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Day 2, part 2: Entering the Lunar Module Journal Home Page Day 3, part 2: Leaking Water and the Top of the Hill

Apollo 15

Day 3, part 1: Flashing Lights

Corrected Transcript and Commentary Copyright © 1998-2023 by W. David Woods and Frank O'Brien. All rights reserved.
Last updated 2023-10-27
Index to events
First communication 049:04:11 GET
Start of light flash experiment 051:37:31 GET
Scott's description of light flashes 052:34:41 GET
The date is 28 July, 1971, and it is the third day of the Apollo 15 mission.
Flight Plan page 3-46.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 40 hours, 5 minutes. We said goodnight to the crew about 7 minutes ago at 39 hours, 58 minutes. During this sleep period, we'll take the lines down [that is, terminate the live feed of the air/ground for the news media] and come up with the hourly status reports. At the beginning of the rest period the spacecraft is in a stable Passive Thermal Control mode, rotating at the rate of about 3 revolutions per hour to maintain the proper thermal equilibrium, exposing all sides equally to the heat of the Sun and to the cold of space. Al Worden, the Command Module Pilot, is wearing the biomedical sensors, and we'll have biomedical data on him during the evening. The main task this evening will be to monitor the status of all the systems and review activities for tomorrow, now - which is actually Houston time, of course - is today, now - but the crew will be awakening in about 8½ hours or so. At the present time Apollo 15 is three thousand - traveling at a speed of 3,979 feet per second [1,213 m/s]; the spacecraft, 143,742 nautical miles [226,210 km] from Earth. This is Apollo Control, standing by.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 41 hours, 7 minutes. The crew is now about 1 hour into their scheduled 9-hour rest period and we have had no further conversations with them. Apollo 15 at this time is 146,050 nautical miles [270,484 km] from Earth. Spacecraft traveling at a velocity of 3,918 feet per second [1,194 m/s]. And again, during the evening, the principal task here in Mission Control will be to monitor the systems on the spacecraft. We have high bit rate data coming to us through the receiving antenna at Parkes, Australia. And we'll be monitoring all the systems on the spacecraft as well as the one crewman on whom we have biomedical data; Command Module Pilot, Al Worden. And we'll be coming up hourly for status reports. This is Apollo Control, standing by.
Flight Plan page 3-47.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 42 hours. The crew has now been in their rest period for about two hours. And in Mission Control, things have steadied down to a routine of watching the spacecraft systems, and looking at activities coming up when the crew awakens, which is scheduled to occur in about six hours. Apollo 15 now traveling at a speed of 3,866 feet per second [1,178 m/s] and [is] out 148,065 nautical miles [274,216 km] from Earth.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 43 hours. The crew now some 5 hours away from the scheduled wakening time. And all systems on the spacecraft [are] continuing to perform normally. We're in a Passive Thermal Control mode, as we have been since prior to the crew rest period, with the spacecraft rotating slowly at a rate of about 3 revolutions per hour. On awakening, the crew will have a relatively light day of activity, primarily involving some photography, and also they will again enter the Lunar Module [to] check such things as the Lunar Module batteries. At the present time, Apollo 15 is 150,293 nautical miles [278,342 km] from Earth and the spacecraft speed is down now to 3,809 feet per second [1,161 m/s].
Flight Plan page 3-48.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 44 hours. The crew now about midway through a scheduled 8-hour [means 9-hour] sleep period. We said goodnight to Command Module Pilot, Al Worden about 39 hours, 58 minutes, and have heard nothing from the crew since that time. Very little conversation on the circuits in Mission Control and none of the flight controllers, in watching the data from the spacecraft, have reported any problems or anomalies. Everything progressing very smoothly at this time. Apollo 15 is traveling at a velocity of 3,754 feet per second [1,144 m/s] now and the spacecraft is 152,481 nautical miles [282,394 km] from Earth.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 45 hours. We've had good data from the spacecraft throughout the evening and have been watching all of the systems. Everything appears to be normal, as it has through the night. The crew is scheduled to end their nine-hour rest period in about 3 hours. Actually they went to bed about an hour later than planned, and we do not plan to give them a call at the scheduled wake-up time. We'll let them continue to sleep if they so desire, probably for at least an extra hour. During the past few minutes, Flight Director Glynn Lunney has been reviewing the status of the spacecraft and all of its systems with each of his flight controllers and also running over the activities scheduled for the crew once they awaken, particularly the LM housekeeping, with the crew entering the Lunar Module and, among other things, checking out some of the systems and checking the batteries on the Lunar Module. Apollo 15 is presently travelling at a speed of 3,700 feet per second [1,128 m/s] and 154,661 nautical miles [286,432 km] from Earth. We do not, at this time, anticipate that there will be any midcourse correction required at the midcourse correction 3 opportunity, which is at 56 hours, 31 minutes. It does appear likely that there will be a midcourse correction at the midcourse 4 opportunity, at 73 hours, 31 minutes. And the present numbers indicate that that would be about 6½ foot per second [2 m/s] maneuver, probably performed with the Service Propulsion System. This is Apollo Control, continuing to stand by.
Flight Plan page 3-49.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 46 hours. Apollo 15, at the present time, traveling at the speed of 3,650 feet per second [1,113 m/s]; the spacecraft now 156,700 nautical miles [290,208 km] from Earth, and, as a point of interest, about 72,000 nautical miles [133,000 km] from the Moon. During the night and early morning, we've been tracking Apollo 15 on the 210-foot [64 metre] dish antenna at Parkes, Australia. Just recently, we went out of acquisition of that antenna and are now tracking with the 85-foot [26 metre] dish at Tidbinbilla; and we've had a good solid lock-on all during the shift, with continuous data from the spacecraft. Everything continues to look good, both - both aboard the spacecraft and with the - with the crew. We've heard nothing from them since we said goodnight to Al Worden some 6 hours ago. The crew is scheduled to end their rest period in about 2 hours, although we do plan to let them continue sleeping for an additional hour or so, if they so desire. A relatively light day scheduled in the Flight Plan. The major activities will be photographic tasks aboard the Command Module. Also, Scott and Irwin plan again to enter the Lunar Module for some housekeeping chores and some systems - systems checks on the Lunar Module. At 46 hours, this is Apollo Control Houston.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control. 47 hours after lift-off, Apollo 15 is now 158,845 nautical miles [294,180 km] from Earth, traveling at a speed of 3,600 feet per second [1,097 m/s]. In Mission Control, we're in the process of a shift-handover at this time. Flight Director Glynn Lunney will be going off-shift and will be replaced by Flight Director Gerald Griffin and his Gold team of flight controllers. The Capsule Communicator on the upcoming shift, the CapCom, will be astronaut Joe Allen. We do anticipate a change of shift briefing. That will occur in the MSC news center briefing room in about one hour. There is about 1 hour remaining in the crew rest period. However, if the crew desires to sleep an extra hour, we plan to allow them to do so. A call will not be made to the crew at the scheduled wakeup time unless we hear from them first. At 47 hours, this is Apollo Control Houston.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control; 47 hours, 56 minutes Ground Elapsed Time. Crew of Apollo 15 still asleep at this time. They're lying in to have an extra hour in their sleep period unless they call first. Spacecraft now 160,800 nautical miles [297,801 km] out from Earth, traveling at an ever decreasing velocity of 3,553 feet per second [1,083 m/s]. Handover is complete from the Black Team of flight controllers to the Gold Team. Flight Director Gerry Griffin going over the day's activities with the various console positions here in the Control Room. The Black Team Flight Director Glynn Lunney will be holding a change of shift press conference in the next few moments in the small briefing room in the Houston news center. And at 47 hours, 57 minutes Ground Elapsed Time; this is Apollo Control.
Flight Plan page 3-50.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control; 49 hours, 3 minutes Ground Elapsed Time and about 1 hour past the scheduled wake-up time for the crew of Apollo 15. Spacecraft Communicator Joe Allen will be giving the crew a call in the next few moments, as soon as the voice net is configured properly. Let's listen in.
049:04:11 Allen: Good morning, Apollo 15; this is Houston. Do you read? Over. [No answer.
Long comm break.
Seems the voice subcarrier is not up yet to the spacecraft. [We're] waiting for the network to be completely set up to handle the two-way communications. Meanwhile, some distance and velocity numbers: Apollo 15 now 163,140 nautical miles [302,135 km] out from Earth; velocity now 3,499 feet per second [1,066 m/s]. We'll leave up the air/ground circuit live until the crew does respond.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
049:09:43 Allen: Good morning, Apollo 15; this is Houston. Are you awake yet? Over. [Pause.]
049:09:54 Worden: Good morning, Houston; this is 15. Reading you loud and clear there, Joe. Good morning.
049:09:59 Allen: Good morning, Alfredo. It sounds like you had a good night's sleep. We're standing by for crew status.
The crew status report is part of the postsleep checklist, as given in page 1-26 of the CSM Systems Checklist, which requires a report of the amount of sleep the crew have managed to get and a reading from their PRD's (Passive Radiation Dosimeters). It also includes a consumables update, cycling of the hydrogen and oxygen cryogenic storage tanks in order to destratify them, and the reconfiguration of the communications system for the coming day's activities.
049:10:06 Worden: Okay, Joe; we certainly did have a nice sleep, and we think your tracking data must be right, the Moon's getting bigger out the window.
From their current position, the Moon's apparent diameter is 2°, nearly four times greater than when viewed from Earth.
049:10:14 Allen: Roger, Al. At least our direction is right.
049:10:20 Worden: [It] appears that way. [Pause.] And, Joe, this is Al. We'll give you a status report here in about 5 minutes, when we get organized.
049:10:34 Allen: That sounds good, Alfredo. And if you'd like, I'm standing by down here with a PAO [Public Affairs Office] Gold Bugle Morning News, if you'd like to hear some? [Long pause.]
049:11:00 Worden: Joe, can you stand by for a minute on that. We wouldn't want our LMP to miss it.
049:11:07 Allen: No, I agree; he should be aware of it. I'll stand by.
Comm break.
049:12:14 Irwin: Joe, Jim's awake here now. Ready to listen.
049:12:20 Allen: Roger. [Long pause.]
049:12:46 Allen: Okay, Apollo 15. This is your friendly news reporter with the morning news. Apparently the Houston Post reported, yesterday, that the Falcon's checkout went smoothly, and the mission is proceeding on schedule. The inside pages show drawings of how you will deploy the Lunar Roving Vehicle. They didn't tell us anything I think we don't already know so I won't go into the details of the drawings. In national news - Now, we may be use - losing communications now; I'll stand by a minute. [Long pause.]
The loss of communications may be due to either a changeover in omni-antennae as the spacecraft rotates or a changeover from one ground station to another as Earth rotates. Either way, it will be dealt with on the ground.
049:13:50 Allen: 15, are you reading Houston clearly?
049:13:55 Worden: Rog, Joe; we're back with you.
049:14:00 Allen: All right. Moving right along, now, in national news, Secretary of Labor Hodgson has asked the United Transportation Union and the rail industry to put their dispute before a neutral panel for settlement. The U.S. Senate will vote today on an amendment to delay a federally guaranteed loan to Lockheed. The vote is expected to be very close. In local news, a Texas animal health commission employee said that he thinks that the Harris County vaccination program against sleeping sickness is almost at an end. I don't know if they're going to institute preflight quarantine on the animals or not. And more than a hundred people were arrested during a raid of the Arlington Country Club in Texas, last night, and gambling equipment was confiscated. Maybe you left town just in time. In sports, yesterday, the Baltimore Orioles increased their lead to four games in the American League East by winning the double header from the Oakland Athletics, 1-0 and 6-4. And the Houston Astro's split a twilight double header last night with the Phillies, 8 to 3 and 5 to 1. Muhammad Ali announced that - and I'll stand - all right, Muhammad Ali announced that he will fight Jerry Quarry, September, in the Astrodome and Ali also wants a rematch with Joe Frazier sometime in March, 1972. The Oilers have trimmed their roster to 59 players by placing two of the players, Johnny Peacock and Tom Smiley, on waivers. Four golfers were inducted into the American Golf Hall of Fame last night. They are Julius Boros, Cary Middlecoff, Jock Hutchinson, and the late Walter J. Travis. And we hate to tell you this, but Elizabeth Taylor is a grandmother, at age 39 when her 19-year-old daughter-in-law gave birth to a 6 pound, 2 ounce girl yesterday. And that's all from the Houston MOCR News Center. [Long pause.]
The acronym 'MOCR,' which is pronounced to rhyme with 'poker,' is the insiders name for what everyone in the outside world, and this journal, calls "Mission Control;" the Mission Operations Control Room. Regarding the regular morning news reports, Michael Collins, in his highly readable autobiography, Carrying the Fire, wrote that during Apollo 11's coast to the Moon, he simply wished Houston would desist while the crew wiped the sleep from their eyes and got themselves organised. However, flight planners felt the need to assign something to each and every moment, from the wake-up call to the last transmission of the day.
049:16:31 Worden: Okay, Joe. Thank you very much for the weather and the news this morning.
049:16:40 Allen: Okay, Al. And I have a CSM consumables update and a number of other things, when you're ready to listen to them. [Pause.]
049:16:55 Worden: Okay, Joe; stand by one.
049:16:58 Allen: Roger.
Comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
049:19:40 Worden: Houston, this is 15. We are ready to copy the consumables update [garble].
049:19:50 Allen: Al, stand by. We're not receiving you clearly.
049:19:58 Worden: Okay. We'll stand by.
049:20:02 Allen: Rog; it's very weak, and severe noise in the background, 15. We're standing by for better comm.
049:20:12 Worden: We understand.
Comm break.
049:21:54 Allen: Al, this is Houston. The noise seems to have quieted down again. Why don't we give it another try?
049:22:09 Irwin: Okay, Joe. Would you like to copy our consumables and then you can pass up S-band. [Pause.]
Jim may be requesting angles for pointing the HGA better.
049:22:19 Allen: Okay.
049:22:23 Irwin: Okay, RCS [quad A], 90 [per cent remaining], [B,] 89, [C,] 90 and [D,] 89. On H2 [tank 1], 92 [per cent remaining], [tank 2,] 90, [tank 3,] 70. O2 [tank 1], 90 [per cent remaining], [tank 2,] 90 and [tank 3,] 85. [Pause.]
049:22:45 Allen: Roger, Jim. We copy all that. Let me give you a set of figures here. They agree very closely to what you've read to us. At GET 48 plus 00; the RCS total was 87 [per cent remaining]; and then Quad A, 86, 87, 86, 87. H2 tank, 92, 92, 70. O2 tank, 90, 92, 85. Over. [Pause.]
Apollo 15 is the second flight to carry three tanks for cryogenic oxygen storage. This change was implemented in Apollo 14 as a direct result of the O2 tank 2 explosion aboard Apollo 13, when the supposedly isolated oxygen tank 1 also lost its contents due to the proximity of its plumbing to the disruption, despite being designed as a redundant system. Additional tanks for both H2 and O2 had already been planned for the extended J-series missions, starting with Apollo 15, to increase their endurance. The third tank for each consumable was added in a separate location within the SM in the same sector as the SIM (Scientific Instrument Module).
049:23:34 Irwin: Okay, I copied all those. [Pause.] As far as sleep, Dave figures 8 hours and two segments; Al was 8 hours for two; and I figure I got 9 hours in about three segments.
Jim will find that he gets better sleep in the LM's hammocks on the Moon than in the zero-g environment of the CM.
049:23:55 Allen: Roger; we copy that. Sounds like that's the most sleep you've had in several months. Out of curiosity, since we're coming up on this eye-flash experiment, I wonder if any of you has noticed any of the flashes yet?
CapCom Joe Allen is referring to the morning's main activity, which is to study the nature of flashes in the eye which had been reported by many, though not all of the previous Apollo crews.
049:24:11 Irwin: Yes, we've noticed them both nights, Joe.
049:24:15 Allen: Okay; I guess we'll talk more about that a little later on. I have a number of other things to read up to you, in whatever order you'd like. They include a fairly extensive Flight Plan update; nothing profound but it will require some - certain amount of writing, and then a few miscellaneous questions which we'd like to ask you. [Pause.]
049:24:45 Irwin: Ok - okay; I guess I can start on the - these Flight Plan bits. [Pause.]
049:24:54 Allen: Okay, Jim. And are you the recording secretary this morning? [Pause.]
049:25:01 Irwin: Yes. [Long pause.]
049:25:14 Allen: Okay, Jim. Before we start, did you get the radiation dosimeter readings for us? [Pause.]
049:25:23 Irwin: We reported them last night. Do you want them again this morning?
Despite a specific mention in the Flight Plan for readings from the dosimeters, the crew seems to have little time for them.
049:25:29 Allen: Apparently, we'd like them again the - this - this morning on the schedule.
049:25:36 Irwin: Okay; stand by.
Comm break.
049:27:11 Irwin: Okay, Joe. I have a radiation report for you.
049:27:15 Allen: Go ahead. [Pause.]
049:27:21 Irwin: Okay, radiation. On Dave, it's 23023; Al, 25009; and mine is 08010. [Pause.]
Each crewmember's PRD was initialised at a different reading so as to preclude confusion. The reading for Al's dosimeter last night was 5008. Presumably the leading "2" had been omitted, in which case, Dave's meter has registered 3 counts, Al, 1 count and Jim, 2 counts.
049:27:44 Allen: We copy those, Jim; thank you. And normally, I guess, we'd like to have those in the postsleep period as opposed to presleep, which is when we got them yesterday. I guess it's in the checklist that way.
Joe Allen is tactfully reminding the crew that, unlike yesterday, when the readings were held off until the presleep period, Mission Control wants the readings in the mornings, during the postsleep checklist.
049:28:00 Irwin: Okay, we'll - okay, we'll normally do it that way.
049:28:05 Allen: Okay; fine, and I'm ready to start with the Flight Plan update. When you're set up to copy up there, I'll start at about 54:50.
049:28:20 Irwin: Okay, let me get 54:50.
049:28:22 Allen: Fine, Jim. And we're coming up on a Omni switch. When we're on the new antenna, I'll start to read. You might want also your LM Activation Checklist handy because we'll be using it later on.
049:28:38 Irwin: Okay.
Long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
049:31:44 Irwin: Houston, how do you read 15?
049:31:48 Allen: Jim, you're loud and clear, and we're ready down here if you are.
049:31:53 Irwin: Okay. I'm at 54:50 on the Flight Plan.
049:31:57 Allen: Okay. Before I start into it step by step, let me just say that it's basically - the - the change is basically moving some of the items around in time, and there's not many changes in procedures involved. The one main thing is, we're going to ask you to go into - into the LM a little early, I guess, earlier then you had planned. And we're going to also request that you give us enough - you bring enough of the telemetry online so we look at the - can look at the LM batteries. And there's no particular reason we want to do this today - nothing that we suspect is wrong - but rather, apparently, the systems people are interested in a better granularity in the data points that they're taking on these batteries. That's the reason for this particular addition. Other than that, I think there's nothing at all very different about this Flight Plan update, other than a few minor changes. And I'll go ahead and start if you're ready.
Allen is making a special effort to ensure that the crew does not become inadvertently alarmed by the nature of the upcoming changes.
He uses interesting jargon, "granularity," when explaining that Mission Control is wanting to gather a greater number of measurements of the condition of the LM batteries, which are so vital to its operation. Originally, the manufacturers of the Lunar Module, Grumman, had intended to power the LM with fuel cells, in a similar manner to the CSM and the Gemini spacecraft that preceded Apollo. Managerial and technical difficulties, mostly concerned with the interdependence of the power system with all other LM systems, conspired with the race to get the spacecraft ready on time, forcing NASA to order Grumman to change to batteries as the power source. Though heavy, batteries have the enormous advantage of simplicity and since the LM was intended to be powered for only a few days, their weight penalty was no worse than the problematic fuel cells.
049:33:11 Irwin: Okay, I'm ready Joe. And we understand.
049:33:15 Allen: Okay; 54:50, [add] the step "If LM/CM Delta-P less than 2.7 psid [pounds per square inch, differential], LM Tunnel Vent valve, panel 12, vent until Delta-P greater than 2.7 psid." [Pause.]
049:34:15 Irwin: Okay. I have "If LM/CM Delta-P is less than 2.7 psid, LM Tunnel Vent valve on panel 12, vent until Delta-P greater than 2.7 psid." [Pause.]
049:34:29 Allen: That's correct. Now turn one page to 55 [hours] plus 15 [minutes in the Flight Plan]. [Pause.]
049:34:48 Irwin: Okay; I'm there.
049:34:51 Allen: Okay. Insert "Stop PTC [Passive Thermal Control] at roll 50 degrees. High Gain Antenna angles: Pitch, minus 48; Yaw, plus 82." [Pause.]
049:35:25 Irwin: Roger. "At 55:15, stop PTC roll 50 degrees; High Gain Antenna: Pitch, minus 48; Yaw, plus 82."
049:35:37 Allen: That's correct. Now, turn back several pages to 3-54 please. And that's the "Cycle film in Pan and Map Cameras" page - procedures page. [Pause.]
049:35:58 Irwin: Okay; I have it.
049:35:59 Allen: Okay. Down near the bottom, delete the line "SM Sector 1, SM/AC Power, Off." And add in its place "Map Camera on" - that should read "Map Camera on Standby/talkback gray." Over.
049:36:34 Irwin: Okay; understand. Delete "SM Sector 1 SM/AC Power off," and add "Mapping Camera on to Standby/talkback gray."
049:36:46 Allen: That's correct. Now, turn back to 55 plus 50, and there's a long series of deleted activities that will follow. These - [are] all because we're not going to do a midcourse [correction] 3, as you're well aware. And I'll call them out line by line, and they'll carry through for - I guess about a page and a half here. At 55:00 [means 55:50].
The Flight Plan is written using the conservative assumption that all eight of the planned midcourse corrections will be necessary. In reality, only a few are required, leading to the expected ritual of Houston reading up deletions to the scheduled activities. Virtually all of the changes are to do with preparations for the burn. Although recording these changes is usually regarded as a chore, it is a welcome one as it means less overall workload for the crew.
049:37:20 Irwin: Okay; go ahead.
049:37:22 Allen: Delete "P30 External Delta-V" and "V49 Maneuver to PAD Burn Att[itude]." Turn the page. [Pause.] Jim, I apparently made a mistake on that. That should have been at 55:50. I think you're at the right - the right place. Continuing on over to 50...
049:37:50 Irwin: Yes; I got it.
049:37:51 Allen: Rog. Continuing to 56 plus 00, delete the next seven lines up to the 2 lines which you should leave in "O2 Fuel Cell Purge" and "Waste Water Dump." [Pause.]
049:38:14 Irwin: Okay; I have that.
049:38:16 Allen: Okay. Continuing - continue deleting the lines below that, down to 57 plus 00. [Long pause.]
049:38:37 Irwin: Okay. So the only two actions we have on that page, 56 hours, is the "O2 Fuel Cell Purge" and the "Waste Water Dump."
049:38:44 Allen: That's affirm. [Pause.] Now, once again backing up to the time, 55 plus 50. [Pause.] That should read "Verb 49 Maneuver to LM Checkout Attitude." [Pause.] And that attitude is "305, 090, 000." High Gain angle: "Pitch, minus 30; Yaw, 276." [Pause.]
049:39:44 Irwin: Okay. "Verb 49 Maneuver to LM Checkout Attitude" at 55:50; the attitude "305, 090, and 000; High Gain: Pitch, minus 30; and Yaw, 276."
049:40:11 Allen: Readback's correct, Jim. I'll stand by until we get another Omni[-directional antenna] change.
049:40:19 Irwin: Okay.
Comm break.
Before the rest period, antenna B was selected. As Mission Control have the ability to remotely switch between antenna D and another which the crew have selected, they can switch between two omnis on opposite sides of the spacecraft, giving essentially continuous coverage and the spacecraft rotates in PTC.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
049:42:48 Allen: 15, Houston. Our comm's quieted down again, and I'll continue if you're ready.
049:42:58 Irwin: Okay. I'm ready, Joe.
049:42:59 Allen: Roger, Jim. At 56 plus 50, start "CSM Systems Checklist, IVT to LM," and this is an item that's moved up from 57:20, by the way. [Long pause.]
IVT is IntraVehicular Transfer, that is, Dave and Jim will transfer to the LM.
049:43:34 Irwin: Okay, at 56:50, start "CSM checklist, IVT to LM."
049:43:43 Allen: That's correct, and you're to start that checklist from the beginning. And at 57 plus 00, you move the CSM PTC procedures to completion of our LM battery checkout. And I guess that's an item for Al. [Long Pause.]
The Flight Plan originally had the third midcourse correction burn being followed by the reinstatement of the PTC (Passive Thermal Control). LM checkout would have occurred while in the PTC mode. Now, with midcourse 3 cancelled, the LM checkout is to be carried out with the spacecraft steady. The PTC will be restarted after the checkout is completed.
049:44:21 Irwin: Okay; understand. I'll move all that there for the PTC until after we complete the battery checkout.
049:44:30 Allen: That's correct, and that should come around 57 plus 50 or perhaps a little later. But, once again, not time critical. We're coming up on 57 plus 30. And, if you'll take out your LM Activation Checklist, page 1-1, please. [Long pause.]
049:45:11 Irwin: Okay; I have it.
049:45:14 Allen: Okay. And this is to start at 57 plus 30. Perhaps you should put a mark in your time line, but then on - on the checklist from page 1-1, delete "Comm carrier, CWG connector." [Pause.] Delete step 2. Delete step 5. [Pause.]
When the crew are unsuited with their inflight coveralls on, or when they have their suits on for activity in the spacecraft, they wear a CWG (Constant Wear Garment), a one-piece undergarment which protects their skin from abrasion from their outer clothing.
049:45:54 Irwin: Okay. On 1-1, I delete "Comm carrier, CWG connector;" step 2; and step 5.
049:46:04 Allen: That's affirm. Do page 1-13. And if you'll turn to that, [pause] do 1-13 except in step 2. [Long pause.]
049:46:34 Allen: In step 2, delete "VHF B Transmitter, Close; VHF A Receiver, Close; CDR Audio, Close." And add the instruction "CB 11, ECS Cabin Fan, Close." [Long pause.]
049:47:24 Irwin: Okay, Joe. On 1-13, under step 2, [I've] to delete "VHF B Transmitter, Close; VHF A Receiver, Close; Commander Audio, Close." And add "CB 11, ECS Cabin Fan, Close."
049:47:38 Allen: That's correct, Jim. Do page 1-14, except in step 5. Delete "VHF A Transmitter, Close; VHF B Receiver, Close;" and delete step 6. [Pause.]
049:48:15 Irwin: Okay. On 1-14, we'll do all that. Under step 5, we'll delete "VHF A Transmitter, Close; VHF B Receiver, Close;" and want to delete step 6.
049:48:28 Allen: Readback's correct, and add step 7. Your comm S-band configuration is "PM, Secondary, Primary, Off; PCM, Off/Reset, Off, and High." [Pause.]
049:49:03 Irwin: Okay. The S-band configuration is "PM, Secondary, Primary, Off; PCM Off/Reset, Off, and High."
049:49:11 Allen: That's correct. We'll want you to stay in that configuration for 15 minutes while we take the data. After that time, do page 1-18 and 1-19. [Pause.]
During the initial checkout and housekeeping yesterday, a full check of the LM's communication system was performed. This included the S-Band High Gain and Omni antennas, which are used for communications with Earth, and the VHF radios used for LM to CSM communications and distance ranging. The deletion of the steps to activate the VHF radios is not only to conserve battery power, but reflects the fact that there is no real need to have a second check of CSM to LM communications. Houston is primarily interested in a "quick look" at the batteries, the status of which is relayed to the ground through the S-band system. If there is any need to communicate between the two spacecraft, Houston can relay any request.
049:49:32 Irwin: Understand, [we are] to stay in that configuration for 15 minutes, then do 1-18 and 1-19.
049:49:38 Allen: Okay, Jim. Sounding fine. Now, back into your time line. At 57 plus 45, proceed with LM housekeeping. And we've got some words here on the housekeeping. I'll read them to you, and I guess - Copy down whatever you think you haven't done yet. [Long pause.]
049:50:14 Irwin: Okay; understand. At 57:45. We're to proceed with LM housekeeping, and go ahead with the - your steps, Joe. I'll note them down.
049:50:22 Allen: Okay. Vacuum [the] Cabin Fan filter. And as a subgroup under this, you unsnap netting around Cabin Fan filter. [Long pause.]
049:50:52 Allen: Then you vacuum the filter. [Pause.] But do not scrub bristles of the vacuum cleaner over the surface of filter. [Pause.] Then, you remove the remaining particles on [the] Cabin Fan filter with sticky tape, using care not to dislodge [the] filter material. [Long pause.]
049:51:39 Allen: Then, you remove the particles on the inlet screen of the vacuum cleaner with sticky tape; and, finally, replace the netting. [Long pause.]
049:52:17 Allen: And, Jim, that's the end of that procedure. Our comm's starting to fade out on us, so we may not be able to copy you. Hopefully, you're copying us clearly still.
049:52:29 Irwin: Yes, we are, Joe. I got that [garble]. [Long pause.]
049:53:18 Allen: Okay, Jim. And just an added note on that. As you're well aware, we're interested in cleaning up as many of those flying glass particles as we can, which is primarily the reason for - for this procedure. [Pause.]
049:53:36 Irwin: Yeah; we quite agree, Joe.
During the first entry to the Lunar Module at 034:33:07, Dave Scott discovered that the outer pane of glass on the tapemeter had shattered. Bits of glass were floating around the zero-g environment of the cabin and he and Jim used their hands and pieces of sticky tape to collect what they could see. Mission Control hope that any remaining pieces will have been caught by the screens in front of the fans which cycle air through the cabin.
The procedures used in this second checkout of the LM are a truncated version of those used at about 34 hours into the mission. After entering and turning the lights on, they will open valves to feed water for cooling and oxygen from the descent stage. Once the electronics have power, the communication system is to be set up to send battery measurement telemetry to Earth via the S-band link. When Mission Control are happy that they have enough data on the batteries, the LM is to be powered down again.
049:53:38 Allen: Okay. At the time, 57 plus 45, the steps "S-band Aux, TV to Science, Pan Camera Power to On," and then, in parenthesis "for five minutes/Off." [Pause.] And finally, "S-band Aux, TV to Off." [Long pause.]
049:54:29 Irwin: Okay, Joe. At 57:45, understand [that] you want the "S-band Aux, TV to Science." Then I missed the information after - after that, and then, finally, the last one was "S-band Aux, TV to Off." [Pause.]
049:54:48 Allen: Okay, Jim. What we're interested in here is looking at the Pan Camera temperature. And the center step, the one you missed, reads "Pan Camera Power to On for five minutes and then Off." [Pause.]
049:55:18 Irwin: Okay; understand. "Pan Camera Power to On for five minutes and then to Off."
049:55:26 Allen: That's correct. At 57 plus 50, "CSM proceed with PTC activation." [Long pause.]
049:55:53 Irwin: Okay. At 57:50, "CSM proceed with PTC activation."
049:56:00 Allen: Roger. And turning over a page to 60 hours. After the step, "S-band Aux, TV, Off," add "Pan Camera Self Test to Off." And...
049:56:22 Irwin: Stand by, Joe. [Pause.]
049:56:33 Irwin: Joe, do you read me now?
049:56:35 Allen: Okay, Jim. Reading you loud and clear.
049:56:40 Irwin: That last information you gave me on S-band Aux, TV. I add that - I added that in at 57:45. [Pause.] Is that correct?
049:56:54 Allen: Jim, no; negative. Turn over the page to 60 hours, 60 plus 00. [Pause.]
049:57:08 Irwin: Okay; I have 60 hours. [Pause.]
049:57:22 Irwin: Okay, Joe. I'm at 60 hours.
049:57:24 Allen: Okay, Jim. This is a new step completely at 60 hours. We did say something at 57:45. I'll come back to that in a minute to make sure that's straightened around. But at 60 hours, after the step in the Flight Plan, S-band Aux, TV to Off, add 2 steps. And they are "Pan Camera, Self Test to Off" [pause] and "Map Camera On, to Off." Over.
049:58:10 Irwin: Okay; understand. Two steps there after "S-band Aux, TV, Off." "Pan Camera, Self Test, Off" and "Pan [means Map] Camera On, to Off." [Pause.]
049:58:23 Allen: That sounds - that sounds good, Jim. [Pause.]
049:58:30 Irwin: Let's go back to 57:45. [Pause.]
049:58:42 Allen: Okay, Jim. At 57:45, the three steps you added in there should be "S-band Aux, TV to Science; Pan Camera Power, On for 5 minutes and then Off; and S-band Aux, TV, Off."
049:59:03 Irwin: Okay; understand that. I guess I got a little confused there, Joe, when you said turn the page, and you turn several pages to get to 60 hours. [Pause.]
049:59:16 Allen: I think you caught me in that. I guess I did. Sorry. [Pause.]
049:59:26 Irwin: Okay. I'm ready to go on to the next one, Joe.
049:59:31 Allen: Okay, Jim. That completes the Flight Plan update, and you should know by now that you have to take me for what I mean, not for what I say. [Pause.] I do have...
049:59:43 Irwin: We do.
Joe Allen is the mission scientist for Apollo 15 and will be the CapCom for the EVAs on the lunar surface. One of his strengths as a CapCom is his use of light humour to smooth over problems and misunderstandings, an ability which works better because of his good working relationship with the crew.
Flight Plan page 3-51.
049:59:45 Allen: Rog. I do have a note, which you can put down in the margin or wherever, and it involves subsequent P23 sightings if required. [Pause.]
050:00:05 Irwin: Okay.
050:00:10 Allen: And the note is "Reduce trunnion to less than 10 degrees before zeroing optics." [Pause.] And then, "Always do optics calibration after optics zero in P23." [Long pause.]
Mission Control are noticing that when the movable optics are motor driven to their zero point, the measurement of their position is shifting slightly. By manually driving the trunnion axis of the optics to a small angle before zeroing them, they hope to limit the speed of their motion and thus the degree of bias drift. There will be another note to the crew about this at 070:38:11.
050:01:02 Irwin: Okay, Joe. For subsequent P23 sightings, we're to reduce the trunnion to less than 10 degrees before zeroing optics, and always do the optics cal[ibration] after the optics zero in P23.
050:01:13 Allen: That's exactly right, Jim. And that is all I have on my Flight Plan update. I guess we've got an afterthought here. I'll get with you in a minute. I do have some other questions which I'd like to ask, but let me give you this addition while you have the Flight Plan there on your lap. And it involves the time 56 plus 20. I'll stand by [for] when you're there. [Long pause.]
050:01:59 Irwin: Okay. I'm at 57 - 56:20.
050:02:03 Allen: Okay. The step is "Direct O2, Open until cabin pressure equals 5.7 psia." [Pause.]
050:02:31 Irwin: Okay; understand. At 56:20, "Direct O2, Open until cabin pressure equals 5.7 psia [pounds per square inch absolute, i.e. relative to a vacuum]."
050:02:37 Allen: That's correct. [Long pause.]
050:02:49 Allen: And, Jim. I'm going to wait until the comm gets a little better before I continue on here. Be a - a minute or so.
050:02:58 Irwin: Okay.
Comm break.
The extensive update to the Flight Plan has taken a full half an hour. The crew should have had their breakfast immediately after they were roused but the Flight Plan update and prior tasks have precluded this.
The Flight Plan calls for battery B to begin to be charged about now. However, it won't be started until about 52:43.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
050:05:53 Allen: Apollo 15, Houston. [Pause.]
050:06:05 Irwin: Go ahead, Joe.
050:06:07 Allen: Jim, we've got about 3 or 4 small questions for you. Your choice whether you'd like to talk about them now or proceed on with the light flash experiment.
Some of the Apollo crews reported seeing light flashes in their eyes, even when their eyelids were closed, while beyond low Earth orbit and therefore above the van Allen radiation belts. The Apollo 15 crew have been allotted a period during each cislunar coast and while in lunar orbit to perform simple experiments to characterise the nature of the phenomenon. The first of these is scheduled to be performed during the coming hour but the late awakening of the crew, and the large number of Flight Plan updates will delay it over an hour.
050:06:18 Irwin: No. We're going to delay that light flash experiment anyway until we get cleaned up here and have breakfast. So you can ask - ask the questions. We'll be thinking about it while we're cleaning up.
050:06:30 Allen: Okay. That sounds good. Our first one: we noted a very small load change on battery bus A yesterday, several minutes prior to your SPS burn, and we're trying to - to chase down what may have caused this. We suspect that you may have - have closed two circuit breakers that should have been closed and just are curious to know if you did close them, or if, when you looked to verify them, they were already closed. And, the circuit breakers in question are the SPS Pitch 1 and Yaw 1 circuit breakers that feed Bat A. [Pause.]
050:07:22 Irwin: Okay. We - we closed those per checklist, Joe.
050:07:27 Allen: Jim, I understand you closed them for the checklist. By that do you mean that you - when you looked at them, you found them open and closed them? [Long pause.]
050:07:53 Irwin: Okay. That's affirm[ative], Joe. They were open, and we closed them per the checklist.
The circuit breakers in question are on the second from bottom row of panel 8, one of the wing panels to the left of the Main Display Console.
050:08:01 Allen: Okay. The guys in the back room here psyched that out pretty well, I guess. Thank you. That - I guess that was a question mostly of academic interest. Al, the circuit breaker in the Lower Equipment Bay, AC2, is still out as you're well aware, and it affects a number of EL [electroluminescent: digital displays extensively used in the CSM and LM, and the predecessors to todays LEDs and liquid crystal displays] and DSKY lights and so on, and we'll want to talk to you later on today about this. It should be no problem in any way, but we do want to talk about - discuss [the] ramifications of the - of the various workarounds which this may involve. And, finally, we've been noting during the night some small oscillations in accumulator quantity, and we'd like for you, please, to check your secondary radiators. Verify that's in bypass. That's panel 377. [Pause.]
050:09:11 Irwin: Okay. We're checking panel 377 now.
050:09:14 Allen: Okay.
Comm break.
The circuit breaker in the Lower Equipment Bay, on panel 226, had popped at 033:48:00 due to a short circuit in the mission timer.
Panel 377 is a small panel with a single control on the left-hand equipment bay.
050:10:45 Irwin: Okay, Joe. On that - on that valve on [panel] 377. It was in Bypass, and Dave just cycled it to - cycled it to Normal and then back to Bypass.
050:11:01 Allen: Okay, Jim. Thank you. [Pause.] And that's all we have down here for the time being. I've been reading the Apollo 15 status report that's put out every two hours. What's normally several pages, is just a page today. And - with very few words on it, the most prominent one being the word nominal, the meaning of which I'm going to look up as soon as I get off this shift. [Pause.]
050:11:39 Irwin: Very good. [Long pause.]
050:11:51 Allen: And, Jim, unless you have any questions, why don't you proceed on with a comfortable breakfast, and we'll be standing by for a callout of when your ready to continue.
050:12:05 Irwin: Okay, Joe. Thank you.
Very long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control; 50 hours, 18 minutes Ground Elapsed Time. The crew of Apollo 15 presently preparing breakfast aboard spacecraft Endeavour. Unstowing all the items for space breakfast. Very lengthy Flight Plan update [was] read up to the crew by spacecraft communicator Joe Allen. The crew said they would be back to Allen to discuss the day's activities after they've had breakfast. [They] also mentioned that they preferred to delay the Visual Light Flash Phenomenon Experiment, which is shown in the Flight Plan at 50 hours Ground Elapsed Time. This particular experiment will be delayed. Visual light flash phenomenon experiment is a result of some experiences by previous flight crews on lunar flights. The crews of Apollo 11, 12, 13 and 14 reported seeing light flashes and streaks of light when they were in the darkened Command Module. Usually when their eyes were closed. Both in translunar and trans-Earth coast and in lunar orbit. These light flashes, at a frequency, ranged anywhere from .5 to 2 events per minute. One conjecture or hypothesis that's been extended to explain this phenomenon is that the flashes are visual phosphenes induced by cosmic rays. There's some controversy, however, as to whether the cause is due to Cherenkov radiation produced by high energy particles traveling through the eyeball or whether the flashes result from ionizing collisions of these high energy particles in the retina or in the visual centers of the cerebral cortex. At any rate, to conduct the experiment, the crew puts on eyeshades, opaque eyeshades, similar to the television quiz show of several years past. It requires that all three crewmen face in the same direction and undergo a dark adaptation period prior to actually beginning an oral description of the light flashes. The crewmen will report such things as the Ground Elapsed Time to the nearest minute. Of course they can't see their spacecraft timing or clock, they have to guess at it. The frequency of flashes, description of the flashes and also the location of each crewman in the Command Module, and the way that each man is oriented. Apollo 15 is now 165,733 nautical miles [306,937 km] out from Earth. Velocity; 3,440 feet per second [1,049 m/s]. Crew in the middle of their morning meal at this time. We'll await their further call to Earth to continue with the day's activities, which includes further checkout and some housekeeping aboard the Lunar Module. At 50 hours, 23 minutes Ground Elapsed Time, and standing by; this is Apollo Control.
The positions of the crewmembers, and the direction in which they are facing is important to the interpretation of the data as they may be shielded from cosmic radiation by each other or parts of the spacecraft.
Flight Plan page 3-52.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 51 hours, 8 minutes Ground Elapsed Time. Apollo 15 now 167,260 nautical miles [309,765 km] out from Earth. Velocity; 3,405 feet per second [1,038 m/s]. Like most men at breakfast, they're probably reading the morning paper because they're sure not saying anything. We expect to hear from the crew of Apollo 15 after they tidy up following the breakfast meal. As mentioned earlier, the Visual Light Flash Phenomenon Experiment has been delayed by the crew. It was originally scheduled for 50 hours. There's nothing time critical about when they do this. Requires all three of them wear the eyeshades for a period of 1 hour, to allow for dark adaptation and then a period of reporting; the flash frequency, shape of the flashes, color, et cetera. We'll continue to monitor the air/ground and leave the circuit up live for the time when the communications do resume. At 51 hours, 10 minutes Ground Elapsed Time; this is Apollo Control.
At about this time, a member of the crew is due to change one of the lithium hydroxide canisters. Canister 6 replaces 4 in receptacle B, with the latter being stowed in compartment B5. The canisters remove carbon dioxide from the air supply by absorbing it into the grains of LiOH which they contain. They also contain activated charcoal to remove odours.
In the air-ground transcript, there is no mention of how smelly it got in the spacecraft. The post-flight debriefing, attended by Deke Slayton, the crew's boss, a little more was expressed.
Scott, from the 1971 Technical debrief: "I thought we had a lot of odors in there."
Irwin, from the 1971 Technical debrief: "I think it was probably due to all the hydrogen systems."
Scott, from the 1971 Technical debrief: "It cleared out pretty well. The spacecraft system cleared it out pretty well."
Irwin, from the 1971 Technical debrief: "Not nearly as well as the LM system. Maybe that's just a function of three versus two guys. Of course, I was contributing my share too. I thought it was pretty gross in there."
Slayton, from the 1971 Technical debrief: "What we are really searching for here is some sort of burn smell up there."
Worden, from the 1971 Technical debrief: "Yes. I recall some powder smell in the tunnel."
Irwin, from the 1971 Technical debrief: "I didn't smell any nitrogen up there."
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
051:23:02 Scott: Houston, 15. [Pause.]
051:23:11 Allen: Go ahead, 15. This is Houston.
051:23:17 Scott: Okay, Houston. We're getting ready to do the light flash experiment, and we'd like to run the tape recorder so we can get the voice marks on it, if that won't interfere with any of your [garble].
051:23:35 Allen: Okay, Dave. Stand by. I'll inquire.
051:23:42 Scott: Okay.
Comm break.
The Command Module is furnished with a tape recorder which can store data from sensors around the spacecraft, and which also includes the ability to record the voices in the cabin. Later, when the HGA is properly configured for sending high rate data to Earth, the stored information can be replayed to Mission Control for analysis. The unit, called the DSE (Data Storage Equipment), can be controlled from within the cabin or remotely, from Earth.
The Public Affairs Officer gave a clue to one of the problems the crew have during the course of the experiment, which is to indicate the time of each flash. He has ventured that they will have to guess the time of each flash. The crew have another idea which is to use the voice-recording capability of the DSE. As the unit also records GET, the timing of each flash report will be available once Mission Control have dumped the recorder's contents to Earth.
051:24:44 Unknown speaker: Tunnel Vent valve.
051:25:05 Allen: 15, this is Houston. [Pause.]
051:25:12 Scott: Houston, 15.
051:25:14 Allen: Roger. In answer to your question on the DSE, we'll handle the DSE from down here when we start the eye flash experiment. We do have a - a request of you before you start the experiment, though. We don't have the necessary oxygen purity in the LM yet that we think that we're going to need for the surface EVAs several days from now. And - consequently, we want you to start to vent the LM once again. We're going to drain it out and fill it with oxygen again later on today. So, if you would please, turn the Tunnel Vent valve to the Vent position before we start the eye flash.
051:26:01 Scott: Okay, Joe. That's in work.
051:26:04 Allen: Okay. [Long pause.]
051:26:16 Scott: Okay, Houston. And we'll take a couple of minutes here and run a hatch integrity check and make sure it's all fixed up, and we'll be with you in about 5 [minutes].
051:26:23 Allen: Roger, Dave. Sounds good.
Long comm break.
If the LM is going to be vented, it is important that the hatch between the CM and the tunnel is properly sealed. The steps for the hatch integrity check are shown in the CSM Systems Checklist, on page 2-9. To summarise them, the tunnel is vented, then the flow of oxygen into the CM cabin from the ECS is studied to see if it increases while the pressure differential is monitored for unexpected changes.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
051:36:01 Scott: Okay, Houston; 15. The Tunnel [garble] the hatch looks good, we're willing to start the experiment.
While the crew carry on with the light flash experiment, the tunnel and LM cabin can be vented.
051:36:08 Allen: Okay, Dave. We're standing by. And I could give you a few reminders on the experiment here, if you'd like them.
051:36:17 Scott: Okay. Go ahead.
051:36:18 Allen: Rog. We're just interested - in primarily a mark from each of the three of you when you notice a - a flash. And then, you might indicate who it is calling it out and then a description, as you see it: position, color, etc., etc. And - if - any - if another one of you notices one in the meantime during the description, call 'Mark' and that one then takes precedent [means priority]. Over.
051:36:54 Scott: Okay. That's about the way we talked it over, Joe. We're all set. Thank you.
051:36:59 Allen: Rog. [Long pause.]
051:37:14 Allen: And, Dave, we'll be standing by for when...
As part of the instructions for the light flash experiment, the Flight Plan asks the crew to set the Kitchen Timer to 50 minutes.
It may seem incongruous in the high tech environment of an Apollo spacecraft, but a Kitchen Timer was indeed carried as a simple, lightweight solution for timing various tasks.
051:37:17 Scott: Okay, Houston.
051:37:18 Allen: Go ahead.
051:37:21 Scott: Okay. If you'll start the tape recorder, we'll start.
051:37:25 Allen: Roger, Dave. [Pause.]
051:37:31 Scott: Okay; Houston, 15. We're starting. [Pause.]
051:37:40 Allen: Roger.
Comm break.
Houston has just realised that, with the current arrangements, they are excluded from the experiment until the DSE is replayed later. It would be wise to have the voice marks given over the air/ground comm as a back-up in case of a problem with the DSE. Also, it would seem likely that Mission Control just want to be involved, rather than listening to static for an hour.
051:38:56 Allen: Dave, this is Houston.
051:39:04 Scott: Go ahead, Houston.
051:39:07 Allen: Roger, Dave. And just wanted to make sure you - you understood that we'd also prefer the mark on real time comm, as well. [Pause.]
051:39:23 Scott: Well, all right.
Long comm break.
There is an lack of reporting of light flash events from the crew in the initial stages of the experiment, probably due to their eyes taking some time to become dark-adapted.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
051:43:30 Allen: 15, this is Houston.
051:43:35 Scott: Go ahead.
Judging by Joe Allen's next comment, perhaps Mission Control are wondering whether they are being left out of proceedings.
051:43:39 Allen: Roger, Dave. Since I've hadn't heard anything, I'll assume you haven't noticed anything yet. And I'm assuming, also, that you are wearing your eyemasks.
051:43:52 Scott: [Garble, probably: We get the] message, Joe, and the window shades are up [i.e. closed], and the cabin is dark.
051:43:57 Allen: Okay. Thank you.
051:44:02 Scott: And we're concentrating pretty hard.
Comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
051:46:16 Irwin: Mark LMP.
051:46:22 Allen: Roger. [Long pause.]
And Lunar Module Pilot Jim Irwin has seen a light flash...
051:46:33 Worden: Mark CMP.
051:46:37 Allen: Rog, Al. [Long pause.]
051:46:55 Allen: And, Al, any sensation other than just a flash?
051:47:01 Worden: Negative, Joe.
051:47:02 Allen: Okay. [Long pause.]
051:47:16 Irwin: LMP Mark.
Comm break.
051:47:28 Worden: Mark CMP. [Long pause.]
051:47:45 Scott: Mark CDR.
051:47:49 Allen: Roger.
051:48:08 Scott: Mark CDR.
051:48:12 Allen: Rog, Dave. And is it a - just a pinpoint, or a streak, or what?
051:48:17 Scott: All coming on the DSE, Joe.
The transcript of the DSE voice recordings does not include this period, implying that the information recorded on the DSE was never received on Earth.
051:48:20 Allen: Okay.
051:48:25 Scott: We can give you that, but it might get confusing. [Long pause.]
051:48:43 Scott: Mark CDR.
051:49:04 Scott: Houston, so far we've all seen just point sources of light, rather than streaks.
051:49:11 Allen: Okay, Dave. And some of us are a bit...
051:49:13 Worden: Mark CMP.
051:49:14 Allen: Roger. [Long pause.]
051:50:14 Allen: 15, this is Houston. If you see something significantly different from the point source, we'd like a real-time voice description of it, as well as a DSE recorded.
051:50:26 Scott: Okay, Houston. Fine. It's just that when we're trying to talk back and forth with the time delay, it's going to get confusing on the comm for us to try and record... Mark CDR.
051:50:37 Allen: Understand, Dave. [Long pause.]
051:51:35 Irwin: Mark LMP.
051:51:38 Allen: Rog.
Comm break.
051:52:52 Irwin: Mark LMP. And this one did have a - a streak nature to it. Like it went from 8 o'clock over to the plus X position.
051:53:07 Allen: Rog. [Long pause.]
051:53:30 Worden: Mark CMP. [Long pause.]
051:53:47 Worden: Mark CMP. [Long pause.]
051:54:12 Worden: Mark. [Long pause.]
051:54:59 Worden: Mark CMP. [Pause.]
051:55:06 Worden: Mark. [Long pause.]
051:55:47 Scott: Mark CDR.
Comm break.
051:57:37 Scott: Mark CDR.
051:57:39 div class="cc": Roger. [Long pause.]
051:58:37 Irwin: Mark LMP.
051:58:40 Allen: Rog. [Long pause.]
051:59:14 Scott: Mark CDR. [Long pause.]
Flight Plan page 3-53.
052:00:04 Scott: Mark CDR.
052:00:07 Allen: Roger. [Long pause.]
052:00:38 Irwin: Mark LMP.
052:00:42 Allen: Roger, Jim.
052:00:45 Worden: Mark CMP.
052:00:47 Spacecraft: Right on. [Long pause.]
052:01:20 Irwin: Mark LMP.
052:01:22 Allen: Roger. [Pause.]
052:01:28 Scott: Mark CDR. [Long pause.]
052:01:40 Scott: Mark CDR.
052:01:41 Scott: Mark CDR.
Comm break.
052:02:58 Worden: Mark CMP. [Long pause.]
052:03:11 Scott: Mark CDR. [Long pause.]
052:03:58 Irwin: Mark LMP. [Long pause.]
052:04:45 Worden: Mark CMP. [Long pause.]
052:05:11 Worden: Mark CMP.
Comm break.
052:06:19 Worden: Mark CMP. [Long pause.]
052:06:33 Worden: Mark CMP. [Long pause.]
052:06:49 Irwin: Mark LMP. [Long pause.]
052:07:50 Worden: Mark CMP.
052:07:54 Worden: Mark CMP.
052:08:05 Worden: Mark CMP.
052:08:19 Irwin: Mark LMP.
Long comm break.
After a cluster of events, with one or two per minute, there is a dearth of flashes for over six minutes.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
052:14:39 Allen: 15, this is Houston. Are you still with us?
052:14:44 Scott: That's for sure. Still here.
052:14:50 Worden: Mark CMP.
052:14:54 Worden: Mark CMP.
Long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
052:18:40 Scott: Mark CDR.
Comm break.
052:19:53 Allen: 15, Houston. Are you still with us?
052:19:58 Scott: Roger. [Garble]. [Long pause.]
052:20:37 Worden: Mark CMP. [Pause.]
052:20:47 Allen: Roger.
052:20:50 Worden: Mark CMP. [Pause.]
052:21:01 Worden: Mark CMP.
052:21:03 Worden: Mark CMP. [Long pause.]
052:21:34 Irwin: Mark LMP. [Pause.]
052:21:44 Scott: Mark CDR. [Long pause.]
052:22:00 Scott: Mark CDR.
Long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
052:26:00 Worden: Mark CMP.
052:26:01 Scott: Mark CDR.
Comm break.
052:27:21 Scott: Mark CDR. [Long pause.]
052:27:48 Scott: Mark CDR.
Comm break.
052:29:00 Worden: Mark CMP. [Long pause.]
052:29:12 Allen: Roger, Al. And we're coming up on about 10 minutes remaining.
052:29:20 Worden: Roger. [Long pause.]
052:29:36 Scott: Mark CDR. [Long pause.]
052:30:02 Irwin: Mark LMP. [Long pause.]
052:30:29 Scott: Mark CDR. [Long pause.]
052:30:59 Scott: Mark CDR. [Long pause.]
052:31:53 Scott: Mark CDR. [Long pause.]
052:32:34 Scott: Mark CDR. [Long pause.]
052:32:48 Scott: Okay, Houston. We've got 60 minutes up here. How's your clock look? [Pause.]
052:33:01 Allen: Dave. We're coming up on 60 minutes here too. And I've - I think that's certainly an adequate period. A couple of quick questions, though. Could you describe for us briefly your positions in the spacecraft during this time?
Note that during the hour, the spacecraft has rotated about three times in its slow PTC roll so there will be no directional information coming from the crew's positions, just a hint of how the spacecraft shields them.
052:33:15 Scott: Okay. We've got it - several comments for you, Joe. Let us un - uncouple here, and we'll talk to you for a while about this.
052:33:23 Allen: Roger. [Long pause.]
052:33:41 Scott: Okay. Houston, 15. I guess - we realize the interest behind this and the significance of the thing and - and we'll each try and describe what we saw in the way of the flashes. And I think - because of the randomnum - randomness of the flashes, it was probably better to let us go ahead and work out the events on the DSE. And I think, also, you'll find on the DSE, when you review the tape, that we've come up with a little scheme to give you some quantitative data, which may or not - may not be the best. And if you have any suggestions on future tests or how we can make it a little better for you, we'd be glad to hear that. As to our positions in the spacecraft, we're in our launch - reenter and launch positions; I'm in the left, and Al's in the center, and Jim's in the right. Do you still copy?
The transcripts of the DSE voice track do not carry the experimental data.
052:34:35 Allen: Roger, Dave. Loud and clear.
052:34:41 Scott: Okay, I guess - as far as my impressions, I would say 90 per cent of them were what I'd call a point source of light. And to give you perhaps an analogy, you might picture yourself sitting high in the stands of the - of the Ice Capades with the arena darkened and some single figure on the - on the ice, like Peggy Fleming, doing a nice thing. And you look across at the other side of the - the dark arena and somebody shoots a flashbulb out of their Instamatic or something, and that would be what I'd call a - a typical flash of intensity 5 on a scale 1 to 5, and we tried to sort these out relative to their intensities. And that - that would be my impression of 90 per cent of what I saw.
052:35:34 Allen: Roger. [Pause.]
The Instamatic is a contemporary low price camera manufactured for the mass market by Kodak. With the electronic flash not yet in the mainstream, flash photography for these cameras uses the flashcube. The cube contains four one-shot bulbs, each of which is rotated away after use.
The Ice Capades were, in one stretched metaphor, not unlike the Instamatic camera in the 60s. As mass market photography saw its ascendancy with the Instamatic and Polaroid cameras, the Ice Capades were the introduction of the masses to the art and sport of figure skating. Where else could you see such talent outside of the Winter Olympics? Going to see the Ice Capades was like going to see the circus, and the whole family went.
052:35:40 Scott: Okay, let Al give you his impressions.
052:35:46 Worden: Okay, Joe. I guess I didn't see the same thing that Dave did - and - talking about the intensity, I guess that's a very subjective thing. But I guess the analogy with the flashbulb [garble] was pretty good for the brighter intensities, and it seems like there was - there was one flash maybe that was of [garble] an intensity in the majority of the [garble].
052:36:07 Allen: Hey, Al - Stand - Al, stand by. Stand by.
052:36:13 Allen: Al, we're starting to lose you because we're changing our Omnis now. Could you stand by a second, and I'll give you a call back.
052:36:21 Worden: Okay, Joe.
Comm break.
052:37:45 Allen: 15, while you're standing by waiting for the Omni to come around where we can read you more clearly - Dave, that was a very, very nice description of the flashes. Of course, we're very pleased with the - apparently, the intensity values that you put on the - on the DSE. And I think our comm - comm is starting to improve here, Al, so I'll be standing by for your continued description.
052:38:17 Worden: Okay, Joe. I guess in addition to - to what's been said already, most of the light flashes seem to be of the order of flashcubes or maybe starbursts that you've seen in the summertime. I saw very few streaks or radial paths of light. They all seem to be just point sources of light, and - and I guess that's really about all I've got to add, Joe; I'll - I'll see if Jim's got something.
052:38:55 Allen: Roger.
052:38:59 Irwin: Joe, I just have one comment, [garble] that's on the tape. And that is, just after the timing [garble] ended, we were taking - about to take our masks off, I had one - very brilliant streak. [Garble]...
052:39:14 Allen: Stand by - stand by.
052:39:16 Irwin: ...[garble] at nine o'clock...
052:39:18 Allen: Jim, stand by a second. Our comm's starting to drop out again, and it may be a partial problem with your microphone position. Stand by just a second though, please. [Long pause.]
052:40:25 Allen: Okay, Jim. We have comm again. Proceed on.
052:40:32 Irwin: Roger. I wanted to comment on one brilliant streak that I had just after the timing period had ended, and I was about - I was in the process of taking the mask off, and there was a brilliant streak, intensity 5, that went from the 9 o'clock position - through 12 o'clock - and out the 3 o'clock.
052:40:55 Allen: Roger, Jim. We copy that. And could you tell us which eye that one was in?
052:41:05 Irwin: Well, it seemed like it went from the left eye to the right eye.
052:41:10 Allen: Okay; very interesting. Endeavour, the Principal Investigators on this, Dick Benson and Larry Pinsky, have followed it closely and are quite pleased, I think, with the data you've given us; they'll be looking at the DSE information in detail and may have a - some definite procedure changes to give to you later, based on the information you've given us so far. And I guess as far as we're concerned, we have no more questions.
052:41:41 Scott: Okay; fine, Joe. We'll be standing by and I - I guess another thing that - that you've picked up - interesting thing, is that the - the flashes are quite easily located relative to either eye or the position within either eye, which I think we found rather interesting.
052:42:00 Allen: That's remarkable, Dave. Right; thank you. [Long pause.]
052:42:21 Allen: 15, when you get squared away there, we'll be looking for - your starting to charge battery B, battery Bravo.
052:42:31 Scott: Rog. Understand. And I might add one more comment that - in discussing that - that last one [meaning Dave's last statement], why, Jim didn't quite have that impression of localization within each eye, although Al and I both do.
This is despite Jim's statement that he was aware of his last reported flash, the brilliant streak, appearing to move from the left eye to the right eye.
052:42:43 Allen: Okay. [Long pause.]
052:43:28 Allen: Jim, this is Houston again. I have a small addition to your Flight Plan update which I can give you whenever convenient for you.
052:43:44 Irwin: Okay; stand by.
052:43:46 Allen: Roger; whenever convenient, Jim. No hurry on it at all.
052:43:59 Irwin: Battery charge B is in process.
052:44:02 Allen: Roger.
Comm break.
The charging of battery B has been held over from 50:00. The crew are about two hours behind the timeline but there is plenty of slack during this day to make it up.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
052:45:57 Irwin: Okay, Joe. I'm ready to copy these additional comments you have for the Flight Plan.
052:46:03 Allen: Roger, Jim. The first one is at 53 hours exactly, and it's just a note for you information. [Pause.]
052:46:17 Irwin: All right, go ahead.
052:46:19 Allen: Roger. In the left-hand side of the Flight Plan there, the "lift off time [if required]." Note that it is not required in this case so we don't have to worry about that. The - second change - is possibly not a change: at 60 hours, six zero hours, I wanted to double check your readback of the addition which I gave to you earlier. And it should read, at 60 hours: "Pan Camera Self Test, Off," and "Map Camera On, to Off." [I] wanted to double check that last step.
052:47:11 Irwin: Roger. I have both of those, Joe, and they occur after the [line which says] "S-band Aux TV, Off."
052:47:17 Allen: Okay; thank you very much, Jim. The third change is an addition to the LM Activation Checklist changes which I gave you earlier.
052:47:33 Irwin: Is it in the Activation Checklist or is it in the Flight Plan?
052:47:36 Allen: I think you copied it in the LM Activation Checklist on page 1-13.
052:47:47 Irwin: Roger. [Long pause.]
052:48:11 Irwin: Okay. I'm on 1-13 of the Activation Checklist.
052:48:15 Allen: Okay, Jim. After the addition on that page, which read, "Circuit breaker 11, ECS Cabin Fan, Closed," add: "Circuit breaker 11, EPS: DC Bus Volt, Closed." [Pause.]
052:48:43 Irwin: Okay; copy: "CB 11, EPS: DC Bus Volt, Closed."
052:48:48 Allen: Okay, Jim. That's it from down here [in Mission Control] for a while.
Long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
052:57:51 Allen: 15, Houston.
052:57:56 Scott: Houston, 15. Go.
052:57:58 Allen: Roger; Dave. The next time one of you floats past the LM/CM Delta-P gauge, could you get a readout for us please.
052:58:10 Scott: Roger; stand by.
052:58:12 Allen: Roger; no hurry.
052:58:17 Scott: 2.0 [psi].
052:58:20 Allen: Copy 2.0. Thank you.
052:58:25 Scott: Roger.
Long comm break.
The LM has been venting over the last hour and a half. Mission Control want to check its progress by having a crewmember look at a gauge next to the hatch. 2 psi differential between the CM and LM is less than they expected and is, in fact, an erroneous reading.
The control for the Tunnel Vent valve is adjacent to the gauge near the CM tunnel hatch. It has four positions: Therefore, to measure the pressure difference across the hatch while the tunnel is venting, the gause should be read with the valve rotated from the "LM Tunnel Vent" position to the "LM/CM Delta-P" position, returning it to Vent after the reading has been taken. Instead, the meter is being read with the valve in the vent position and as the gauge is not connected to anything in that position, the reading is erroneous. Mission Control will crack this problem during an exchange at 054:22:49.
Flight Plan page 3-55.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
053:01:31 Allen: Apollo 15, go to P00 and Accept, please, for a clock sync update.
053:01:39 Scott: Roger. P00 and Accept.
Comm break.
By selecting program 00, essentially a 'do nothing' routine, and switching to Accept, the crew makes it possible for Mission Control to upload information to the computer. Here, they want to ensure that the CMC clock is correct by uplinking an accurate time from Earth before the crew synchronise the Mission Timer with it.
053:03:25 Allen: Your computer, Dave.
The update is complete and Allen is informing Dave that he can switch the computer out of Accept.
053:03:30 Scott: Roger. [Long pause.]
053:04:09 Allen: Dave is that time okay?
053:04:16 Scott: Rog. We're within about - 1200 to the mission timer. [Pause.]
053:04:29 Allen: Sounds pretty good to me. [Long pause.]
053:04:59 Allen: That's the old Noun 65 trick.
Noun 65 samples the time in the CMC (Command Module Computer) allowing Dave to compare it to the Mission Timer.
053:05:04 Scott: Rog. I guess I should have said 12 centiseconds.
053:05:12 Allen: Oh Yes. Mercy, yes.
053:05:18 Scott: Oh yeah.
Long comm break.
Woods, from 1998 correspondence with Scott: "Can you remember if the disparity between the freshly synchronised CMC and the mission timer was 12 minutes, 00 seconds; or could it be 12 seconds? The word 'miniseconds' was taken from the technical transcript."
Scott, from 1998 correspondence: "A mini-second may have been 1/100 of a second, as a millisecond would have been 1/1000 of a second."
Scott, from 1998 correspondence: "Much of the apparent idle banter between us and Joe Allen, in particular, had specific implications or "hidden meanings" based on many simulations and Joe's superb qualities as a CapCom (and person) - these were often just quips that added some levity and another dimension to the sometimes dry communications up and down - but only meaningful if one were on the 'inside.'"
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
053:08:38 Allen: 15, Houston. Requesting Block on the Up TM [uplink telemetry].
053:08:44 Scott: Oh, Rog. Thank you.
Very long comm break.
Having been asked to configure the computer to accept uplinked telemetry from Mission Control, the crew is being reminded to return the Panel 2 switch to Block, i.e. to block incoming data.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control. 53 hours, 15 minutes Ground Elapsed Time. Distance and velocity [are] now 171,365 nautical miles [317,367 km] from Earth; velocity, 3,315 feet per second [1,010 m/s]. Apollo 15 air to ground communications still live. This is Apollo Control.
Around 54 hours into the mission, and before the crew settle down for lunch, the film in the Mapping and Panoramic Cameras is due to be cycled. However, the crew are deferring it until later. See 055:39:08.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
053:56:11 Worden: Hello, Houston, 15. [Pause.]
053:56:17 Allen: Hello, 15, this is Houston.
053:56:21 Worden: Hey, Joe, I just did a Delta-V and null bias check if you want to copy some numbers.
At regular intervals throughout the flight, the ability of the EMS (Entry Monitor System) to display changes in the spacecraft's velocity is tested. See commentary after 007:41:13 for a fuller explanation of the test.
053:56:27 Allen: Go ahead, Al.
053:56:32 Worden: Okay, the Delta-V check was - test was satisfactory. It was a residual minus 21.0 [fps] in ten seconds, and the null bias was .8 feet in 100 seconds.
053:56:51 Allen: Okay, Al. We copy. Thank you.
Comm break.
053:58:09 Allen: And, Al, this is Houston.
053:58:13 Worden: Yeah, go ahead, Joe.
053:58:15 Allen: Roger. Will you be starting into your lunch break now?
053:58:21 Worden: Affirmative. [Pause.]
053:58:28 Allen: Okay. That sounds like a good idea. [Long pause.]
Lunch is scheduled to begin at 054:00:00 so beginning it now will place them back on the timeline after the morning's late awakening.
053:58:55 Allen: 15, Houston. If anyone by chance floats past the LM/CM Delta-P gauge, we'd like another read-out.
053:59:05 Worden: Okay, Joe. We'll get that for you.
Very long comm break.
Flight Plan page 3-56.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
054:12:28 Allen: Apollo 15, Houston.
054:12:34 Worden: Houston, 15. Go ahead, Joe.
054:12:36 Allen: Roger, Al. Would you tell Jim, please, that I've got a - a change Echo to his LM Activation Checklist, when he finishes with lunch and wants to copy it down. No hurry on it, but I don't want to forget it.
Critical Apollo documents, like the Flight Plan and checklists, were being constantly revised leading up to, and during the flight. Each carried a letter of the alphabet that was incremented each time the contents were changed.
054:12:52 Worden: Okay, Joe. I'll tell him.
Long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
054:22:49 Allen: 15, Houston.
054:22:56 Scott: Houston, 15. Go.
054:23:00 Allen: Roger. The next time somebody goes down into the kitchen to mix up some food, could you read the Delta-P gauge for us, please. [Pause.]
054:23:14 Scott: Roger. It's 1.9 [psi]. [Pause.]
054:23:24 Allen: Copy 1.9. Thank you.
Comm break.
1.9 psi (13.1 kPa) is still an erroneous reading as the Tunnel Vent valve is in the incorrect position for the reading. It appears to Mission Control that the Tunnel Vent valve is not working as it is supposed to, and after some thinking, they decide to check that they have copied the number properly and that the correct procedure is being used to read it.
054:25:22 Allen: 15, Houston.
054:25:28 Scott: Houston, 15. Go.
054:25:30 Allen: Rog, Dave. As luck would have it, we lost our comm just as we got the Delta-P number from you. We copied 1.9. Verify that for us, please. And, also, would you make sure that the valve is still in the Vent position.
CapCom Joe Allen displays his excellent tact here, as elsewhere in the mission, especially during the EVAs on the surface. Rather than flatly telling Dave he thinks his pressure reading is wrong, Allen uses the excuse of comm breakup to gently quiz Dave about the reading.
054:25:49 Scott: Roger. I checked that. It[the valve]'s [position is] LM Tunnel Vent and it's, well - 1.9 to 2 - pretty close.
054:26:01 Allen: Okay, Dave. Thank you. Just leave it in that position.
054:26:07 Scott: Roger.
Comm break.
Now Mission Control believe that either the valve is not operating properly or the gauge reading method is suspect.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
054:28:33 Allen: 15, this is Houston. We have a further question about that LM Tunnel Vent valve.
054:28:44 Scott: Okay; go ahead, Joe.
054:28:46 Allen: Roger, Dave. We should have had a much greater drop in pressure - during the - the time between these two readings. We want to confirm that you went to the Delta-P position to read the meter this second time. Over.
054:29:08 Scott: Oh, no. I thought you just wanted the reading in the Vent position.
054:29:13 Allen: No, sir. Apparently we have to go over to Delta-P, get a reading, and then go - return to the Vent position.
054:29:22 Scott: Yeah, that's absolutely correct, Joe. Thank you. We'll do that.
Comm break.
054:29:58 Scott: Okay. In the LM/CM Delta-P [position] - it's 2.9 [psi], and then back to LM Tunnel Vent it's 3.5 [psi].
054:30:10 Allen: Okay, Dave. We copy that. Sounds so much better.
054:30:15 Scott: Yes, it sure does, doesn't it.
Very long comm break.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
This is Apollo Control at 54 hours, 44 minutes Ground Elapsed Time. Apollo 15 still in Passive Thermal Control, or bar-b-cue mode, in which they roll about the longitudinal axis to stabilize the thermal response or heating on the spacecraft. [They are] scheduled to leave Passive Thermal Control shortly after 55 hours Ground Elapsed Time and prepare for the LM checkout and housekeeping. Present distance from Earth, 174,203 nautical miles [322,623 km]. Velocity; 3,254 feet per second [992 m/s]. Air to ground circuit with the crew still up live at 54:45; this is Apollo Control.
Flight Plan page 3-059.
[Download MP3 audio file. Clip courtesy John Stoll, ACR Senior Technician at NASA Johnson.]
055:02:36 Irwin: Houston, this is 15.
055:02:40 Allen: Roger, 15; go ahead.
055:02:45 Irwin: Joe, I understand you have another change to the Activation Checklist.
055:02:49 Allen: Roger, Jim, I had to change Echo for you. I'm up to change Foxtrot already, if you're ready to copy.
055:02:57 Irwin: I'm ready to copy, Joe
055:03:00 Allen: Okay. Nothing very profound here. It - it has to do with the LM housekeeping/cleaning procedures I read to you at 57 plus 45. And the procedures which I read were basically a cleaning of the vacuum Cabin Fan filter. And it involved unsnapping a netting around the Cabin Fan filter, running the vacuum cleaner over it, and finally replacing that netting. And we've had second thoughts about that entire procedure down here - mainly, because the netting is in too cramped an area to get to comfortably - it takes a long time to take the netting off and replace it, and the - the procedure is, actually, not too effective, anyway. So - we want you to delete this entire step, and I have two more to add instead of this particular step at 57 plus 45. Am I clear so far?
055:04:15 Irwin: Ah, yes, you're clear so far. Do you still want us to turn the cabin fan on?
055:04:21 Allen: Roger, Jim. In fact, the procedure now reads like this. Before you begin the LM Activation Checklist and you're entering the LM, we want you to vacuum all the LM accessible areas such as Velcro, places like that, where dirt and particularly glass particles have accumulated. Then, when you've cleaned it to your satisfaction, tape the vacuum cleaner to the [ascent] engine cover. Let it run while you're doing the rest of the housekeeping activities. Over.
055:05:11 Irwin: Okay; I understand, Joe.
055:05:13 Allen: Okay, Jim. And then, finally when you're through with the housekeeping activities, clean the vacuum cleaner inlet screen with sticky tape. We think you'll probably find glass particles there which you can remove conveniently with the sticky tape. [Pause.]
055:05:38 Irwin: Okay; I copy.
055:05:42 Allen: Okay, Jim. That's all I had for you really.
Comm break.
055:07:15 Irwin: Joe, this is 15 again.
055:07:17 Allen: Go ahead.
055:07:20 Irwin: Roger. Did you confirm that you still want us to turn the cabin fan on?
055:07:26 Allen: That's correct. We - we confirm that. We want the cabin fan turned on.
055:07:36 Irwin: Okay. And assume if we - if we should see any glass on the cabin fan filter, then I suppose we should try to get down there with tape and clean it off. [Pause.]
055:07:50 Allen: Roger, Jim. That's right. It just - we do not now want you to unsnap the netting around that cabin fan filter, in spite of what we told you earlier. It still might be possible to clean that area with sticky tape - without unsnapping the netting, though.
055:08:13 Irwin: Okay; I understand.
055:08:17 Allen: Basically, as - I know you understand. We - we just want as much of the glass in the LM cleaned up as you can find. [Pause.]
055:08:39 Irwin: Okay. I think we cleaned it up pretty well yesterday, but we'll do it again.
055:08:53 Allen: Roger. Just look around. It may not take much at all to take it.
Very long comm break.
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