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Apollo 15

Solo Orbital Operations - 2

Corrected Transcript and Commentary Copyright © 1999 by W. David Woods and Frank O'Brien. All rights reserved.
Last updated 2016-06-21
[This section primarily covers the sixth day of the mission, 31 July 1971.]

[At 112:10:09 GET, about half an hour into Al Worden's scheduled 7-hour rest period, he and Mission Control finished their voice communications. While Al sleeps, the spacecraft and its science instruments continue operating under the watchful gaze of Mission Control.]

[Four of the science experiments mounted in the Service Module's SIM bay have been operating while Al has been asleep. The Gamma-ray Spectrometer and Mass Spectrometer instruments are both fully deployed on the end of their respective booms. The spacecraft is flying with the SPS (Service Propulsion System) engine bell facing into the direction of flight so that the Mass Spectrometer's inlet also faces into any oncoming molecules of the lunar atmosphere. Later in the mission, this instrument will be operated facing away from the direction of travel to compare detection rates. Molecules detected in this orientation will be attributed to gases coming from the spacecraft.]

[The Alpha Particle Spectrometer and the adjacent X-ray Spectrometer have also been operational. The former is trying to detect the presence of radioactive radon gas released from the decay of uranium and thorium in the lunar surface, while the latter is analysing the X-ray fluorescence of the rocks as they are bathed in the solar X-ray flux. This yields data about the constituent elements of the lunar material.] [It is now 6½ hours later and time to begin the first full day of solo activities. It is the sixth day of the Apollo 15 mission and the date is July 31, 1971. Endeavour is on its twenty first revolution around the Moon and its current orbit is roughly 102 by 120 km (65 by 55 nautical miles). There are about 20 minutes remaining on the current near-side pass before LOS (Loss Of Signal) so there will be a flurry of activity while Al gets through the postsleep checklist and a platform realignment and Mission Control make various updates to him and the spacecraft's computer.]

[CSM Flight Plan pages 3-147, 3-149, 3-151, 3-153, 3-155, and the current page, 3-157.]

118:48:16 Henize: Alfredo, Houston is calling. How are you doing up there?

118:48:25 Worden: Good morning, Houston; this is Endeavour. Doing - doing fine. Reading you loud and clear.

118:48:32 Henize: Glad to hear from you, Endeavour. We'd like to have Accept, when you have a chance to reach up that direction.

118:48:43 Worden: Okay. You've got it.

[Al places the computer in Program 00 - simply known as "POO" - and throws the Up Telemetry switch to Accept. The computer can now accept uplinked data from Mission Control and in this case, they are sending up a revised state vector. This is a set of six numbers associated with a particular time. They define the spacecraft's position in three dimensions, and its velocity as resolved into three orthogonal velocity components.]
118:48:54 Henize: Roger. And down on panel 230, Mass Spectrometer, Multiplier, High, at your convenience.

118:49:07 Worden: Okay. Discriminator's in High.

[Al has misheard the call from Mission Control and confused Multiplier with Discriminator.]
118:49:11 Henize: Thank you. And, I've got that batch of updates there, whenever you can copy.

118:49:20 Worden: Okay. I'll wake up first.

[Woods, from 1999 correspondence with Worden - "Did you find getting into the swing of work somewhat difficult in the morning? It always seems surprising that after the wake-up call, Mission Control would get straight into the day's business without allowing time for the body to ramp up in its efficiency."]

[Worden, from 1999 correspondence - "It was not generally difficult to begin work in the morning [Houston time of course], because I was usually awake by the time they called. Also, I spent roughly half the time on the back side of the Moon, and so had about an hour each revolution when I could not talk to Houston in any event. As I recall, I was up and going before talking to Houston because I did not sleep that much during the orbital phase. A lot to do, plus I did not need as much sleep during flight."]

[Worden, from the 1971 Technical Debrief - "My impression of the operations of the spacecraft was one of complete confidence in the equipment on board. Things worked very smoothly, and I didn't have to keep an eye on all the gages all the time. There was very little noise on board. The only things I recall hearing are the suit compressors. I ran them most of the time with the three sets of suit hoses out and screens on the return, so the suit compressor noise was there. Also, I could hear a pump operating in the Service Module, which I assumed was the water glycol pump. Those are about the only two continuous noises that I had during the lunar orbit operations.]

["The rest of the spacecraft ran just beautifully the whole time. The fuel cells ran without a problem. In fact, everything ran just beautifully, and I really had no concern for the operation of the spacecraft during the lunar orbit operations. The only things that were off-nominal, of course, were the burns - the circularization burn and the plane change burn, where we had the problem with the SPS main A pilot valve circuit breaker. I made both of those burns on a single bank and they were nominal, except for that particular circuit breaker [for the mission timer] being left out."]

118:49:23 Henize: Go ahead; enjoy it. [Long pause.]

118:49:41 Henize: Al, on that mass spectrograph, we want the Multiplier, High and the Discriminator, Low.

118:49:54 Worden: Okay; understand. Multiplier, High, and Discriminator, Low.

118:50:00 Henize: That's - that's the right way, yeah. [Long pause.]

[The switches which control the Multiplier and Discriminator of the Mass Spectrometer are side by side on panel 230, the SIM bay panel.

Diagram showing layout of panel 230 which controls the SIM bay.

The Multiplier switch adjusts the gain of the electron multipliers and would be set to High to compensate for their decreasing gain.]

[The Discriminator switch alters the sensitivity of the pulse counting circuit in the instrument. Set to Low (sensitivity), it can reduce high background counts caused by sunlight entering the inlet.]

118:50:16 Henize: And, if you can reach up to the panel 3 there, we'd like High Gain [Antenna], Auto, at your convenience.

118:50:27 Worden: Okay; you have it. [Long pause.]

118:50:42 Henize: And, Al, the computer is yours at anytime.

[Long comm break.]

[The new state vector has been uplinked to the computer. Mission Control are due to send a Mapping Camera photo PAD, the state of Endeavour's consumables and changes to the Flight Plan.]

118:54:56 Worden: Okay, Houston. This is Endeavour. I'm ready to copy some updates there, Karl. [Long pause.]

118:55:26 Worden: Hello, Houston, Endeavour.

118:55:29 Henize: Endeavour, this is Houston. The first thing we'd like get through to you are the Mapping Camera photo PADs over on the next page at 119:30.

118:55:42 Worden: Okay, Karl. Go ahead.

118:55:44 Henize: "Start: 119:34:33; stop: 121:33:02." And a note to that is that the - the - the extend/retract times on the Mapping Camera seem to be getting longer with time, and, until further notice, we'd like for you to record and send down the Delta-T on each extend and retract.

118:56:19 Worden: Okay; understand. Yes, those times do seem to be getting longer, and I'll record Delta-T and tell you what they are.

118:56:27 Henize: Roger. And, over there at 119:20, on the mass spectrometer boom retract, it says "record the retract time Delta-T." Instead of "in barber pole," we want all of these in the future "from switch on to gray." That corresponds to what we can monitor here on the ground, and we - we need to - we need to calibrate - comparison of your data and ours. I'm sorry; that's not what we monitor, but this is - this is - this is...

118:57:02 Worden: Roger. Instead you want that "switch on to gray."

118:57:05 Henize: Right. That compares with our test calibration data, that's what I should say. And while I'm reading up...

118:57:13 Worden: Okay.

118:57:14 Henize: ...while I'm reading up to you, I'd also like to get something in on the ECS [Environmental Control System] radiators, the outlet temperature is running high 10 to 15 degrees [Fahrenheit], primary radiator outlet temperature. And we like for you to verify, first of all, that Flow Control on the ECS Radiators is Auto and Power. Is that the way they're setting?

118:57:40 Worden: That's verified. Auto and Power.

118:57:43 Henize: Okay. And three circuit breakers over on panel 5, ECS Radiators, Controller, AC1 and AC2 should be closed, and, also Controller Heaters, Main A should be closed. All three closed.

118:58:04 Worden: Yes, that's verified. They're all closed.

118:58:06 Henize: Okay; thank you. You got a status report to send down to us?

118:58:17 Worden: Okay. Got about 5 and a half to 6 hours of sleep in 2 segments. My PRD [Personal Radiation Dosimeter] is reading 23105, but I'm not sure that's any good. And no medication, and standing by for consumables update, the rest of it.

118:58:37 Henize: Roger. Consumables update. Are you ready?

118:58:44 Worden: Roger. Go ahead.

118:58:46 Henize: The time is 118:00; RCS total is 60 - is 63 [percent]; quad A, 63; 64; 61; 64; H2 tank 1, 76.9; 75.6; 51.9; O2 tank 1, 79.3; 87 - 82.5; 61.7.

118:59:31 Worden: Roger on the consumables.

[Long comm break.]

[CSM Flight Plan page 3-159.]

[Al is performing a P52, option 3, IMU platform alignment which is using the landing site orientation as its REFSMMAT.]

119:03:20 Henize: Al, if you can listen while you work, I got a couple of short goodies for you before you go round the corner. First of all, the experimenters on the SIM bay are as happy as can be. I think on the Gamma-ray experiment, they say on that first rev data, they have enough to justify the whole flight; they're so happy with it. I have a more complete science report for you, which I will send up on the next rev. And just bringing you up to date on the news, the egress down on the surface will be beginning on schedule in just about one hour.
[One of the unfortunate things about the Apollo SIM bay instruments is that throughout the program, they only covered relatively narrow strips of the Moon. Ideally, on a mission devoted to mapping, such as the cancelled "I" missions which were to have complemented the "J" missions, the CSM would be in a polar orbit for a full month. This would allow the Moon to turn once completely on its axis under the spacecraft's orbital plane and let all the instruments gather data and images on the entire surface, including the poles. On a mission primarily intended to land, the extreme limitations imposed by fuel and consumables rule out a concurrent mapping mission. The SIM bay carried on the "J" missions like Apollo 15 must make the best use of the orbital profile available within a landing mission.]

[Endeavour's 6-day presence and 26° orbital inclination limit coverage to a swathe which changes little between orbits. Therefore, data from the first orbit represent a huge increase in our knowledge. Subsequent orbits only add minor modifications to that data set and allow cross-checking.]

[Karl Henize mentions the results from the Gamma-ray Spectrometer. Gamma-rays emanate from the Moon's surface by the natural decay of radioactive isotopes in the lunar regolith or by bombardment of the soil by the incessant blast of cosmic rays. The specific energies of those gamma-rays reveal much about the composition of the top 10 centimetres or so of the surface. Already, scientists are having a quick look at data coming from the Gamma-ray Spectrometer and can see variations coinciding orbit after orbit with the large scale features that Endeavour flies over.]

[The Gamma-ray Spectrometer is particularly good at detecting whether the lunar basalts are KREEPy in nature; the importance of which is only dawning on the lunar science community as Apollo hits high gear.]

[Rocks from Apollo 12 and later from Apollo 14 were found to be enriched in certain rare earth elements including samarium, uranium and thorium. Additionally, they contained unusually large concentrations of potassium and phosphorous. Some of these elements make the rocks slightly radioactive. Using the chemical symbols of these two elements and adding an acronym for rare earth elements, lunar geologists came up with the adjective "KREEP" to describe rock samples which differed from others because of this enrichment.]

[The landing sites for Apollo 12 and 14 are relatively close to each other while that for Apollo 11 is over 1,000 km to the east and KREEP had not been found there. Geologists wanted to know how this very interesting type of rock was distributed across the Moon and the Gamma-ray Spectrometer would provide that information.]

[KREEP is so interesting because its formation is crucial to understanding how the Moon evolved. It is formed when huge regions of magma below the surface slowly crystallize as the Moon loses heat. Some elements, such as potassium, phosphorous and the other radioactives do not fit the developing crystal lattice very well because of their atomic-scale geometry. Therefore these "large-iron lithophiles" (as they are dubbed) are known as "incompatibles". As the volume of molten rock within the body of magma decreases, its composition alters as it becomes enriched in these incompatibles, their radioactivity helping to keep the remaining magma molten. Therefore rocks which form from this residual magma are described as being KREEPy. Their presence implies that the Moon was once a hot, igneous body and could sustain this heat for long enough for chemical differentiation to take place and a crust of lighter materials to form.]

119:04:00 Worden: Hey, that all sounds real good, Karl. And, as you can see, I'm right in the middle of a P52 here. I'll have the second star and the gyro torquing angles in just a second.

119:04:10 Henize: Roger. [Long pause.]

119:04:50 Worden: And if you've got those torquing angles, I'll get them on the minute.

119:05:01 Henize: We don't have any CMC data at the present time. You'll have to read them down to us, Al.

119:05:08 Worden: Okay, Karl. I'll read them to you. P52: the stars were 01 and 36. The torquing angles were minus 3 balls 28; minus 3 balls 58; plus 3 balls 12; and they were torqued out at 119:05 on the minute.

119:05:33 Henize: We copy all of that. Loud and clear. Thank you. [Long pause.]

[The stars for this P52 were Alpheratz (01), the principal star of Andromeda and which forms the top left corner of the square of Pegasus, and Vega (36), the major star of the summer constellation of Lyra, both in the northern sky. The error in the platform alignment in the x, y and z axes respectively (given by Noun 93) was found to be 0.028°, 0.058°, 0.012°.]
119:05:52 Henize: And as you go around the corner Al, all your systems are looking good.

119:05:59 Worden: Roger, Karl. Thank you. See you on the other side.

119:06:02 Henize: Roger.

[Very long comm break.]

[Endeavour disappears from sight of Earth around the western limb of the Moon in darkness. The 22nd revolution will commence at around 119:30, just as the spacecraft returns to the sunlight.]

[Having completed the platform realignment, Al rolls the spacecraft 40° clockwise and places the CSM in a "pointy-end-forward" maneuver which faces the SIM bay at the lunar surface by rotating it in sync with the orbital period. This attitude will be held to an accuracy of ±0.5° to permit accurate pointing of the Mapping Camera during its upcoming operation. The reason for the 40° roll is to ensure the guidance platform is not taken through gimbal lock as the spacecraft turns around. Every time Al makes the spacecraft do an about-turn he has to make this roll maneuver first.]

[Other items during this far-side pass are to power down the Mass Spectrometer, retract the Gamma-ray and Mass Spectrometer booms, open the Mapping Camera's covers and extend it, switch on the Laser Altimeter, then get breakfast. The Mapping Camera is to be started at 119:34:33. Note that Al will be timing the retraction of the Mass Spectrometer's boom from when he throws the switch to begin the operation, to the point when the talkback indicator changes from barber pole to gray.]

119:54:58 Worden: Allo, Terre. Salute de l'Endeavour.
[Al's phrase "Hello Earth; Greetings from Endeavour!", on this occasion in French, will be encountered regularly during his solo mission - often in other languages such as Arabic.]

[The English version of this phrase became the title of Al's collection of poetry written in the period directly after the flight.]

[Woods, from 1999 correspondence with Worden - "Is there a story behind the phrase's regular use during the mission?"]

[Worden, from 1999 correspondence - "Yes, there is a story behind that phrase. Farouk [El-Baz] and I, as you know, decided on Endeavour as the name for the CM."]

[Al and the other CMPs for the J-missions were trained by Farouk to carry out descriptive geology based on aerial views of the lunar landscape.]

[Worden, from 1999 correspondence - "[It was] a name that we got out of a book on explorers that Farouk had brought with him from Washington. He picked up the book at National Airport on his way down to the Cape for more training sessions with me. As part of those discussions, we decided to do something different on my flight to make it more interesting and to let the world know we were there for everyone. We thought up the phrase 'Hello Earth: Greetings from Endeavour' as an initial comment whenever I came into radio contact with Houston. Then we decided the phrase should be given in all languages that we could include. Farouk went back to Washington and, together with some of his friends, translated the message in the languages you refer to. He wrote them down phonetically so I could give the best delivery possible during flight. I gave that message whenever I could as I was establishing radio contact. It then became the title of my book, and a copy of the original hand written, phonetically spelled, message was included in the book."]

Hello;Greetings from Endeavour in nine languages

119:55:10 Henize: Endeavour, this is Houston. How are things going up there?

119:55:17 Worden: Roger, Karl. Going okay, I think we might have a problem also with the Mass Spec. boom. Let me give you some times here. The Mapping Camera retracted in 4 minutes and 30 seconds. The Gamma-ray retracted in 2 minutes and 30 seconds. I'm sorry, the Mapping Camera extended in 4 minutes and 30 seconds, the Gamma-ray retracted in 2 minutes and 30 seconds. And the Mass Spec I let retract for about 4 minutes, didn't get a gray, went to deploy for a few seconds, back to retract for a few seconds, and it finally went gray and retract. So I don't really have a good accumulated time on - on how long it was in barber pole.

[The retraction of the Mass Spectrometer's boom will become an increasing aggravation for the rest of the mission. The anomaly is discussed at 141:42:46.]
119:56:04 Henize: We copy.
[Comm break.]
119:57:21 Henize: Al, you may be interested to know that Dave is walking around on the lunar surface now.

119:57:32 Worden: Very good, very good.

119:57:34 Henize: And I have a Mapping Camera PAD, and a...

119:57:37 Worden: I knew it was coming.

119:57:39 Henize: ...and a Flight Plan update for you when you have a chance to copy.

119:57:45 Worden: Okay. You caught me right in the middle of breakfast. Stand - stand off on that for a while.

119:57:49 Henize: No rush, no rush.

[Comm break.]
119:59:08 Henize: Al, this is Houston. Why don't you go ahead and eat, and let me read up the science summary to you.

119:59:15 Worden: Hey, good idea, Karl. Go ahead.

119:59:21 Henize: Okay, here we go. In general, all orbital science experiments are working very well, and we have some very happy principal investigators [PI]. The X-ray PI reports count rates higher than expected, which gives good spatial resolution. Real time data shows a signature of magnesium, aluminum and silicon, so far. And appear to be differences cropping up between the mare and the highlands. The Mass Spectrometer PI reports good operation with many peaks appearing, and so far they've clearly identified neon and argon. Gamma-ray is happy, with improved data since separation of the LM - and spectral features are appearing in the data. The Alpha Particle experiment reports seeing a radon peak over Procellarum - and possibility of some other peaks over other areas of the Moon. I'll let you know more about - more about that later. The photo team tells us - the photo team tells us that the Mapping Camera is working well - and the laser is going great. The Pan Camera appears to be getting about 80 percent of its frames in good - in good quality despite the V-over-H sensor problem. And in general, they say. "Keep up the good work. It's looking great."

[CSM Flight Plan page 3-161.]
120:00:55 Worden: Okay. What's the matter with the V-over-H on the - on the Pan Camera? You indicated yesterday, I guess, that there was a problem with it, but nobody ever explained what the problem was.

120:01:17 Henize: Roger, Al. I'm not sure that its well understood - it - it's - all we can say is that it's operation is erratic; sometimes it manages to get the - the motion compensation right, and sometimes it doesn't quite make it. That's the problem we're working on down here trying to understand...

[The V-over-H sensor on the Panoramic Camera measures the rate at which optical detail passes by, the value of which is essentially inversely proportional to the spacecraft's height. A control signal is derived form the sensor's output which alters the degree of compensation the Panoramic Camera makes for this motion.]
120:01:36 Worden: I understand.

120:01:37 Henize: ...in greater detail.

120:01:41 Worden: Yes, okay. [Long pause.]

120:02:24 Henize: Endeavour, let's have High Gain Antenna [HGA], Auto, please.

120:02:31 Worden: [Antenn]a going Auto. [Long pause.]

[If the HGA is being use for communications around the Moon, it is customary for it to be switched from Reacq(uire) to Auto a few minutes after AOS (Acquisition Of Signal) once a good link has been established with Earth.]
120:02:57 Worden: Karl, if you've got a paper and pencil there while I'm - while I'm finishing up breakfast here, let me run down some cameras - magazines with you.

120:03:xx Henize: Good.

120:03:xx Worden: I just - took inventory of all the mags last night. And, thought I might just read through the list for you, and...

120:03:18 Henize: Okay. Hold on a second...

120:03:21 Worden: ...you might see what is left on the mag now.

120:03:24 Henize: Hold on a second, and I'll copy those. But there's a Flight Plan change in just a few minutes I'd like to get to you. The Mapping Camera Image Motion, which is scheduled at 120:10, we'd like to have at 120:16.

120:03:45 Worden: Okay, understand. You want to slip that down to 120:16.

120:03:49 Henize: That's correct.

120:03:51 Worden: Mapping Camera Image Motion increase.

120:03:54 Henize: That's affirmative, Al. And go ahead with your read-down.

[Al has access to three types of photographic cameras on Endeavour, the film for which is kept in interchangeable magazines. Magazines A to L have 16-mm film loaded for the Maurer Data Acquisition Camera (DAC).Mags M to S carry 70-mm film of various types; colour, low speed black & white, very high speed black & white and UV sensitive film, which are used with the Hasselblad camera to produce the distinctive 60 by 60-mm images. A Nikon 35-mm camera is also onboard, loaded with very high speed black & white film and sporting a fast f/1.2 lens for very low light photography.]
120:04:02 Worden: Okay, as promised to Spencer, the mags are as follows. First, the 16 millimeter stuff; mag A's been used a hundred percent; mag B's been used a hundred percent; C and D haven't been used; E's been used about 4 percent; F is still full; G is full; H has been used 25 percent; I, full; J, K, and L are full. Okay, on the Hasselblad, I'll call out the number of frames used. Okay. Mag M, Metro 100 - 1, 5, 3, are the frames used; and Nectar is 42; O is 39; and P and Q are 0; R is 20, and S is 40. And no 35 millimeter film has been used.

120:09:15 Henize: That came through loud and clear, Al.

120:09:21 Worden: Okay,

[Comm break.]
120:11:05 Worden: Houston, Endeavour.

120:11:08 Henize: Endeavour, this is Houston. Go ahead.

120:11:14 Worden: Okay. Just thought I'd orient you a little bit as to where I am, Karl. At the present time, I am directly over Picard, and I'm coming up on Proclus, here, very shortly. And from this particular angle, looking at Proclus, the fan pattern out of Proclus is really magnificent. It covers about, oh, I'd say, about 240 degrees of arc, and you can the see ray pattern way, way out into Crisium; way out into - into the highlands, both north, east, and south of Proclus. And, the excluded zone is very well defined. It's very clear where - where the exclusion is. And I'll give you a little better description when we get up closer to it.

[The most conspicuous feature of Proclus, a bright ray crater which lies on the western edge of Mare Crisium, is that its ray system is incomplete with a sharply defined region covering about 120 degrees of its western side where there is a complete exclusion of rays. The cause of the excluded zone has been a mystery to geologists and Al will study it further, especially at 128:07:19 and 143:52:09.]
120:12:04 Henize: That sounds fantastic, Al. Do you think you're going to solve the secret of that excluded zone?

120:12:13 Worden: You never know. [Long pause.]

120:12:40 Henize: Al. Could you please confirm that your H2 fans are off?

120:12:50 Worden: Negative, Karl. They're on. Sorry about that.

120:12:55 Henize: Okay. We'd like to have them off, Al.

120:13:00 Worden: Okay, they're off. [Long pause.]

[The fans in the hydrogen tanks are used to "destratify" or mix up any variations in the density of the tanks' supercold contents so that accurate quantity measurements can be taken. The oxygen tanks also contain fans but after the Apollo 13 incident, these were never used.]
120:13:22 Henize: And, they've just been deploying the TV camera on the lunar surface, and we had some of our first looks at Hadley Delta and St. George, and what do you know, it looks just like all the pictures they've been drawing for us.

120:13:36 Worden: Hey, Super. It sure looks the same from up here.

120:14:01 Henize: Endeavour, 15. Could we please have Optics Zero.

120:14:09 Worden: Roger. Optics Zero. [Long pause.]

120:14:52 Henize: And we've got 10 seconds for changing Image Motion on the Mapping Camera, Al.

120:15:00 Worden: Roger.

[Comm break.]

[The Mapping Camera is taking shots of the Taurus-Littrow area where Apollo 17 will land.

Mapping Camera image, AS15-0565M, of Littrow crater and the Taurus Mountains including the Apollo 17 landing site.

[This image from the Mapping Camera, scanned and donated by journal reader Robin Wheeler, shows the Apollo 17 landing site at the bottom of this image. This image is notable in the way it displays the contrast between the lighter surface of the mare to the west and the dark landscape that lies just south of Clerke and into the valley floor where the Lunar Module Challenger would land two missions hence. Al will describe this during the next orbit at 122:18:17]

120:16:30 Henize: Al, there's no rush on it, but I'm waiting for your cue before I send up Flight Plan update.

120:16:40 Worden: Okay, Karl. I'll be ready in a minute.

[Long comm break.]
120:20:21 Henize: Endeavour, this is Houston. Rover has just hit the ground. You don't see it down below you, do you?

120:20:34 Worden: I'm not quite there yet, Karl, but I'll look when I go over.

120:20:37 Henize: Roger.

[Comm break.]
120:21:50 Henize: Endeavour, we'd like to have Pan Camera Power, Off.

120:22:02 Worden: Okay, all turned off now.

120:22:05 Henize: Thank you.

[Long comm break.]

[Al's scheduled meal period has just ended. Endeavour should make its closest approach to the landing site at about 120:26:30. However, Al does not mention whether he can see the rover sitting beside Falcon on the surface and from 60 nautical miles away, is unlikely to. It is tough enough to see the LM from this altitude, and even so, most that can be seen is the 22 metre long shadow. He might be lucky to see the disturbed surface due to a color change if it was over a wide enough area, but even that is dubious.]

120:28:26 Henize: Endeavour, the first part of that Flight Plan update is to delete the Gamma - Gamma-ray boom deploy at 120:33. We want to be sure to get that one. Delete "Gamma-ray boom, deploy."

120:28:43 Worden: Okay, Karl. I'll delete it.

[Comm break.]

[Around now, Al is due to charge battery B, part of a program of regular charging which ensures that the Command Module's three online batteries are topped up and ready to supplement the power from the fuel cells whenever there is a heavy demand. The CM carries two further batteries for firing pyrotechnic devices but, apart from monitoring, these are left untouched until they are needed.]

120:31:01 Worden: Okay, Karl. Looks like I'm set for business for the day now. And, go ahead with your Flight Plan update.

120:31:09 Henize: Okay, Al. And first of all, on the Gamma-ray boom, the reason for that, is the fact that we're getting a little gain change every time that we deploy and retract it. It's not serious, but we'd like to sort of leave it as it is until we study the problem a little longer. You've already deleted the extension at 120:33. We also, then, will delete the retraction at 121:27.

120:31:46 Worden: Okay. 121:27. Roger.

120:31:51 Henize: And while you're on that page, the Mapping Camera photo...

120:31:55 Worden: [Garble]

120:31:56 Henize: Roger. And while you're on that page, the Mapping Camera photo PAD is as follows. Start, 121:39:34; 122:32:43. Would you like to read that back?

120:32:14 Worden: Okay. 121:39:34, and T-stop is 122:32:43.

[These start and stop times are for the majority of the next pass from sunrise to sunset. During that period the spacecraft attitude will be set so that the camera is looking 25° forward of vertical.]
120:32:20 Henize: That's correct. And just on the same page again. The attitude - the attitude there at 121:37, instead of reading a roll angle of "000," should be "142" [degrees]. That's for the P20 option 5.
[Program 20 will be used to orient the spacecraft at a constant 25° pitch-up with respect to the local horizon throughout the defined Mapping Camera operation. Option 5 means that the computer will work out this attitude by direct calculation from its knowledge of the position of the Moon.]
120:32:45 Worden: Okay, understand. Roll angle of 142.

120:32:49 Henize: That's correct. The next correction is all the way up at 125 hours and 44 minutes. [Long pause.]

120:33:07 Worden: Okay, go ahead.

120:33:08 Henize: And, this is one of those general things. On reporting the Delta-T, it should be from switch on to talkback gray.

[Al is keeping a note of the time it takes to deploy the SIM bay's two booms, and the Mapping Camera on its track. This note is a reminder of the events he should use for these timings.]
120:33:23 Worden: Okay.

120:33:25 Henize: And, we have exactly the same thing at 129 hours and 20 minutes.

120:33:42 Worden: What was that again? What time was that?

120:33:45 Henize: At 129:20, the same thing, the switch - the Delta-T that you read back to us is switch on to talkback gray. And really, I suppose, we should make this a generality - that we don't have to put it in the Flight Plan every time.

120:34:04 Worden: Roger. I'd agree to that.

120:34:06 Henize: Incidentally, I have a question in that connection - [It] says verify that times previous to 118 hours were from switch on, beginning time. Do you recollect that?

120:34:26 Worden: Karl, the way we time it onboard here, is you have to hit the switch, and then look at the mission timer. Now, the - the Gamma-ray is taking about 6 seconds to go from switch on to barber pole, the Mass Spec was going on immediately to barber pole, so it didn't make any difference in the case of the Mass Spec. And in the Gamma-ray, the most it could be off is 6 seconds.

120:34:54 Henize: Right. And, - I guess on the Gamma-ray when you reported the time - do you recall which it was that you were giving us, switch on or talkback barber pole?

120:35:06 Worden: Talkback barber pole.

120:35:08 Henize: Okay, fine. That's the way the instructions were, originally.

120:35:18 Henize: We have a comm change. It's simply an error in our Flight Plan at 128:10.

120:35:35 Henize: And, at 128...

120:35:36 Worden: Okay, go ahead.

120:35:37 Henize: ...at 128:10, the first step in that configuration is "VHF AM A, Simplex." The second step is to change "VHF AM B," delete "Duplex," and make that "Off."

120:36:06 Worden: Okay. Understand you want Simplex A in, B - and B, Off.

[These are preparations that Al will make for a possible communications check with the LM using VHF frequencies as Endeavour flies over the landing site.]
120:36:10 Henize: That's correct, and at 149 hours, 37 minutes, we do the same thing.

120:36:30 Worden: Okay, gotcha.

120:36:32 Henize: And at 149:37, we also want to add "mode Vox."

120:36:54 Worden: Okay. Understand, "mode Vox."

120:36:56 Henize: Roger. And, I think the last item to come up is again the comm change at 169 hours and 20 minutes - that we put "A, Simplex" and "B, Off."

120:37:44 Worden: Okay, Roger. Got those.

120:37:46 Henize: Okay. That takes care of our current Flight Plan updates.

120:37:52 Worden: Roger.

[Long comm break.]

[The current status of the SIM bay instruments are that the Mapping Camera is in the middle of a photo PAD, and the Gamma-ray, X-ray, Alpha Particle and Laser Altimeter experiments are all operating, though the Gamma-ray Spectrometer is undergoing some diagnosis of changes observed in the gain of the instrument following each extension and retraction cycle of its boom.]

120:44:44 Henize: Incidentally, Al, we'd like to have the Gamma-ray Gain - Gain Step go through its usual procedures here, even though we don't have the boom extended.

120:44:56 Worden: Okay, Karl.

[Long comm break.]

[The Flight Plan has two instructions, 11 minutes apart, to switch off then on the system within the Gamma-ray Spectrometer that discriminates between gamma-ray and non gamma-ray events. This system is called the Gain Step Shield.]

120:53:52 Henize: Al, we'd like to have the Gamma-ray Gain Step back to the center position, please. [Long pause.]
[This switch throw puts the Gain Step Shield back on.]
120:54:47 Henize: Endeavour, this is Houston. The down-link doesn't seem to be coming through very good; could you give me a comm check?

120:55:06 Worden: Hello, Houston; Endeavour. How do you read?

120:55:09 Henize: Roger. That's loud and clear, thank you.

120:55:14 Worden: Okay. I'm back on Vox now, Karl.

120:55:17 Henize: Okay, good.

[Comm break.]
120:58:03 Henize: Endeavour, this is Houston. Surface activities are coming along swimmingly at the present time. The - the rover has already been driven - made one circle around the LM so far, and they're about ready to take off on traverse number 1.

120:58:23 Worden: Oh, very good. Got the rover going, huh?

120:58:26 Henize: Roger...

120:58:27 Worden: ...good

120:58:28 Henize: That's good news. And a time reminder here. Over at 21:03 is the time to configure the DSE, as you go around the corner.

120:58:42 Worden: Okay, Karl. 21:03.

[Long comm break.]

[CSM Flight Plan page 3-163.]

121:04:47 Henize: Al, this is Houston. As spacecraft Endeavour swings majestically around the eastern limb of the Moon, all systems are Go.

[Actually, Endeavour is swinging around the western limb of the Moon but Karl Henize might not be completely mistaken. Exactly ten years before Apollo 15, the International Astronomical Union reversed the convention whereby the side of the Moon's disk towards the Earth's eastern horizon, as seen from the Earth's surface, was referred to as the eastern side and the other side of the disk was called the western side. Known as the astronomical convention, it explains why Mare Orientale, meaning the Eastern Sea, was so named by its discoverers, Patrick Moore and H. P. Wilkins, despite being on the western side of the Moon as the modern convention would have it. The change meant that lunar maps would be using a similar convention to terrestrial maps; north is up, west is left; the Sun would be said to rise in the east, just as it does on Earth.]
121:04:58 Worden: Hey, I'm suppose to say that.

121:05:00 Henize: Oh, okay.

121:05:06 Worden: See you on the other side, Karl.

121:05:08 Henize: Righto, see you then.

[Very long comm break.]

[At 121:22 approximately, Endeavour will begin its twenty third orbit of the Moon. By the Flight Plan, this is a quiet far-side pass for Al and his major task comes just after he begins the new orbit and passes over the terminator into the sunlight. The current operation of the Mapping Camera finishes at 121:33:02; the spacecraft is pitched upwards 25° to allow the camera to take forward looking oblique views of the Moon, and the photography recommences at 121:39:34. The change in attitude means that the other SIM bay instruments are no longer in their optimum attitude with respect to the surface and their data is degraded for the time being. They are not scheduled to be properly pointed until around 125:50. The alteration in attitude also requires Al to reestablish communication through the Manned Space Flight Network via the S-band omni-directional antenna D. A few minutes after, Al will use angles in the Flight Plan to point the HGA and try and reacquire communication via it.]

[As the spacecraft passes over Tsiolkovsky, the Mapping Camera takes AS15-0757M, a spectacular image of this remarkable 200-km crater. West is to the top, north to the right.]

121:53:08 Worden (onboard): Hello, Houston; 15 - Endeavour.

121:53:20 Henize: Endeavour, this is Houston. How do you read?

121:53:23 Worden (onboard): I read you loud and clear.

121:55:32 Henize: Endeavour, this is Houston, how do you read? And, we seem to have a small comm problem. Please stand by.

121:55:41 Worden (onboard): Roger, Houston. Endeavour standing by, and I'm reading you 5 square.

121:55:51 Worden: Houston, Endeavour is standing by. I'm reading you 5 square.

121:55:55 Henize: Roger. And, I'm reading you loud and clear, with a good bit of noise over the top of you.

121:56:04 Worden: Roger.

[Long comm break.]

[CSM Flight Plan page 3-165.]

[LiOH canister number 11 is replacing 9 in unit A, with 9 being stowed in compartment A9. After this, Al begins his exercise period.]

122:02:10 Henize: Endeavour, this is Houston. We'd like you to go ahead and try acquisition of the High Gain Antenna with the angles in the Flight Plan.

122:02:25 Worden: Roger, Houston. Stand by for one minute.

[Long comm break.]

[The attitude of the spacecraft is constant with respect to the Moon's surface but is continually changing with respect to the stars and Earth as Endeavour follows the curve of the lunar surface. Therefore, an attitude which was unsuitable at AOS may now be within the limits of the HGA.]

122:05:55 Henize: Endeavour, this is Houston. The information we have on your attitude indicates that you're a little bit off for those forward obliques. And, we'd like to see your Noun 78 if possible.

122:06:09 Worden: Okay. They were as per [the] Flight Plan. In fact, Karl, I wanted to mention that to you. When I loaded Noun 78 with plus 126.30 and plus 045.77, the computer came up with an angle, or an attitude of 149, 089, and 344.

122:06:41 Henize: We copy.

122:06:54 Worden: Guess you better run that one through the mill down there again.

122:06:56 Henize: We're chewing on it. [Long pause.]

[The Flight Plan instructed Al to load two numbers, plus 126.30 and plus 045.77, into Noun 78 but the resulting attitude does not have the Mapping Camera pointing 25° forward so Al is suggesting that the values for the required attitude be computed again. This author (Woods) believes that since the Flight Plan does not include the third item for Noun 78 (omicron), then Al is still using the old value from 119:12, a value of 180°. The problem is discussed again in an exchange at 126:46:10]
122:07:51 Henize: Al, you may be interested to know that the Rover has crossed quite a bit of territory, now. And, they're on the edge of the rille, having a good look into it.

122:08:03 Worden: Very good. The things seems to be working okay.

122:08:07 Henize: Roger. They'll be at Elbow corn...Crater in just a couple of minutes.

[Comm break.]
122:09:50 Henize: Endeavour, you can give us Auto on the High Gain [Antenna]. And, Al, Vance is sitting beside me here. He's been downstairs talking to the PIs [Principal Investigators] about the Pan Camera, and has some good words for you.

122:10:13 Worden: Okay. Go ahead, Vance.

122:10:15 Brand: Hey, morning, Al. Hey, first of all, Izzy said to tell you that your...

122:10:20 Worden: Good morning, Vance. Hey, I'm - I'm looking at our favorite crater right now.

122:10:24 Brand: Is that right? It couldn't be King Crater?

122:10:29 Worden: Yes, sir. I'm right over Proclus, now. Proclus.

122:10:33 Brand: Okay. Very good. Hey. Izzy has a message for you.

122:10:43 Worden: Very good. How's Izzy?

[Izzy is Isidore Adler, the PI for the X-ray Fluorescence Spectrometer.]
122:10:44 Brand: He's good. He says to tell you that you make a dandy spectrographer - for X-rays, that is. He's getting a lot of data in. I guess, actually, a little more activity that they expected, and they seemed real pleased about that.

122:11:04 Worden: That's good. That ought to keep Pete and Jack busy.

[As far as we can tell, "Jack" is Jack Trombka who was a member of the team responsible for the X-ray Spectrometer. Thus far, we haven't determined who Pete is.]
122:11:07 Brand: Getting into the Pan Camera. I don't know how much has been explained to you. It's - it's taking pictures - about 80 percent of them are good. And, the problem's in the V-over-H sensor, which I'll try to explain here, briefly. The V over H sensor is drifting, which means that, occasionally, it drifts down to the - to the place where it thinks that - you're out of the 45- to 80-mile limit. Whenever it does that, why, it - the camera is commanded back to a nominal 60 [nautical mile] setting. As it turns out, it drifts enough that it - it's out of this band most of the time. And that's actually good because you're at 60 miles, so it's - it's going back to the 60-mile limit, probably to give you 80 percent of the time good pictures. The fault - we're not quite sure where it is; people are working on that. It's probably either in the sensor or upstream just a little ways in the electronics.

122:12:26 Worden: Roger, Vance. I understand.

122:12:30 Brand: And, other than that, Al, I haven't got much to report [to you]. The data seems to be coming in on all the experiments, and it's looking pretty good.

122:12:44 Worden: Yes, I noticed just - some - some problems with getting the booms in and out, Vance; but, outside of that, everything seems to be okay. The Mapping Camera is taking about four and a half minutes to retract now. And, I had a little trouble getting the Mass Spec. in the last time, and I ran it out and in a couple of times, before it finally came all the way in.

122:13:04 Brand: Roger. Auto on High Gain.

122:13:11 Worden: Roger, Auto.

122:13:18 Brand: And, Al. The next time you extend and retract the boom, they'd like a - a hack on it - and on the Mapping Camera, too, because, - stand by. I'm sorry, they'd like hack - a time hack when you start extending the Mapping Camera and when it gets out, because they're looking at the current signatures and that sort of thing on it.

[Mission Control will carefully watch how the electrical current varies in the bus that supplies the Mapping Camera's motors. They hope that it might provide clues to what is slowing the mechanism which extends and retracts the lens.]
122:13:50 Worden: Okay. They want to help me keep time, do they?

122:14:04 Brand: We're just looking at the real time electrical, both signatures, when this - this thing is working - extending and retracting, Al. And, we'd like to have a hack so we will know when you - when we can start looking.

122:14:21 Worden: Okay, I understand them then. You - you're watching the voltage levels or power levels in the motor that drives the extend - release.

122:14:31 Brand: That's affirmative.

122:14:36 Worden: Okay.

122:14:37 Brand: Okay. Back to Karl.

122:14:42 Worden: Okay, Vance.

[Long comm break.]
122:17:54 Worden: Houston, Endeavour.

122:17:58 Henize: Endeavour, go ahead.

122:18:04 Worden: Okay, Karl. This may be the wrong attitude for we want, but it's such good viewing attitude that - let me make a couple observations while we're here.

122:18:12 Henize: Great. We're listening.

[On each orbit, Al is passing over the Taurus mountains with a slightly more southerly track. This pass takes him just north of the dark floored valleys of Taurus-Littrow. The Mapping Camera is taking forward-looking oblique shots of the area.

Mapping Camera image, AS15-0835M, of Littrow crater and the Taurus Mountains including the Apollo 17 landing site.

In this image, the zero-phase effect brightens that part of the Moon's surface that is directly opposite the Sun from the spacecraft. Al has twelve minutes remaining in his exercise period but he seems to be having more success exercising his vocal chords and descriptive talents than his cardiovascular system. And why not? This is what Farouk El-Baz trained him for.]

122:18:17 Worden: Okay. I'm right directly over Littrow at the present time. And, I can see all the way around - to the Apennine front - encompassing all of Serenitatis between here and there - except to the north over by Posidonius. So, I got a very good view of Sulpicius Gallus - and that sort of extends off my 10, 11, to 12 o'clock position. And the observation I wanted to make, in particular, was - the - the distinct way that the - that the rilles do follow - the old mare basin. And, the fact that the second color band that we discussed in Littrow - seems to be continuous right on across the - the basin into Tranquillitatis and on around - almost a shelf - a continental shelf - appearance - on into the Sulpicius Gallus. And, that seems to be that second color band that we noticed in Littrow. There is a darker color - coloring - in the uplands in Littrow and closer to the - to the front or closer to the basin of - of Scarp. But the second band seems to go all the way around Sulpicius Gallus. And, then - as you follow Sulpicius Gallus on around a little bit more to the west, that color banding is still there. I can see a distinct boundary between it and the - and the Serenitatis basin itself - inner basin - but it turned into a little more brownish color from the grey color that we saw before.
[Journal Contributor David Harland - "When Apollo 17 overflies Sulpicius Gallus, CMP Ron Evans spots an orange tint across the whole area, suggestive of pyroclastic glass from a fire fountain connected with the rille. Evidently the Apollo 15 crew don't pick upon this hint."]

[Woods - "Beyond grey and tan, do you recall ever seeing any other shades and hues on the Moon?"]

[Scott - "From orbit? Yeah. Chocolate brown. As I recall, looking into the Sun, at a low Sun angle it was chocolate brown. I forget what flight came back and said it was brown."]

[Woods - "10 was the first. 8 talked about grey, nothing but grey. 10 talked about it being tan. Mike Collins says either of them. Take your pick. But what I'm interested in is that subsequently there was a hint of - you know when Jack Schmitt saw the orange soil, and then they began to perceive hues of colour all around the edge of Serenitatis."]

[Scott - "Sure. I think that's because you get - your mindset is [tuned into it]. You get opened up a little bit. We saw green and since there's green on the rim, right? When we first saw the green rocks, we couldn't believe they were green. They were really green."]

[Woods - "On the surface?"]

[Scott - "Yeah. They're green. But your mind is not set to see colour and once you see colour and you open up the mind, then you can see more colour. It's like, there's green here, there must be other things here now because that's really green."]

[Woods - "It's like the way that Al was trained to spot volcanics and it appeared that he thought he had found volcanics because that was what he was trained to find. And as a result, Apollo 17 goes off to Shorty crater."]

[Scott - "Yeah."]

122:20:08 Henize: Roger, Al. You're coming through loud and clear.
[Comm break.]

[Endeavour's current, slightly nose-up, attitude is giving Al a much more forward looking view than usual and he is taking good advantage of the approaching vista. Al's observations of colour in the Serenitatis/Littrow area is part of a series of observations which will be crucial to the subsequent decision to put Apollo 17 down in the Western edge of the mare, just into the Taurus Mountains. See also the air-ground comm at 079:23:46 and, especially, at 128:12:46.]

122:22:27 Worden: Houston, Endeavour. Karl, I've got Hadley Rille in sight now in front. Have a very commanding view of the whole countryside.

122:22:39 Henize: Beautiful. Any chance of spotting Rover tracks down there, do you think?

122:22:52 Worden: Well, I got the binocular out and I'll let you know.

[Long comm break.]
122:26:37 Henize: Al, while you're getting a beautiful view from up above, we just got a - some beautiful pan shots of Hadley's Rille and saw all sorts of blocks and bedrock sticking out of the rim of it.
[Henize is referring to the television pictures being beamed to Earth from an antenna on the Lunar Rover. Ed Fendell in Mission Control operates the camera remotely while the surface crew go about their business.]

[Dave and Jim have driven southwest to where Hadley Rille takes a sharp turn left to run north. They have parked on the rim of a crater which sits on the outer edge of the bend and is, appropriately called Elbow. As they work collecting samples and documenting the place, Fendell pans the TV camera north to look along the inside of the rille. Both walls are visible as are numerous blocks protruding from the walls and boulders littering the floor.]

[The Mapping Camera is also capturing Al's commanding view.

Mapping Camera image, AS15-0854M, of the Apollo 15 landing site.

The distance from top to bottom of this image is about 180 km. A chain of mountains can be seen running from southwest to northeast. These are Montes Apenninus. Their shadowed slopes facing into the mare form the Apennine Front.]

122:26:53 Worden: Roger, Karl. I can vouch for the rocks and the blocks in the bedrock in the rille. I can see it from here with a binocular. I didn't have much luck picking up the Rover. I think I got a - I think I got a look at the - at the LM again through the binocular - but I wasn't real sure.

122:27:10 Henize: Very good. [Long pause.]

122:27:25 Henize: You must be just about over the area south of Archimedes, there, with all those sinuous and - and linear rilles. That's pretty choppy country, isn't it?

122:27:39 Worden: Yeah, that's affirmative. And that's right where I'm at now, just south of Archimedes and this - hummocky, hilly terrain south of Archimedes is, in fact, quite full of - of rilles, although they're very subdued rilles. They - they don't have much definition to them, even in this low Sun angle. But, they're combinations of linear rilles, which seem to run northwest, southeast and sinuous rilles, which have no particular direction. And then, I noticed a couple of rilles have - in fact I'm looking at one right now - in this, we see a small crater pair just to the left of Archimedes and a real light feature running to the east out of it. And that rille feature has a - a series - a whole succession of - of craters running right down the rille.

[A side-looking image from the Mapping Camera, AS15-1541M, shows the rille/crater chain systems south of Archimedes very well.]
122:28:38 Henize: Right down the rille. Any - any sort of blankets around these craters? Does it look like volcanic chain there coming out of the rille?

122:28:54 Worden: Well, it certainly looks like a volcanic chain. Let me check and see if I can see any rims to them.

122:29:10 Worden: No, I don't see any rim - rim deposits associated with them. In fact, the craters that I'm looking at are irregular in shape, elongate in direction of the rille, and they look distinctly like collapsed features in a lava tube.

122:29:30 Henize: Very interesting.

122:29:39 Worden: They didn't seem to have any particular shape except that they were elongate in the direction of the rille and I didn't notice any particular - any build up around the - the mountain. In fact, in this particular Sun angle, which is rather low, I didn't really see much elevation around them. So, I assume that they're depressional, kind of collapsed features, rather than build up features of positive relief.

122:30:06 Henize: Roger.

122:32:18 Henize: Okay, Al. The Mapping Camera comes off in about 30 seconds.

122:32:26 Worden: Okay, Karl.

[Very long comm break.]

[Endeavour is just passing into the Moon's shadow and the next ten minutes are scheduled as busy ones for Al. The Mapping Camera reaches its T-stop time and its attendant switches are thrown - the camera goes Off, then to Standby mode one minute later; the Image Motion switch goes to Off as does the Laser Altimeter. Next task is to maneuver the spacecraft to the deep space measurement attitude then prepare two cameras in window 4, the right-hand docking window, for photography of the solar corona before sunrise, in an operation commencing at about 123:15. The Data Acquisition Camera (DAC) will provide a 16-mm movie of the event while the Hasselblad camera will take stills, both using very high speed black and white film. The Hasselblad shutter speed is preset to one second.]

122:42:53 Henize: Al, whenever you're ready, I've got a couple of photo PADs for you.

122:43:06 Worden: Okay, Karl. I've got all the camera setups for the solar corona. And they're all checked out and ready to go, so I'll stand by for your PAD.

122:43:14 Henize: Beautiful. Over on the next page at 123 hours and 16 minutes, solar corona. The time is 123:16:50. And down there at 123:50, the UV photo PAD, 123:49:49.

122:43:42 Worden: Okay, Karl. Understand. The solar corona PAD is 123:16:50, and the UV is 123:49:49.

122:43:54 Henize: That's correct.

[Comm break.]
122:46:32 Worden: Houston, Endeavour.

122:46:35 Henize: Endeavour, go ahead.

122:46:40 Worden: Roger. If you are ready down there, I'll go ahead and retract the Mapping Camera now. If you want to watch the data.

122:46:59 Henize: Stand by a second.

122:47:04 Worden: Okay; I'm waiting.

122:47:18 Henize: Okay. You're Go to retract the Mapping Camera, and give it the mark.

122:47:26 Worden: Okay. On my mark.

122:47:28 Worden: Mark.

[Long comm break.]

[Mission Control will watch the signature of the voltages and currents being fed to the motors of the Mapping Camera's retract mechanism.]

122:51:21 Worden: Okay, Houston...

122:51:22 Worden: Mark.

122:51:23 Worden: Talkback is gray.

[Long comm break.]

[Al has given a mark at the start and stop times of the Mapping Camera. On this occasion the camera took 3 minutes, 54 seconds. The last time Al measured it, it took 36 seconds longer.]

122:56:58 Henize: Al, this is Houston. I hate to start bothering you right when business is getting heavy here, but we find that waste water is accumulating faster than we anticipated, and in order to avoid a waste water dump before we planned it, we'd like to have you fill up a water bag. Looking at your - looking at your current schedule, we recommend you start that right away and get it done.

122:57:31 Worden: Roger, Houston.

122:57:33 Henize: And, Al, that is on page C/2-28, for waste water.

122:57:55 Worden: Roger, Karl. Thank you.

122:58:04 Henize: They say it will take about 8 minutes to fill a bag.

[Comm break.]

[Water is produced in the fuel cells as a by product electricity production. The quantity produced is proportional to the amount of electricity generated. This water is available for the crew to drink and rehydrate their food, and to provide feedwater for the spacecraft cooling system. The unused fraction builds up in the waste water tank in the Command Module and there are planned times when this is dumped overboard. Note that contamination from a dump would affect the operation of the Mass Spectrometer. In this case, Al will bag some excess water to allow the next water dump to occur when intended.]

[With the Mapping Camera retracted, the covers for it and the Laser Altimeter are closed. Likewise for the X-ray and Alpha Particle Spectrometers.]

122:59:50 Worden: Houston, Endeavour.

122:59:53 Henize: Go ahead, Endeavour.

122:59:58 Worden: Okay, Karl. Say again the page number, please.

[CSM Flight Plan page 3-167.]
123:00:00 Henize: The page number is C/2-28, and the bag is down in the - in the L-shaped bag, they tell me.

123:00:14 Worden: Roger. I've got the bag out.

123:00:20 Henize: And before you go around the corner, I should tell you that the configure DSE should be done at 123:10.

123:00:32 Henize: And a reminder that that is a low bit rate command this time.

123:00:35 Worden: Roger.

[Comm break.]

[Mission Control have reminded Al to configure the Data Storage Equipment (DSE) seven minutes after LOS - slightly later than usual. The spacecraft's attitude is not optimised for gathering data via the SIM bay instruments and the quality of data from them is degraded. Al will therefore set the DSE to record data at a low bit rate while he makes this far-side pass.]

123:03:16 Henize: Okay, Al. We have one minute to LOS. All systems are looking good, and enjoy that solar corona.

123:03:28 Worden: Roger. Thank you.

[Very long comm break.]

[As seen from the Earth, the Moon is at first quarter just now and its eastern limb is in the middle of the lunar day. Endeavour passes across the near side travelling east to west, and enters lunar night half way across the Moon's disk. It will come back out into sunlight midway through the far-side pass. Al has placed Endeavour in the Solar Corona attitude and gone to a 5° deadband. He has also configured two cameras, one 16-mm movie and one 70-mm still, both with very fast black and white film, to try and capture pictures of the solar corona in the minutes prior to his sunrise.]

[At 123:16:50, he will reset and start the mission timer from 000:00:00, and then will dim the interior lights of the Command Module. Remember, because of an earlier electrical problem, he cannot use the timer in the LEB (Lower Equipment Bay) and must depend on the one on the Main Display Console, even though it may not always be in the best position to see. At 05:00 on the timer, he starts the DAC with a shutter speed of 1/125; throughout, the DAC will run at one frame per second. At 06:40, he changes the DAC's shutter speed to 1/500. From 06:50 to 07:50, he shoots a frame on the Hasselblad every ten seconds, each time increasing the shutter speed from its initial speed of one second, through 1/4, 1/8, 1/15, 1/30, 1/60 and finally 1/125 when he takes the final shot in the sequence, before setting the shutter to 1/500. This sequence starts at AS15-98-13309 in the "Index of 70-mm Photographs." Frame AS15-98-13311 is an example from this series. At 08:00, he will stop the DAC. At that point the Sun should rise and soon after, Endeavour begins orbit number 24. Al will repeat the process on the near side by taking photographs of the sunset.]

[Having removed the photo equipment from the window, he maneuvers Endeavour to an attitude for taking UV photographs of the lunar horizon and the Earth rising over it through window 5, the rightmost, quartz paned window. The UV photography will, of course, coincide with AOS. Al will use a special UV transmitting 105-mm lens on the Hasselblad camera, along with magazine N containing the UV sensitive film.]

[The start time for the first series of UV photographs is 123:49:49. Earlier in the mission, similar sequences of UV images were taken, eight at a time, two each through four filters. However, during the first day, at 009:23:31 GET, Mission Control modified the exposure for one of the two shots taken through filter 2, shortening it from 20 seconds to only 2. This was to pertain to all the UV photos of Earth for the rest of the mission, though Houston had intended to send reminders of this change. The first set of eight taken of Earth rising above the lunar horizon are AS15-99-13441 to 13448. A montage of 13441, 43, 45 and 47 show the results from the four filters. The exposure change on filter 2 does not appear to have been implemented in this or the next set of eight. Interestingly, the spectral characteristics of filter 3 seem to have completely obscured the lunar surface while keeping a bright image of the Earth.]

123:54:46 Henize: Endeavour, this is Houston. How do you read? [Long pause.]

123:55:07 Henize: Endeavour, this is Houston. How do you read?

123:55:15 Worden: Hello, Houston; Endeavour. Did you call?

123:55:25 Henize: Roger, Endeavour. We copy you. A bit noisy yet. On the second set of UV photos at T-start plus 7 minutes, a number that we have for you is 56 minutes and 49 seconds, if you haven't already computed it.

123:55:46 Worden: Roger.

[Long comm break.]

[The Flight Plan calls for the second set of UV photos of the Earth to commence at T-Start plus 7 minutes which is 123:56:49. These are AS15-99-13449 to 13456 which have been compiled to show the differences between them. According to the "Apollo 15 Preliminary Science Report", the UV photography of the Earth is intended to provide "calibration data to support the study of planetary atmospheres by telescopic observations in the UV spectrum." Note that in the brightest Earth images, there are multiple images which may have been caused by reflections between the quartz window and the Lexan shield, designed to protect the crewmembers from excessive UV exposure.]

[CSM Flight Plan page 3-169.]

124:03:18 Henize: Endeavour, we'd like to have Omni Alpha.

124:03:25 Worden: Roger. Omni Alpha. [Long pause.]

124:03:56 Worden: And, Houston, Endeavour.

124:04:01 Henize: Go ahead, Endeavour.

124:04:12 Henize: Go ahead, Endeavour.

124:04:13 Worden: Houston, Endeavour. How do you read now?

124:04:14 Henize: Go ahead. Endeavour.

124:04:15 Henize: We're reading you loud and clear.

124:04:18 Worden: Okay, Karl. Okay, In between taking pictures here, I've been trying to collect this stuff for the waste water dump or for the waste water collection. I got the bag out, but I'm having trouble finding that female QD. Do you know where it is?

[The QD is the quick disconnect fitting for the waste water which Al needs to fill the bag.]
124:04:30 Henize: Standby. And, in the meantime, we'd like to verify that in Noun 79, we got 5 degrees.

124:04:38 Worden: That's affirmative.

[This is a confirmation that the current deadband is set to 5°, this being the range of attitudes around the ideal, within which the spacecraft will make no attitude correction.]
124:04:39 Henize: Thank you. [Long pause.]

124:05:21 Henize: Omni Bravo on the way to High Gain [Antenna].

[They will use Omni B while waiting for the changing attitude of the spacecraft to bring the HGA into its range of operation.]
124:05:30 Worden: Roger. Omni Bravo.

[Comm break.]

[With the UV photography out of the way, Al orients the spacecraft once more to photograph the solar corona as the Sun sets behind the Moon. Mission Control will calculate an accurate time for the sunset with the T-Start time being 5 minutes before that, and the time that Al will start his counter.]

124:07:17 Henize: And, Al, I have the solar corona start time any time you're able to copy.

124:07:27 Worden: Okay, go ahead.

124:07:37 Worden: Go ahead with the T-start time.

124:07:39 Henize: Roger. T-start is 124:32:22.

124:07:48 Worden: 124:32:22.

124:07:51 Henize: That's correct.

[Comm break.]
124:10:15 Henize: Al, you may be interested to know that the fellows on the surface have completed a very successful EVA-1 and are back on the LM at the present time.

124:10:28 Worden: Very good. EVA-1 finished, huh?

124:10:34 Henize: Except for the ALSEP part of it.

124:10:48 Henize: Al, the best information we have on that female QD fitting is that it would be in the waste management system backup bag in A-8.

124:11:06 Worden: Okay. I'll look some more.

[Long comm break.]
124:14:36 Henize: Al, we seem to be at the right attitude and we can bring up the High Gain if you'd give us a Pitch, minus 45; and Yaw, 208.

124:14:48 Worden: Okay. Minus 45 and 208.

[Long comm break.]
124:18:55 Henize: Al, this is Houston. About that - filling up the water bag. Unless you're underway with it already, our basic priority here is to go ahead and get configured for the solar-corona shots; and you can forget the water unless you're already into it.

124:19:18 Worden: Roger. I've got everything, I think, I'll do now, except I still can't find the female QD.

124:19:25 Henize: Okay. I would say let's worry about that later. And the word is that we'll just go ahead with the normal dump on the backside as it's scheduled in the Flight Plan.

124:19:42 Worden: Okay. That sounds good to me. [Long pause.]

124:20:11 Henize: Al, is there any useful comment on the condition of window 5?

[These comments are requested in the Flight Plan because, unlike the other windows, its panes are made from quartz rather than glass so as to transmit ultraviolet light.]
124:20:22 Worden: I don't think so, Karl, other than the fact that it looks very clear. There aren't - it's not smudged or anything right now.

124:20:29 Henize: Very good.

124:20:35 Worden: In fact, window 5 is in - certainly in better shape than window 1.

124:20:41 Henize: I see.

124:20:43 Worden: There are a bunch of little specks or spots all over the outside of it. It looks like dust that's collected there. Window 5 is almost clear.

124:20:52 Henize: I see. The UV people are lucky then. Very good.

[Long comm break.]
124:25:32 Worden: Houston, Endeavour.

124:25:35 Henize: Go ahead, Endeavour.

124:25:40 Worden: Okay. Just went over the landing site and - grabbed the binocular to take a look and - saw a glint of light off the LM again and it's the same location that I called out before.

124:25:42 Henize: Beautiful.

[Long comm break.]
124:31:28 Henize: Al, the solar corona photography should is - start in about one minute.

124:31:36 Worden: Roger, Karl. Right with you. Count down 45 seconds.

124:31:40 Henize: Roger.

124:31:48 Worden: Incidentally, you could probably call it on your DSKY. I'm counting down in P32.

124:31:53 Henize: Okay.

124:31:58 Worden: Might try it anyway.

124:32:12 Henize: Roger. There - we see it going.

[Very long comm break.]

[Al is repeating the earlier process by photographing the solar corona just after sunset using the DAC and the Hasselblad. Note that Endeavour's attitude is still being kept within the wide limits of a 5° deadband. Note also Al's use of the computer as a timer to circumvent the loss of the Mission Timer in the LEB. See transcript and comments at 148:33:17 and 153:23:44 for further about this and its repercussions.]

[The solar corona photograph sequence ends at AS15-98-13325. At the time of writing, these were not available for inclusion in the journal.]

124:49:28 Henize: Al, let me have the High Gain Antenna, Auto.

124:49:37 Worden: Roger; Auto. And I'm maneuvering from the next one.

124:49:43 Henize: Roger.

[Comm break.]

[The "next one" Al is referring to is his next photographic target which is the lunar Lagrangian point, L4. Interestingly, the Flight Plan calls this "lunar libration" although this term is usually applied to that property of the Moon's orbital motion which allows us on Earth to see slightly more than half of its visible surface; actually about 59%.

Diagram displaying Lagrangian points

The Lagrangian points, named after Joseph Louis Lagrange, 1736-1813, are found when two massive bodies are in circular orbits around their common centre of gravity. Five points in the orbital plane exist where the gravitational and momentum forces are in equilibrium and small objects can, theoretically, be held in stable position. Using the Earth-Moon system as an example, L1 and L2 are on either side of the Moon along the Earth-Moon axis; L1 in front of the Moon, L2 behind. L3 is on the opposite side of the Earth from the Moon. L4 and L5 are in the path of the Moon's orbit, but are 60° ahead and behind it respectively. It was thought that over eons of time, interplanetary matter might have accumulated at these points and that, with proper lighting conditions, it might be possible to photograph them from lunar orbit. In the case of Jupiter and the Sun, the Trojan Asteroids are known to inhabit the L4 and L5 points in Jupiter's orbit. Spacecraft, such as the Sun-studying SOHO, have been placed in orbit around the L1 point between the Earth and the Sun to allow uninterrupted solar viewing.]

124:52:28 Henize: Endeavour, we'd like to have an Omni Delta. [Long pause.]

124:52:59 Worden: ...

124:53:04 Worden: ...

[Long comm break.]
124:57:52 Henize: Endeavour, this is Houston. How do you read? [Long pause.]

124:58:12 Henize: Endeavour, this is Houston. How do you read?

124:58:21 Worden (onboard): Ah, ha!

124:59:l0 Worden (onboard): Hello, Houston; Endeavour. How do you read?

124:59:56 Worden (onboard): Hello, Houston; Endeavour.

[Comm break.]

[Al is scheduled to put the X-ray Spectrograph into standby mode. It has been operating non-stop since about 111:40.]

[CSM Flight Plan page 3-171.]

125:00:25 Henize: Endeavour, this is Houston. How do you read?

125:00:31 Worden: Okay, Houston. Looks like we're just going over the hill here. Just wanted you to know it looks like my mission timer on the main panel is shot.

[Al has already lost the timer in the LEB. If this one on the Main Display Console is lost too, it will be a major nuisance as Al tries to coordinate his many science tasks.]
125:00:44 Henize: Roger, Al. We read and we would like to have Command Reset and Low Bit Rate [on the DSE].

125:00:52 Worden: Roger. Command Reset and Low Bit Rate.

125:00:53 Henize: Probably...

125:00:54 Worden: The timer's - it - the mission timer stopped at 124:47:37.

125:01:17 Henize: Roger. This is the...

125:01:19 Worden: I've reset it for 124:59.

125:01:22 Henize: This is the one on panel 1, is it? Or - the mission timer, huh?

125:01:27 Worden: That's affirm.

125:01:30 Henize: Is that - Is that DET in a...

[Karl Henize's exchange with Al has got a little confused and left Henize thinking that Al is referring to the Digital Event Timer on panel 1 of the Main Display Console. Al is referring to the Mission Timer on the top right-hand corner of the large central panel, panel 2.]
125:01:32 Worden: That's right.

125:01:33 Henize: Roger.

125:01:38 Worden: No. The DET is over on the left side.

125:01:40 Henize: Roger. You mean the main mission timer over on panel two then.

125:01:48 Worden: That's affirm. Mission timer on panel two.

125:01:52 Henize: Got you.

125:02:15 Henize: All systems are looking good, Al. See you on the other side.

[Very long comm break.]

[In a far-side pass that's less hectic than the previous one, Al will concentrate on taking photographs of the L4 Lagrangian point (or libration point as it is called in the Flight Plan).]

[Worden, from the 1971 Technical Debrief - "The lunar libration photography was performed using the 35-mm camera with the very high speed black and white film. The camera was mounted in window number 4, the right-hand rendezvous window, through a shield that was placed in front of the window to screen any interior lighting from the lens of the camera. I always had to take considerable time and patience to put the lens in the slot in the opening in that filter to make sure I got a good field of view in that camera. The filter or the shield really didn't seem to fit as well as I thought it should. So it took me a little bit more time to make sure that the shield was around the lens and the lens was in the window properly. Once that was done, I found the 35-mm camera very easy to use, and all of the low-light-level photography was done as per the Flight Plan."]

[After he has come back into the sunlight at the start of revolution 25, he will purge the fuel cells, do a waste water and urine dump and then return Endeavour to the correct attitude for SIM bay operations with the spacecraft's "nose" pointing in the direction of travel. Prior to AOS, the X-ray and Alpha Particle experiment covers are opened, the X-ray equipment is switched on, and the Gamma-ray boom is extended. The SIM bay instruments resume sending good data to Earth.]

[After AOS, Al is due to configure the Hasselblad with an 80-mm lens and magazine S, loaded with low speed (50 ASA) black & white film. This is for a series of photographs he is due to take of the terrain between Mare Crisium and Mare Serenitatis, to be followed by a visual observation of Hadley Rille. The photographic record shows that he has set up the camera well before this as he has taken four shots of Tsiolkovsky, frames AS15-94-12777 to 12780. Obviously a favourite target, this 200-km crater on the far side attracts interest partly because it is so distinctive and spectacular. One of the few patches of dark mare on the far side, Tsiolkovsky contrasts strongly with the dominant light-coloured and battered landscape which surrounds it. AS15-94-12778 shows the interior of the crater as taken from the north demonstrating the albedo difference between the central peak and the floor.]

125:51:18 Henize: 15, this is Houston. We'd like to have you go Wide Beam on the High Gain Antenna, and then to Narrow.

125:51:30 Worden: Okay, Houston. This is Endeavour. Going Wide Beam, going back to Narrow.

[This may be to help the HGA achieve a successful lock onto Earth. A narrow beamwidth requires a higher pointing accuracy and the antenna could have been just out of range or it may have locked up on a sidelobe of the its radiation pattern or on a reflection from the spacecraft hull. Putting it in widebeam mode gives the control electronics different parameters to work to and forces them to relock.]
125:51:36 Henize: Roger.

125:51:56 Henize: That's sounding better, Al. How're things going up there?

125:52:03 Worden: They're going okay, Karl. Looks like I've caught up a little bit. Got all the dumps out of the way, and got the libration photography. Looks like I'm going to be handicapped a little bit because of the mission timer, but we'll press on.

[There are three switches adjacent to the Mission Timer display on panel 2 which preset any desired time into the timer's display. Another switch below that can be used to start, stop and reset the timer.]
125:52:17 Henize: All right. Our understanding on the mission timer is, that even though you tried to reset it, it still refused to count up. Is that correct?

125:52:26 Worden: That's correct. And I thought what I'd do now is reset to zero and start.

125:52:33 Henize: Roger. And for future reference, we'd like...

125:52:38 Worden: It counts from zero, Karl. I...

125:52:41 Henize: Roger - you say it is counting, but it had - it had - to start from zero to start counting again?

125:52:50 Worden: Yes. Well, let me pick a random number and see if it will count from there. I just tried to tell you the correct times...

125:53:37 Worden: Okay, Houston; Endeavour. Looks like we must have just run across a little funny there, Karl, because it started okay now and is running.

125:53:45 Henize: Roger. Do you have a time source, or would you like a hack down here to get it started again, on the right number?

125:53:54 Worden: I used the CMC time.

125:53:58 Henize: Roger. [Long pause.]

[Al can recall GET by using Verb 06 to call up Noun 65 (or maybe 36) on the DSKY. This displays mission time. He is relieved to have retained use of the redundant mission timer.]
125:54:38 Henize: And now for a future reference, we'd like to know whether you found the quick disconnect?

125:54:46 Worden: Negative.

125:54:51 Henize: We copy. [Long pause.]

125:55:41 Henize: We copy. Al, they want me to ask you once more about - tell - tell you once more where - where the location was. The waste management bag in A-8, but I think you know that already. Incidentally, it's a rather short thing, 2 or 3 inches long. It's got a thread on one end and a quick - quick disconnect on the other.

125:56:04 Worden: Yes, Karl, that's exactly what I was looking for. And, problem is, the waste - the small waste management bag is not in A-8 right now. I'm going to have to - have to look around. Maybe Dave or Jim got it out on the way out. I'll look around and see if I can find it.

125:56:18 Henize: Okay, fine.

125:56:21 Worden: I just haven't had - haven't had the free minutes since they came up to do that.

[Al's odd syntax may indicate that his mind is elsewhere at the moment, perhaps looking through compartments and trying to stop everything popping out.]
125:56:28 Henize: Right. And there's no reason now to be troubled by it at all. We were just asking that for future reference. Sounds like it's only a matter of it being dis - misplaced somewhere, so let's forget it. [Long pause.]

125:57:13 Henize: Endeavour, we'd like to have High Gain Antenna, Auto.

125:57:24 Worden: Okay, Houston; Endeavour. You've got High Gain, Auto, and I've got the Pan Camera Power, On.

125:57:31 Henize: Very good. Any time - any time on this rev, we'd like to have an update on the magazines. And in the meantime, let me give you a few good words on the surface activity. The boys have spent the last hour deploying the ALSEP, and I think all of the experiments got out, except we had some trouble, as anticipated, with the - with the drill. Dick Gordon is down here saying "I told you so." The - Dave was in the process of making - for the world discus record, when he just about fell flat on his face he threw it so hard. That was - that was the high spot of the whole ALSEP deployment procedure.

125:58:19 Worden: How far did he get it?

125:58:23 Henize: Oh, I suppose we'll claim something like 2 or 3 kilometers. Who knows for sure. [Laughter]. But the gyrations he went through to keep his footing after that big heave...

125:58:31 Worden: Better than golf balls, even.

125:58:33 Henize: Yes, yes. It was really funny to see him scrambling to keep his footing though after he swung around.

[Comm break.]

[At 124:48:02, Dave Scott took the opportunity to give the discarded pallet from the heat flow experiment, part of the ALSEP package, a really good throw in front of the TV camera and, in the process, lost his footing. As he spun, he fell onto his hand and managed to upright himself as part of the pirouette. See the Apollo 15 Lunar Surface Journal for more details.]

[The golf balls Al refers to are the ones that Alan Shepard took to the Fra Mauro highlands, along with a modified golf club head, during Apollo 14. At the end of his and Ed Mitchell's second and last EVA, Al Shepard attached the head to the handle for the contingency return sample and took a swing. He didn't make good contact with his first hit but claimed to have sent the second going for miles and miles. A photograph of the event is in the book Moon Shot but readers should note that it is only a paste up. There was TV coverage of the event but no photography. In 1990, Alan Bean, LMP on Apollo 12 turned artist, captured the moment in a painting showing the golf ball soaring high above the LM Antares.]

125:59:47 Henize: Okay, Al. We're ready to have the Pan Camera Power, Off.
[Long comm break.]

[CSM Flight Plan page 3-173.]

126:03:05 Henize: Endeavour, this is Houston. You can turn Pan Camera Power, Off, now.

126:03:17 Worden: Roger, Houston. Got it off.

[Comm break.]

[The Panoramic Camera was only on for six minutes. This may simply be to advance the film and prevent it setting around the transport mechanism as was regularly done during the coast to the Moon. It is seventeen hours since the camera was last used.]

126:06:00 Worden: Houston, Endeavour.

126:06:03 Henize: Go ahead, Endeavour.

126:06:16 Henize: Endeavour, this is Houston. Go ahead.

126:06:22 Worden: Okay, Karl. Just for your information, I finally dug all the way through A-8 and got a hold of the quick disconnect. And it's - it's as I expected it. But, it was there, and we're squared away now.

126:06:34 Henize: Very good. That makes people feel better down here. We did stow it, after all.

126:06:41 Worden: Yes, well, one of my problems is that I've got the center couch underneath the right-hand couch, and I've also got the L-shaped bag and a few other things stowed on top of A-8. So, it's not so easy to get to.

126:06:53 Henize: Right-o. We understand.

[Long comm break.]

[This break in the communication is while Al takes photographs of the mountainous area between Mare Crisium and Mare Serenitatis.]

[Worden, from the 1971 Technical Debrief - "General photography within the spacecraft: I had inserted in the Flight Plan at the beginning of each day's activities those magazines that would be required for that day's activities. That worked very well in helping me organize the photography for the day. I used one of the fabric containers just to the left of the side hatch as a storage bin for the magazines and for the cameras when I wasn't actually using them. That worked very well, because, with the center couch out, I was standing in a position which was very accessible to that particular compartment and to window 5 and window 4 and to the side hatch for taking pictures. It was very convenient and worked very well."]

[The Sun is now quite high over the eastern side of the Moon's disk (about 70°) and the highland area Endeavour is flying over shows no sign of shadow. Beginning at the western shore of Mare Crisium, Al takes a "strip" of 29 photographs, AS15-94-12781 to 12809, shooting one every 20 seconds until he is over Mare Serenitatis. All of these images, as available to the journal, are strongly vignetted with the corners completely darkened. This vignetting may represent the outline of the main hatch window.]

[The first two images, AS15-94-12781 and 12782 show two craters lying on the southwestern fringe of Mare Crisium. Yerkes is a 36-km flooded crater seen in outline on the right, named after an American millionaire, 1837-1905, who financed the building of the largest refractor in the world. The 14-km Greaves is a typical slump-walled simple crater. William Greaves, 1897-1955, was the Astronomer Royal for Scotland. The next eight images, 12783 to 90, are rather bright with the Sun at about 60° elevation, and the lack of shadows make features difficult to recognise. This is Palus Somni, the Marsh of Sleep, punctuated by craters Glaisher, Crile and the unusual geometry of Proclus and its rays, as seen to the right of 12786. Glaisher, 1809-1903, was an English meteorologist while Crile, 1864-1943, was an American physician.]

[With frame 12791, we begin to see the contrast between the light-coloured highlands and the dark basalt of Sinus Amoris, or Bay of Love. This bay is on the northeastern shore of Mare Tranquillitatis. Along the border between the two, craters Franz and Proclus D pass through the frame with each shot, seen best at the bottom of 12794. Julius Franz, 1847-1913, was a German astronomer who studied the Moon. Again, we have a contrast between the old, eroded Franz on the left and the much fresher Proclus D to the right. Beyond Franz and isolated in the middle of Sinus Amoris is the small, bowl-shaped crater Theophrastus at only 9 kilometres in diameter. It is named after a Greek philosopher, 372-287 BCE. Beyond it, two very old and broken, flooded rings come into view through images 12795 to 12798; evidence of preexisting craters that, apart from their very rims, were completely inundated by the mare lavas. They are Maraldi D and E. The dark-floored crater they are named for comes into view in 12797 along with the much brighter and fresher Gardner. Both are best seen in AS15-94-12799. Maraldi, 40 km in diameter, is on the right, very degraded and was named after an Italian astronomer, 1709-1788, while the 18-km Gardner, on the left, is named after an American physicist, 1889-1972. There is a distinctive patch of dark material lying between Gardner and Maraldi, which presages the larger areas of low albedo which ring much of Mare Serenitatis.]

126:12:30 Henize: Al, the boys are in the LM, and they're repressurizing the cabin now.

126:12:38 Worden: Roger, Karl. Sounds like they had a pretty good day.

126:12:42 Henize: Yes, sir. They had a terrific day. I think they're going to sleep well tonight.

126:12:51 Worden: Yes. I wouldn't be surprised.

[Long comm break.]

[Al continues his strip of photographs. Vitruvius is a distinct, relatively fresh 30-km crater with a dark floor which comes into view in AS15-94-12799. Marcus Pollio Vitruvius was a Roman architect of the first century BCE. By frame 12803, we see crater Fabbroni on the left, 11 km in diameter and named after an Italian chemist, 1752-1822. A series of valleys in the centre of the frame were probably flooded from the same lavas which filled the Serenitatis basin. The floors of these valleys are strikingly dark and in frame 12804, this dark material can be seen to extend a few kilometres into Mare Serenitatis where there is a transition to the slightly lighter basalt which makes up the bulk of the mare surface. The valley nearest the bottom of frame 12803 will later come to be known as the valley of Taurus-Littrow and will be the spectacularly beautiful landing site for Apollo 17 in December 1972. (The landing site is circled.) The remaining photos of this strip, AS15-94-12805 to 12809, move out across the expanse of Mare Serenitatis, a near featureless surface save for the countless small craters with which it is pockmarked.]

[As Endeavour comes towards the landing site on this orbit, the Flight Plan calls for Al to put into practice some of the training he received in geology description from Farouk El-Baz.]

126:16:33 Henize: Endeavour, this is Houston. You getting a good look at Littrow up there?

126:16:40 Worden: Yes, sir. Just went by Littrow. And right over Serenitatis now, coming up on the landing site.

126:16:48 Henize: Very good. Hey, you been looking the Littrow for a couple of days now. Are you forming any opinions whether that dark area is lava flow or ash flow?

[Henize is specifically referring to the dark patches around the shore of Mare Serenitatis which Al has just photographed. He hints at the problems lunar geologists are having in trying to interpret this dark colouring.]

[At this time, the conventional wisdom was that extruded lava would be dark after it formed and slowly become lighter by the sand-blasting of micrometeoroids over huge spans of time. Thus it was held that the slightly lighter expanse of Mare Serenitatis represented older material, and the darker fringes, shown in AS15-94-12803 and 12804, might be evidence for later, perhaps recent volcanism. If so, geologists were hoping Al might be able to spot the signs of lava flows or deposits of ash.]

126:17:03 Worden: Well, Karl, if I had to give you the opinion right now, I'd say it was all some - some kind of ash. I don't - I'm not sure it's flow. But it certainly is - it looks like a deposit over the entire surface. You can see it - mostly in the upland areas and down in the mare areas and mostly in - in valleys - in depressions, this stuff seems to have collected almost like it was - there was some mass wasting down the hills making the - making the valleys darker in color and maybe a little thicker with that kind of material. But there are - there are still at least three different distinctive colorations in the Littrow area, going from dark gray to a sort of brownish color. And it was the dark gray that looked like it was an ash fault to me, and I'm not sure about intermediate. It looks more like it could have been a flow, and I can see even through - through the binocular I can see the contact where it - there's a - it looks like a flow front between that and the mare - the normal mare coloration which is a little lighter in color.

126:18:23 Henize: Okay. I guess we better let you go back to work on Hadley, which is coming up any minute now.

126:18:31 Worden: Roger.

[Long comm break.]
126:23:04 Worden: Houston, Endeavour.

126:23:07 Henize: Go ahead, Al.

126:23:12 Worden: Okay, Karl. I'm over the Hadley area now. I've gone by it. And nothing more to report on the Hadley, except one observation that I meant to make on the last pass and didn't. I'll make it now. That is that the landmark, 15 dash 40, is readily visible, even with the naked eye. You don't need a sextant to see it.

[It is unclear what Al is referring to by landmark "15 dash 40". On page 2-17 of the Flight Plan, there is a table of landmark data which goes up to 15-6.]

[As well as his planned visual observations, Al takes five images of the landing site; AS15-94-12810 to 12814. From 102 km up, the 80-mm lens on the Hasselblad (photographers would call it a standard lens for the 60 x 60-mm format) does not provide particularly detailed views. However, they are good images of much of the length of Hadley Rille.]

126:23:35 Henize: Very good. [Pause.]

126:23:46 Henize: Does that secondary crater complex stand out in any special way that gives you some idea as to its origin?

126:23:58 Worden: Well, I didn't look at it from that standpoint where I was going over it before, but - I guess I'll have to take a special look at that to answer your question.

[Very long comm break.]

[It seems certain that Karl Henize is asking Al his opinion of the North Complex, a collection of craters dotted around a low hill just north of the landing site. Dave and Jim are scheduled to visit it as part of their final EVA in two days time but problems extracting a deep, 3-metre core will use up the time allocated for the trip. The origin of the North Complex is a matter of some debate to the geologists attached to the mission. It was hoped that it might give up some interesting samples because it was believed either to represent the deepest material that was blasted during the formation of the Imbrium basin, or that it was of a volcanic origin.]

[Seen from above, the topography of the North Complex is suggestive of lava outpourings because of the lobate nature of the scarps around its base, leading some to suggest a volcanic origin. However, another camp of scientists perceived a much more violent tale to be told by this land form.]

[Studies of the cratering process show that the deepest material excavated by an impact is to be found on the rim of the resultant crater, shallower material being sent further in the ejecta blanket. Other geologists theorised that the hill at the centre of the North Complex was the summit of one of the hummocky deposits laid down by the "base surge" of material from the Imbrium impact. If this was so, the hill was made from rock brought up from very deep within the Moon and which was subsequently surrounded by the lavas which make up Palus Putredinus on which Falcon now sits. The theories continue with the craters around the hill, Chain, Icarus and particularly Pluton, which have coincidentally excavated the hill and which, by the same process, would have brought up material from the hill onto their rims.]

[If the latter theory could have been proved correct, then Pluton would have given insight to the North Complex, and the rocks of the North Complex would have given insight to the interior of the early Moon.]

[This pass is a relatively leisurely one for Al and he has time to study and enjoy the bleak landscape passing below. He is due to carry out a platform realignment using program 52. Having just passed the landing site, where it is early in the lunar day, he soon flies over the terminator. The shadows are long and relief on the surface is much more apparent. In the SIM bay attitude, the Sun is behind the spacecraft which explains Al's answer to the next question from the ground. However Karl Henize is probably asking what effect the low sunlight has on the view of the ground below.]

126:34:05 Henize: Hey, Al, how's that sunset look down below you?

126:34:15 Worden: Well, I can't see it from here Karl.

126:34:20 Henize: Any chance - you have got light - in the Aristarchus area yet? Seeing anything down there?

[The beginning of Al's next reply suggests he misheard Henize's question, as he hasn't reached Aristarchus yet, and may have thought he was being asked about Aristillus or Autolycus. These two very prominent craters are just to the west of the landing site near the eastern shore of Mare Imbrium, whereas Aristarchus is beyond the western edge of that mare. Although Aristarchus is still in the lunar night, its quadrant of the lunar sphere is being dimly lit by the Earth.]
126:34:27 Worden: Negative, Karl. I'm beyond it, and it looks like - I'm looking in the wrong direction anyway. Will say this, though. There is - there - seems to be a cloud that seems to be moving along with me. I guess from that last dump. And it - drifted out. Pretty well dispersed right now, but every little particle of that cloud reflects the sunlight like a mirror.

126:34:55 Henize: That's a very interesting observation. You still see some of it out there now, do you?

126:35:04 Worden: Yes, that's affirmative. I do, and - Now, I dimmed the lights down; and I have a pretty nice view of the Moon in Earthshine.

126:35:14 Henize: Ah, hah. Any chance you see Aristarchus? Are you, - maybe you're not looking that way, I guess. Are you looking down on Aristarchus by any chance?

126:35:27 Worden: Well, just a second, and I'll turn the lights down and let you know.

126:35:30 Henize: Good. That's Schröter's Valley, you know, and was once known to glow red.

[Comm break.]

[In view if the sensitive instrumentation built into the Service Module, news of this cloud of possible contaminants around the spacecraft will generate some interest among the investigators who are trying to refine the quality of the information coming from their experiments.]

[Henize has had a chance to restate his query about Aristarchus and clear up the confusion.]

126:37:53 Worden: Hello, Houston; Endeavour.

126:38:00 Henize: Did you call, Al?

126:38:04 Worden: Roger, Karl. I've been sitting here looking at Aristarchus, and I finally had to check the map to make sure; because it's - it's so bright in Earthshine, it's almost as bright, it seems like, as it is in sunshine. Very, very bright crater. It looks very much like Copernicus at night.

126:38:25 Henize: I'll be darned. Sounds real interesting.

126:38:29 Worden: Yes. And I can quite clearly trace out Schröter's Valley going off toward the northwest. I can't see it. It's a little bit out of range; it's north of [my] track, and so it's somewhat out of range for me to see.

[As Henize says, red glows were indeed reported around the area of Aristarchus and Schröter's Valley. Despite the modern view that the Moon is essentially an inert body, reports by telescopic observers persist of various "transient phenomena"; glows, flashes, clouds and the like. In To A Rocky Moon by Don E. Wilhelms, a most readable and entertaining history of lunar exploration by one of its participants, there is a mention of these red glows being seen around the rim of Aristarchus in 1963 by an experienced observer, Jim Greenacre, during telescopic mapping of the Moon. Four other observers, including the director of the Lowell Observatory, confirmed the sightings, causing a ripple of excitement in the press. Apollo 15's groundtrack makes it the first manned craft to get within eyeball range of it.]

[The western side of the lunar disc is dominated by the huge, irregularly shaped Oceanus Procellarum or Ocean of Storms. At 23.7°N, 47.4°W, sited roughly in the middle of this mare, the 40-km Aristarchus is the source of a well developed ray system and together, they are one of the brightest features on the Moon. It seems fitting that it is named for the Greek astronomer (circa 310 - 230 BCE) who taught that the Sun was at the centre of the universe rather than the Earth, over 1,700 years before Copernicus' similar theory toppled western thinking. During a full Moon, Aristarchus is difficult to miss and is even visible in the dim light of Earthshine. It sits at the corner of a polygonal plateau where many small craters form the sources of a multitude of sinuous rilles. One in particular, Schröter's Valley, is one of the largest sinuous rilles on the Moon and a favourite of Earth observers. Up close, it has a double structure consisting of a narrow rille snaking down the flat floor of the main valley.]

126:38:44 Henize: Very good. Hey. Spence [Spencer Gardner] is asking me to remind you about the film magazine update if you have any time yet this rev.

126:39:00 Worden: Okay. I'm going to have to go back through the Flight Plan and get the numbers out. But I will do that.

126:39:10 Henize: Okay. I'm not sure we want you to do that at the expense of anything else here, like to P52. Hang on.

126:39:22 Worden: So, I'll go ahead and do the P52, Karl.

126:39:24 Henize: Right. We'd rather have you do the P52 if there is any either/or there.

[Comm break.]

[Al is carrying out the P52 realignment, and as is normal for his lunar orbit sojourn, it uses option 3, REFSMMAT orienting to the landing site orientation.]

126:42:32 Henize: We've got your torquing angles, Al.

126:42:39 Worden: Okay, Karl. Get them [torqued] out in a minute.

[Comm break.]
126:45:06 Henize: Hey, Al. You've got a couple of people interested down here in particle clouds now. And, first of all, we'd like to have you verify that you saw particles all the way until you went into the shadow. I certainly believe you did. You were telling me about them just as you were in that position. And likewise, if you have a chance at sunrise tomorrow where you are in that same position, with the Sun illuminating you, but not the background, could you see if you - there is any remaining signs of those particles?

126:45:38 Worden: Okay, be glad to. Now, as far as how long I saw them; I saw them as long as the spacecraft was still in sunlight. However, I was beyond the terminator - surface terminator. And, - right now, looking out the window I don't see any of them.

Diagram showing when spacecraft enters shadow

[At Endeavour's current orbital height of 100 to 120 kilometres, the time between passing over the Moon's terminator and eventually passing into the Moon's shadow is between 6 and 7 minutes. On Earth, this is the principle that allows artificial satellites to be viewed from the ground. As long as it is night time for the observer and they are near enough the terminator for the illuminated satellite to be above their local horizon, then the satellite ought to be visible (cloudy weather permitting).]

126:45:55 Henize: Okay, fair enough. And I got some words for you on that bad attitude that we had on the oblique mapping camera photography this morning. If...

126:46:09 Worden: Okay.

[Henize is referring back to 122:05:55 when it was discovered that Noun 78 values for P20, passed up to Al by Mission Control, gave an erroneous attitude for oblique photography by the Mapping Camera.]
126:46:10 Henize: Evidently, we - sent you up the right attitude angles, but some how or other we had a - slightly erroneous omicron. And, the actual photograph - I think we were something like 10 or 15 degrees off attitude - were perfectly good. No problem there. But, we have gone to the Flight Plan and made sure in the future that we will have the proper omicron and everything will be right on the nose.
[The value for omicron Al had used was from a previous setting for P20 and had not been redefined.]

[The term "omicron" is a little tricky to explain, so this author (Woods) apologises if he manages to lose anyone in this explanation. First, to recap on the situation, Al has been using one of the tracking programs in the computer, P20, to keep the SIM bay pointed at the Moon during its operation. Usually, this is to point the SIM bay instruments at the surface directly below the spacecraft - the sub-spacecraft point.]

Diagram showing location of spacecraft axes.

[The programming of the computer is always based around a defined set of axes as shown in the above diagram.]

Diagram showing how SIM bay vector is defined.

[Imagine a line coming out of the spacecraft which is perpendicular to the SIM bay. Of course, this line corresponds to the line-of-sight of the cameras and other instruments in the bay. It can also be thought of as a vector which can be defined in term of the spacecraft's coordinate system. Program 20 can align this vector with the line-of-sight to the Moon's centre. Two angles are entered into Noun 78 which define this vector: 90° (the Axis YAW, rotated away from the spacecraft X-axis) and 52.25° (the Axis PITCH, measured from the rotated axis or in this case how far around the Service Module).]

Diagram showing SIM bay vector being kept pointing at Moon's centre.

[Aligning this vector with the line-of-sight to the Moon's centre ensures that the SIM bay is looking directly down.]

[Option 5 of P20 allows a third angle to be entered into Noun 78. This third angle is called "omicron". It sets the attitude of the spacecraft around the above vector. Imagine the spacecraft was skewered on the end of a physical rod. You might then imagine being able to twirl the spacecraft on the end of this skewer. This rotation is the quantity labelled omicron. It is defined as the angle between the spacecraft's X-axis and the negative motion vector (opposite the direction the spacecraft is moving).]

Diagram showing omicron of 0 and 180 degrees.

[Therefore, in the normal SIM bay-facing-down attitude, an omicron of 0° makes the spacecraft fly engine first (Blunt End Forward or BEF) and the X-axis is aligned with the negative motion vector. An omicron of 180° makes the spacecraft fly with the CM's probe in front (Sharp End Forward or SEF).]

[The oblique photography by the Mapping Camera required the spacecraft to be pitched up by 25°. The Axis YAW and Axis PITCH angles required for this made the old setting of omicron of 180° meaningless and resulted in incorrect pointing of the camera.]

126:46:42 Worden: Okay.

126:46:43 Henize: Just in case you wondering what in the heck went wrong that time. [Changing subject.] And, I have a TEI-37 any time you have time to copy it.

[When only photographs depend on it, an error of this magnitude in the spacecraft's attitude is not a great problem. Also, virtually all major burns have the platform aligned in such a way that the FDAI (Flight Director Attitude Indicator) points in a cardinal direction (0 or 90 degrees, for instance), so attitude errors would be more apparent. Of course, if something didn't look just right, they would scrub the burn and try again later. However, Mission Control will be keen to ensure that a similar error does not occur during the rest of the mission.]
126:46:53 Worden: Okay. Just a minute. [Long pause.]

126:47:39 Worden: Okay, Karl. Go ahead with the TEI-37.

126:47:47 Henize: Say again, Al.

126:47:52 Worden: Go ahead with your TEI-37 PAD.

126:47:56 Henize: Roger. TEI-37, SPS/G&N; 37350; plus 0.60, plus 1.01; 151:00:17.43; plus 2979.1, minus 0745.2, minus 0243.3; 180, 109, 349; the rest is NA. Ullage, 2 jets for 17 seconds - 17 seconds - and the longitude at Tig is minus 179.52. That's all.

126:49:03 Worden: Okay, understand. TEI-37, SPS/G&N; 37350; plus 0.60, plus 1.01; 151:00:17.43; plus 2979.1, minus 0745.2, minus 0243.3; 180, 109, 349; 2 jets, 17 seconds; longitude Tig is minus 179.52.

126:49:34 Henize: That's all correct.

[Long comm break.]

[Interpretation of the PAD is as follows:

Purpose: This is another abort PAD for an early return home at the end of the 37th orbit if there is a problem. It replaces the previous abort PAD and ensures that Al continues to have a usable get-home burn should communications be lost. Of course, he would wait for the surface crew to get back up to him first.

System: The burn would use the SPS engine under the control of the Guidance and Navigation system.

CSM Weight (Noun 47): 37,350 pounds (16,942 kg).

Pitch and yaw trim (Noun 48): +0.6° and +1.01°.

Time of ignition, Tig (Noun 33): 151 hours, 0 minutes, 17.43 seconds.

Change in velocity (Noun 81), fps (m/s): x, +2,979.1 (+908.0); y, -745.2 (-227.1); z, -243.3 (-74.2). These velocity components are expressed with respect to the local vertical/local horizontal frame of reference.

Spacecraft attitude: Roll, 180°; Pitch, 109°; Yaw, 349°. The attitude angles are given with respect to the current REFSMMAT.

SPS propellants are settled in their tanks by firing the plus-X thrusters on all four quads around the Service Module for 17 seconds.]

[Al should be beginning his meal period about now but waits until around LOS.]

126:53:02 Henize: Al, how is your exercise machine going up there. Getting all you need for the - big day in the future.

126:53:14 Worden: Right now I'm trying to figure out your film usage.

126:53:17 Henize: Oh, ho.

126:53:26 Worden: Yes, the exerciser is working fine. The rope's getting a little frayed right now.

126:53:30 Henize: You're really putting in all your hours on it, are you? Glad to hear that.

126:53:39 Worden: Got to keep in shape.

126:53:43 Henize: Righto.

[Scott, from the 1971 Technical Debrief - "As we were on the way to the Moon, we were using the [Exergym] and trying to use it correctly, but it looked like the rope was wearing. There was quite a bit of fraying on the rope. So we decided that, instead of having everybody work out twice a day, to let Al have it twice a day and Jim and I would do something else on the other time. That way Al would have the benefit of the thing."]

[Worden, from the 1971 Technical Debrief - "Well, I don't know what it's going to boil down to. The Exergym is good for keeping some muscle tone, but I found that there was just no way I could get a heart rate established and keep it going. There was just no way I could do that. So I finally decided on a combination of two exercises. I used the Exergym a little bit, just to keep my shoulders and arms toned, and I ran in place. I took the center couch out and wailed away with my legs, just like running in place as a matter of fact. I didn't say anything to the ground, but the doctors watching the biomeds called up and said, "Hey, you must be exercising. We can see your heart rate going-up." And they kept me advised as to what my heart rate was. It worked out very nicely, I thought, because they could tell you that you're up to 130, going up to 140. Then I would exercise a little bit harder, and true, even though I wasn't exerting any pressure on anything, just moving the mass of your legs around really gets your heart going. I'm really convinced that that's the way to exercise in flight; get that kind of motion going and keep it going - not let up on it at all. I did that for 15 to 20 minutes at a time. I just ran in place as hard as I could. As a matter of fact, I thought I'd strained some muscles that I had never used before because I was just free wheeling my legs and wasn't exerting any pressure on anything. I really thought that was a useful exercise, and as far as cardiovascular was concerned, I thought that was a much better exercise than the Exergym. I used the Exergym just for muscle tone. I think it's good for that. It's a good thing. You can pull against that and it's almost like doing situps."]

[Scott, from the 1971 Technical Debrief - "That's the best way to really keep yourself up to snuff up there, especially for people in the Command Module. They really don't have anything else. I guess our recommendation would be to get that small ergometer and put that onboard, because that's the only way you're going to get a dynamic exercise."]

[Worden, from the 1971 Technical Debrief - "I found out that with the center couch out, there's just almost the right amount of room. In fact, the same thing could be done up in the tunnel area. You don't need a whole lot of space. In fact, that particular exercise doesn't take as much space total as does using the Exergym."]

[Irwin, from the 1971 Technical Debrief - "We strained against the struts, against the bulkhead, and against the straps; this was kind of an isometric form of exercise. I think it's almost as good as the Exergym."]

[Scott, from the 1971 Technical Debrief - "You can put your feet on the bulkhead and hold onto the seat struts and do deep kneebends against your arms."]

[Worden, from the 1971 Technical Debrief - "In fact, Dave had the spacecraft moving all over every time he'd exercise. I'd sit there and watch the [spacecraft motion] rates jumping up and down. He was really moving us around."]

126:53:47 Worden: You might also be interested to know that, at least up to this point, we've eaten every morsel of food that was allotted for us at that time.

126:53:56 Henize: Sounds like you're really living it up, up there. Chuck Berry says he's delighted.

[Comm break.]

[Chuck Berry is the Chief Flight Surgeon, and not a reference to a classic '50s R&B singer.]

126:55:16 Worden: Houston, Endeavour.

126:55:18 Henize: Go ahead, Endeavour.

126:55:22 Worden: Okay, [I've] got a quick rundown on the film for you. The DAC magazine, Hotel, is - has 65 percent left; and for the Hasselblad, mag Metro is - I've used 155 frames, November: used 56 frames; Romeo's used 40 frames; Sugar used 80 frames, and Nikon, I've used 16 frames. And let me reverse the first one just to make it consistent. I've used 35 percent out of magazine Hotel for the 16 millimeter. That makes it all consistent.

126:56:12 Henize: Very good, Al. That came through loud and clear. [Long pause.]

126:56:55 Henize: Al, everybody down here is sending up bouquets to you for having done such a great job in a crowded period.

126:57:06 Worden: Well, thank you very much, sir.

126:57:08 Henize: And all the systems down here are looking in good shape as you go around the corner.

126:57:16 Worden: Okay, Karl. Thank you.

126:57:25 Worden: I think I'll get something to eat.

[Very long comm break.]

[CSM Flight Plan page 3-175.]

[The spacecraft is maintaining its attitude within a 5 degree deadband while the Gamma-ray, X-ray and Alpha Particle experiments continue to collect data. During LOS, the DSE stores the collected data which will subsequently be replayed to Earth on the next front side pass. Compared to previous missions, a far higher density of information is being recorded on the DSE tape, primarily due to the demands of the SIM bay experiments. Meanwhile, Al is having his meal and at his sunrise, he will begin his 26th orbit.]

127:47:44 Henize: Endeavour. We'd like to have a narrow beam, please.

127:47:53 Worden: Narrow beam.

127:47:57 Henize: Thank you. [Long pause.]

127:48:08 Henize: And what's new on the west limb of the Moon?

[As he did at 121:04:47, Henize is again using the outdated "astronomical" convention when referring to the lunar hemispheres as Endeavour has just reappeared around the eastern side of the Moon.]
127:48:17 Worden: Well, I must confess, I wasn't watching. I was eating.

127:48:27 Henize: Enjoy it. Looks like, looking at the Flight Plan, looks like you finally had a restful sort of eat period.

127:48:31 Worden: That's true, and it certainly was good. Incidentally, I did look for the - the particle cloud that was around me at sunrise, and it looked like it had diminished somewhat from the sunrise - or from the sunset terminator. But it may have been - it may have been the angle of the sunlight also.

127:48:51 Henize: But you definitely did see some particles yet?

127:48:55 Worden: Fewer particles.

127:48:58 Henize: Fewer particles, but still - still some were there, were they?

127:49:03 Worden: That's correct.

127:49:16 Henize: And how do you enjoy that coquina soup?

[The authors of the Apollo 15 Flight Journal had never heard of coquina soup, but after some laborious searching through all the cookbooks in their kitchens, they found it! Quoting from the classic Joy of Cooking:

Coquina Broth:

If you are lucky enough to be on a beach in Florida, collect Coquinas, the native little periwinkle clams, in their rainbow-hued shells, in a sieve at ebb tide. Rinse them clean of sand, then barely cover with water. Bring slowly to a boil, and simmer for about 10 minutes. Pour the broth through a fine sieve. We think perhaps Nail Soup is better!]

127:49:25 Worden: Almost as good as the parsley soup.

127:49:28 Henize: Wonderful. Brewed it myself.

127:49:36 Worden: It's better than nothing, you know?

127:49:38 Henize: [Laughter] Is that all you can say for it?

[Long comm break.]
127:57:52 Henize: Al, this is Houston.

127:57:59 Worden: Go ahead, Houston.

127:58:01 Henize: Okay, If you'll give us Accept, we'd like to up - update your state vector.

127:58:10 Worden: Okay. You have it.

127:58:11 Henize: Roger. And we've a comm check coming up with the LM and the - the time - the earliest time at which you've got a contact with them is 128:14:14.

127:58:27 Worden: Understand; 14:14.

127:58:29 Henize: Roger. And Bob [Parker] is onboard now. So I'll be signing off and seeing you in the morning.

127:58:43 Worden: Okay, Karl. Go home and have a nice dinner and I'll talk to you in the morning.

127:58:47 Henize: Righto.

[Comm break.]

[CSM Flight Plan page 3-177.]

128:00:04 Parker: And, Al, it's your computer.

128:00:10 Worden: All righty. Good morning.

128:00:13 Parker: Evening.

[Long comm break.]

[Al's ironic humour again!]

128:03:37 Worden: Houston, Endeavour.

128:03:40 Parker: Go ahead, Endeavour.

128:03:45 Worden: Okay, Bob. I'm just coming over - over Picard at the present time, and wanted to make a comment that it looks like there are - there are several ring structures inside the - the basin itself. They're all concentric, and I don't see a great deal of relief on those that look they're in the bottom of the basin. But looking at the - looking at the - scarps around the - the - the outer ring, Picard looks - looks like it's just - almost a caldera type. They look almost like - fault plains along - along the outside. And I can see in the - in the - in the outer wall very distinct layering. For instance - the top - right at - right at the top is a very thin dark layer, and that runs all the way around. And there's a light colored layer. And then there are alternating dark and light layers all in about the same distance from the top of the crater all the way around.

[Picard (23 km) is the largest crater on Mare Crisium with Peirce (18.5 km), further north, being the second largest. Images AS15-94-12752 and 12832 show these craters, including the layering within their walls. Since the illumination is high, albedo variations are most visible to Al. He will add to his description tomorrow at 143:49:24]
128:05:11 Parker: Roger; copy, Al. That sounds like a pretty complete description.

128:05:25 Worden: And, as a matter of fact, Bob, I can make that same observation about Peirce - especially Peirce Alpha. This - I - I notice the same kind of layering and the same kind of horizontal lineaments in the - in the wall of the crater.

128:05:51 Parker: Beautiful. The King [Farouk El-Baz] will be proud of you.

[Comm break.]

[Al is fulfilling his descriptive brief as he moves over the territory to the east of the landing site.]

[The third target subject of Al's visual observations is coming up. As an example of lunar ray craters, Proclus is exceptional as there is a zone encompassing about 120° within which almost all the rays are excluded.]

128:07:12 Worden: Houston, Endeavour.

128:07:14 Parker: Go.

128:07:19 Worden: Okay, Bob. I'm up over Proclus now and that's one of the visual targets. And a couple of comments about Proclus, which weren't too obvious from the pictures we've seen before. The - the edge or the segment of the crater, which is in the excluded zone of the ray pattern - which - the ray pattern, by the way, is very distinct even from directly - directly overhead. That little segment of the crater wall seems to be - discontinuous with the - with the rest of the crater. In other words - the - the crater, if you - if you made a circular ring - and you showed that as the crater, then - then this little chunk in that - in that quarter where the excluded zone is, lies outside of what you would describe as a circle for the crater itself. It's - it's like a little dimple in the crater itself. And I can't see anything in particular there close to the rim that would account for any shadowing - any physical shadowing of the ray pattern. But I - I can see a diagonal fault zone that runs down into that little dimple that I just described a minute ago, and runs into that dimple from the east side. I couldn't pick one out on the west side, but it's very distinct on the east side.

128:08:56 Parker: Beautiful.

128:08:57 Worden: And, in addition to that, I didn't see - I didn't see a great deal of difference in the - in the terrain or in the structure of the terrain across the excluded zone.

[Al's description of the faulting within Proclus leads to a theory adopted in the Apollo 15 Preliminary Science Report which explains the remarkable ray system around the crater as "ray shadowing by structural control." Lunar geologist Paul Spudis confirms that this theory has been discounted in favour of one which favours oblique impact as the cause of the excluded zone and prominent ray pair.]
128:09:12 Parker: Got it.
[Long comm break.]
128:12:37 Worden: Houston, Endeavour.

128:12:41 Parker: Go ahead.

128:12:46 Worden: Okay. I'm looking right down on Littrow now, and a very interesting thing. I see the whole area around Littrow, particularly - particularly in the area of Littrow where we've noticed the darker deposits, there are a whole series of small, almost irregular shaped cones, and they have a very distinct dark mantling just around those cones. It looks like a whole field of small cinder cones down there. And they look - well, I say - I say cinder cones, because they're somewhat irregular in shape. They're not all - they're not all round - they're positive features - and they have a very dark halo, which is mostly symmetric, but not always, around them individually.

128:13:41 Parker: Beautiful, Al. [Long pause.] Real Video file (357K)

[Part of Al's description is included in the above Real Video file, taken from NASA's post-mission documentary.]

[Al's observation of cinder cones at this point, along with his earlier descriptions of distinct coloration in the region, provide one of the major driving arguments to send Apollo 17 to the Taurus-Littrow region in December 1972, to look for evidence of lunar volcanic activity. This was despite counter arguments from other quarters that another landing site at the edge of a major mare would be too similar to the Apollo 15 site, and that the ground track of Apollo 17's SIM bay instruments would cover a landscape little different to 15's; a point countered by differences between the instrumentation aboard the two spacecrafts' bays.]

[Worden, from the 1971 Visual Observations Debrief - "They [the cinder cones] are all fairly small features, but they're very distinct. I noticed them most in [the valley of Taurus-Littrow]."]

[El-Baz, from the 1971 Visual Observations Debrief - "Were they clear?"]

[Worden, from the 1971 Visual Observations Debrief - "Oh, yes. They were funnels."]

[El-Baz, from the 1971 Visual Observations Debrief - "With the craters always on top?"]

[Worden, from the 1971 Visual Observations Debrief - "Yes; and they were very sharp, very distinct, and quite small. And they were neat symmetrical things, too. They weren't broken down any way that I could see. They didn't look like they'd been warped much since they first got there. I didn't see any of them partially obscured by an impact."]

[El-Baz, from the 1971 Visual Observations Debrief - "You also said something about aprons around them - that some of the aprons are symmetrical, some unsymmetrical."]

[Worden, from the 1971 Visual Observations Debrief - "Oh, yes. They're very dark materials perfectly around it.]

["The black spots are what drew my eye to it to begin with. The aprons are even darker than the material that covers the whole area. Then, when I looked at them a little closer, I said, 'Hey, that's a cinder cone,' because then I could see the cone right in the middle of that dark area. They were certainly darker than the surrounding area."]

[It is sometimes said that because the CMPs on the "J" Apollo missions had been trained to look for volcanics, then that is exactly what they found. Al's "cinder cones" is a case in point. One of his cinder cones is Shorty Crater, which when visited by Gene Cernan and Jack Schmitt, was found to harbour deposits of orange soil. Attracting much media attention, this orange soil does, indeed, come from volcanic processes. However, it consists of tiny orange glass beads which were sprayed while molten from a fumarole or "fire fountain" 3.64 billion years ago. Shorty crater is not volcanic, but the impact which created it had simply excavated ancient volcanic deposits, forming a ejecta blanket of dark material. Readers can find a more detailed and highly lucid history of lunar geology in Don Wilhelms' book, To A Rocky Moon.]

[Part of the following exchange between Endeavour and Falcon, is taken from the Apollo Lunar Surface Journal.]

128:14:34 Parker: And, Al, you might want to be reminded at this point, we're getting towards the VHF [communication with Falcon].

128:14:42 Worden: Thanks, Bob. Just going to give them a call. Hello, Falcon; this is Endeavour. [No answer.] Hello Falcon; Endeavour. Hello, Falcon; Endeavour.

128:15:02 Worden: Hello, Falcon; Endeavour. [No answer]

128:15:49 Worden: Hello, Falcon; Endeavour. [No answer]

128:16:56 Scott: Hello, Endeavour; Hadley Base.

128:16:59 Worden: Hello there, Falcon. How you doing?

128:17:01 Scott: Hey, we're doing just fine. How are you doing? [Pause.] How things going up there, Al?

128:17:16 Worden: Hey, going real fine, Dave. We - we're just doing the photography bit and doing a few visual observations. And I've taken a look at you a couple of times down there. How's it going there?

128:17:29 Scott: Okay. You're all broken up. You must be just coming over those mountains again.

128:17:33 Worden: Yes, I am. The rille is just coming into sight now.

128:17:40 Scott: See if you can see any tracks down there.

128:17:42 Worden: Well, I looked for them before, but couldn't see any, while I got the monocular.

128:17:48 Scott: Well, we got all the way up pretty close to...We got to St. George, got to Elbow, and got most of the things done.

128:17:58 Worden: Very good, very good. I understand it was a very successful EVA.

128:18:01 Scott: Yeah, it's pretty nice. I understand that the old SIM bay's gobbling up the data faster that the Moon can produce it.

128:18:07 Worden: Yes, it appears that they're getting some pretty good stuff now.

128:18:12 Scott: Is everything nice and clean up there?

128:18:14 Worden: Sure is. I hope that it is.

128:18:16 Scott: Boy, is it dirty down here!

128:18:20 Worden: I'll bet it is.

128:18:22 Scott: But we're going to bring you some.

128:18:25 Worden: Okay. [Pause.]

128:18:31 Worden: Are you finished for the day's activities now?

128:18:34 Scott: Yeah, we're just climbing out of the suits right now, and buttoning them up, and getting ready to power down.

128:18:42 Worden: Very good. Get a good night's sleep.

128:18:45 Scott: You, too!

128:18:49 Worden: Oh. I'm living the life of Riley up here now.

128:18:53 Scott: Yeah, I guess there's enough room for one guy now, huh?

128:18:58 Worden: Very comfortably.

128:18:59 Irwin: Don't get too spoiled, Al.

128:19:02 Worden: I won't, Jim; I'll save some room for you.

128:19:07 Scott: And save us some food!

128:19:09 Worden: Save you some food?

128:19:10 Irwin: Yeah.

[Eric Jones, Apollo 15 Lunar Surface Journal. - "Worden has hot-water to use in preparing his meals, a luxury the LM crews have to do without."]
128:19:13 Worden: I'm not sure there'll be any left. I have a well-stocked pantry here. [Long pause.]

128:20:19 Worden: Well, Davy, I think I got you on the monocular.

128:20:24 Irwin: Hey, that's great! Can you see the [Rover] tracks?

128:20:27 Worden: No, I can't see any tracks, Jim, but I can see discoloration, rather circular, that looks like it's around the LM.

128:20:40 Irwin: That's good. Maybe you can see the ALSEP.

128:20:47 Worden: Is it over east of you?

128:20:49 Irwin: No, it's west about 300 feet. [Pause.]

128:20:58 Worden: No, I don't have it.

128:21:04 Scott: No, it's not very big. You're looking at best at something that's 2 to 3 feet.

128:21:13 Worden: Yes, all I've got's the monocular.

128:21:15 Scott: Oh, well. [Long pause.]

128:21:30 Scott: Well, have a nice time. We're going to go back to work. We'll talk to you later.

128:21:34 Worden: Okay; get to work, and I'll talk to you tomorrow.

128:21:38 Scott: Okay. [Long pause.]

128:22:12 Worden: Houston, Endeavour. Mapping Camera is going to Extend now.

128:22:20 Parker: Copy.

[Comm break.]
128:23:46 Parker: And Endeavour, we'd like Auto on [the] High Gain [Antenna], please.

128:23:54 Worden: Roger, Houston; going Auto.

[Comm break.]
128:26:14 Worden: Houston, the Mapping Camera talkback is gray.

128:26:17 Parker: Roger; copy. Thank you,

[Comm break.]

[This extension of the Mapping Camera along its track has taken about 4 minutes, as advertised in the Flight Plan.]

128:28:33 Parker: And, Al. We have a Mapping Camera photo PAD for you, when you're ready to copy.

128:28:45 Worden: Roger Bob. Go ahead.

128:28:50 Parker: Okay. T-start; 129:26:52; T-stop; 130:26:30. And it says note: at T-start, Map Camera Image Motion, Increase; talkback barber pole, plus 4. And at 130:08, Mapping Camera Image Motion, Increase, talkback barber pole. Over.

128:29:43 Worden: Roger; understand. Mapping Camera photo PAD. T-start, 129:26:52; T-stop, 130:26:30; and at T-start you want the Image Motion Increased to barber pole, plus 4; and at 130:08, you want Image Motion Increased to barber pole.

128:30:02 Parker: Roger.

[Very long comm break.]

[Endeavour has moved into the lunar night and the Flight Plan is giving Al a quieter time at the moment. As well as extending the Mapping Camera, he also powers up the Laser Altimeter. Towards the end of this near-side pass, he begins an exercise period. Even in the Apollo age, it is known that extended weightlessness has detrimental effects on some of the body's systems and that one way to combat them is to exercise regularly and vigorously. Unlike his crewmates, who are working hard, physically, against the gravity field of the Moon and the resistance of their suits, Al's tasks are much more of a mental nature. Floating around, something which should be done gently in any zero-g spacecraft, and flicking switches are about as much physical activity as Al receives during his working day, and these exercise periods are even more important to him if he is to be in good shape when he returns to Earth.]

128:51:37 Parker: And, Endeavour, Houston. We can terminate Batt B charge at this time, please.

128:51:46 Worden: Roger, Houston. Will do.

[Long comm break.]

[Battery B will have begun charging at around 120:30, based on the Flight Plan.]

128:55:01 Parker: And, Endeavour; Houston. We're 4 minutes to LOS. A couple of comments before you go around the corner. First, the surgeon thinks you may have loosened part of your EKG harness while you were exercising. Like you to check that at your convenience. Second, we have a new Gamma-ray [boom] retract time on the back side of 129:20. Over.

128:55:44 Worden: Roger, Houston. Understand going around the back side. I'll check on that biomed harness. I may have loosened it exercising. And understand you want the gamma-ray boom retracted at 129:20.

128:55:57 Parker: Roger. We won't be able to see it to keep track of the [retraction] times, remember, Al. And, also I guess the Mass Spec. people would appreciate any more comments you can think of, next time you take a look at those particles at sunrise. Over.

[Parker's first comment refers to the change in Al's methodology when timing the retraction of the Gamma-ray boom. Since he will be around the far side, Houston will not be able to keep an eye on it for him.]
128:56:15 Worden: Okay, Bob. Will do. [Long pause.]

128:56:38 Worden: Houston, Endeavour. One last comment.

128:56:41 Parker: Go.

128:56:45 Worden: Okay. When I took the battery B off charge and checked the systems test meter for battery pressure - battery compartment pressure - and it was - systems test meter read 1.4, which is - looks like it's getting pretty close. Is that test - test meter still working all right?

128:57:06 Parker: Roger. Stand by. We're looking at that.

128:57:11 Worden: Okay. [Long pause.]

128:57:46 Parker: Okay. That's - they say that's nominal. That looks good.

128:57:52 Worden: Okay. Thank you. [Long pause.]

[The Systems Test Meter simply reads voltages between 0V and 5V. The signals from all the sensors on the spacecraft have been electronically ranged to provide voltages within this range. According to the Apollo Operations Handbook, Vol 2, the nominal pressure range within the battery compartment is somewhere less than 1 psi [6.9 kPa] which corresponds to a reading of less than 0.2 on the Systems Test Meter.]
128:58:46 Parker: And, Al, if you read, we'd like to have your DSE configured.
[Very long comm break.]

[CSM Flight Plan page 3-179.]

[Endeavour will begin it's 27th revolution about the Moon about halfway around the far side, just as the Sun rises on the spacecraft. Soon after, as he crosses the terminator, he will start the Mapping Camera. Photography of the daylit portion of the Moon near the terminator is especially important because the low sun angles help to pick out topography detail which aids subsequent analysis of the imagery, especially height determination using stereo pairs. Further away from the terminator, visible detail is much more dependant on surface albedo, which shows little variation over small scales. The coming near-side pass will be a busy one for Al with both spacecraft and SIM bay operations.]

129:47:38 Parker: Endeavour, Houston. We'd like Reacq and Narrow, if you can. And we have good biomed data.

129:48:20 Worden: Houston, Endeavour. How do you read?

129:48:22 Parker: Loud and clear.

129:48:28 Worden: Okay. Reading you loud and clear also.

129:48:59 Parker: Endeavour, we have a small series of updates here, if you're ready to copy.

129:49:11 Worden: Stand by one.

129:49:54 Worden: Okay, Houston; Endeavour. Go ahead with your updates.

129:49:56 Parker: Okay. First one is a change to your erasable load printed in the G&C checklist. This change has already been made in the computer. It's on page 9-4 and I'll wait for you on that one.

129:50:13 Worden: Okay. Stand by. [Long pause.]

129:50:45 Worden: Okay, Bob. I'm here.

129:50:48 Parker: Okay. And on column Delta, line 05, we will change that number from "01571" to "01605." Over.

129:51:06 Worden: Understand. That's column Delta and octal ID 05, change to "01605."

129:51:16 Parker: That's verified. And all the next updates here are in the Flight Plan.

[The value is a manual update to the Guidance Computer. Updates to the computer can be done two ways; first, the ground can radio changes to the computer via telemetry, or the crewmember can enter the data directly. For updates provided by Houston, the computer is put in an idle status (P00, or program 00) and the data uplinked; updates provided to the crew are done in through Program P27, and the data is entered through Verb 71. The table Worden and Parker are discussing contains a list of predetermined loads to the computer that are required to be performed.]
129:51:29 Worden: Okay. [Pause.]

129:51:37 Worden: Okay. Go ahead.

129:51:39 Parker: Okay. At - These are changes to the bistatic radar at 130:52, "P00 at pitch 177 degrees." And we're deleting the "P00 at pitch 171," at 130:54 there.

129:52:03 Worden: Okay. And what time do you want that. At 130:52?

129:52:06 Parker: That's affirm.

129:52:13 Parker: And at 131...

129:52:16 Worden: Okay.

129:52:17 Parker: ...at 131:10, we will change the Verb 49 maneuver to bistatic attitude from "067, 171, 00" to "067, 177, 00." So the Pitch changes to 177. Over.

129:52:41 Worden: Roger. Understand. Change the Pitch to 177.

129:52:43 Parker: Okay. At 131:32, we're going to change the Noun 78 values. We're going to change R2 to "plus 067.00." That's R2.

129:53:07 Worden: Okay. Understand. Change R2 from "047.50" to "067.00."

129:53:14 Parker: Roger. And at 131:39, the "start auto pitch rate" attitude there will be the same as the Verb 49 inertial attitude updated at 131:10, which means we'll change that to - from "171" on the inertial to "177." Over.

129:53:41 Worden: Roger. Understand.

129:53:47 Parker: Okay. And I have a Camera photo PAD for you. Pan Camera. Go to T-start at 1...

129:53:56 Worden: Okay. Go ahead.

129:53:57 Parker: T-start, 130:18:05; T-stop, 130:19:16. Over.

129:54:14 Worden: Understand. Pan camera photo PAD T-start, 130:18:05; T-stop, 130:19:16.

129:54:22 Parker: Roger. And I have a TEI-37 PAD for you if you can find a copy of a PAD.

129:54:39 Worden: Roger. I have a TEI-37 PAD. Is there any change?

129:54:45 Parker: Roger. Yes, there is a change.

129:54:50 Worden: Okay, Go ahead.

129:54:52 Parker: Roger. TEI-37, SPS/G&N; 37350; plus 0.60, plus 1.01; at Noun 33, 150:59:30.08; Noun 81, plus 2979.1, minus 0748.6, minus 0219.6; 180, 109, 349; and the rest of the PAD is unchanged. Ullage, 2 jet for 17 seconds; and other comments - longitude at Tig will be minus 179.22. Over.

129:56:08 Worden: Roger. Understand TEI-37 PAD, SPS/G&N; 37350; plus 0.60, plus 1.01; 150:59:30.08; plus 2979.1, minus 0748.6; minus 0219.6; 180, 109, 349; two jet, 17 seconds, and longitude Tig is minus 179.22.

129:56:42 Parker: Roger. Readback correct; and that's the end of the updates for the moment.

129:56:48 Worden: All righty. [Long pause.]

[The changes to the TEI-37 PAD compared to the version sent up at 126:47:56, are a slightly earlier ignition time and Delta-V which is about one foot per second less.]
129:57:30 Parker: And, Endeavour; we'd like to get the callout which was at 129:50 for the Gamma-ray Gain Step to Shield, Off. Over.

129:57:51 Worden: Roger; understand.

129:57:52 Parker: And, we, - you can get that most anytime soon. For 10 minutes; it is not critical yet, I guess, as far as the start time is concerned. [Long pause.]

[As long as the Gain Step shield is off for ten minutes, Mission Control are not bothered exactly when the period starts.]
129:58:54 Worden: Houston, Endeavour.

129:58:56 Parker: Go ahead, Endeavour.

129:59:01 Worden: Okay, the Delta-T on the Gamma-ray boom retract was 3 plus 07.

129:59:07 Parker: Copy. Thank you.

[Comm break.]

[This is well within the expected value of 3 minutes, 15 seconds as given in the Flight Plan and indicates the mechanism is working well.]

[CSM Flight Plan page 3-181.]

130:01:02 Parker: And, Endeavour; Houston. When you have a moment, High Gain [Antenna] in Auto now.

130:01:09 Worden: Okay. Going Auto. And do you want the onboard read-outs now, Bob?

[As happened last night, the Bistatic Radar Experiment will take up the entire duration of Al's next near-side pass, which is also his last before his rest period. Therefore, Al is scheduled to carry out those items in the presleep checklist which require radio communication with Earth.]
130:01:22 Parker: Yes. We'll take them.

130:01:27 Worden: Okay. Crew status. Better than most, I guess. PRD was 23135. Battery C, 37 [volts]; Pyro Bat A. 37; Pyro Bat B, 37; RCS in order, 71, 69, 70, 71.

130:01:58 Parker: Okay. We copy all those.

130:02:02 Worden: Okay; and cryo fans have been cycled.

130:02:06 Parker: Copy.

[Long comm break.]

[Note that only the fans within the H2 tanks are cycled.]

130:11:21 Parker: Endeavour, Houston.

130:11:28 Worden: Houston, Endeavour. Go ahead.

130:11:30 Parker: Roger. And the people down here are suggesting that on your presleep checklist, we omit the 'Direct O2 to On' for the rest of your solo flight because you aren't just breathing down the cabin that much, and I guess it will save a little bit of oxygen and eliminate the possibility of cracking a relief valve there. So we'll delete that section from your...

130:11:50 Worden: Okay, Bob, that sounds good. I didn't notice. Yes, okay, I noticed last night I set it at 5.7, or it was very close to 6, and it didn't drop a bit during the day today.

130:12:07 Parker: Roger. I guess that's what we're noticing too.

130:12:14 Worden: Incidentally, just going over the Littrow area again. I described the - what looked like - some, at least, fumarolic vents. They look like small cinder cones to me. And every time I look at them, they - that firms up my impression more and more that they're vol - volcanic cinder cones. Also, I noticed one rille, and I'd like to try and get some pictures of it here before we get too far away from Littrow on the next - maybe tomorrow. Looks very distinctly like the roof, or the - the top of the rille is collapsed in some places, and the rille is exposed in other places.

130:12:59 Parker: Roger. It'll make a few theorists pretty happy about that.

130:13:05 Worden: Yes, yes; it might - it might confirm some things about rilles. It's - its a little difficult to see whether it is in fact a collapsed feature in some of the - in those parts of the rille, or whether it's something else that I'm seeing. But it looks very much like portions of - the - the rille have a collapsed roof. And, in fact, the one I was looking at, works it's way into what looks like one of the - one of the ridges. It was very ridgy to the - to the north and then turned into a rille as it went south.

130:13:47 Parker: Roger. Copy. Keep talking like that, and we might end up going to Littrow sometime.

130:13:54 Worden: [Laughter] Yes. [Long pause.]

[Al is firming up his impression about volcanism in the Littrow area and Parker's last comment turns out to be most prophetic. Note that, although Al mentions seeing fumarolic vents at Littrow, the features he is attributing to the term are young craters with dark ejecta blankets. Yet evidence of fumarolic vents will be found by Apollo 17 at an exposure of orange soil at station 4 (Shorty Crater).]
130:14:26 Parker: And, Al, already you've generated enough interest for people to ask if it's underneath you, so that the Mapping Camera might be getting it now.

130:14:37 Worden: Yes. The Mapping Camera should be getting it.

130:14:40 Parker: Beautiful.

130:14:45 Worden: I suspect the - the Mapping Camera might not have enough detail to pick it up as well as we'd like. Although, I don't know, I can see it with the 10 power binocular without any trouble.

130:15:01 Parker: Copy. And, just so we don't forget it, we got about 3 minutes to T-start for the Pan Camera.

130:15:13 Worden: Roger. Right with you. Countdown 2:50 now.

130:15:17 Parker: Right on.

[Long comm break.]

[AS15-0993M is from the crop of Mapping Camera images being taken during this pass.]

Mapping Camera image, AS15-0993M, of the Apollo 15 landing site.

130:19:25 Worden: Okay, Houston. That does the Pan Camera pass over Hadley Rille, and you can let me know when the lens is tucked in.

130:19:39 Parker: Roger. [Long pause.]

130:20:00 Parker: Go ahead. [Pause.]

130:20:09 Parker: And, Al, we verify the lens is tucked. You can turn the power off.

130:20:16 Worden: All righty; thank you, sir.

[Comm break.]
130:21:37 Parker: And, Al, while you're getting ready for [stopping] the Mapping Camera, if you'll let us, we'll get a E-memory dump.

130:21:46 Worden: Okay, Bob. Stand by one.

130:21:48 Parker: Roger.

[Long comm break.]

[As he comes over the terminator towards lunar night, Al is finishing the current Mapping Camera operation. Among the images taken during the current Mapping Camera pass is a picture of Timocharis which has been kindly donated by Michael Light, whose book Full Moon, is an astonishing illustration of Project Apollo. The book includes four consecutive Mapping Camera images of Timocharis including this image, AS15-1005M, taken during the current pass 27. This striking frame comes from the Metric Camera within the Mapping Camera system and displays the hallmarks of classic crater morphology; hummocky lobate ejecta blanket to about one crater radius out from the rim, radial sculpture beyond, then distinctive clusters of secondary impacts on the mare surface with "V"-shaped profiles pointing towards the crater.]

130:28:01 Parker: And, Al, we're noticing the Laser, I guess - Vance told you earlier, it's kind of going down hill a little bit, and we'd like to turn it off at this time. It's working about 50 percent right now, so we'd like to turn it off right now.

130:28:16 Worden: Roger, Bob. Laser is coming off. And the Mass Spec. boom is coming out.

130:28:25 Parker: Copy.

[Long comm break.]

[The Laser Altimeter is being switched off about 15 minutes earlier than planned. Both the Mass Spectrometer boom and the Gamma-ray boom are being deployed and Al is timing them. The Mass Spectrometer instrument must now be allowed to outgas before being operated during Al's rest period.]

130:32:26 Worden: Houston, Endeavour. [Pause.]

130:32:37 Parker: Say again, Endeavour.

130:32:41 Worden: Okay, Bob. I've got some good accurate times for you on the boom extensions.

130:32:45 Parker: Okay.

130:32:49 Worden: Okay. It's from switch actuation to - when the barber pole goes gray. And the Delta-T for the mass spec was 2 minutes, 39 seconds - 2 plus 39, and the Delta-T for the Gamma-ray was 2 plus 41; 2 plus 41.

130:33:09 Parker: Copy, thank you.

130:33:14 Worden: Roger.

[Long comm break.]

[The Mass Spec. boom is having no problem extending. Its problem comes when it is retracted. The next task is a P52 realignment, option 3, REFSMMAT is based on the landing site orientation.]

130:37:36 Parker: Roger. We're looking at your torquing angles and you're Go.

130:37:36 Worden: Roger.

[Very long comm break.]

[Now the X-ray experiment is put in its standby mode, the Mapping Camera is retracted and the covers for these experiments are closed. Only the Gamma-ray and Alpha Particle experiments are operating and their data is soon to be degraded as the spacecraft will be put in an attitude for the Bistatic Radar Test. This test will occur during the next nearside pass.]

130:50:07 Parker: Endeavour, Houston. Over.

130:50:14 Worden: Houston, Endeavour. Go ahead.

130:50:16 Parker: Roger. One small change to your Flight Plan. Reminder of the change that we made yesterday, as well. At 133:17, remember the Mass Spec. peoples now want Discriminator and Multiplier to Low. You remember that?

130:50:49 Worden: Roger, Bob. I've got it. It's showing in Low at 133:17.

130:50:54 Parker: Roger. Just a reminder. And another reminder: when you get ready to go to sleep, you can go to Reacquire and Narrow [on the high gain antenna] with [angles of] plus 25 and 185, and then we won't disturb you when you come AOS on the pass after next, when you should be - already asleep.

[The "Reacquire" function of the Service Module's HGA (High Gain Antenna) gives the communications system a degree of autonomous operation, as regards pointing to Earth.]

[The control electronics of the antenna are able to keep it pointing towards Earth even as the attitude of the spacecraft changes; as it does while orbiting the Moon with the SIM bay pointing towards the surface. Of course, the antenna can only do this if the spacecraft's structure, or the Moon, are not in the way. As the HGA is mounted on the opposite side of the Service Module from the SIM bay (and the SIM bay is pointing at the Moon) then the spacecraft is unlikely to get in the way during near-side passes. Of course, during far-side passes, the Moon is obscuring the line-of-sight of the antenna.]

[Primarily intended for operation during PTC (Passive Thermal Control), "Reacquire" adds to this Earth pointing function. If some situation, usually going behind the Moon, causes the HGA to lose lock, it slews the antenna to pointing angles which have been preset on controls on panel 2 of the Main Display Console. Since Mission Control know the attitude the spacecraft will be in when it reappears around the Moon, they can predict the most appropriate angles to set the panel 2 controls to, so that the antenna will be aimed properly and regain lock each AOS without intervention.]

130:51:18 Worden: Roger. Understand; High Gain angles are plus 25 and 185.

130:51:23 Parker: Roger. I think they're in your checklist too, Al.

130:51:36 Worden: They could be, Bob. I looked for them last night and couldn't find them.

130:51:40 Parker: I figured as much.

130:51:45 Worden: Roger. And incidentally, the Delta-T on the Mapping Camera retract was 3 plus 15.

130:51:55 Parker: Copy.

[Long comm break.]

[The mechanism to retract the Mapping Camera is working well as the timing is well within the expected four minutes.]

130:55:50 Parker: And Endeavour as you go around the hill, good night.

130:55:56 Worden: Okay, Bobby. Goodnight.

[Very long comm break.]

[CSM Flight Plan pages 3-183 and 3-185]

[Endeavour will begin orbit number 28 during this far-side pass. Before then, Al's only task in the Flight Plan is to maneuver Endeavour into the correct attitude for the bistatic radar test. Once into the 28th orbit, he will configure the S-band and VHF radio systems for the test. Just before AOS, at 131:39:00, a slow, automatic pitch maneuver will be initiated at a rate of 0.083° per second with a deadband of 0.5°. The Bistatic Radar Test begins at this point and continues throughout the near-side pass of rev 28. Meanwhile, Al has his evening meal. Note that there can be no telemetry or voice communication while the test is in progress. At LOS during the 28th orbit, the spacecraft is returned to the SIM bay attitude with the SPS engine pointing in the direction of flight. On commencement of the 29th orbit, SIM bay science will be resumed. Simultaneously, Al begins his rest period, while data is being received from the Gamma-ray Spectrometer, X-ray Fluorescence Spectrometer, Alpha Particle Counter and Mass Spectrometer. Although, at AOS on orbit 29, the rest period has begun, Gordon Fullerton, the night CapCom has some loose ends to tie up with Al.]

[CSM Flight Plan page 3-187.]

133:46:13 Fullerton: Endeavour, Houston. Over. [No answer.]

133:46:46 Fullerton: Endeavour, this is Houston. Over. [No answer.]

133:47:15 Fullerton: Hello, Endeavour. Endeavour, this is Houston. Over. [No answer.]

133:48:07 Fullerton: Hello, Endeavour. This is Houston in the blind. If you read, go Reacq and Narrow at angle of Pitch, plus 25; and Yaw, 185. That's Pitch, plus 25; and Yaw, 185. Over.

133:48:45 Worden: Hello, Houston; this is Endeavour. Go ahead.

133:48:48 Fullerton: Okay, Al, this is Houston. You're loud and clear now. I would like to suggest going to the presleep configuration before you bed down for the night there on the comm.

133:49:03 Worden: Yes. Roger. Will do, Gordo.

[Comm break.]
133:52:02 Fullerton: Endeavour, Houston. Over.

133:52:08 Worden: Yes, go ahead, Gordo.

133:52:10 Fullerton: Okay. If you've gone through the presleep checklist, we noticed a couple of things. The optics power should go off, and also - in your DAP load, go to all ones in R-1. And, we'd like a call when you finally turn in and turn the voice mode off, just before you do that, please. Over.

133:52:36 Worden: Yes. Okay, Gordo. Haven't been through the checklist yet.

133:52:40 Fullerton: Okay.

[Very long comm break.]

[The DAP (Digital AutoPilot) is a routine in the spacecraft's computer which keeps the attitude within defined limits. Two registers, R1 and R2, within the computer define its current status. A fuller explanation can be found at 106:14:46.]

[CSM Flight Plan page 3-189.]

134:02:45 Fullerton: Endeavour, Houston. No need to acknowledge, but we need the Mass Spec. Discriminator to Low as per an earlier update. Over. [Long pause.]

134:03:28 Worden: Houston, Endeavour.

134:03:30 Fullerton: Go ahead.

134:03:35 Worden: Gordon, was that Mass Spec, Discriminator, Low or Multiplier, Low? I got an update about 5 hours ago. It was - they said Multiplier, Low.

134:03:51 Fullerton: Okay. I guess the update was on Discriminator. Actually, they're both suppose to be low, Multiplier and Discriminator, Al.

134:04:01 Worden: Okay. I understand you want them both Low.

134:04:04 Fullerton: That's affirmative.

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