Apollo 15

This chapter continues coverage of day 11 of the flight of Apollo 15. The date is 5 August 1971. The primary event coming up is for Al Worden to go outside the spacecraft and manoeuvre himself to the SIM bay where he will retrieve large film canisters that contain photographic coverage gained by the Mapping and Panoramic cameras. Jim Irwin will assist Al by standing up in the hatch.

The procedures for the EVA begin on page 3-1 of the CSM Systems Checklist.

Long comm break.

Comm break.

Mission Control's request refers to the LCG (Liquid Cooled Garment) that Dave was wearing three days ago when he and Jim Irwin returned from the Moon's surface. After re-entering the Command Module and while preparing to jettison the Lunar Module Falcon, he had trouble sealing the water connection to the LCG and had to use a plug instead. If returned to Earth, then analysis of the problem, believed to be caused by dust contamination, can be made in time for the next flight.

Comm break.

Woods, from 2004 mission review: "Suited and unsuited in the Command Module in weightlessness. Is that a particularly difficult task. Is it easier or more difficult than doing so on the Moon. You got three guys in a small space and no gravity."

Scott, from 2004 mission review: "The only added difficulty in weightlessness is sort of getting to a position where the other guy can help you get in the suit and hold the suit. That's no big deal. The work on the suit is getting it zipped, getting it plugged, getting it checked. All that stuff. Yeah it was probably a little more difficult than... [laughs] They're both hard. If I say weightlessness is more difficult than one-sixth-g then the implication is that one-sixth-g is easy. Not easy. Very, very hard."

The V over H sensor is part of the Panoramic Camera's system. The sensor optically determines the rate at which the landscape is passing below, allowing the camera to adjust for the smearing that would occur if uncorrected.

Long comm break.

Flight Plan page 3-354.

Endeavour has probably been manoeuvred to the required attitude for Al's EVA. Appropriate angles are given in the Flight Plan for aiming the HGA (High Gain Antenna). To use them, the crew assume manual control of the antenna's mounting gimbal and dial in the given angles using two knobs to the lower right of the Main Display Console, panel 2. Nearby gauges let them monitor the antenna's actual orientation.

Now that the spacecraft is in the proper attitude, the A and B thruster quads are disabled. These are adjacent to the SIM bay and would pose a danger to Al as the spacecraft constantly fires thrusters to maintain its attitude. Guard rails are installed over the centre of the Main Display Console to ensure that controls, particularly those concerning the RCS, are not nudged. The three crew don their suits, Dave and Jim wearing their surface EVA suits, and get connected to the spacecraft's suit oxygen circuit. Al's 7.4-metre umbilical is different in that it includes a tether connected between a fixing on the CM and a waist belt he will wear around the outside of his suit. The umbilical also carries wiring for communication and biomedical telemetry. Jim also has a waist belt and a shorter, 2.2-metre tether as he will stand in the CM hatch during the EVA, helping control Al's umbilical, operate the TV and 16-mm cameras and bring the film cassettes into the cabin.

Very long comm break.

During this hour of communications silence, the crew continue their preparations for the EVA.

Scott, from the 1971 Technical debrief: "On the night after TEI, Al started configuring the cabin, stowage-wise, so that we'd be set up for the EVA. I think he put at least 2 hours into configuring the cabin the night before."

Worden, from the 1971 Technical debrief: "Yes. There was a lot of detail stuff, like putting things into the EVA bag, getting the purge valve out, and getting a lot of the little stuff out of the stowage containers. We tied the rock bags up to the sides of the spacecraft, rather than tying them down on top of the lockers. That way we could get in and out. Rearranging the stowage was kind of the detail part of some of the EVA prep that we did the night before."

Scott, from the 1971 Technical debrief: "The point is that when we got into the EVA day - when we got up that morning for the EVA - the cabin was already in good shape. Everything was set up so that we could proceed into the EVA prep according to the checklist with a minimum amount of shuffling. At the outset, I'd like to say that the checklist was excellent. The procedures ran very smoothly. I don't think anything was out of order. We had a very complete set of procedures overall. Everything got done according to the book, and it was very good. The only problem was time. We got up that morning and we had a few SIM bay things to do. Al had some P23s to do, and as soon as he finished his P23s, we started into the checklist and the portion called "Cabin Prep for EVA." We started that at 237:30 GET. It's really called in the Flight Plan to start at 239:30, so we started 2 hours early in the cabin prep for EVA. We went through every step line-by-line to make sure it all got done. It flowed very smoothly with no hitches, and it just took a little time to get everything done. We ended up just about on time for the pressure integrity checks. That means that it took us almost 2 hours longer than preflight planning. We were very happy that we had started early. We were glad that we had Al configure the cabin the night before to take care of the little details. I think it will pay off if you get started early on the EVA, because it really takes a lot of time making sure that you get everything done."

Worden, from the 1971 Technical debrief: "Most things you do on board take a little longer than you would expect them to preflight. That's because you take a little bit more care with what you're doing in flight. You do it much more methodically than you do preflight. That was particularly true of the EVA prep. We went through the checklist very carefully, very methodically, and we never rushed at any time. It flowed very smoothly but a little slower than we anticipated."

Scott, from the 1971 Technical debrief: "Which I think was good in that case, because it was the first time through for that EVA. It was nice to have a comfortable time pad all the way through. We knew we had a good time pad all the way through, so perhaps we were not operating at maximum efficiency relative to time. We were taking our time because we knew we had the pad."

So that Mission Control, and the public too, can watch the progress of Al's excursion along the Service Module, a pole has been provided so that the colour TV camera and the 16-mm movie camera can be mounted far enough from the CM main hatch to gain a reasonable view of his activities around the SIM bay. The pole will be attached to the inside of the open hatch.

When Dave and Jim walked and drove on the Moon, they each carried a backpack called a PLSS (Portable Life Support System) which provided all the required consumables to keep them alive and fit for over seven hours. The PLSS provided oxygen, cooling water and it scrubbed CO₂ out of the air. If, however, a suit were to be punctured for some reason, the flow-rate from the oxygen supply would likely not be high enough to sustain the crewman against the falling pressure. For this contingency, both Dave and Jim carried an extra package on top of the PLSS called the OPS (Oxygen Purge System), the prime component of which was a very high pressure bottle of O₂ which could be quickly released through a regulator. Though the PLSS's were discarded on the Moon, the two OPS units were retained in case Dave and Jim needed to transfer to the CM by an EVA. Now one unit will provide Al with his emergency supply during his EVA.

Flight Plan page 3-355.

This illustration, taken from the J-mission Apollo News Reference, shows the layout of the SIM bay. The V over H sensor is to the lower right of the Panoramic Camera's lens. Though difficult to see on this picture, its plume shield is like a lens hood projecting forward. During the EVA, Al will engage his feet in the foot restraint to the left. Facing right, he will have access to the majority of the bay, particularly the film cassettes which he must retrieve.

Towards the latter part of the spacecraft's time in lunar orbit, Al began having problems retracting the boom carrying the Mass Spectrometer. This problem is discussed more fully earlier in this journal but its essence is that the boom mechanism sticks when it becomes cold.

The next exchanges are the crew's comm checks. Dave and Jim will use a PTT (Push to Talk) switch. Al will be on VOX, his transmissions being made automatically by a voice-operated switch. In the available air/ground recording for the next few seconds, Dave's challenges are very faint. Al's responses are clear.

Comm break.

Very long comm break.

Comm break.

Comm break.

Comm break.

Comm break.

Worden, from the 1971 Technical debrief: "There was a lot of discussion about cracking the side hatch valve to maintain the cabin pressure during the EVA prep. That's particularly true when I was flowing through the umbilical. I thought that operation worked very well. I didn't see any problem at all with opening the side hatch valve just a little bit to relieve the cabin pressure."

Scott, from the 1971 Technical debrief: "Except that it was easier for me to do it than it was for you."

Worden, from the 1971 Technical debrief: "That's right."

Comm break.

Comm break.

Comm break.

Comm break.

The main, or side hatch has a depressurisation valve built into it. It is operated by releasing a handle and winding the valve open. The crew are only 4 minutes behind their planned timeline.

Comm break.

Comm break.

Flight Plan page 3-356.

Mention of the crew's heart rates brings up the point that after the flight Dave had concerns as to whether Jim should have gone through the hatch for this EVA in light of the heart rhythm irregularities seen by the ground

Scott, from 2004 mission review: "I think we should have had a discussion. We had a private loop. We could have had a comms loop discussion with the Flight Director and whoever, and they could have said, 'Jim's got a problem,' and we probably would have changed the EVA procedures."

Scott, from 2004 mission review: "We could have switched - I just sat in the left couch. I didn't do anything. Jim didn't have a big job but he was standing in the hatch, helping Al. Suppose he had had a heart attack and died? Would have been a bad day. Would have been better to put Jim in the left couch and let him just relax, and let me do his job, which wasn't a big deal. But nevertheless, I'd have switched it."

Woods, from 2004 mission review: "Had something happened, you would have been in a more secure position."

Scott, from 2004 mission review: "Yeah. I mean if I had known Jim had a problem, then I would have said, 'Let's switch roles for Al's EVA and you just sit there in the couch and watch the world go by.'"

Harland, from 2004 mission review: "Well you'd done a head-out-of-the-hatch on [Apollo] 9 so you know what's involved there."

Scott, from 2004 mission review: "Yeah. I'd understand the hatch. Yeah. At the very least, we'd have had a nice discussion with the Flight Director, 'nice' being full disclosure of the situation and full discussion of what's the best thing to do."

TV transmission from the spacecraft begins about now. The following video file begins at 242:04:23.

Al's EVA has been described as the first interplanetary spacewalk, in an age that placed much prestige on space "firsts". Apart from the three Apollo EVAs to retrieve SIM bay film cassettes, every other EVA from a spacecraft in freefall has taken place in low Earth orbit, never more than about 600 kilometres away from the home planet. This was still true at the time of writing thirty years after the event.

Scott, from the 1971 Technical debrief: "Hatch opening occurred about 5 minutes after the planned hatch opening. The integrity checks went very well. The procedures played just exactly as they were laid out in the checklist and just like we've seen them in the chamber. I'm glad we ran those chamber runs because that helped us, Jim and I, to understand what you were doing with your equipment."

Worden, from the 1971 Technical debrief: "I think so, too. We were all well prepared for the EVA."

Worden, from the 1971 Technical debrief: "After getting the hatch open, the first thing I did was take the TV and the DAC and mount them on the bracket in the hatch. The hatch didn't get fully opened the first time. When I got part way out, I guess you opened the hatch the rest of the way so that the camera was pointing down along the SIM bay. I just went outside the hatch, grabbed the first handrail, and positioned myself just outside the hatch until Jim got in the hatch to observe and to watch the umbilical."

Later in the Technical Debrief, when the crew discuss simulations, Al discusses the training he did in the WIF (Water Immersion Facility). This technique, where an EVA crewmember dons a spacesuit, modified for use underwater and weighted to give neutral buoyancy, to give an impression of how the body moves in a zero-g environment has become the preferred method of training for the lengthy EVAs performed almost routinely in low Earth orbit.

Worden, from the 1971 Technical debrief: "I thought the training program for the EVA was just right. There wasn't too much. I thought there was an adequate amount of training. The sessions in the WIF could have been reduced somewhat because the sensation of neutral buoyancy is sufficiently removed from zero-g that with too much training in the WIF, it almost turns out to be negative training. The operation is so much more difficult in the WIF than it is in flight or in the zero-g airplane that fewer sessions in the WIF would have been in order. Maybe one or two sessions in the WIF, instead of a large number of them, would be perfectly adequate. The zero-g airplane was invaluable. The one-g trainer going through the prep and the post was completely adequate. I thought that particular training program was outstanding."

This illustration outlines how Al is to progress along from the CM hatch to the foot restraints in the SIM bay. Having exited the CM (1), he uses handholds mounted all along the side of the Service Module (2) until he is over the bay (3). Further handholds surrounding the SIM bay allow him to rotate (4) until his feet are in the correct position to engage them in the foot restraint (5), giving him full access to the bay.

Worden, from the 1971 Technical debrief: "I went hand-over-hand down the SIM bay and to the left around the Mapping Camera. I just floated myself over the Mapping Camera instead of going around it down into the SIM bay. I put my feet in the foot restraints and just stood there for a minute, resting and looking at the SIM bay, and waiting for Jim to get himself positioned in the hatch."

Jim starts the 16mm Maurer movie camera about now using film magazine F and we can make a comparison with the video coverage to pin down the time. Unfortunately, the camera jams after exposing one frame. Dave's next utterance confirms the timing of this event.

Comm break.

Worden, from the 1971 Technical debrief: "The Pan Camera went just as I had anticipated it would go. I pulled the metallic cover off the Pan Camera and released it. Then, I pulled the fabric cover off. The force that it took to pull both of those covers off was just as I had expected and remembered from preflight. It was the same operation. I pulled the pin on the Pan Camera cassette, tethered myself to it, and pulled the release handle. It came out even easier than I had expected. The mass of the Pan Camera cassette was a little bit more than I had expected, but it was no problem handling it. I just very carefully drifted it back towards the hatch, keeping my hand on the handle and maneuvering myself back. I did release it at one time, because I had to use both hands to maneuver myself over the Mapping Camera. But I didn't release it clear to the end of the tether. I just let go for a minute, repositioned myself, and then grabbed it with the handle again. I thought that went very smoothly."

Worden, from the 1971 Technical debrief: "The transfer back through the hatch went just as we'd done before, too. I handed the Pan Camera cassette back in through the hatch. You tethered it and then released my tether. That was pretty much as we'd done before; no problems there."

Scott, from the 1971 Technical debrief: "I put it down in the LEB and it stayed. I left it on the tether and it never got in your way. No problem."

At some point during the EVA, Jim takes five photographs with a Hasselblad camera using magazine Q.

Comm break.

Worden, from the 1971 Technical debrief: "The Inconel cover on the Mass Spectrometer was cocked about 30 degrees from the closed position. I reached over and grabbed the cover and moved it a little bit. It's a fairly flimsy cover, but I wanted to see if it was jammed against anything. One corner seemed to be hung up. I released it, but the cover stayed where it was. I really couldn't close it. Then, I looked down inside the Mass Spec. itself and noticed that the guidepins were through the guide slots in the experiment itself, indicating that it had at least positioned itself on the base of the boom itself. I wasn't sure at the time. That's something I hadn't looked at preflight. I wasn't sure just how far those guidepins should come through the slots to indicate that the Mass Spectrometer was fully retracted. So I called down to the ground and said that the tip of the guidepins were just through the guideslot. They called back and said that it wasn't fully retracted then, because the guidepins should be through the slots far enough so that the cylindrical part of the guidepin could be seen. So, that indicated to me that the Mass Spectrometer wasn't fully retracted. That was all I could see on it. I couldn't see around the Mass Spectrometer. I couldn't see down into the SIM bay at that point because the cover was obscuring the view."

Worden, from the 1971 Technical debrief: "I pulled the cover off the Mapping Camera, I noticed that that particular cover was a little more difficult to release than I had anticipated. That particular cover is set under a flange on either side. It's held down by some pins at the release end of the cover. I had to twist it a little bit and pull it a lot harder than I had anticipated to release it from the flanges on the side. But, it did come off all right; there was no problem. The fabric cover underneath got hung up on one corner. The fabric has a rubber slot that it fits into around the edges, and it's almost an airtight seal. That rubber-slotted flange hung up in one corner, and I had to pull it three or four times before I got it released. After that, everything was just as I had anticipated."

Worden (continued): "I tethered the Mapping Camera cassette, released it, and it was a very easy operation after that. I brought it back into the hatch, as we had practised preflight."

Al's view of Jim at this point was the inspiration for a painting of the scene by Pierre Mion for National Geographic.

Worden, from the 1971 Technical debrief: "I think the concern at the time was that the Laser Altimeter/Mapping Camera contamination cover was binding against the side - forcing it to stay in the Extend position. I went back out and looked, and there was about three-fourths of an inch to maybe 1 inch clearance between the cover and the Mapping Camera itself. From that, I concluded that the cover hadn't anything to do with it. I looked underneath the Mapping Camera, and I looked around all of the edges to see if there was something binding, maybe something that had lodged alongside the Mapping Camera. Everything looked clean to me. There was nothing that was impinging on the Mapping Camera at all. The stellar shield was still out, but of course, it would be with the camera extended. At that point, it was maybe 12 to 15 inches away from the SIM bay mold line. So, there was nothing I could tell from there that would shed any light on why the Mapping Camera did not retract."

Worden, from the 1971 Technical debrief: "I went back in the hatch, pulled the quick release on the TV camera bracket, which we had decided to do preflight. Rather than releasing the handle itself, we pulled the Marmon clamp, releasing the pole. I sent the pole in the hatch, backed into the hatch myself, and pulled the hatch closed. I thought that went very easy. It took hardly any force at all to close the hatch. It operated very smoothly and very freely. I pulled it right down to the point where it was closed. A couple of pumps on the handle, and the latches were over and off. It was very simple operation."

Worden, from the 1971 Technical debrief: "Once we got the side hatch open, from that point to the time we closed the hatch, the whole operation went almost exactly as it had in preflight training, both in the zero-g airplane and the Water Immersion Facility. I don't recall anything during the EVA that I thought was off-nominal. As a matter of fact, it was so much like preflight, that I really had no anxieties about the EVA at all. The whole thing went just as smooth as it could."

Worden (continued): "It was just as we practised. That's the key to the whole thing - good solid practice before flight. Be well prepared for what's going to be out there and for the kind of body motions that are required to get back into the SIM bay and into the foot restraints."

Worden (continued): "In true zero-g it was really much easier than it had been even in the zero-g airplane. I think there's some rotation that you get in the zero-g airplane that does affect your motions a little bit. True zero-g is just much easier. If you can do it in a zero-g airplane and in the Water Immersion Facility, in flight it is easy."

Comm break.

Al gets a question along the same lines during the inflight press conference tomorrow. When asked why he came in so soon, he answered that he came in when the job was done. The following interview with Dave, conducted in 2004, was before I discovered it was Worden who said he should have stayed out longer.

Woods, from 2004 mission review: "Al seemed to spend an awful short time outside. You told him you should have stayed there longer. He was all for get out there, do the job, get back in. That seems a bit of a shame from his point of view."

O'Brien, from 2004 mission review: "I would imagine that you would have a little bit of free time, but this wasn't time critical. You were plugged into the CSM. You weren't in a rush."

Scott, from 2004 mission review: "Weren't in a rush, but on the other hand, the purpose was to get the film and get back in. I think Al did the right thing. Came back in. I mean, it'd be nice to stay out and float around and look around but, why? So if you stay out and float around and look around and then something goes wrong during that period, then you say, 'Why did I do that?' So I think what you do is you do your job and you get back in and close the hatch and say, 'Gee, that was wonderful. I had a great time. I did my job.' I think to float around out there is exposing yourself to an unnecessary risk. It's low risk, but on the other hand, it's high risk. So what if that last minute is a time you popped a leak for some reason? Eh? So shoot, get the job over. As sort of an analogy, we used to fly airplanes in bad weather. Rule was always; go to your destination, finish your mission and then play around because if you got to get down, you got fuel."

Woods, from 2004 mission review: "You say to him here, 'You should have stayed longer.'"

Scott, from 2004 mission review: "He got it done very quickly and very efficiently and came back in and the comment is, 'Geeze, you were having a good time. Why didn't you stay a while?' But I didn't really mean that. I meant it in a positive way. 'You should have stayed out there and stayed longer. You were doing really great, terrific.' But if you look at the seriousness of it, he did exactly right. He got his job done and he got in."

Woods, from 2004 mission review: "On both of your Apollo flights, somebody went out through the main hatch of the Command Module. That's an impressive piece of engineering, an outgoing door that holds against 5 or 6 psi. After the Apollo 1 tragedy, were you involved at all in the redesign of that?"

Scott, from 2004 mission review: "Yeah. They had all these working groups to fix all the problems. Not just the fire-related problems. All the problems kind of stuff. And I was on the working group with the probe and drogue and with the hatch and with the EMS and something else. But, yeah, I was pretty much in the middle. And in the hatch thing, they brought McDonnell Douglas guys in to really help them with that."

O'Brien, from 2004 mission review: "Really?"

Scott, from 2004 mission review: "Yeah, well, Gemini had an outward-opening hatch, right? They brought in the MacDac guys to help the Rockwell guys redesign the hatch."

Woods, from 2004 mission review: "And as it happened, you were the first person to really test it on Apollo 9."

Scott, from 2004 mission review: "Ah, but it worked. It was really a good hatch."

Long comm break.

Comm break.

Comm break.

EVA times are measured from the time cabin pressure indicates less than 3.5 psi until it rises above this figure again. Although nearly 40 minutes were clocked for the EVA, the hatch was only open for twenty of those, though the Flight Plan had 53 minutes set aside for it.

Long comm break.

The crew are raising the cabin pressure by bleeding the contents of the OPS oxygen bottle. The Flight Plan calls for them to do this until the bottle is depleted. However, on this occasion, doing so provides too much air. With the cabin repressurised, they can doff their suits and begin configuring the cabin for the rest of the journey home.

With the cabin returned to pressure, the crew can settle down for the remainder of their day which will be taken up with UV photography, a little bit of X-ray astronomy and another period of onboard navigation exercises using Program 23.