Apollo 15 Lunar Surface Journal

Post-landing Activities

Corrected Transcript and Commentary Copyright © 1996 by Eric M. Jones.
All rights reserved.
Last revised 27 June 2011.

MP3 Audio Clip ( 9 min 19 sec ) by David Shaffer

104:57:55 Mitchell: Falcon, Houston.

104:58:00 Scott: Houston, Falcon. Go.

104:58:01 Mitchell: Rog. On page 1-2 where you get to setting your S-Band to Slew, I've got some new angles for you because of your attitude.

104:58:12 Scott: Okay.

[These are the pointing angles for the S-Band antenna on the top of the LM, identical to the one shown in close-up in a LM-9 photo by Randy Attwood.]

104:58:13 Mitchell: It's a minus 71...

104:58:14 Scott: Go ahead, Ed.

104:58:15 Mitchell:...and a minus 58. Sorry, plus 71 and minus 58.

104:58:22 Irwin: Copied...(Stops to listen to the correction) Okay; a plus 71 and a minus 58.

104:58:29 Mitchell: That's affirm.

[These antenna pointing angles differ only slightly from the values on Surface 1-2 (plus-73 and minus-62) which, of course, were calculated pre-flight on the assumption that the LM would land perfectly upright.]
104:58:32 Scott: Okay, Ed...Okay, Ed. We'll give you a little quick summary here before we get on with it. The general terrain looks exactly like what you had on 14.
[The Apollo 14 site has very hummocky terrain, with rises and falls of a few meters over distances of several tens of meters. The hummocks are formed by the overlap of very old craters, much eroded by eons of bombardment by particles ranging down to sand-grain size.]
104:58:40 Scott: And many of the craters that we use for ID were completely washed out with no shadows, and that's probably because the topo data just wasn't that good. And I think we're sitting a little off in attitude, but we're in fairly good shape. And, when we get around to the SEVA (Stand-up EVA), we'll try and pin down the location exactly. I had a little bit of dust at 150 (feet) and completely obscured at 50 feet. It was IFR (Instrument Flight Rules) from then on down. And the rest of it, you could probably see it (from the telemetry) as well as we could.

104:59:18 Mitchell: Okay, Dave. We copy. Thank you.

104:59:23 Scott: Rog. (Long Pause)

[At about 106:44, they will depressurize the cabin and open the overhead (docking) hatch so that Dave can stand on the ascent engine cover and look around and take pictures for about a half an hour.]
104:59:40 Mitchell: And Falcon, Houston. Do you have an estimate of your landing site? (Pause)

104:59:50 Scott: There's a long pause there, Ed.

104:59:53 Mitchell: Roger.

[Scott - (Laughing) "That means, 'I don't know where we are, Ed'. We're trying to pick our surface location on a map that's 20 meters in resolution, and we really need detail down to less than 20 meters. It isn't there. And we were trying to imagine all sorts of things to fit."]

[Jones - "As far as I know, you were the only crew that didn't have high-resolution Orbiter pictures or high resolution Command Module pictures. For 17, they had good photos that Al Worden got on your flight."]

[Scott - "Part of the landing site discussion earlier on was (based on the fact that areas) to the south of Hadley were (covered at) pretty good resolution, and they tried to draw some analogies between the south and the north. And the conclusion was you really couldn't, because the geology was totally different. So, the question was: should we land in the south where there was higher resolution, or in the north, where we did land, where there was lower resolution but much better geology? And the answer was: it's safe enough to land up there, so land up there."]

104:59:59 Scott: I think...As best I could find, I think we're fairly close to Salyut. But I guess the best thing to do is to press on and get to the SEVA where we can take a look around. It's very hummocky, and, as you know, in this kind of terrain, you can hardly see over your eyebrows. There's very little to tell us exactly where we are in our local position.
[Dave knows he isn't very far from the target point and, with the Rover, a miss of a few hundred meters will hardly matter. He had planned to land at map coordinates BQ/74, which is about 500 meters north of Salyut Crater. He actually landed near BS.4/73.3 or about 600 meters north and about 175 meters west of the target. He is just northwest of Last Crater. A detail from Pan Camera frame 9377, taken from the Command Module, shows the LM on the surface about four hours after the landing. The planned landing point is just off the bottom of the detail, about 200 meters south of the southern rim of Last Crater. The landing site coordinates are 26.1008 degrees north latitude and 3.6527 east longitude. ]

[In a 1995 letter, Dave speculated that the fact that he landed much farther off target than either Pete Conrad or Al Shepard could have been due to a combination of the lack of good site photography, the lack of shadow craters near the target point, the steep descent trajectory (25 degrees rather than the 14 degrees used on prior missions), and the new guidance algorithms that were used in conjunction with the steep descent.]

105:00:24 Mitchell: Completely understand, Dave.

105:00:29 Scott: (Chuckles) Okay, thank you. You can probably explain it to the folks back there better than I could.

[Scott - "It was good having Ed Mitchell in this part of the mission, because, not only is he very good, but he also had just recently had the 14 experience, which gave us a lot of comfort in flying it, that we're talking to a guy who's been there. It's a subtle thing, but from my perspective - and I think from Jim's as well - if the guy on the horn has been there, you feel that you can get a lot more reliable information than from somebody who hasn't been there. So, if he says something, you have comfort and can take it in very quickly. Whereas, if a guy hasn't been there and he offers some sort of advice, it's probably good advice but you don't take it quite as quickly. So that's why these comments with Ed Mitchell. 'Cause he'd been there and I knew that he knew what I knew. That's sort of nice. That was a good plan to have that kind of guy working that part of the mission."]

[Jones - "I have the impression that Ed was about as good as anybody who ever flew on the right side."]

[Scott - "Oh, I think so. Ed's a super kind of guy. Very competent, very quick, tuned in very well. And I was real pleased that we got him during this part of the mission. And the same way with Joe Allen on the surface stuff. We can work better if we have a high comfort level. If you know the guy who's handling the rest of the world back there is good and you know he has experience, it gives you a very high comfort level in what you're doing and you can focus on the other things. If there's an uncertainty somewhere, then you allow more margin for that uncertainty. But, if you have an Ed Mitchell, who is a certainty, then you don't have to allow as much margin. It's tradeoff and it makes it all work better. That's why, whoever put Ed on there - Deke probably, and we got to say yea or nay on the CapComs - had a good idea. I liked it a lot. Because the guy is very good, has been there, and we can talk without talking. I mean, here's a conversation where we're saying a lot, but we're not saying much. And you can hear from the tone of the voices, 'Ed, you tell them. You were here. You can tell all those guys back there.' Good system."]

105:00:35 Mitchell: Dick (Gordon, the backup Commander) wants to know where Falcon Crater is, if you can see it?

105:00:42 Scott: I think we're in it.

105:00:45 Mitchell: (Over background laughter in Houston) That's what we figured. (Pause)

[Scott - "There are a lot of innuendoes in this thing - and I can't remember them all. We all worked together for so long and so closely that, after a while, you've got to get some humor and life into it to keep it interesting; and Dick and I worked together on 8, 9, and 12. So we had a lot of time together; and there's a lot of subtleties and inside stuff in these comments. Which the people in Mission Control would never understand. I'll have to go think about Falcon Crater. There's a subtlety in here. Some of these may be a bit risqué. I don't remember this particular one."]

[Scott - "As a preliminary answer, I'll say we wanted to name a crater on the Moon Falcon Crater. And I think we decided that, wherever we landed, by definition, would be Falcon Crater."]

105:00:51 Mitchell: Endeavour, Houston.

105:00:56 Worden: Houston, Endeavour. Go ahead.

105:00:57 Mitchell: Rog. I have your camera Pads for you.

105:01:04 Worden: Okay, stand by 1. (Long Pause) Okay, Houston; Endeavour. Go ahead.

105:02:02 Mitchell: Roger, Endeavour. Rev 15, Map(ping) camera Pad. T-start, 105:52:58; T-stop, 106:17:57. (Pause) And your camera Pad...

105:02:32 Worden: Roger. Houston...

105:02:33 Mitchell: ...Pan camera Pad is the same.

105:02:37 Worden: Okay, Houston. Understand mapping camera and pan camera Pads are the same. T-start, 105:52:58 and T-stop 106:17:57.

105:02:47 Mitchell: That's correct. Your Rev 16 map camera Pad...(Pause while he gets an instruction from the Flight Director) Endeavour, Houston, give us P00 (Program Zero-Zero) and Accept, and we'll up-link while we're talking here.

[Scott - "Program Zero-Zero was pronounced 'Pooh', after (A.A. Milne's) Winnie the Pooh."]

[With the computer in P00 and Accept, Houston can directly load revised state vectors - spacecraft positions and velocities - and other data.]

105:03:08 Worden: Okay. You've got Accept, and I'm in a middle of a maneuver (that is, a spacecraft re-orientation) right now.

105:03:12 Mitchell: Okay. Leave it in P20.

105:03:18 Worden: Okay.

105:03:21 Mitchell: And your T-start 106...

105:03:22 Worden: Go ahead with rev 16.

105:03:24 Mitchell: Roger. T-start, 106:56:51; T-stop, 108:55:19.

105:03:39 Worden: Understand. T-start, 106:56:51. T-stop, 108:55:19.

105:03:52 Mitchell: That's a good readback, Al. (Long Pause) Endeavour, Houston. If you'll give us an Enter, we can go ahead with the load.

105:05:11 Worden: Okay. (Long Pause)

[The NASA Public Affairs commentator tells the press that a preliminary estimate of where Dave landed, based on LM guidance system data, is 1900 feet (570 meters) south of target. The LM is actually about 625 meters NNW of the target.]
105:05:27 Irwin: Houston, are you copying the AGS Cal(ibration) values?

105:05:34 Mitchell: That's affirm, Falcon.

[Comm Break. The Abort Guidance System Calibration procedures are on Surface 1.2.]
105:06:47 Mitchell: Endeavour, Houston. The computer's yours.

105:06:52 Worden: Roger; Houston. (Pause)

[Here, Mitchell is telling Al that the uplink has been completed and that he can switch out of P00.]
105:07:08 Mitchell: Endeavour and Falcon, Houston. Could I talk with (you) a minute? (Pause)

105:07:20 Worden: Houston, this is Endeavour. Go ahead.

105:07:26 Mitchell: And Falcon, Houston. (Pause)

105:07:33 Scott: Go ahead, Houston, Hadley Base here.

[Scott - "You notice, there, we went from Falcon to Hadley Base. That was by design. 'Cause we decided, once we're on the ground, it was no longer a flying machine, it is not the Falcon. It has changed into a base. And then it will fly again. Probably you've discussed the many roles of the Lunar Module with the other guys. It was a marvelous piece of machine with so many features built in. It was so many different things. Which is pretty remarkable when somebody started with a plain piece of paper. It's home now, and a laboratory, and all those other things. The locker room, the dining room, the bedroom, the observation tower, communications center, data processing center, and a flying machine. If you stop and look at the design of the LM, it's bloody remarkable!"]
105:07:36 Mitchell: Okay, crew. The President sends his regards through (NASA Administrator) Dr. (James) Fletcher, and I read: "The President sends his congratulations to the entire ground team and the Apollo 15 crew on a successful landing and sends his best wishes for the rest of the mission."

105:08:00 Scott: Rog; Houston. Thank you. Our appreciation...

105:08:02 Worden: Houston, this is Endeavour. Thank you very much.

105:08:03 Scott: ...to the President, and I'd like to thank you, too, for the support we've had.

105:08:07 Mitchell: Roger. Roger. (Pause)

105:08:16 Scott: And, Houston, the Hadley Base here. Tell those geologists in the Backroom to get ready because we've really got something for them.

105:08:24 Mitchell: Which group of guys in the back room?

[Comm Break]

[Flight controllers in the Mission Operation Control Room (MOCR) were supported by teams of experts working in support rooms scattered around the Johnson Space Center and at various off-site contractor facilities. The science support team occupied one of these so-called backrooms. Because the Apollo Lunar Surface Journal concentrates on the EVAs, when we refer to the capitalized Backroom, we are always talking about the team in the science support room. Dave's remark at 105:08:16 indicates that, at this point in the mission, he is also thinking only of the science team.]

[Jones - "Is Ed making a reference to two camps of folks wondering about what you would see?"]

[Scott - "I don't think so. It was a reference to the geology team in the Backroom. But I don't know what Ed meant, here. But it refers to Silver and Swann and Muehlberger and Schmitt and all, because they were all hanging on the edge. I'd been in the Backroom during Apollo 12. I know what the Backroom looks like. I'm on the Moon, but I know almost exactly what's going on in Mission Control. All that information and knowledge makes it easier for us to work. And, as I say, makes us more interested in what we're doing. We're not just talking to a tape recorder. Gordon Swann's our Geology PI (Principal Investigator) and I'm talking to him just like I'm talking to you across the table. And I know that, when I'm talking about some surface feature, I know exactly what he's looking at when he's listening to me. And I can probably anticipate his question. It's team work that developed from working together for months and months and months and years, so the communications almost become like, you know, a pro-basketball team. Magic Johnson (a professional basketball star with the Los Angeles Lakers at the time of the mission review) doesn't have to say where he's going to pass the ball. But Byron Scott knows he's going to get the ball, or James Worthy. And we have the same kind of thing. When you get this team work going and you pass the ball, you don't have to look. It's the no-look pass; and the guy catches it and he makes two. So, when we talk about geologists in the Backroom, we've all ready worked with those particular people in the field, many times. We know what they're looking for."]

[During this Comm Break, Dave and Jim have probably reconfigured their circuit breaker panels as per Surface 1-3 and 1-4 and have pulled window shades up across the windows in preparation for doing some star sightings so that they can check the alignment of the inertial platform which provides the absolute point of reference for the PGNS.]

MP3 Audio Clip ( 10 min 14 sec ) by David Shaffer

105:10:56 Worden: Okay Ed. If you've got the gyro torquing angles, I'll torque them out on the minute.

105:11:05 Mitchell: Roger. We copied (the angles).

105:11:13 Worden: Okay, Houston; Endeavour. I'll wait until the even minute to torque them out.

105:11:18 Mitchell: Roger. On the even minute. (Pause) Falcon, Houston. Stand by on your stars, and let us give you some new ones.

105:11:33 Scott: Okay. Standing by.

[Because of the LM tilt, the stars listed on Surface 1-5 are not the ideal ones to use for the platform alignment.]

[Scott - "As you know, we had 36 stars that we learned and used as navigation stars. On Apollo 9, we did a lot of star work. I'd been working on the G&N (Guidance and Navigation), so the sextant and the star catalog were part of my early responsibilities (in Gemini). So, when we got to go on Apollo 9, and started finalizing what we were to do, part of what we had to do was a thorough check of the G&N because, on Apollo 9, we turned it off for the first time. Prior flights had left all the Guidance and Navigation running. On 9, we decided that it was mature enough to shut it down. But, when you turned it on again, you had to align it with the stars. I was Command Module Pilot and that was my job."]

["In (earlier) training with Neil (for Gemini 8), flying across the countryside, what we would do is look up and we would practice our stars. We didn't get much southern hemisphere practice (that way), but we got that in the planetarium (see below). We used to pick out remote (fainter) stars and test each other on the constellations. (That) teaches you what you need to know in these alignments, which go very quickly if you know your stars. If you can find a star quickly and verify it is, indeed, the star you want, you can align your platform much more quickly than if you have to go look at a star chart, look at 122, and figure out where that fits in. You don't have time for that. You've got to know it."]

[" We had 36 stars and, when we started, there were only 33 with prominent names. Now there are 36 with prominent names. The three that didn't have names are now called Navi, Dnoces and Regor. If you go look at the (Apollo) star catalog, there are a lot of stars - all the ones you're familiar with - and then these three."]

[Dave is, of course, overstating the case when he says that there were "three that didn't have names" because, in fact, the three already had names that had long been recognized by the astronomical community. "Navi" is Gamma Cassiopeia; "Dnoces" is Iota Ursa Majoris; and "Regor" is Gamma Velorum. Dave is referring to the fact that Gamma Cassiopeia does not have a traditional Arabic or European name and that the traditional Arabic names of the other two - Suhail (Regor) and Talitha (Dnoces)- are not as familiar to most people as those of such stars as Polaris, Betelguese, Arcturus, etc. See the article Dnoces, Navi, and Regor by E.C. Krupp in the October 1994 edition of Sky & Telescope.]

[Scott - "And do you know where the names came from? For the record: Virgil Ivan Grissom, Edward H. White II, and Roger Chaffee. I hope they got left in the catalog."]

[For readers who have not tumbled to the connection between the star names and the Apollo 1 crew, "Navi" is "Ivan" spelled backwards, "Regor" is "Roger", and "Dnoces" is "Second".]

[During our Apollo 15 mission review, Dave recalled that the stars had been named for the Grissom crew after the Apollo 1 fire; but educators Betty Niver and Mary Zornio called my attention to a story in Wally Schirra's book to the effect that, long before the fire, Grissom conspired with the Director of the Morehead Planetarium, Tony Jenzano, to name the three stars after the members of his crew. Journal Contributor Charles Rolston notes that there is also a discussion of the star names in the James Michener novel Space.]

[In a 1996 discussion of the question, Dave Scott recalled that, during his early involvement in Gemini, all of the astronauts spent time with Jenzano at Morehead in Chapel Hill, North Carolina, learning their way around the sky. He speculated that it was during one of these visits that the naming took place and, indeed, has found a November 1966 checklist which contains the new names. Dave was a member of the Jim McDivitt crew that backed up the Grissom crew until they were assigned to the mission that became Apollo 9.]

[Late in 1996, I was able to contact Jenzano, who provided the following clarification: "The great majority of celestial navigation training for the Mercury, Gemini and Apollo astronauts was conducted at the Morehead Planetarium in Chapel Hill, North Carolina. At the time a summary report was written in 1969, the astronauts had already logged over 1700 hours of training at the Morehead Planetarium. Training continued up to the Apollo-Soyuz mission in 1975. In 1959, Link Trainers were designed and constructed (by Jenzano) which mirrored the view the astronauts would have in their capsules while in space. The astronauts memorized specific constellations and significant stars and utilized this information with accompanying star charts in order to be able to plot their position in space at any given time. The Mercury trainer had the capacity to yaw left or right in order to simulate the action of the thruster rockets. New trainers were constructed for the Gemini (and Apollo) missions."]

["I was not involved in the 'renaming' of the stars (Navi, Dnoces, and Regor). Shortly after the Apollo (1) tragedy, NASA sent star charts from the mission for me to review and edit. In that review, I noticed three stars on the charts that had been named incorrectly and included this information in my report back to NASA officials. I made no attempt to discern why the star names were incorrect. Several years later, I met with one of the original Mercury astronauts, Wally Schirra, at a conference and, in the course of the conversation, the renamed stars were mentioned as a private joke made by Gus Grissom. When I returned home from the conference, I looked through my records and retrieved the letter I had written to NASA. I then copied the letter and sent it to Mr. Schirra. In the (cover) letter to Mr. Schirra, I acknowledged that, obviously, I had inadvertently 'spilled the beans' on the astronauts. I noted that, if I had known, I might have 'gone along with the joke' to see how far it would go!"]

105:11:36 Mitchell: Okay. The first pair, we will have star 3 (Navi) in detent 3; star 12 (Rigel) in detent 6. Second pair...

105:11:48 Scott: 3 in detent 3 and 12 in detent 6.

[Star 3 is Gamma Cassiopeiae (Navi) in the constellation Cassiopeia and star 12 is Beta Orionis (Rigel) in Orion.]
105:11:52 Mitchell: That's affirm. Second pair, we'll have star 61 - that's Epsilon Orionis - in detent 6. Then Noun 88, plus 10975, plus 99373, minus 02127. Star 122, Schedar, is your second (and will be) in detent 3. Noun 88, plus 54566, plus 09353, plus 83277. And if you're questioning, there weren't any other nav star pairs available, apparently.

105:12:59 Irwin: Okay, Ed. I understand. For the first P57, it's 3 in detent 3 and 12 in detent 6. And then for the second pair, it's star 61 in detent 6, and the Noun 88 values are plus 10975, plus 99373, minus 02127. And then star 122, in detent 3; plus 54566, plus 09353, and plus 83277.

105:13:38 Mitchell: That's a good readback, Jim. (Long Pause)

[Jones - "Now, the numbers Ed read up were star coordinates so that you could use the AOT (Alignment Optical Telescope) and check to see that the stars were where they were supposed to be and fine tune the platform alignment."]

[Scott - "Yeah. Or you could drive the AOT to the stars with the computer. You could enter it into the computer so you would align your platform based on the stars, and you'd be ready to go. And then we put everything to sleep and then woke it up again for the take-off. Let's see. There were some other things we could do with the AOT. It was not nearly as sophisticated as the sextant and the scanning telescope on the Command Module, but it was pretty good. And the whole scheme of using the spiral and cursor on the AOT was pretty clever. Very few moving parts, and you could do an awful lot with it. And, somewhere in the back of my mind, there's something tied in with the rendezvous, but I can't remember what it is."]

[Note that, on Surface 1-5, they will do the platform alignment twice, each time with a separate pair of stars. Note, also, that Ed did not read up the coordinates of the first new pair of stars - numbers 3 and 12. Those were already in the computer.]

[Jones - "The AOT with which you're doing the stellar re-align is above the panel between the two of you. What was the position of that?"]

[Scott - "We could both reach it. There wasn't any problem with that."]

[Jones - "I'm certainly well aware that you had to coordinate your movements when you both had the PLSSs (the backpacks or Portable Life Support System) on. With the PLSSs off, hoses on, and soft suits, was there a little bit of elbow room?"]

[Scott - "Yeah. It was reasonably comfortable for a fighter airplane. You don't have any need to go anyplace. I mean, the switches are all laid out, the panels are laid out, everything's laid out for you to be in one place; so there's no need to go anyplace else. So, as long as you're standing there doing your job, it's fine. Still, the inside volume was small and the range of things that we had to do are especially amazing in today's perspective of wide-body airliners."]

[Jones - "Was standing in one-sixth gravity okay?"]

[Scott - "Yeah. I don't recall whether we had the restraints on at this time or not. I don't know when we took them off. But they tend to hold you down on the floor. I don't remember thinking anything about one-sixth g at this time. I mean, we were busy. You block all that stuff out."]

[Jones - "But you could stand for a long time in one-sixth g and never notice it."]

[Scott - "I've never thought about it. You could stand a long time in one g and never notice it. We stood in the simulators for hours and hours."]

[Jones - "It depends on how busy you are."]

[Scott - "It was not a noticeable difference."]

[In Houston, the Flight Director is told that the fuel and oxidizer tank pressures have dropped below vapor pressure and that, unless the vents are closed, further venting will result in undesirable cooling of the Descent Stage.]

105:14:02 Mitchell: Falcon, Houston. Your vent's complete. You can terminate.

105:14:08 Scott: Roger. Thank you.

[Long Comm Break]

[During this Comm Break, Ed Mitchell reminds the Flight Director that the Command Module is about to go behind the Moon and asks if there is any unfinished business that needs to be conducted prior to LOS (Loss-of-Signal). The Flight Director conducts a poll and finds that there is none.]

105:19:38 Mitchell: Endeavour, Houston. 1 minute until LOS. You're looking good from here. (Long Pause) Endeavour, Houston. 30 seconds to LOS. Do you read?

105:20:09 Worden: Houston, Endeavour. Rog.

105:20:13 Mitchell: And you look good from the ground, Al. We'll see you on the other side.

105:20:18 Worden: Okay, Ed.

[Comm Break. Dave and Jim are finishing their first pair of stars.]
105:22:11 Mitchell: Falcon, we copy your Noun 93.
[O'Brien - "Once the stars have been sighted through the AOT, Noun 93 displays the angular distance that the platform must be moved to bring it back into correct alignment."]
105:22:17 Scott: Okay; we'll torque them at 22:30.

105:22:21 Mitchell: Stand by one.

105:22:25 Scott: Standing by.

105:22:31 Mitchell: Okay; proceed with your torquing.

105:22:36 Scott: On the way. (Pause) Okay, Houston. Standing by on the RLS (Reference Landing Site).

105:22:54 Mitchell: Stand by one.

105:22:58 Scott: Okay. (Pause)

105:23:04 Mitchell: Okay; let's reject those, Dave.

105:23:09 Scott: All right, reject.

[Comm Break]

[The torquing angles are changes in the platform alignment derived from the sightings on the first pair of stars. Houston has decided that those angles don't make sense. Dave and Jim will now proceed to the sightings with the second pair of stars.]

[In Houston, the Flight Director is told that Dave and Jim have incorrectly loaded the final digit of Noun 88 into the computer. Mitchell notes that the mistake can be caught when the numbers are re-loaded.]

105:25:53 Mitchell: Falcon, Houston. When the Noun 88 (the star coordinates) comes up again, hold it, please.

105:26:00 Scott: Okay, Houston. I didn't copy the name of the star, but how about Castor or Pollux or Betelgeuse or somebody like that?

105:26:13 Mitchell: Okay; stand by. We'll tell you which one it is; we think it's in the middle of the belt (in the constellation of Orion), Dave.

105:26:17 Scott: Which one, Jim?

105:26:22 Scott: Alnilam! Alnilam! Yeah, we got that.

105:26:25 Mitchell: Rog; it's the middle star.

105:26:30 Scott: Sure, old (playing with syllables) Aludiman!

105:26:33 Mitchell: You're right. (Pause)

105:26:43 Scott: It's nice to see friends. (Pause)

[Scott - "There's a story about that one. But I don't remember the story. But we knew him well. Names of stars mean a lot more than numbers. I remember one star that we used near the Big Dipper, the name of which I can't recall, but there's a star in the Big Dipper, near one of the stars that we used, which was the north star at the time the pyramids were built. It is no longer the north star. Many people forget that things in the heavens change over time, and the things that were there when the pyramids were built are different from the things that are there now. It was fun going through that kind of rationale, because it helps you become familiar with the sky. And that's why the comments 'it's nice to see old friends', because, once you become familiar with the sky, then you look up and you can very quickly orient yourself. And the constellations make it easy to do that. So the Arabs (who provided most of the star names used now) did a great job."]

[Journal Contributor Ron Wells notes that the pole star at the time of the pyramids was Thuban, also known as Alpha Draconis.]

[Scott - "Between Apollo 1 and Apollo 9, we were out in LA and we used to spend a lot of time in the (Griffith Park) planetarium because we were identifying the stars to be used, and developing the stories to help us remember which ones they were. It was supposed to be work, right? You sit in the planetarium all day and lean back in those chairs and listen to some scholar...What was the name of that guy? Dr. Clement Shaw ran the planetarium and he was a marvelous teacher. We would go through the heavens and he would relate these stories and star charts and all that sort of thing. It was a fun part of it."]

105:26:56 Scott: Okay, Houston. We can use this one, but we don't have the Noun 88 for it.

105:27:03 Mitchell: Yes, you do. That's what we gave you, Dave.

105:27:09 Scott: Okay; we'll try it again. (Long Pause)

105:27:31 Scott: Houston, why don't you read us the Noun 88s again then, please?

105:27:34 Mitchell: Roger. Plus 10975. (Pause)

105:27:43 Scott: Go.

105:27:45 Mitchell: Plus 99373. (Pause)

105:27:56 Scott: Go.

105:27:57 Mitchell: Minus 02127.

105:28:05 Scott: Okay; that's exactly what we just loaded. We'll see where it takes us.

105:28:10 Mitchell: We're seeing it...On the last register, we're seeing a minus 02124.

105:28:22 Scott: Sure, that's just a round-off.

105:28:25 Mitchell: Yeah, you're probably right.

[Scott - "What I'm doing is loading the coordinates into the computer to drive the AOT so that it lines up with a star. And you look in the AOT and see the star and you know that everything's where it's supposed to be. You notice a little deviation from normal procedure where he reads up the numbers instead of me reading the numbers back to him? Instead of copying them, I was just punching them into the computer directly."]

[Jones - "And they could look and see what was in the registers."]

[Scott - "Yeah. And then he called up and said 'Hey, we see a different number,' And that's because it rounds off the last five digits based on what it sees internally. And then it drives the AOT to the star and, if the spiral and cursor cross on the star, the computer knows where it is. Everybody knows where they are."]

[Jones - " How did the G&N system compare with state of the art at the time?"]

[Scott - "It was state-of-the-art. It depends on what you call state-of-the-art, which is a function of where in a cycle of technological growth some system may be. Often people call it state-of-the-practice, which is later than state-of-the-art. But, in terms of contemporary technology, this was a unique system, but it was based on the Polaris guidance system. That's where it came from. And it had been an evolutionary process to incorporate the IMU - the Inertial Measurements Unit, the inertial platform - that was used, basically, on Polaris into Apollo with some sort of celestial capability. And that's how they came up with the scanning telescope and the sextant in the Command Module, and the AOT in the Lunar Module. You didn't have the capability of the drive electronics - nor the room - in the Lunar Module, so they had to come up with some other scheme that wasn't as mechanically driven like the Command Module sextant and scanning telescope. It didn't cover as much sky, but it didn't need to because, on the lunar surface you're fairly well fixed. At the time, it was so-called state-of-the-art. I don't think anybody else was using this directly, because there weren't any other specific applications. The Apollo guidance computer was unique, with very little erasable memory. But there were reasons for that. One was reliability. And the other, which I thought was a great idea, was that you couldn't change it before flight 'cause it was a hard-wired memory. Everybody likes to change things before flight. And that's when you get into trouble, as we have learned. Last minute changes, software didn't get verified, something glitches. For its day, it was on the front edge."]

105:28:30 Scott: And...Let's take a look at the Noun 79, and that's not even close.
[O'Brien - "Dave is having difficulty locating star 61, Epsilon Orionis, in the AOT. Noun 79 displays the AOT coordinates of the star, but unfortunately, Houston has given him the wrong coordinates."]
105:28:36 Mitchell: Okay. (Pause) Dave, we specified it for detent 6, and the computer's giving you detent 5.

105:28:54 Scott: I should have noticed that, Ed; I'm sorry. (Long Pause)

[Scott - "There was a knob on the telescope that you rotated to put it in the detents."]

[Jones - "So it was a mechanical change rather than a computer change."]

[Scott - "Each of the six detents would point to a different 60-degree field-of-view in the hemisphere above the LM. There was no mechanical articulation (capability of movement) within a detent other than rotating the cursor and spiral. The computer numbers for a star within the field-of-view of a particular detent were unique."]

105:29:15 Mitchell: Okay, Dave, the spiral should be about 330 and the cursor about 148, if that helps.

105:29:25 Scott: (That's) right on.

[Long Comm Break]

[Dave's 'right on' means that the cursor and spiral readings Ed gave him are exactly what he is seeing in the AOT.]

MP3 Audio Clip ( 13 min 36 sec ) by David Shaffer

105:34:10 Mitchell: Falcon, Houston.

105:34:14 Scott: Go.

105:34:15 Mitchell: If you'd like some help being coached on to this next star, it's in (the constellation) Cassiopeia, and we're suggesting detent 3. (It should) be a spiral of 181, a cursor of 23, and it should be just to the left of Navi, the bright star to the left of Navi.

105:34:39 Scott: Okay.

105:34:41 Mitchell: And we'll give you the Noun 88s when you get to them.

105:34:42 Scott: Oh yeah, Schedar. Rog.

105:34:44 Mitchell: That's affirm.

105:34:47 Scott: Okay. (Pause) Okay; we'll cycle back, Ed. (Long Pause)

105:35:49 Mitchell: Okay, Falcon; Houston. (We) observed your cycle back. We'll to have to rerun that first star again.

105:35:58 Scott: Yes; Rog, Ed. The reason I did that was because we need to stick an erasable load in here on the Noun 79.

[Comm Break]
105:37:25 Scott: Okay, Houston. It doesn't look like the program is running exactly right.

105:37:31 Mitchell: What seems to be the problem, Dave? It looks good from here.

105:37:39 Scott: (Sounding a bit doubtful) Okay, we'll try; but we're in a loop here where it won't accept detent 6, I believe; but we'll press on.

105:37:48 Mitchell: It's always going to give the first one it computes, Dave. (Pause) Change it to (detent) 6 and go ahead.

[Comm Break]
105:41:15 Mitchell: Okay, Dave, you ready for your second Noun 88s?

105:41:21 Scott: Well, I think we've got them on board if that's what you read us.

105:41:24 Mitchell: Rog. You're going great; keep going. (Long Pause)

105:42:17 Scott: Okay, Ed; I have Schedar.

105:42:19 Mitchell: Very good, Dave.

[Comm Break. They are doing the second star sighting and, in the next exchange with Houston, are at the bottom of checklist page Surface 1-5.]

[Scott, from the 1971 Technical Debrief - "The (platform) alignment was straightforward once we got the (Noun) 88 procedures squared away...The new procedures developed by MIT to perform P57's was very good and save quite a bit of time. We had an extra pad (that is, a time cushion) in there based on the old techniques of having to cursor and then spiral. Now that you can go straight through, it saves quite a bit of time and it's a valuable improvement in the program."]

[Even with the confusion, the platform alignment has only taken about a half an hour. On Apollo 14, for example, the alignment done at this same point in the mission took about an hour.]

105:45:40 Scott: Okay, Houston; the torquing angles are up.

105:45:44 Mitchell: Roger. Stand by. (Long Pause) Okay, Pro(ceed).

105:46:11 Scott: Okay; they're in. (Pause) And how about the RLS (Reference Landing Site)? Do you want to take it?

105:46:23 Mitchell: Negative, Falcon.

105:46:27 Scott: Roger on the negative.

105:46:32 Mitchell: Okay, Falcon; Houston. We need to redesignate the rendezvous radar to 180, 270, 00 for thermal protection.

105:46:49 Scott: 180 and 270.

105:46:53 Mitchell: That's affirm. (Long Pause)

[Jones - "I think you're parking the rendezvous radar (LM-9 photo by Randy Attwood) so that it doesn't heat up. It was up on top of the LM, but you could park it to minimize the cross-section to the Sun. Is that right?"]

[Scott - "Thermal considerations were always important. The environment of the Moon is different from the environment of the Earth, and thermal considerations are quite different."]

[Jones - "You don't have convective heating or cooling."]

[Scott - "Yeah, that's the atmosphere that provides that here on Earth. But the difference in the heat, the temperature. There's no protection from the Sun (clouds and absorption by atmospheric gases reduce heating on Earth). All this stuff can get real hot."]

105:47:18 Mitchell: And, Falcon; Houston. As soon as you get the radar parked, we're ready for the E-Mod dump.

105:47:25 Scott: Roger.

[Comm Break. In E-Mod dump they will download the entire contents of the computer memory to Houston. This item is at the top of Surface 1-6.]

[Jones - "Could they read the whole memory?"]

[Scott - "They could read the same thing we read."]

[Jones - "That is, they could read the display."]

[Scott - "They had the same numbers we had. When I say 'the torquing angles are up' I've got them on the DSKY and they've got them on their DSKY."]

[Jones - "For them to look at the whole memory, you'd have to do a E(rasable)-memory dump?"]

[Scott - "I don't remember, exactly, but they could see practically everything we could see. There wasn't much of a memory to read. It's not like today's computers. 2000 words of erasable (memory), and the other 36,000 (words) was all hard-wired programs. I don't know if any of the other guys have discussed it with you, or whether it's even relevant, but the use of the computer on Apollo was unique. And it's interesting that it never caught on any place else. As you know, the Apollo computers used Verbs and Nouns that were represented as two-digit numbers. And you could talk to the computer that way, and the computer would talk back to you. And once you learned it, it was an amazing tool. Because you could get vast amounts of data which could be interpreted into vast amounts of information on what was going on and what the computer thought. The communications between the crew and the computer, I thought, were just excellent. And, once you learned these Verbs and Nouns, you could very quickly go in and out of the computer and gather a lot of data, and you could also tell the automatic system what to do and how to do it. Where to go, how to maneuver, and that sort of things. And the people on the ground could read what we could read. It was a way of communicating with the ground."]

[Jones - "How much exposure was there to the details of that kind of stuff before somebody got assigned to a backup crew? Or was that the first real exposure?"]

[Scott - "In general, that was the first real exposure. I had a lot of exposure 'cause I worked on it from the day I got there. In fact, on Apollo 9, Rusty Schweickart and I helped the MIT guys write a program two days before launch for orbital rate drive on the Command Module so we could take the - gosh, I forget what we called that particular type photography - the four cameras we had on Apollo 9 were mounted in the window of the Command Module and had to be pointed directly at the ground as the spacecraft flew over the ground. And we found out, right before launch, that there was no way to keep the cameras pointed directly at the ground, because the spacecraft was programmed to fly inertial modes, not orbit rate modes. So the guys at MIT very quickly devised a little loop in the program to enable us to command the spacecraft to rotate at Earth orbit rate and, thereby, enable the cameras be continuously pointed at the ground. The Apollo Command Module was never designed to do that; that was not its job. With most satellites today, Earth-observation satellites, that's their job; that's what they do."]

["The (Apollo computer) programs - albeit hard-wired - were quite flexible in a certain sense, if you knew how to get into them. I had spent a lot of time on that part of the world. But, in general, when somebody like Al or Jim was assigned to a crew, they really had not had practical exposure to how it worked. They had been taught, they'd been in simulators; but, only in how you would run it in the mission, and what it could do for you. Some people did not like it at all."]

["Some people thought there were far too many commands - verbs, nouns, availability - and wanted an automatic system, totally, which was the old controversy between modes and functions. Apollo was a function control spacecraft in that, by combining switches, you could tell the spacecraft to perform certain functions. In contrast, the Soviet approach at the time was mode control. You push a button and the spacecraft will automatically complete a job as a mode, totally. So you have very little functional control. Many people prefer the mode over the functional, and vice versa. And there was a classic set of cartoons that the MIT people had, which were always sort of funny. They had two types of astronauts: one type were the functional control types (Charles Stark Draper Laboratory Archives, photograph number 24861, used with permission), if you will, and here's three guys in a spacecraft with arms and legs everywhere and buttons and switches. And the other picture (Charles Stark Draper Laboratory Archives, photograph number 24860, used with permission) had three guys sitting back, chewing their bubble gum, and they have a button that says 'Go' and another one that says 'Come Home' - the two ends of the spectrum. There was a lot of controversy, and some people in the Astronaut Office did not like all this functional stuff and thought that the system should be designed in a more mode control sense, so that you wouldn't have to worry about all the extra things that you could screw up. If you had more opportunity to do things, you've got more opportunities to screw up. And a lot of the functional control was not necessary in a normal mission. On the other hand, if you had some abnormalities and some problems, in my opinion it was great to have the availability of some of the functions, because you could back things up if you had certain failures. And you could also tell the computer to have the spacecraft do things for you. You had more control over the situation, but you had to spend more time learning it. So it's a trade-off. I think it was a great system and, even though it was hard-wired, it was quite flexible."]

["The Verbs/Nouns idea would be good for computers today. It's how we speak and how we work - how we do things - and it was the way they set up the computer. The verb said 'display' and you push a noun 'torquing angles' and, bang, there they are. In the landing programs, you've heard P64 and P66. Those were essentially modes. You put it into P64 and it does this and P66 and it does that. But you could break out of that and you could go fly it manually and you could look at the display and it would tell you what it would have been doing. So you had that flexibility."]

[Jones - "You mentioned people getting some exposure to some aspects of this in simulators prior to getting assigned to backup crews. I know that there were the full-up LM simulators and the Command Module simulators that were basically used only by the prime crews and the backup crews. Were there lower level simulators?"]

[Scott - "There were mock-ups. And there were part-task simulators. And there were engineering simulators. And the contractors even had simulators before they got the Apollo simulators running. And that's a whole 'nother area of discussion."]

["There are two schools of thought on how you build a simulator for something like this. One school says you use actual flight hardware as much as you can. The other school says you build everything with software. And the decision was made on Apollo to build everything with software, and they had great problems because they couldn't get the software to exactly represent the hardware and they couldn't get the interfaces to work. So when we were getting ready for Apollo 9, boy, they had major simulator problems. I used, on the Command Module, a Guidance and Navigation simulator at Rockwell in Downey. They had installed a G&N system and had interfaced it with the stabilization and control system, and they had built a facility, out of necessity, in order to interface and test these things, and it was actually a simulator. So I spent a great deal of time in this facility training and, at the same time, I became their worker, if you will, to run the programs they were developing. They had to integrate the hardware and the software and they had to integrate the SCS and the G&N. So they brought all these pieces together to make them play and I had the benefit of being able to run these programs for them. And, McDivitt and Schweickart spent a lot of time, too, working the same problem on the Lunar Module in Bethpage - trying to get all this stuff to play, which was part of our role (as crew). It became a great training facility and developmental facility in that we participated with the engineers in writing the programs, because the software had to be compatible with the hardware and also with operations. So you needed a flight-operations person in there (that is, an astronaut rather than an engineer or flight controller) who could say whether or not you could fly it that way. It was a rather complex process that was pretty interesting."]

["When you ask about simulators, per se, there were many devices that enabled somebody to get some experience on the various systems. You could go to the manufacturer's facility and sit in the spacecraft and run tests. That's training. You're learning about how the system works, and that's part of simulation."]

[Jones - "And they're learning about how the system works."]

[Scott - "Yes, and that's a part of the process that doesn't exist today, because the vehicles today are all built. So the people involved don't get the benefit of that sort of growth/developmental area, where you put things together and you have to solve problems just to get things to work properly. When you go through that you learn how to solve problems when they don't work normally. That's why I go back to this whole methodology of Apollo. What was it we did that made it work? It did work, and you can talk about how it worked and what was done. But the thing that I think is important in all this is the evolutionary methodology on how it all came together. Because it was unique. Nobody'd ever done this before. It didn't fall into place; it was driven into place and this is one part of it."]

["I don't know what experience Al and Jim had, specifically, when they were assigned to the crew, because I wasn't involved in what they were doing. They were selected in what, '67 or '68 or something like that. I got selected in '63 and, when they came on board and were given training, I was so involved in Gemini VIII and Apollo 1 that I don't know specifically what sort of training they got."]

["Now, relative to the simulators, they ran them 24 hours a day and a lot of people would run them at 2 or 3 in the morning to get experience on them. I mean, there was a backlog of people waiting in line to get in the simulators. The prime and backup crews had priority. The support guys had second priority. And a lot of things were done in the simulators that weren't exactly training. They were developmental for procedures - in what do you do and how do you do it. And it was a great device to determine a sequence of events, and integrate a sequence of events. If astronauts weren't in them, the training guys were in them. It just ran all the time, and were invaluable. We had a set in Houston and a set at the Cape. We could have never done the program without them, and that's probably one reason the program worked. They solved the software problems and, by the time you got in flight, you had a lot of time in simulators of such high fidelity, and a lot of time in the spacecraft running tests that they were old friends. You know, if a switch was sort of loose - that's an exaggeration - but, if there were idiosyncrasies or uniquenesses in the spacecraft, you already knew that. And, if there had been a problem in test where there might be, within some of the spacecraft, a generic type of glitch - not an unsafe condition but, you know, a little something that was unique to that spacecraft - you knew that."]

[Jones - "Sort of like a pressure point on a door in your house that you've learned about from experience. Other people might have a little trouble opening it, but you don't."]

[Scott - "And if there was a problem somewhere, one of us would have known it because we had probably been involved with the system in development. Another contributor to the success of the program was the familiarity of the crew with the total system. The little boys in their white spacesuits didn't go out on Day 1 and get in their brand-new spaceship and go to the Moon. It wasn't that way. As sort of an aside, people always, 'weren't you scared on launch day?' No. We had run that so many times, we could hardly wait to get going. Obviously, you get a little apprehension, if you will, of 'Boy, I hope it all works.' But it isn't like most people think, because they see the astronauts on the TV get in the truck and go out and get in the rocketship; and their perception is that that's the first time you ever saw it. And they're putting you in this thing. You know, they have the guards there to make sure you go in. And they slam the door shut and lock it and then they light the fuse. No, it wasn't that way at all. (Going back to the original thread) There was never enough simulator time. Everybody worked it pretty hard."]

105:49:27 Scott: Okay, Houston; here comes your E-Mod dump.

105:49:30 Mitchell: Roger; ready. (Pause)

105:49:47 Scott: And, Houston, (as per checklist page Surface 1-6) we'll be standing by for your Stay NoStay.

105:49:54 Mitchell: And, Roger, you have a Stay.

105:49:59 Scott: Got a Stay; thank you. (Long Pause)

[Journal Contributor Harald Kucharek notes that, in his book Failure is not an Option, Gene Kranz says that 'Stay NoStay' originates with Howard Tindall in one instance from the legendary series of Tindallgrams: "Once we get to the Moon, does Go mean 'stay' on the surface, and does NoGo mean abort from the surface? I think the Go NoGo decision should be changed to Stay NoStay or something like this." Tindall can be seen standing, third from the left, next to Deke Slayton, in Apollo 13 photo S70-35013.]

105:50:49 Mitchell: And, Falcon; Houston. We're going to delete the 10-minute delay, so you can go right into P06 and power down.

105:51:00 Scott: Roger.

[Comm Break. NASA's Public Affairs commentator mentions to the press that, because of the problems they had with the star sightings, they are a little behind the timeline. As indicated on checklist page Surface 1-6, they had planned to wait ten minutes after performing the E-Mod dump before opening the IMU (Inertial Measurements Unit, the inertial platform) circuit breaker and, thereby, power it down. They will, instead, perform an immediate powerdown.]

[Irwin, from the 1971 Technical Debrief - "There was a little bit of confusion on the P57, using two Noun 88 stars. That held us up a bit. It was just because we hadn't done it recently."]

[Scott, from the 1971 Technical Debrief - "Yes, I think the problem was that we never got confirmation from the ground that the erasable load in the P57 was the right thing to do. We did it, and it seemed to finally work. I guess, not having worked with Noun 88's for a long time, it took us a little while to get through it. I think we ended up fairly close to the timeline in spite of that."]

[Scott - "PAO is focused on whether we're ahead or behind. Our focus was getting the job done right. We're probably behind because we've run this AOT exercise, which is very important. You take things in priority as you go along. The most important thing is landing; you couldn't care less about Rovers or anything else. Once you get on the surface, the most important thing is getting the spacecraft stabilized, getting it aligned, getting it powered down."]

[Jones - "Ready to go home."]

[Scott - "Yeah. And, frankly, you don't care about geology, you don't care about anything else. You got to care about what's going on. So if we get behind on the timeline for some geology, we don't care. The focus is on getting the job done right. And I think, a lot of times, people miss the emphasis and get locked in to something that is not the important thing at that time in the mission."]

["A lot of times on some of the early missions, I know the geologists were maybe a little miffed that the guys didn't spend more time on geology. But I think it's because the focus - and, again, I go back to 12 because I had exposure to what they were doing - was on, by golly, landing that thing where you're supposed to land it and doing that right. And then, if you can do some geology, terrific! That's icing on the cake. You need to look at each part of a mission, and look at each mission, to see what its objectives were."]

[Jones - "The PAO guy's talking to the media; and, of course, the networks want to know when they can put the pretty pictures on..."]

[Scott - "And, in his world, being behind is something to note. But in the world of reality, on board, we don't really care; because what we care about is making sure that the spacecraft is stable and that everything is in proper order so that then we can go do the science part and relax because home-base is okay."]

105:52:19 Scott: And, Houston; 15. ED batteries both check at 37.

105:52:24 Mitchell: Roger; Roger. ED Batts.

[Long Comm Break]
105:55:45 Mitchell: And, Falcon; Houston. We're having changeover (of flight control teams) down here; didn't get a chance to say "real good job" on that descent.

105:55:57 Scott: Okay; thank you, Ed. And (we) appreciate all your help, too. The comm was super today, and everybody back there was right on top of it all the way. We sure appreciate that help.

105:56:07 Mitchell: And looked real good from here, Dave. We'll see you on lift-off.

105:56:13 Scott: Okay, thanks Ed-o. (Long Pause)

[Astronaut Joe Allen takes over as CapCom. The new Flight Director is Milton Windler, who is taking over from Glynn Lunney.]
105:57:01 Allen: Hello, Falcon; this is Houston.

105:57:06 Scott: Hello there, Houston; how are you?

105:57:10 Allen: Super down here, Dave and Jim. From what I heard, it was not only a good landing, it was a great landing. And it sounds like you didn't even bend anything.

[Jones - "Is this a reference to the longer engine bell?"]

[Scott - "Probably. That had been discussed. But, at this point, we don't know that yet because we haven't looked at it."]

[Jones - "A dry wit."]

[Scott - "Oh, yes. Joe's got a very dry wit. He's very quick."]

105:57:22 Scott: Well, I hope not, Joe. But we're sure in a fine place here. We can see St. George (Crater); it looks like it's right over a little rise. I'm sure it's much farther than that. We can see Bennett Hill. We see something off at our, like, 1 o'clock that's a pretty good elevation. We're not too sure of that, but we'll give you some more detail later on.

105:57:44 Allen: Roger. We're standing by.

[Comm Break]

[Clock positions are given relative to the forward, west-facing windows. 12 o'clock is west; 3 o'clock is north; and so on. Bennett Hill is named for trajectory designer Floyd Bennett.]

105:58:55 Allen: Falcon, Houston.

105:59:00 Scott: Go, Houston.

105:59:02 Allen: Dave, we've got some vital questions down here. First, did you see the rille on the way down?

105:59:12 Scott: (Guffawing) Sure, Joe. Easy.

105:59:16 Allen: Roger. And did you read the VHF call from Endeavour right shortly before the landing?

105:59:26 Scott: Negative.

105:59:31 Allen: Roger.

105:59:35 Scott: Why? Did he have something to say?

105:59:39 Allen: I'm sure he did, Dave; but we're wondering if you ever heard him call you on VHF. It sounds like we're going to have to do a VHF comm check.

105:59:51 Scott: No, we tried that comm check 3 minutes prior to PDI and we got no response. And Houston verified that the Endeavour could hear us, but we did not hear him.

[O'Brien - "In the Apollo 15 Mission Report, the cause of Falcon's failure to receive Endeavour was attributed to a simple checklist error. In the checklists, the Command Module was transmitting on 296.8 MHz, but the Lunar Module was receiving on 259.7 MHz."]
106:00:05 Allen: Roger. We copy. And we have Rev 16 through 20 lift-off times when you're ready.

106:00:13 Scott: Okay; give us 5 minutes to clean up the cockpit here. (Pause)

106:00:23 Allen: Roger, Dave. We're standing by. (Pause) And be advised the Backroom's doing slow rolls just from your first description there.

106:00:39 Scott: Okay, we've got a lot more coming. Stand by.

[Comm Break]

[The "Back Room" is the Science Support Room. Dave and Jim are probably reconfiguring switches and circuit breakers as indicated on checklist pages Surface 1-7 through 1-11. The NASA Public Affairs commentator tells the press that the current best estimate of the LM location is 300 feet north and 300 feet east of the planned landing site. They are getting closer.]

[Jones - "Could you help me understand the importance of the VHF comm check?"]

[Scott - "As I recall, there were two things the VHF did. It gave you a direct voice link between the LM and the Command Module, but it was also the source of Command Module ranging for rendezvous. The Command Module did not have a ranging device on it and, for a Command Module rescue, you needed to know the range (distance between the two spacecraft), the range-rate (speed of approach). You would get that from the VHF. It's not a Doppler, frequency shift. It's a direct linkage between the two VHF systems which enables the range change to be incorporated in the Command Module guidance logic."]

["Not only did the VHF give you comm - which was necessary because, on the backside of the Moon, you've got to be able to talk to the other guy - but it also gave the Command Module the ability to perform the rendezvous, in many different modes. As an example, the Command Module Pilot could get all the rendezvous data out of his computer and call the Lunar Module for a LM-active rendezvous. So we could actually perform the active rendezvous in the Lunar Module while getting the range data out of the VHF ranging and the Command Module computer."]

["Those are the sort of things that are functional control, in a sense. They are not built into the system, per se, but they give you a lot of capability and flexibility. Those are some of the things that some people did not like, because it took a lot more training and a lot more understanding to be able use them effectively. We liked it, as a crew, because it gives you that kind of flexibility and gives you comfort that you have many more ways to get home. And, if you're sitting on the surface in the Ascent Stage and you lose all your comm with the ground, and you lose your radar, you still have rendezvous capability because you can talk to the Command Module. We trained in this - between ourselves and Al Worden - and we knew that Al could give us the data, or he could perform the rendezvous and come get us. We'd run all of that in training, and we'd run these several different methods. So, this is just a little piece of the checklist; but, in the event of problems, as you know, it's not the big one that gets you, it's the aggregate of all the little ones that get you. Many times, in airplanes, when you start having little problems, you have more little problems. So part of what we planned and trained for was to stop little problems very quickly. To take care of things so they didn't start to build up. And, if you were in the LM on the surface and started having problems, we had several layers of backup which would enable us to get out of that hole."]

["Several of those layers went through the rendezvous sequence in which you could start losing systems. For example, we could lose part of the PGNS and the AGS. Not all of it because we had to have attitude control, but we could lose a lot of it and still do the rendezvous. And that was, in part, because of the VHF link, which was built into the Command Module - for voice only - during Apollo 9. They didn't understand rendezvous when they built it. It wasn't designed to have a range rate capability. As we went through Gemini, we found out that the key elements are angle, range, and range rate. The Command Module didn't have that and so, in order to give that to the Command Module, they defined the VHF ranging requirement during preparation for Apollo 9 and, on subsequent spacecraft, incorporated a VHF ranging system. It's not a big thing in the checklist but, in the event of problems, it could become a very big thing. And that's why we go through this and Joe says, 'maybe we ought to have another VHF comm check.' Well, that isn't because some engineer in a backroom has his nose bent out of shape because his checkout procedure didn't get done. It's because the overall system recognizes that it's another level of protection, and let's not miss that level, let's go ahead and make sure it's in place."]

[Jones - "It only takes a minute or so. Let's do it and make sure we've got it."]

[Scott - "That's right. It may not appear to be important on the surface but, in these layers of mission rules and backup systems, it's in there; and there's some guy in the backroom watching his layer saying 'Uh oh. Boy, in the VHF comm check, there's something wrong there.' Now maybe Worden heard us and we didn't hear him. Maybe we were engrossed in this landing - which we probably were - and wouldn't have heard him, because we were talking to ourselves and maybe we blocked him out. But, on the other hand, maybe there's a problem with the VHF. So the guy in the backroom who's responsible for that, it's his job to make sure nothing slips down the crack, and he'll call up through the system and say, 'Hey, wait a minute, I didn't get my VHF. I want my VHF.' Now, some people would think, now here's an engineer who's a little tweaked because he's not a part of the thing. That's not it at all. It's part of the total system and everybody wants to make sure it's all there. It goes back to the Apollo methodology. Why did it work? One reason is that there's some guy in some backroom somewhere who says 'Wait a minute. The VHF didn't get closed.' Other people would say ' VHF? It's no big deal. We've got comm.' 'No, I want my VHF checked.' The Flight Director, who understands all this, says 'Get the VHF checked, guys.' That's part of why Apollo worked. 'Cause we had this attention to detail. We didn't have to use the VHF. Nobody ever had to use the VHF. Everything worked fine. It was easy, so you forget all these layers of capabilities that were built in. But it could have been important had certain problems occurred. Fortunately they didn't. But who knows about the next time. You may not be as lucky."]

[Jones - "If you do it often enough, you're going to have to use it."]

[Scott - "It's a little thing and doesn't have anything to do with the lunar surface operations - other than the fact that we are preoccupied with all this, making sure it's all set before we go out and do geology. Once we get ascent and rendezvous set, it's much easier for us, and we're much more comfortable in forgetting about it and putting it behind us. You get out and you don't have to say 'You know, we're five kilometers from the LM. I just remembered, the VHF didn't work. Hey Houston, do we have a problem with the VHF?'"]

[Jones - "'And how come you guys aren't watching it?'"]

[Scott - "'What happened back there? Al Worden was supposed to call us and he didn't call us and I didn't hear him.' And Allen says 'Pick up the rocks!' 'Wait a minute, man. I'm five kilometers from my little LM and that's 240 thousand miles from home and I just realized, I think we have a problem.' I don't want that."]

106:04:05 Irwin: Okay, Joe; this is Jim. I'm standing by to copy some lift-off data.

106:04:13 Allen: Roger, Jim. Lift-off time for T-16, 108:39:45; T-17, 110:38:00; T-18, 112:36:13; T-19, 114:34:26; and T-20, 116:32:39. Over.

[T-16 refers to the 16th orbit of the Moon by the Command Module.]
106:04:59 Irwin: Okay; the readback, Joe. 108:39:45; 110:38:00; 112:36:13; 114:34:26; 116:32:39. Over.

106:05:16 Allen: Roger, Jim. Readback's correct. Sounds good.

[Long Comm Break]

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