to use the Mass Spec. today so you can delete these particular steps about retracting, or about extending the boom, et cetera. We just are not - That was it. Delete any action on the Mass Spec.

162:22:16 Worden: Okay. Okay Karl. Understand.

[Comm break.]
162:23:45 Henize: Endeavour, this is Houston. As you go around the corner, all your systems look to be in good shape.

162:23:53 Worden: Roger, Houston. See you at the other side.

[Very long comm break.]

[Endeavour begins its 44th revolution of the Moon during this far-side pass.]

[Al's first task is to flip the CSM around from flying with the SPS engine facing forward, to flying with the apex of the Command Module facing forward. As always with these turnaround maneuvers in lunar orbit, he has to roll the CSM clockwise by 40° first. This avoids the computer taking the spacecraft's attitude through one which would cause gimbal lock. With the SIM bay restored to looking down, he can begin his breakfast. Then, as Endeavour approaches the sunset terminator, an hour-long period of photography by the Mapping Camera begins, which will last until it reaches the sunrise terminator over the western side of Mare Imbrium.]

[CSM Flight Plan page 3-247.]

163:14:01 Henize: Endeavour, we'd like to have Narrow Beam on the High Gain [Antenna].

163:14:16 Worden: Okay, Houston. Got it.

[At AOS (Acquisition Of Signal), the High Gain Antenna (HGA) is pointed in approximately the correct direction to face Earth. Appropriate angles for Al to set are given in the Flight Plan. The antenna's beamwidth is set to be wide to give a better tolerance of pointing errors. Then, on switching the antenna's control systems to Reacq(uire), it moves to a position which gives the best signal strength from Earth, whereupon Al switches the beamwidth to Narrow, improving the focus of the antenna's reception pattern and the quality of the radio link (its signal to noise ratio). On this occasion, Karl has pre-empted Al switching to narrow beamwidth.]

[Though Al's breakfast is not due to finish for another twenty minutes, his next comm shows he has clearly finished so Karl can proceed with two updates, a PAD for the plane change burn and another for an emergency return to Earth.]

163:14:23 Henize: Very good, Al. You're coming through loud and clear. What's new up there?

163:14:30 Worden: Oh, I've just had a very nice breakfast and getting ready for today's activities.

163:14:36 Henize: Excellent. [Long pause.]

163:14:58 Henize: Our major business on this rev is to get squared away for [the] plane change [burn] and as soon as we have good comm, I want to review with you the changes we need in your SPS burn cue card.

163:15:16 Worden: Okay. Stand by.

[Comm break.]

[Soon after Apollo 15 began its journey to the Moon, an indicator light gave notice of a fault in the SPS primary control circuitry which was eventually traced to a short circuit within one of the arming switches for the big engine. The fault means that procedures for firing the SPS must be modified so that it is controlled by the secondary system, the B control bank. Only during long burns is the primary, or A system brought in manually. The cue card which Al carries for the plane change burn must also be modified.]

163:17:04 Henize: Endeavour, this is Houston. I guess we can go ahead with the plane change data anytime you're ready to copy.

163:17:14 Worden: Okay, Karl. Stand by one.

163:17:16 Henize: Let's start out with the cue - with the cue card, if that's okay with you. [Long pause.]

163:17:54 Worden: Okay, Karl. Go ahead.

163:17:56 Henize: Okey-doke. As you know, this burn is going to be [a] fairly normal burn on bank B only. The only really special thing to remember is to close that SPS Pilot Valve Main B [circuit breaker] at 2 minutes before the burn. To make sure that we've got all the verifications and everything else straight though, let's go back into the cue card and do some verifying right after you cycle the cryo fans and before you go into your Delta-V check. And at that point, we've got, first of all, EMS Function off. Verify that before you put in the EMS breakers. Second is the circuit breakers, EMS Main A and B, both of them, closed. Third step there is to verify that the circuit breakers, Group 5, both of them are closed. And the fourth step there is to verify at this point that both of your SPS Pilot Valve circuit breakers are open. The only other change to the front side of your cue card is the trivial point down below when you're checking your Stabilization Control circuit breakers on panel 8, that there's only 10 of them closed at this time, instead of 12.

163:19:34 Henize: Right. That's the Stabilization Control...

163:19:38 Worden: Roger, Karl...

163:19:39 Henize: ...and SPS breakers.

163:19:40 Worden: ...I understand. Yes. The SPS burn is going to be a nominal bank B burn - bank B only burn. But to get set up for it, we want to check - after cycle cryo fans, check that EMS is off, get the two EMS circuit breakers in, check that the Group 5 circuit breakers are closed, and check that the SPS Pilot Valves both are open at that time. And then down where it says 'CB Stability Control, panel 8, and SPS 10 or 12', we'll make that a 10.

163:20:11 Henize: Roger. And then over there on the back of the card... Would you give us High Gain, Auto, right now, Al?

163:20:26 Worden: Okay. [Pause.]

163:20:33 Henize: And on the back side of the card at - at minus 2 minutes, we have - the Delta-V - just above the Delta-V Thrust, we want to put in the circuit breaker, SPS Pilot Valve Main B, closed, at that point, followed immediately by your Delta-V Thrust switch, which in this case is your B switch, not your A switch. Cross out the "A." Down below...

163:21:02 Worden: Roger; understand.

163:21:03 Henize: Down below...

163:21:04 Worden: You want the SPS Pilot Valves, Main B, Closed, before Delta-V Thrust B switch to Normal.

163:21:10 Henize: That's affirmative. And down below at plus 3 seconds, you can cross out the Delta-V Thrust switch, Normal, there since this is a single bank burn. And - Al, we'd like to have High Gain Antenna, Wide Beam, for about 5 seconds and then, Narrow.

163:22:03 Henize: And the final point in the checklist is in the cleanup down below, preferably after circuit breaker SPS Pitch 1 and Yaw 1, open. Let's get our circuit breakers cleaned up here. Let's put in circuit breaker SPS Pilot Valve Main B, open. Also, circuit breakers EMS, both of them, open.

163:22:38 Worden: Roger; understand. In the cleanup, about where CB SPS Pitch 1 and Yaw 1 are open, we'll pull CB SPS Pilot Valve Main B, open, and CB EMS, two, open.

163:22:52 Henize: That's correct. And that - assuming that your cue card was clean to start with, that should give you a - a good cue card, not only for the plane change but also for any rescue maneuvers and also for the shaping burn.

163:23:08 Worden: Roger; understand.

[The changes to the cue card essentially ensure that control of the SPS is transferred to the B bank only. Karl Henize has pointed out that as well as holding for the plane change burn and any burns used in the event of rescuing the LM, the revised cue card can also be used for the 'shaping' burn. This burn will occur just before the crew leave lunar orbit. It will alter the shape of their orbit in such a way that the subsatellite they will subsequently release can expect a longer lifetime before the perturbation effects of the Moon's lumpy gravity cause it to impact the surface.]
163:23:14 Henize: I have - and, I have - the comments here on trimming your residuals, if you're ready to copy those.

163:23:33 Worden: Okay. Stand by. [Long pause.]

163:23:55 Worden: Okay. Go ahead.

163:23:57 Henize: Okay. The LOPC [Lunar Orbit Plane Change] residuals. First of all, trim Vgy to 0, - 0.2 feet per second. Next, and this is because our quad C RCS is low and we're trying to conserve it, in - in the trimming. If you have a negative Vgy, roll 90 degrees counter-clockwise and use your minus-Z thrusters. If you have a positive Vgy, roll 90 degrees clockwise, and use your minus-Z thrusters. And, one final comment here is during - during the burn, we would like to keep the Oxidizer Flow Valve in the Decrease - Decrease position.

[If an SPS engine burn does not result in exactly matching the required change in velocity, it is customary for the residual Delta-V to be made up by using the RCS thrusters. Mission Control are slightly concerned that the propellant levels for one of the four thruster quads, quad C, is significantly lower than for the others and wish to conserve what's left. They have looked at the possible trims that Al might have to do and find that two of them can be transferred from quads A and C to quads B and D by rotating the spacecraft by 90°.]

[Henize's final remark refers to the PUGS, a system for controlling the mixture ratio to the SPS engine.]

163:24:57 Worden: Understand you want the Oxidizer Flow Valve in the Decrease position.

163:25:02 Henize: Affirmative.

163:25:13 Henize: And did everything come through on the trim.

163:25:28 Worden: Roger, Karl. You - you wanted to add to - to the - trim rules that we already have established for the plane change. That if the residual is a plus Vgy greater than two tenths of a foot per second, then we roll clockwise 90 degrees and use the minus-Z thrusters. Otherwise the same as printed in the Flight Plan.

163:25:55 Henize: That's affirmative, Al.

163:26:01 Worden: And also, you want the PUGS valve in decrease.

163:26:07 Henize: That's affirmative. And the next - the next bit of information I have for you is the plane change PAD.

163:26:28 Worden: Okay, go ahead.

163:26:31 Henize: Okay. Purpose, PC [Plane Change], SPS/G&N; 37202; plus 0.33, plus 1.07; 165:11:31.96; minus 0009.2, plus 0330.3, plus 0018.4; 0 roll, 0 pitch, 0 yaw; 064.4 - Say that again for HA. 0064.4, HP is plus 0053.3; 0330.9, 0:18, 0319.1; 36, 012.8, 39.2; the rest is NA. The set stars are Deneb and Vega; 189, 256, 330. Ullage, we would like two quads, B and D quads; 17 seconds, 17 seconds. And that's all.

[The PAD is interpreted as follows:

Purpose: The purpose of the burn is to change the plane of Endeavour's orbit to compensate for the rotation of the Moon since Falcon landed. Then, when Dave and Jim launch from the surface, the plane of their orbit will match Al's.

System: The burn will be made by the SPS engine under control of the Guidance and Navigation system.

CSM Weight (Noun 47): 37,202 pounds (16,875 kg).

Pitch and yaw trim (Noun 48): +0.33° and +1.07°.

Time of ignition, Tig (Noun 33): 165 hours, 11 minutes, 31.96 seconds.

Change in velocity (Noun 81), fps (m/s): x, -9.2 (-2.8); y, +330.3 (+100.7); z, +18.4 (+5.6). The velocity components are expressed with respect to the local vertical/local horizontal frame of reference. As this burn's major task is to change the plane of the orbit, we can see that the y component, the out-of-plane component that will achieve it, is much larger.

Spacecraft attitude: Zero on all three axes. Al's next realignment of the guidance platform will be to a new REFSMMAT which matches the burn attitude. Then, when Al comes to make the burn, he only needs to align the spacecraft so that the FDAI (Flight Director Attitude Indicator or "8-ball") reads zero degrees on all axes. This will ease the task of monitoring the attitude during the burn.

HA, expected apocynthion of resulting orbit: 64.4 nautical miles (119.3 km).

HP, expected pericynthion of resulting orbit: 53.3 nautical miles (98.7 km).

Delta-Vt: 330.9 fps (100.9 m/s).

Burn duration or burn time: 18 seconds.

Delta-Vc: 319.1 fps (97.3 m/s).

Sextant star: Star 36 (Vega, in Lyra) visible in sextant when shaft and trunnion angles are 12.8° and 39.2° respectively.

GDC align stars: Stars Deneb (number 43) and Vega (number 36) to be used for GDC align in case the IMU cannot be used. The align angles are 189°, 256°, 330°.

SPS propellants are settled in their tanks by firing the B and D plus-X thrusters for 17 seconds.]

163:28:17 Worden: Okay, understand. This is plane change 1; SPS/G&N; 37202; plus 0.33, plus 1.07; 165:11:31.96; minus 0009.2, plus 0330.3, plus 0018.4; roll, pitch, and yaw are all zeros; 0064.4, plus 0053.3; 0330.9, 0:18, 0319.1; 36, 012.8, 39.2. Vega and Deneb are set stars. And 189, 256, 330. Ullage is two jets, 17 seconds, using quads B and D.

163:29:18 Henize: That's all correct. [Long pause.]

163:29:54 Henize: Al, we'd like to verify that the Oxidizer Flow Valve was in the Decrease position at the end of the last burn and has been there since then.

163:30:08 Worden: Negative, Karl. It was in Normal at the end of the last burn, which was the circularization burn and it was - it's been in Normal since then. It's in Decrease now; I put it there after you called it out on the PAD.

163:30:21 Henize: Thank you, Al. [Long pause.]

163:31:10 Henize: Just a reminder, Al. Since I've been reading a lot of things to you, about the Pan Camera Mode, Standby; Power, On.

[The Panoramic Camera was due to be operated four minutes ago to move the film through the guide rollers and avoid it setting in position. The timing of this operation is not critical.]
163:31:20 Worden: Roger. It's there now.

163:31:32 Henize: And I have a TEI-52 PAD anytime you're ready to copy.

163:31:51 Worden: Okay, go ahead.

163:31:54 Henize: TEI-52, SPS G&N; 36003; plus 0.60, plus 1.07; 180:31:51.88; plus 3030.0, minus 0893.9, minus 0231.0; 180, 088, 346; the rest is NA. We have two jets for 17 seconds with the B and D quads, Bravo and Delta quads. The Lambda at Tig is plus 177.77; and it is assumes LOPC; and ascent REFSMMAT.

[An interpretation of the PAD follows:

Purpose: This PAD provides the information required for a early return to Earth in case of an abort situation, with a burn at the very end of rev 52.

System: The burn, if required, would be made using the SPS engine under control of the Guidance and Navigation system.

CSM Weight (Noun 47): 36,003 pounds (16,331 kg).

Pitch and yaw trim (Noun 48): +0.6° and +1.07°.

Time of ignition, Tig (Noun 33): 180 hours, 31 minutes, 51.88 seconds.

Change in velocity (Noun 81), fps (m/s): x, +3,030.0 (+923.5); y, -893.9 (-272.5); z, -231.0 (-70.4). The velocity compononets are given with respect to the local vertical/local horizontal. The large positive x component shows how this is a prograde burn to leave lunar orbit.

Spacecraft attitude: Roll, 180°; Pitch, 88°; Yaw, 346°. As Henize points out later in the PAD, the reference for these attitude angles is the lift-off, or ascent REFSMMAT.

All other normal items required for a full burn do not need to be sent up.

SPS propellants would be settled in their tanks by firing the B and D plus-X thrusters for 17 seconds. Mission Control are planning their maneuvers to conserve the propellants in quad C.

The burn would be made when the spacecraft is over the lunar longitude of +177.77°.

The PAD assumes that the upcoming plane change maneuver has occurred and that Endeavour's inertial platform is aligned to the ascent, or lunar lift-off REFSMMAT.]

163:33:14 Worden: Roger; understand. TEI-52, SPS/G&N; 36003; plus 0.60, plus 1.07; 180:31:51.88; plus 3030.0, minus 0893.9, minus 0231.0; 180, 088, 346; 2 jet, 17 seconds, using quads B and D. And Lambda Tig is plus 177.77; and the PAD assumes the plane change and asc - ascent REFSMMAT.

163:33:59 Henize: That's all correct. [Pause.]

163:34:11 Henize: Endeavour, we're ready for Pan Camera Power, Off, now.

163:34:22 Worden: Roger. Power is Off.

[Long comm break.]
163:41:51 Henize: Endeavour, a reminder on the Gamma-ray Gain Step. We need the Shield, Off, at this point.
[Long comm break.]
163:46:37 Henize: Endeavour, this is Houston. We have one small change in our set-up for the plane change burn, and that is that we would like to leave the Oxidaze - Oxidizer Utilization Valve [means Oxidizer Flow Valve, on panel 3 of the Main Display Console and part of the Propellant Utilization Gauging System (PUGS)] on - in the Normal position. We'd like it Normal instead of Decrease as we previously told you.

163:47:06 Worden: Okay, going Normal on the PUGS Valve.

163:47:10 Henize: Roger; and the boys on the surface have the TV tuned up for us now and we're getting some lovely landscape pictures - Hadley Delta, et cetera. Those hills there are just beautiful, round, bare hills, a lot like the ones you see around San Francisco. It's a beautiful sight. They're just about loading up the Rover and getting ready to head off toward the South Com[plex] - first of all, to the rille for a quick visit and then off to the South Complex.

[Henize means the North Complex, a collection of larger craters and a small rise about 3 kilometers north of Falcon. However, the visit to North Complex is not to be. Time lost in extracting a deep core sample will essentially cost the surface crew their trip to this potentially interesting geology site.]
163:47:44 Worden: Roger, Karl; understand. Did you say they are going to cut it a little bit short today?

163:47:49 Henize: Right. They're going to cut it between one and two hours short because they got in - they wanted to get their normal sleep today; and, I guess they won't do quite so much exploration in between, but they still expect to get to the South Complex. Pardon me, that's the North Complex.

163:48:08 Worden: Roger, understand.

[Very long comm break.]
163:59:06 Henize: Endeavour, this is Houston. It's time to turn off the Mapping Camera.
[Comm break.]

[The Mapping Camera finishes it's hour of operation as Endeavour passes over the Moon's sunrise terminator, flying towards lunar night.]

[CSM Flight Plan page 3-249.]

[In preparation for the plane change burn, Al begins powering down the experiments in the SIM bay, retracting the Mapping Camera and closing the various covers.]

164:02:05 Henize: Endeavour, this is Houston. If you'll go P00 now, you'll have a shorter maneuver down in your maneuver to the P52 attitude. And, if you'll give us Accept, we'll send up state vector and other burn information.

164:02:22 Worden: Okay, Karl. You've got it; P00 and Accept.

[Long comm break.]

[P00 is Program 00 which is the computer's 'do nothing' state. Placing the computer in this mode will suspend the operation of P20, which, up to now, has been keeping the SIM bay pointed at the Moon by rotating the spacecraft in step with its orbit. The Flight Plan includes a set of attitude angles for use during the upcoming platform realignment so Mission Control are suggesting that by going to P00 a little earlier, there will be less maneuvering to do to reach this attitude, thereby saving RCS propellant. Going to P00 and throwing the Uptel(emetry) switch to Accept also allows Mission Control access to the computer's erasable memory for the uploading of data.]

164:07:38 Henize: Al, the computer is yours; you've got a state vector, a target, and a REFSMMAT.
[These are the items which were uploaded into the erasable memory. Al can put the Uptel switch back to Block and change the program when it suits him. The state vector they have sent is a more accurate representation of their velocity and position at a particular time. They also uplinked a value for the Delta-V required of the next burn and a definition of the angles th guidance platform should be at when the plane-change burn occurs.]
164:07:47 Worden: Okay, Karl; thank you. [Pause.]

164:07:58 And, Houston; Endeavour. I've got the SIM bay powered down now, and turning back all the jets - turning on all the jets.

164:08:07 Henize: Roger, Al; we understand.

[Comm break.]

[Al will be aware that Mission Control want to save RCS quad C and, as the Flight Plan requires that all four RCS quads be enabled, he is presumably reminding them of that.]

164:09:15 Henize: Endeavour, this is Houston. You can expect us to give you a No - Go/No Go for LOI [means LOPC or lunar orbit plane change] before LOS. No, that's - that's right; that's a Go/No Go for plane change - pardon me, I'm a little bit behind time here - before LOS, and since your burn is so close to AOS, we'd like to give you a procedure here, so that we can lock up without your having to go over there to throw - to throw any switches. Can you copy it now?

164:09:51 Worden: Roger, Karl; go ahead.

164:09:55 Henize: Okay. After LOS, we'd like to have you put the High Gain [Antenna] Track to Manual, and dial in Pitch, minus 10; Yaw, 251. When the high gain angle - when the High Gain Antenna [angle] meters read Pitch, minus 10 and Yaw, 251, then go to Track and Reacq with Narrow Beam. Then, if your Squelch is Off, your High Gain Antenna acquisition will be indicated at AOS by a loss of noise.

[The next time Endeavour reappears around the Moon's eastern limb, Al will be within only a couple of minutes of the plane change burn. Such burns are usually only carried out at the nodes of an orbit (where the orbit crosses the equator) and as the landing site is near the Moon's zero longitude meridian, the nodes are over the west and east limbs, near the points where LOS and AOS occurs. Mission Control would like to watch the performance of the spacecraft during this burn but don't want to interfere with Al's preparations. Since they know very accurately the attitude the spacecraft will be in, they can calculate appropriate angles for pointing the HGA. Then, at AOS, it ought to be able to lock to Earth without Al's intervention. These angles are as printed in the Flight Plan.]
164:10:43 Worden: Okay. Understand you want me to position Pitch, minus 10; Yaw pl - Yaw to 251; go Reacq, Narrow, and make sure the Squelch is Off.

164:10:52 Henize: That's affirmative.

[Comm break.]
164:12:31 Henize: Endeavour, this is Houston. You're Go for plane change 1.

164:12:39 Worden: Houston, Roger; Endeavour. Understand Go.

[Comm break.]

[Al is carrying out the first of two realignments of Endeavour's guidance platform or IMU (Inertial Measurement Unit) using P52. The first of these is with respect to the existing landing site REFSMMAT which allows engineers to see how far the platform has drifted since the previous realignment, an important gauge of the IMU's performance. Once he has made two sightings of stars with the spacecraft's sextant, the computer will use the resultant information to calculate how far the platform ought to be torqued to regain perfect alignment. Al will display those numbers on the DSKY where Mission Control can read them via telemetry. This is the last time the platform will be aligned to the landing site REFSMMAT.]

164:17:39 Worden: Okay, Houston; Endeavour. I've got the gyro torquing angles up. You through copying them?

164:17:43 Henize: Endeavour, we've copied them. Thank you.

164:17:48 Worden: Okay.

[Long comm break.]

[With the first P52 out of the way, Al does another, but this time the realignment is with respect to the "Plane Change Orientation", a new REFSMMAT which was uplinked by Mission Control ten minutes ago. Since this new REFSMMAT has the same orientation as will be adopted by the spacecraft during the plane change burn, Al can expect the FDAI displays to show 0° in all axes when he goes for the burn.]

164:21:18 Henize: Endeavour, this is Houston. We're 2 minutes from LOS, and all of your systems look to be in excellent shape.

164:21:28 Worden: Roger. Thank you, Karl.

[Very long comm break.]

[During this far-side pass, when Endeavour begins its 45th revolution of the Moon, Al is primarily concentrating on preparing the spacecraft for the plane change burn. Of the major burns of the SPS in lunar orbit, only this and the later orbit shaping burn prior to subsatellite launch occur in view of the Earth, in this case, very shortly after AOS.]

[CSM Flight Plan page 3-251.]

[The numbers entered into P30 are checked. P30 is a program specifically for accepting the information relevant to a burn into the computer. Then the spacecraft is maneuvered into the correct attitude for the burn. The attitude is checked by viewing stars through the sextant. The event timer is set to count up to the moment of ignition. Loose equipment is stowed, and Al enters P40, a program which will take care of the burn, based on the information fed in by P30.]

[CSM Flight Plan page 3-253.]

165:09:45 Worden: Okay, Houston. I've got 1 minute and 45 seconds until the burn.

165:09:50 Henize: Roger, Endeavour. Houston reads you loud and clear, and we're standing by.

[Comm break.]
165:11:06 Worden: Average g.
[The G&N system is ready to monitor the acceleration produced by the burn.]
165:11:09 Henize: Roger. [Pause.]

165:11:18 Worden: Ullage. [Long pause.]

[Al is firing the B and D plus-X thrusters to settle the contents of the SPS propellant tanks and ensure pressurising gas is not ingested into the engine.]
165:11:41 Worden: Thrust on. [Long pause.]

165:11:54 Worden: Thrust off.

[Comm break.]
165:13:00 Worden: Houston, Endeavour. If you're copying the DSKY, you'll see residual as .2, .2, and .3, so no trim.

165:13:09 Henize: We copy and concur, Al, and it looks like a beautiful burn.

165:13:17 Worden: Yes, sir. It certainly does.

[Long comm break.]

[After maneuvering the spacecraft to an attitude suitable for viewing stars at the next P52 platform realignment, Al prepares to restart some of the SIM bay science. The Gamma-ray and Alpha Particle Spectrometers are switched on, and the X-ray and Mass Spectrometers are placed in standby. As the SIM bay is not specifically pointed at the Moon, the data coming from these instruments is not particularly meaningful.]

165:23:02 Henize: Al, if you'll give us Accept, we'll send up a lift-off REFSMMAT and a RLS update.
[The computer is already in P00 (program 00, its 'do nothing' state) so all Al has to do is throw the Uptel switch. With the plane change burn out of the way, the guidance platform no longer requires to be aligned to the plane change orientation. For the rest of the time in lunar orbit, the platform will be aligned to the "lift-off" or "lunar orbit orientation" so Henize is offering to send up a new REFSMMAT. Along with this is an update to the RLS (Radius of Landing Site), Mission Control's most accurate calculation of the distance from the centre of the Moon to the landing site. Al and Mission Control are ahead of the timeline here by about 25 minutes.]

[The lift-off REFSMMAT has the X-axis of the guidance platform parallel to the local vertical at the landing site, pointing away from the centre of the Moon. Its Z-axis is a horizontal vector at the landing site. This vector is parallel to the plane of Endeavour's orbit and points in the direction of travel. As the Moon is turning, these two vectors only hold true for one instant of time and this is defined as the moment of Falcon's expected lift-off. This is the "REFSMMAT 00" time and it will be updated to Endeavour later. Were Falcon to be sitting perfectly upright on the lunar surface and facing exactly downrange, its FDAI would read zero in all three axes just before lift-off. The LM's tilt will therefore show in the FDAI.]

165:23:12 Worden: Okay, Karl. And if you're ready, I'll give you the rest of the burn status report. It's just the EMF and things like that.

165:23:19 Henize: Go ahead.

165:23:23 Worden: Okay. Tig was on time, and looked to me like the burn time was 18 seconds; Delta-Vc was minus 10.6 [fps, 3.2 m/s]; fuel is now 26.4 [percent]; oxidizer is 26.2 [percent]; and Increase-Decrease [i.e. PUGS manipulation] is Decrease 25.

165:23:50 Henize: Thank you. We copy. [Long pause.]

165:24:19 Henize: And, Al, in case of confusion on that Mass Spec[trometer], we do want the experiment switch on Standby.

165:24:28 Worden: Oh, okay, Karl. Yes, there must have been some confusion because I had scratched that off my Flight Plan. Okay, going Standby. [Long pause.]

165:25:17 Henize: Endeavour, Houston. The latest bulletin from Hadley Rille tells us that the crew, after spending an unusual amount of time at the LM trying to get back the core drill, with which they were only partially successful, are now moving across the lunar surface and they're currently at Hadley Rille giving us some beautiful views of the rille.

165:25:47 Worden: Very good. How is the TV from there, Karl?

165:25:50 Henize: Our TV down here is just beautiful.

165:25:57 Worden: Good. Save a copy for me.

165:26:00 Henize: We sure will, Al.

165:26:06 Henize: Hey, Al. Vance says "Do you want us to put it on your EMF."

165:26:10 Worden: Tell Vance he's got the wrong EMF, I'm afraid. Sure would like it, though.

165:26:21 Henize: Righto.

165:26:25 Worden: And you tell Vance I got cartoons on right now.

165:26:28 Henize: Say again.

165:26:33 Worden: Just tell Vance I got cartoons on. He'll know.

165:26:41 Henize: Okay, Al. [Long pause.]

165:26:59 Henize: Al, we'd like to have you stay in Accept, but give us a Verb 33, Enter.

[Comm break.]

[Verb 33 - Proceed without DSKY inputs.]

165:29:13 Henize: Endeavour, this is Houston. We'd like to have the Gamma-ray Gain Step up three times, please.

165:29:26 Worden: Roger, Karl. Gain Step up three times.

165:29:29 Henize: Affirmative. [Long pause.]

165:30:00 Henize: Al, you can go to Block now. We've had some conflict in commands in that update to you and you got your LR - RLS update, but you didn't get the new REFSMMAT.

165:30:16 Worden: Okay, Karl; understand.

[Comm break.]

[Al starts a 30 minute exercise period about now.]

165:31:22 Henize: Endeavour, this is Houston. Will you please give us Accept?

165:31:30 Worden: Okay. You've got Accept.

[Comm break.]
165:33:16 Henize: Al, give us Verb 33, Enter. And that should complete your REFSMMAT...

165:33:26 Worden: Okay. You got it.

165:33:27 Henize: ...and you can go to Block.

165:33:33 Worden: Okay. Thank you, sir. [Long pause.]

[That is the second attempt to upload the new REFSMMAT.]
165:34:15 Henize: Endev - Endeavour, we would like High Gain [Antenna], Auto.

165:34:24 Worden: Auto.

165:34:28 Henize: Thank you.

[Long comm break.]
165:41:02 Henize: Al, the medics told me that they can see that you are exercising per the Flight Plan. Would you like to know what peak value you get? Peak value on heart rate, that is.

165:41:15 Worden: Yeah. I'd be interested in that, Karl.

165:41:16 Henize: Yes. Let's see how high you can - you can...

165:41:17 Worden: Yes.

165:41:18 Henize: ...work her up. It'd be good to really churn her up for a while. [Long pause.]

165:41:52 Henize: Okay, they got you at about 100 beats per minute for a moment.

165:42:00 Worden: Very good. [Long pause.]

165:42:25 Henize: We record 116. [Long pause.]

165:42:47 Henize: You made 120. Man, you must be burning that thing up. [Long pause.]

165:43:26 Henize: Got you at 126.

[Comm break.]
165:46:22 Henize: They say that looked like a real good stretch of exercise there, Al. Should stand in good stead a couple of days from now.

165:46:32 Worden: Roger. I sure hope so, Karl; been keeping it up just for that reason.

165:46:35 Henize: Very good.

165:46:40 Worden: And I think it makes a difference in - in your whole outlook and - the - restful way that you can do this flight, too. A little exercise and I get a good night's sleep also.

165:46:54 Henize: Yes, you're probably right.

[Long comm break.]
165:55:57 Henize: Al, I have a REFSMMAT zero time for you when you have time to copy.

165:56:10 Worden: Okay, Karl. Go ahead.

165:56:11 Henize: 171:37:18.89.

165:56:26 Worden: Understand 171:37:18.89.

165:56:32 Henize: That's affirmative.

[Very long comm break.]

[The REFSMMAT 00 time is the time for which the new REFSMMAT, just uplinked to Endeavour's computer, matches the conditions on which it is based. Remember, it is a set of axes defined with respect to the landing site, but, because of the Moon's rotation, they are current only at a particular time and that time is made to coincide with lift-off. Essentially, the time given by Henize represents the expected lift-off time for Dave and Jim in Falcon.]

[CSM Flight Plan page 3-255.]

[Next, Al does the first P52 realignment of the guidance platform to the lift-off REFSMMAT. Since the previous P52 was so recent (less than 2 hours ago), there is no need to check the drift of the platform by realigning to the plane change REFSMMAT first. Once finished, Al brings the gimbal torquing angles onto the DSKY display where Mission Control can read them.]

166:08:31 Henize: Al, we've got your angles and you can torque them.

166:08:39 Worden: Okay, Karl. Torquing on the minute.

[Long comm break.]

[Endeavour is maneuvered to the SIM bay attitude with the CM apex forward, and then Al deploys the boom carrying the Gamma-ray experiment. The covers for the Alpha Particle and X-ray Spectrometers are opened though Al omits to switch on the latter. Mission Control will remind him after AOS.]

166:17:48 Henize: Endeavour, this is Houston. All of your systems are Go as you go around the corner, and I hope to have a science update for you on the next rev. In the meantime, I can report that the X-ray data is beginning to show very clear patterns from highlands to mare region. It looks as though we are going to - we - we are high in magnesium in the mare and high in aluminum in the highlands, which tends to confirm the anorthosite theory for the highlands. It gets rather exciting when the data starts adding up like that. And the Laser Altimeter has shown us that the back side of the Moon is indeed further from the center of the Moon than the front side. This had been a theory previously, and now you seem to have proved it with good solid data. Lots of things are beginning to fall into place, and - What a mission, that's all we can say.

166:18:56 Worden: Sounds pretty good so far, Karl. And I'm getting the SIM bay ready to have another shot of that.

166:19:09 Henize: Okay; we've been watching your maneuvering there. Have a good go at it.

166:19:16 Worden: Okay, Karl. [Pause.]

166:19:26 Henize: And the Rover boys at Hadley Rille have just had a tremendous session picking up all sorts of useful samples. The TV has been beautiful, the - All sorts of layering shows - in the - in the edge - in - in the - in the rille walls, and it's just very exciting.

166:20:05 Worden: It sounds great.

[Very long comm break.]

[As Endeavour goes around the far-side of the Moon to begin its 46th orbit, Al has very little in the time line except to begin his meal period at 167:00, just a few minutes before AOS.]

[CSM Flight Plan page 3-257.]

167:13:59 Henize: Endeavour, this is Houston. How do you read? [No answer.]

167:14:36 Henize: Endeavour, this is Houston. How do you read? [No answer.]

167:15:19 Henize: Endeavour, this is Houston. How do you read?

167:15:28 Worden: Hello, Houston; Endeavour. Loud and clear.

167:15:31 Henize: Roger. Hear you likewise, loud and clear.

[Comm break.]
167:16:51 Henize: Endeavour, we'd like High Gain [Antenna], Auto.

167:17:00 Worden: Okay. It's in Auto.

[Comm break.]
167:18:02 Henize: Endeavour, we need Wide Beam for 5 seconds and then Narrow.
[Comm break.]

[The HGA has probably locked onto a reflection from the skin of the spacecraft. Switching it to a wide beamwidth will help it reacquire the signal from Earth.]

167:21:06 Henize: Endeavour, would you confirm that [the] X-ray [Spectrometer] is On, please. [Long pause.]

167:21:23 Worden: Endeavour, negative. It's - it's off right now, Karl.

167:21:28 Henize: Roger. We'd like to have it on, please. [Pause.]

167:21:40 Worden: Roger. Going On. And sorry about that, Karl. I switched it one position thinking I had it On, but it was really Off.

167:21:50 Henize: Righto. [Long pause.]

[The X-ray Spectrometer was to have been switched on prior to LOS.]

[Worden, from the 1971 Technical Debrief - "I found that my single biggest problem with the operation of the SIM bay was in not being continuously aware of the state of the various experiments in the SIM bay. The only indicators on board are the talkbacks associated with each of the instruments. In both the stowed position and the operate position, those talkbacks are always gray. You really have no way on board of identifying the mode of operation of each of the instruments without going back and referring to the Flight Plan and knowing that you've performed the functions on the Flight Plan as prescribed. This caused some confusion at times when we had real-time updating, because then, the SIM bay got in a non-standard configuration with respect to the Flight Plan. It was very difficult, without a lot of discussion from the ground, to determine the mode of each of the instruments and what had to be done at the next step. It would be great if there were some indication on board of the mode that each instrument was in at the time."]

167:22:15 Henize: Al, another bulletin from Hadley Rille. The crew is back at the LM and starting their closeout. Just a few minutes ago, I saw them perform the philatelic wonder of the century.

167:22:34 Worden: So, it's all out now, huh?

167:22:36 Henize: Roger. [Long pause.]

167:23:23 Henize: And, Al, you'll be fascinated to know that Galileo's theory of gravitation has been confirmed. Dave just dropped a hammer and a feather and they hit the ground simultaneously.

167:23:38 Worden: Did you ask him what kind of a feather it was?

167:23:42 Henize: A falcon feather; yes, indeed.

167:23:46 Worden: How about that.

[Comm break.]
[The falcon is the mascot of the United States Air Force Academy and the services of a falcon's feather were employed on the Moon in a little bit of theatre suggested by Joe Allen. In a simple experiment intended for the TV audience, Dave dropped the feather and a geology hammer simultaneously to demonstrate that in a vacuum, objects of differing mass fall at identical speeds. Galileo had stated they would about 350 years earlier, and the crew of Apollo 15 had just proved him right. Readers who wish to read about this event should read the Apollo 15 Lunar Surface Journal at 167:21:58.]

[In 1986, Apollo 12 LMP and artist Alan Bean rendered the event in a painting that was used as the frontispiece of a NASA history book on Apollo lunar exploration, Where No Man Has Gone Before.]

167:24:55 Henize: Al, we're up to the time to turn Pan Camera mode, Standby and Power, On.

167:25:03 Worden: Okay, Karl. [Long pause.]

[Even though it is not being used, the Panoramic Camera must be powered up regularly to move the film through the system and avoid it setting around the camera's idlers and guides.]
167:25:19 Henize: Hey, we got a few special words also on water dumps - I guess you got one coming up in about 3 hours. They're anxious, in the future, that we don't run the waste water below 10 percent, because of possible malfunctions of the waste inlet valve, causing the suit exchanger to have oxygen breakthrough. So they'd appreciate your keeping a close eye on the - on waste dumps and - waste tank water quantity.

167:25:53 Worden: Okay, Karl. Will do.

[Comm break.]
167:28:48 Henize: Endeavour, Pan Camera Power, Off, now, please.

167:28:48 Worden: Power is coming Off. [Long pause.]

167:29:57 Henize: Al, while you're eating up there, we've got the morning news. Are you in a situation to listen?

167:30:07 Worden: Okay; yeah, Karl. Glad to hear it.

167:30:10 Henize: Okay. It looks like we've avoided a steel strike down here. The steel workers and management agreed to a one-dollar per hour pay increase last night, boosting the straight time rate to 4.45 [dollars] per hour. Maybe we should take up that trade, huh?

167:30:29 Worden: Sure sounds like it.

167:30:31 Henize: The mercury dipped to 68 degrees yesterday, a record low for the first of August in Houston; we've had some real pleasant weather here. Too bad that either you or I haven't been - had a chance to get outside to enjoy it, huh?

167:30:48 Worden: Yeah, wait 'til next week, and we'll take a vacation.

167:30:51 Henize: You said it. Representative Edith Green, Democrat of Oregon, said, "Students and parents have been misled into thinking that a college degree is the only road to success." She advocated more vocational and technical training. On the sport scene, Arnold Palmer and Jack Nicklaus combined their talents to score an easy 6-stroke victory in the National PGA Championship at Ligonier, Pa. They were 27 under par into 72 holes. The Astros smothered Montreal 8 to 1, but are still in the second division, 11 and a half games behind San Francisco. And here is a flash hot off the wire. It's only - it's only 200 years old, but very apropos of the leak that you sprang a couple of nights ago and also the big leak in the LM a couple of days ago. And the dispatch is as follows: The Endeavour, the original Endeavour, sprang a leak off the Great Barrier Reef at 11:00 p.m. on 11 June - on 11 June 1770. It was necessary for them to dump 40 tons of consumables to prevent sinking; then they sailed on with 40 feet of water in the hold. And this information comes to you courtesy of Honeysuckle Tracking Station in Australia.

167:32:24 Worden: Hey, that's very nice of Honeysuckle to tell us that. And I guess you ought to know that when we sprang a leak the other night, we didn't notice that any water had escaped. But when I made the plane change burn today, I found it, and it was sitting right in the middle of the after - of the heat shield.

167:32:43 Henize: [Laughter.] Very good. How much water was there? Can you estimate that?

167:32:49 Worden: Had a great big puddle of water.

167:32:51 Henize: A pint?

167:32:53 Worden: Oh, I'd estimate maybe a pint. Yeah.

167:32:56 Henize: Okey-doke.

[Comm break.]

[Burns of the SPS engine will tend to cause any water floating about the cabin, or condensing on any surfaces, to collect towards the centre of the aft bulkhead, a curved surface which carries the heatshield on its outside.]

167:35:30 Henize: Al, here's a little more of an update on the operation of the SIM bay experiments. The Gamma-ray, X-ray, and Alpha Particle Spectrometers are continuing to collect good scientific data. I already told you about the - the X-ray data showing regional differences very clearly. I went downstairs and looked at it myself, and it really is almost on a kilometer by kilometer basis. You can see, when you go from a highland in - into a mare; very interesting. The Laser Altimeter, as I already told you, has shown a lot of interesting things about the altitudes on the Moon. But - I'm not sure whether you know it or not - but it's essentially belly-up [i.e. dead, or not working] at the present time. We don't have much hope for it in the future. But the data that we did get out of it was very interesting and very good. And I guess that's about all I can say at the moment.
[The X-ray data was showing a strong correlation with the data from the Laser Altimeter before the latter instrument died. The importance of the results from the these two instruments is nicely conveyed in a story related in the excellent Apollo: The Race to the Moon by Charles Murray and Catherine Bly Cox, one of the best books about the genesis and progress of the Apollo program. It relates how Jack Trombka, an experimenter in the science back room, was plotting the results from the X-ray Spectrometer showing the concentration of aluminium in the lunar regolith along the orbital track. During this process, he saw that someone had already put a completed plot on the wall which looked essentially the same as the one he was working on and, astonished, asked how come someone else had acquired his results before he had. The other plot, however, was of altitude, as measured by the Laser Altimeter and all at once he knew that one of the great questions of the Moon's history had been answered.]

[Aluminium is a relatively light element and the discovery that its concentration increased with altitude strongly implied that at one time, the Moon must have been largely molten to allow that element to tend to rise to the surface. The popular theory that the Moon had always been a cold body since its accretion was knocked down once and for all and the understanding gained from the molten Moon theory has provided an important foundation for our understanding, not just of the Moon, but of the whole solar system.]

[Current theories contend that very soon after the Moon's formation, it's mantle was completely molten in what is descriptively called a "magma ocean." Within this fluid mass, gravity allowed the various constituents of the magma to migrate up or down, according to their weight, such that the fresh crust tended to have a high concentration of aluminium. The fact that strong evidence of this chemical differentiation is still extant today is testament to the extraordinary antiquity of the Moon's surface when compared to the Earth's.]

[The Gain Step Shield on the Gamma-ray Spectrometer is switched off for roughly ten minutes to give some data from the instrument without any discrimination between desired and undesired events. This is part of the instrument's regular calibration checks.]

167:36:36 Worden: Roger, Karl. Thank you. That all sounds very interesting.

167:36:43 Henize: I'm not sure I told you previously...

167:36:45 Worden: And, Karl, you say - that the Laser Altimeter is just about gone now, huh?

167:36:55 Henize: Yeah. I think most people have admitted that it's not - it's giving us useless data. It has given us useless data on the last couple of attempts to use it, and we have very little hope for it now.

167:37:19 Henize: Incidentally, the Pan Camera is deteriorat - deteriorating to some extent. That V over H problem is getting - getting worse, not - it's - it's not completely bad yet, but we're getting a lower percentage of good frames, maybe 60 or 70 percent now.

167:37:51 Henize: And in connection with this deterioration of the Pan Camera, there is some feeling that as time goes by, it's getting poorer and poorer and that maybe we should occasionally pulse it on the self-test cycle to take just a - five frames on - on interesting regions as we go along in order to get the film used up before it really deteriorates to a greater degree. I guess we're asking for your opinion on that. Do you have any feeling about that?

167:38:24 Worden: No, but it sounds like a good idea. It seems to me like, good or bad, it'd be a shame to leave some unused film in the camera.

167:38:33 Henize: Roger. Well, we'll hang loose on that, and I think - I think really we ought to get a better evaluation down here as to how we - how to really use up that remaining film. People are thinking about it now.

167:38:45 Worden: Right. I agree.

[Comm break.]
167:39:59 Henize: Al, when I talked about pulsing the self test there, I - I didn't completely have the picture clear in my own mind. If the V over H sensor is giving us problems, this is one way to get around it, because, if we take our five frames in self test, we're essentially cutting the V over H sensor out of the circuit and taking a - a nominal [degree of] image motion compensation there, which would be better for us. So it's possible that, when we wind up using that film, that we'll have somebody sitting down in the lower equipment bay - probably after you're all three together again - pulsing that switch every 30 seconds.

167:40:41 Worden: Roger, Karl; understand. It sounds fine.

[Very long comm break.]
167:54:06 Henize: Al, we're ready to have Gamma-ray Gain Step back to center [Shield, On].

167:54:15 Worden: Okay; Going Shield, On. [Long pause.]

167:55:00 Henize: And it looks like you're going to have your fun this rev by having a good look at Aristarchus, huh?

[Henize is referring to the Flight Plan which calls on Al to make some visual observations of the Aristarchus plateau.]

[The region around Aristarchus combines this relatively recent 40-km crater, with an extraordinarily rich collection of rilles which once fed lava into Oceanus Procellarum (Sea of Storms) and the distinction of being one of the brightest regions of the Moon. Later in the mission, this area will be the focus of closer study and photography.]

167:55:10 Worden: Yeah, that's right, Karl. I've looked at Aristarchus a couple of times already in Earthshine, and I'll tell you even in Earthshine, that thing is spectacular. I can see Schröter's Valley; it shows up very white, and the crater Aristarchus with the rays extending to the west are all - they're all very, very visible.

167:55:29 Henize: Roger. [Long pause.]

167:55:43 Worden: And I'm just at the terminator now.

167:55:49 Henize: We copy.

[Long comm break.]

[CSM Flight Plan page 3-259.]

168:04:11 Henize: We see you moving over to the antisolar point to take some gegenschein photos. It's about time we solved that problem, Al. Take some good ones. That Nikon camera ought to do a good job for us.

168:04:26 Worden: Well, we are all set up here, Karl; and, if the Nikon will do it, we'll get them.

168:04:33 Henize: Very good. [Pause.]

[The Nikon 35-mm camera is being carried to take photographs in very low light and prove the capabilities of the camera for future missions. Loaded with 6,000 ASA black and white and fitted with a very fast f/1.2 lens, it is hoped that various astronomical phenomena can be captured while the spacecraft is out of sight of both the Earth and the Sun. The Nikon is also used for photography of the lunar surface illuminated by Earthshine, and the solar corona as visible just prior to sunrise and just after sunset.]

[The gegenschein is a patch of light very faintly visible at a point in the sky directly opposite the Sun. It is believed to be caused by dust in the plane of the solar system preferentially reflecting back towards the Sun in a manner similar to the reflective signs at a roadside, or the bright "zero phase" light seen on the lunar surface if one looks directly away from the Sun. Al must maneuver the spacecraft so that window 4, the right-hand rendezvous window, faces the anti-solar point.]

168:04:43 Henize: Did you see the seven rilles of Aristarchus, Al?

168:04:52 Worden: Certainly did. [Garble.] Not much to relate at this time as far as Aristarchus - or descriptions - visual observations are concerned in Earthshine. As a matter of fact, it was so close to the terminator that I wasn't really dark-adapted enough to see much except the very light colored crater Aristarchus and its ejecta pattern and a very light-colored Schröter's Valley and - which kind of surprised me. Schröter's Valley has about the same lightness as the interior of Aristarchus itself.

[Two Mapping Camera images of Aristarchus taken later in the mission are AS15-2606M and 2610M.]
168:05:39 Henize: Roger. Didn't see any red spots up there, huh?
[Henize is alluding to the observation, on 29 October 1963, of red spots in and around Aristarchus by Jim Greenacre, an experienced lunar observer and mapper at the Lowell Observatory. His observation was confirmed by several others. It caused a stir at the time as it seemed to be strong evidence of current lunar volcanic activity.]
168:05:45 Worden: No, I sure didn't.

168:05:58 Henize: Al, the time line on the surface is going very well now, and they're just about ready to repress.

168:06:07 Worden: Oh, very good.

168:06:09 Henize: Hey, as I look back over towards Tsio - Tsiolkovsky, I see your new orbit is taking you over the crater Alden. Do me a personal favor and sneak in a shot of it, if you can.

168:06:22 Worden: Okay.

[Long comm break.]

[Alden is about 600 km west of Tsiolkovsky and just beyond the Moon's limb.]

[Al is about to get busy as the time for Falcon's lift-off approaches and his first preparatory task is to retract the boom carrying the Gamma-ray Spectrometer and configure the SIM bay to a low level of operation for the next three hours, when he will power it down completely.]

168:16:13 Worden: Houston, Endeavour.

168:16:17 Henize: Endeavour, go ahead.

168:16:22 Worden: Okay. You ready for me to turn the Data Systems, Off? [Pause.]

168:16:42 Henize: Roger, Al. If you have secured the SIM bay experiments, we're ready for the Datum [means Data] System, Off.

168:16:50 Worden: Okay, we're secured now. [Long pause.]

[With the SDS (Scientific Data System) switched off, only data from the Gamma-ray Spectrometer is gathered as it takes a separate route through the spacecraft.]
168:17:47 Henize: Okay, Al; as you go around the corner, all of your systems are looking in good shape. Have fun with the gegenschein photos.

168:17:57 Worden: Okay, Karl; hope so, and see you around the other side.

168:18:01 Henize: Righto.

[Very long comm break.]

[As the Moon's phase approaches full, the Sun is increasingly towards the near-side, along with the Earth. Much of the far-side is in deep darkness and it is within this profound darkness, as Endeavour commences its 47th revolution, that Al hopes to use the Nikon 35-mm SLR camera to photograph the gegenschein, a patch of faint light reported to be visible in that part of the sky opposite the Sun.]

[Worden, from the 1971 Technical Debrief - "There was some afterglow in the [internal spacecraft] floodlights, and I taped the floodlight above the right-hand rendezvous window to reduce the light from that source."]

[The spacecraft is to be pointed at two points on the celestial sphere. The first is Al's anti-solar point, directly opposite the Sun from Endeavour. The other is the Moulton point, another name for the L2 point of the Sun-Earth system.

Diagram showing Lagrangian points.

This is the Lagrangian point beyond Earth's orbit which is thought to harbour gatherings of interplanetary dust. These two points are separated by roughly 15° as seen from Al's vantage point. Two frames are exposed in each direction, one for one minute and one for three minutes. If the gegenschein is due to back-scattering from dust in the plane of the solar system, it should show in the anti-solar photos. If dust at the Moulton point is responsible, the second pair of photos should show it.]

[The Flight Plan gives Al attitudes to point the spacecraft, the right rendezvous window and therefore the camera at the anti-solar and Moulton points. Unfortunately, the attitude figures given in the Flight Plan are wrong. According to the 1971 post-mission report, incorrect signs were used (i.e. plus or minus were reversed) sometime during the calculation of these angles, rendering the exercise unsuccessful and postponing it to the Apollo 16 mission.]

[A few minutes before AOS, the 16-mm movie camera, or DAC, is mounted in the eyepiece of the sextant to photograph the LM from orbit. To keep the sextant pointing at the landing site, Al is to use P24, one of the tracking programs. There are two other tasks in the Flight Plan before AOS. The lithium hydroxide canister is changed in the "A" receptacle. Canister 13 replaces 11, which is stowed in compartment A9. Also, Al carries out a self-test on the rendezvous radar.]

[CSM Flight Plan page 3-261.]

[Falcon is due to lift-off at 171:37:22, about 2½ hours from now. For this event, and the subsequent rendezvous, Dave Scott has specifically requested that Ed Mitchell be CapCom. Ed was Lunar Module Pilot on Apollo 14 and therefore has recent experience in the direct ascent and rendezvous about to be executed.]

[Scott (from the Apollo 15 Lunar Surface Journal in conversation with Eric Jones) - "Ed Mitchell has come on as CapCom because he's the expert in the rendezvous. We would normally have a new CapCom for launch; but the CapCom is specially Ed Mitchell because Ed really understands the rendezvous - just like Joe Allen really understood the geology. Ed did the direct rendezvous on 14, so I wanted Ed Mitchell there. I shouldn't downplay rendezvous. It's not trivial. It's got to be done very carefully. Aviation, like the sea, is not inherently dangerous; but it is terribly unforgiving of any carelessness, incapacity, or neglect. So you want your best guy on. And we thought Ed was - as you well know - very good. So, if things get off nominal, you've got the A Squad down there taking care of you. It's important. That relaxes us, you know, to know we've got a good guy."]

[Jones - "Thanks for putting that in here."]

[Scott - "Well, it's a team kind of thing, and when you get all the A players in there, you win the game, right?"]

169:06:07 Mitchell: Endeavour, Houston, Standing by.

169:06:16 Worden: Houston, Endeavour's on.

169:06:18 Mitchell: Okay, Al. Good morning.

169:06:24 Worden: Is it morning, Ed?

169:06:26 Mitchell: Yeah, it's morning down here, Al. Al, we've got a couple of changes for you. We're going to delete the P22 because the LM crew needs a little extra time, and substitute a P24 from the Command Module for it. If you've already got your camera on the sextant, sorry about that. If not, delete it.

169:06:49 Worden: Okay. I've already got it on, but that's no problem.

[The LM crew were due to perform a P22 which, on the software of Falcon's computer, uses the rendezvous radar to make navigation fixes with the Command Module, giving a check of the radar system in the process. Instead, Al will use Endeavour's optics to fulfil the same navigational purpose, giving the crew on the surface more time to get themselves sorted after their last EVA and prepare for lift-off.]

[Scott, from the 1971 Technical Debrief - "We skipped a P22 with the Command Module because we were somewhat behind time, there, and that didn't seem to be too necessary anyway. With that elimination, we were pretty much right on the timeline all the way up to lift-off, and everything went as per schedule. I think we had run this a number of times in the simulator and felt pretty comfortable with it, even though I remember commenting that that was probably the fastest two hours we spent in the whole flight."]

[As he will now be taking marks on the LM through the sextant, Al must remove the DAC currently mounted in the sextant eyepiece.]

169:06:53 Mitchell: Okay. We'll give you a P24 landmac - landmark track PAD whenever you're ready.

169:07:05 Worden: Okay, go ahead.

169:07:07 Mitchell: Okay. Your target's the LM. T-1, 169:34:08; T-2, 38:15; TCA, 40:38; T-3, 41:06; south 3 nautical miles; and your attitude will have changed a little, Al. We're using roll, pitch and yaw of 000 350/231 and 000. Noun 89, latitude 26.107; longitude over 2, plus 01.828; altitude, minus 013.26; and, at 169:25 in your Flight Plan, change the R2 of Noun 78 to minus 080.00.

[The PAD is interpreted as follows:

Al will be taking marks on the LM using the sextant.

T-1 (169:34:08 GET) is the time that the landing site is on Endeavour's horizon and is 6 minutes, 30 seconds before closest approach.

T-2 (169:38:15) is 4 minutes, 7 seconds after T-1 and is when Al begins rotating the spacecraft at orbital rate to keep it pitched down 22° from the local horizon.

TCA (169:40:38) is the time of Endeavour's closest approach to the landing site.

T-3 (106:41:06) is 6 minutes, 58 seconds after T-1 and 28 seconds after TCA. It marks the end of the landmark tracking mode. Al will have about 2 minutes, 51 seconds to view the landing site.

At TCA, Endeavour will be 3 nautical miles (5.6 km) south of the landing site.

Roll, pitch and yaw: 0°, 350/231° and 0°.

Landing site latitude: 26.107° north.

Landing site longitude over 2: 1.828° east. True longitude is therefore 3.656° east but the computer uses a scaled figure to preserve accuracy.

Landing site altitude: Minus 13.26 nautical miles (24.56 km) below the reference lunar sphere. As Mitchell will soon point out, this is clearly wrong. The value for the altitude of the landing site in Noun 89 is quoted to two decimal places Mission Control seem to have given it to three places. The correct value should be 1.33 nautical miles (2.46 km).

Ed has made another small error in the time of the next change which he will shortly correct. At 169:15, not 169:25, the second value in Noun 78 should be changed from minus 65° to minus 80°. This value is called Axis Pitch and it partly defines a vector coming from the spacecraft. This is the vector which will be made to point at the centre of the Moon during the tracking operation.]

169:08:50 Mitchell: Al, I gave you a wrong time [for the R2 change]...

169:08:51 Worden: Roger, Ed; copy...

169:08:55 Mitchell: 169:15 is the time where that should be. I don't see it there.

169:09:04 Worden: Okay, Ed. I have - I have that one in the Flight Plan now; at 169:15, R2 is minus 068.00.

169:09:13 Mitchell: That's affirm; and we're substituting minus 080.00.

169:09:26 Worden: Understand; substitute for that minus 080.00.

169:09:30 Mitchell: That's affirm, Al.

169:09:31 Worden: Okay; here goes the landmark tracking PAD. P24 on the LM, T-1, 169:34:08; T-2 is 38:15, 40:38, 41:06; that's 3 miles south; roll, pitch, and yaw are 000, 350/231, 000. Noun 89's are plus 26.107, plus 01.828, minus 013.26; and I've changed R2 of the DAP load.

169:10:12 Mitchell: Okay, Al; and we will need marks on them of course.

169:10:18 Worden: Roger.

169:10:23 Mitchell: Be back with you in a little while.

169:10:27 Worden: Oh, okay.

[Very long comm break.]
169:20:33 Mitchell: Endeavour, Houston.

169:20:38 Worden: Houston, Endeavour; go ahead.

169:20:40 Mitchell: Al, it seems like we had a - error on that last PAD I read you. The altitude should be minus 001.33. Understand?

169:20:54 Worden: Understand the altitude should be minus 001.33.

169:20:57 Mitchell: That's affirm. Sorry about that.

[Long comm break.]

[Al is setting up the VHF comm system for a check with the LM. However, the LM crew are busy with their lift-off preparations and the comm check will be deleted.]

169:26:28 Mitchell: Endeavour, Houston. Omni Charlie, please.

169:26:34 Worden: Omni Charlie.

[Comm break.]
169:29:05 Mitchell: Endeavour, Houston. On your High Gain [Antenna], go Wide and Manual, please.

169:29:17 Worden: Roger. Wide and Narrow - Wide and Manual.

169:29:19 Mitchell: Thank you, Al.

169:29:25 Worden: Okay. Any angles you want me to put in?

[Comm break.]

[CSM Flight Plan page 3-263.]

169:30:42 Mitchell: Endeavour and Falcon, Houston. We're going to delete the VHF check at this pass, just to give you a little more time.

169:31:00 Worden: Roger. Endeavour's got the VHF set up anyway.

169:31:04 Mitchell: That's fine. We just won't - bother the LM with it.

169:31:11 Worden: Okay. You might tell them though, I've got my - if you want to check out the rendezvous radar, I've got the transponder on.

169:31:19 Mitchell: Al, you're in the mud. You'll have to try me on that one again.

169:31:25 Worden: Okay. Just wanted to let you know that I've also got the rendezvous transponder on.

169:31:30 Mitchell: Okey-doke. Thank you Al.

[Comm break.]
169:33:14 Mitchell: Endeavour, Houston. One minute to T-1.

169:33:20 Worden: Roger. Thank you.

[Long comm break.]
169:37:45 Mitchell: 30 seconds to T-2. [Pause.]

169:38:03 Mitchell: 10 seconds to T-2, Endeavour.

169:38:10 Worden: Roger.

[Long comm break.]

[As Endeavour passes over the landing site, Al uses the 28-power sextant to observe the LM, align the optic's reticle on it and take marks. A knowledge of the time and angles of these marks along with an accurate understanding of the CSM's orbit allows determination of the LM's state vector.]

169:41:37 Worden: Okay, Houston; Endeavour. Through with tracking, but I'm not sure they're very good marks.

169:41:43 Mitchell: Okay, Al; we understand. High Sun angle may have made it difficult.

169:41:56 Worden: Yeah, I seemed to have a lot of interference sextant, from the landmark, by the sight - part of the optics.

169:42:03 Mitchell: Understand, Al. [Long pause.]

169:42:16 Mitchell: Al, do you think you saw him at all?

169:42:24 Worden: Yeah. I think the first couple of marks were on him, Ed, but I couldn't hold him.

169:42:29 Mitchell: Okey-doke.

169:42:31 Worden: I kept - I kept losing him.

[Very long comm break.]

[Worden, from the 1971 Technical Debrief - "I did the LM visual at about 170 hours and was never able to identify the LM on the surface. Two things I think caused that particular result. One was that the Sun angle was very high and that there was no discernible shadow from the LM, which helped me on the first LM visual to recognise and locate the LM. The second was because of the Sun angle, or at least I assume it was because of the Sun angle, the landmark line-of-sight part of the optics cast a very red or bright pinkish to red image in the sextant, which was very difficult to see through to actually look at the terrain. The landmark image kept sweeping through the sextant as I was looking at the landing site in the sextant. It was so bright at times that I couldn't see the actual image of the terrain. That also added somewhat to the confusion. Maybe that can be explained in terms of the geometry of the optics and the particular Sun angle at the time. I wasn't able to pick up the LM and I don't feel that that was a very successful landmark tracking pass."]

[Al's workload is beginning to build up. He puts a heater on to warm the Rendezvous Radar transponder. He maneuvers to an attitude suitable for the upcoming P52 realignment of the guidance platform. At this attitude, he will also be able to check the alignment of the COAS (Crew Optical Alignment Sight) which is mounted in the left, number 2, rendezvous window. There are a pair of angles relevant to this attitude for Al to point the HGA. There may be a problem with Al's current communication setup as Mitchell will have some trouble raising Al for the next half hour or so.]

169:57:51 Mitchell: Endeavour, Houston. In the blind, give us the best Omni[directional antenna], please. [Long pause.]

169:58:17 Mitchell: En - Endeavour, Houston. Best Omni, please. [No answer.]

[Comm break.]
169:59:52 Mitchell: Endeavour, Houston. In the blind, best Omni, please. [No answer.]
[CSM Flight Plan page 3-265.]
170:00:03 Mitchell: Endeavour, Houston. Best Omni. [No answer.]

170:00:13 Mitchell: Hello, Endeavour. Best Omni, please. [No answer.] [Long pause.]

170:01:08 Mitchell: Endeavour, Houston. Give us best Omni, please.

170:01:18 Mitchell: I... [Long pause.]

170:01:55 Mitchell: Ende...

170:01:59 Unknown Speaker: Endeavour, Houston. Best Omni. [No answer.]

170:02:13 Unknown Speaker: Endeavour, Houston. Best Omni. [No answer.]

[Long comm break.]

[Around 170:06, Al realigns the gyroscopically-stabilised platform at the core of the spacecraft's IMU (Inertial Measurement Unit) to the lift-off REFSMMAT. He then goes on to calibrate the pointing accuracy of the COAS. Still Mission Control are unable to raise him.]

170:07:23 Mitchell: Endeavour, Houston. How do you read? [No answer.]

170:07:32 Mitchell: Endeavour, Houston. Best Omni, please. [Long pause.]

170:07:55 Mitchell: Endeavour, Houston. How do you read? [Long pause.]

170:08:29 Mitchell: Endeavour, Houston. How do you read? [Pause.]

170:08:44 Mitchell: Endeavour, Houston. In the blind. Best Omni, please. [No answer.]

[Comm break.]
170:09:54 Mitchell: Endeavour, Houston. Best Omni, please. [No answer.]
[Comm break.]
170:11:08 Mitchell: Endeavour, Houston. [No answer.]
[Comm break.]

[It is now half an hour since Mission Control last heard from Endeavour and time for Ed Mitchell to read up information relevant to the upcoming rendezvous is running out as Endeavour approaches the western limb and LOS.]

170:13:34 Mitchell: Endeavour, Houston. How do you read? [Long pause.]

170:13:59 Mitchell: Endeavour, Houston. How do you read? [Long pause.]

170:14:40 Mitchell: Endeavour, Houston. [No answer.]

170:14:47 Mitchell: Endeavour, Houston. In the blind. How do you read? [No answer.]

170:15:02 Mitchell: Endeavour, Houston. Give us your best Omni, please. [Long pause.]

170:15:29 Mitchell: Endeavour, Houston. In the blind. I'm going to give you a lift-off time: 171:37:22.36. We'll uplink you at AOS since we have no contact. And, Endeavour; Houston. TPI, 172:29:39.00. I'll repeat, lift-off, 171:37:22.36; TPI, 172:29:39.00. CSM weight for your DAP, 35995.

[In the final couple of minutes before LOS, Mitchell reads up the GET timings for lift-off and the final phase of rendezvous. The final figure is Endeavour's weight (which properly ought to be referred to as mass) which is used in the Digital Auto Pilot routines when they calculate how much to fire the RCS jets when controlling the spacecraft's attitude.]
170:17:15 Mitchell: And, Al, if you read. Let's come around to AOS. Trying to get comm. We'll have a lot of work to do.

170:17:35 Mitchell: Endeavour, Houston. One minute to LOS.

170:17:41 Worden: Roger, Houston; Endeavour. And did you get the gyro torquing angles, Ed?

170:17:47 Mitchell: Al, we haven't had you for the last 20 minutes. Did you get my uplinks - or rather my PADs up?

170:17:57 Worden: Negative.

170:17:58 Mitchell: Okay. Let me give you one quickly. You've got 40 seconds to LOS. Tig is 171:37:22.36. TPI, 172:29:39.00. Your CSM weight 35995. I'm going to lose you in about 15 seconds. We'll get all your uplinks and the rest of the PADs at AOS.

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