On the day after TEI, the command module pilot of the J-missions took centre stage. The cameras of the SIM bay had photographed their images onto long lengths of photographic film stored in large circular magazines, which were now sitting in the service module, itself to be discarded in a few days time when it would burn up and be destroyed in Earth's atmosphere. The film therefore had to be brought into the command module's cabin, the only part of the spacecraft that would survive reentry. To bring it in, the CMP had to perform a spacewalk.
Extravehicular activity (EVA) is the name NASA gave to what everyone else calls walking in space. At the time of Apollo, it specifically referred to time spent in a space suit when the air pressure outside the suit could no longer sustain life. It was another of those essential techniques for Apollo that NASA had to learn during the Gemini programme.
Edward White, on Gemini 4, was the first NASA astronaut to leave his spacecraft. Part of his brief was political, as America wanted their spacewalking astronaut to stay outside longer than Alexei Leonov had done for the Soviets a few months earlier. White floated around on the end of his umbilical and gingerly tried various techniques for moving around outside a spacecraft. Apart from some exertion when getting back into the cramped cockpit, White made EVA appear easy.
When Eugene Cernan attempted to don a jet-powered back pack on Gemini 9, he was the first to attempt to do substantial work during EVA. Cernan quickly found how difficult it was to keep control of body position in a completely Newtonian environment. The slightest twist, push or turn against the spacecraft would send his mass flailing away from where he wanted to go. Soon, the stress of his exertions began to take a toll on him, and because the suit could not cope with the heat he was generating, his visor began to fog up on the inside. When he was exhausted, he was called back by his commander, Tom Stafford. Almost unable to see through his visor, he drew himself hand over hand along his umbilical back to the hatch. Re-entering the cabin proved to be even more terrifying, as the two crewmen, their suits stiff with the air pressure within, battled to get Cernan far enough down into his seat to be able to shut the door.
In light of what could have been a horrifying incident, NASA began to treat EVA very seriously indeed. During the final three flights of the Gemini programme, Mike Collins, Dick Gordon and Buzz Aldrin refined the techniques needed for safe operations outside a spacecraft. Handholds and foot restraints were added, a methodical approach was taken to all the movements needed for the EVA, and an underwater facility for training was developed.
For all the experience that was gained on Gemini, little actual EVA time was logged during the Apollo Moon programme in terms of a crewman floating outside the hatch of a weightless spacecraft. A lot of outside activity was logged on the Moon, but this was in a one-sixth g environment that the crews found very pleasant. During the Earth orbit operations on Apollo 9, Dave Scott and Rusty Schweickart had made tentative forays out of their CM and LM respectively: Scott just putting his head out of the CM hatch while Schweickart placed his feet in so-called 'golden slipper' foot restraints on the LM's porch for a test of the back packs the crews would wear on the Moon. From Apollo 10 to Apollo 14, no crewman left the CM hatch for an EVA, although all crews trained for the possibility that, in the event of a docking problem, they might have to transfer from the LM to the CM via an EVA through the side hatches of both vehicles. When space walking finally came to Apollo on the last three Moon flights, it was something special. Only Alfred Worden, Ken Mattingly and Ron Evans have the distinction of having performed an interplanetary EVA when they ventured outside the CSM to retrieve film magazines from the SIM bay.
Preparation for the EVA took a considerable amount of time because the spacecraft was packed with boxes of rock samples from the lunar surface. Also, three crewmen had to get suited up in the confined space of the CM, each methodically helping the other to check the integrity of his suit. Oxygen for all three men came from the spacecraft's suit circuit with a particularly long umbilical for the CMP to allow him to get to the SIM bay. This made for a cluttered cabin with gloves and helmets floating among loops of hoses while three astronauts clambered into cumbersome space suits, two of which were extremely dirty from 20 hours of work in the dust and dirt of the lunar regolith.
The CMP carried an additional emergency supply of oxygen from a package his crewmates had brought back from the Moon. The oxygen purge system (OPS) normally sat at the top of a crewman's PLSS back pack when used on the lunar surface. Its function there was to act as a standby in case of a failure in the suit. If a hole were to open up in the suit or a problem were to occur with his oxygen supply, the OPS could supply oxygen from a very high pressure tank that would give the crewman extra minutes to deal with the situation. Although the backpacks were jettisoned on the surface, the OPS were returned with the surface crew in case they had to support an EVA from the LM to the CSM. One of the OPS was transferred to the CSM to give their colleague an emergency supply during his EVA.
A television camera and a film movie camera were mounted on a pole so that, once the hatch door was fully open, the pole could be inserted into a receptacle in the door, raising the cameras high enough to film the EVA and give Houston a live view of its progress. The spacecraft's attitude was changed so that the Sun shone obliquely across the SIM bay, but did not shine directly into the cabin. All of its RCS thruster quads were then disabled, except for the one furthest from the SIM bay, so that minor manoeuvres could still be carried out while the CMP was outside.
When all the crewmembers were safely sealed into their suits, the air in the cabin was expelled to space by opening a valve in the main hatch. Then, once the internal pressure in the cabin had dropped to a very low level, the main hatch could be opened, venting the last wisps of gas. ''Okay, Houston. The hatch is open.'' Cernan, now in command of his own mission, Apollo 17, and an EVA expert himself, kept a close eye on his two rookie crewmen, Jack Schmitt and Ron Evans. Schmitt's role on the EVA was to stand in the hatch and keep an eye on Evans, look after his umbilical and take the film magazines from him, passing them down to Cernan.
''Hey, there's the Earth, right up ahead,'' said Evans as he positioned himself in the hatch. ''The crescent Earth.''
''Okay, Ron. You've got a Go for egress,'' informed Cernan.
''Beautiful,'' replied Evans.
''Okay, and just take it slow,'' said Cernan, speaking from experience.
The door shielded the hatchway from the Sun. ''Man, that Sun is bright,'' said Evans as he cleared the door. He was wearing a lunar extravehicular visor assembly (LEVA) that had been worn by one of his colleagues on the Moon and brought with them in the ascent stage.
''Pull down that visor, Ron. You're going to need it,'' advised Cernan.
''You're a long way from home. We don't want to lose you.''
The LEVA went over the crewman's clear helmet to provide additional protection from the light and heat of the Sun, and as extra protection from micrometeorites. It included two visors that could be pulled down if needed; a clear visor for additional UV blocking; and a sun visor that was coated with an extremely thin layer of gold to reject both light and heat. This gold visor has become part of the astronaut's iconography, being seen in all the most famous images showing a man on the Moon.
On Apollo 16, it was Ken Mattingly who made the EVA to the SIM bay. ''Okay. How about if I get rid of the jett bag first?'' One of the first tasks was to throw out the trash. All the disposable items they could find were packed into one bag that was gently pushed into deep space, probably to enter Earth's atmosphere and burn up a few days later.
''Bye-bye, bag. Okay. Okay, I'll go out and get the TV.''
As Mattingly squinted in the Sun, he reminded Charlie Duke to bring down his visor too.
''Ooh! Charlie, you'll need the outer visor as soon as you get into the hatch.'' Mattingly manhandled the coils of his umbilical out of the hatch then placed the camera pole into its receptacle in the door. He then worked his way along the handles, hand over hand, to the SIM bay, inspecting the side of the service module as he went. The CMPs' training had helped them define that the best way to get to the bay was to move along the SM until hovering above the instruments, then use the handholds around the bay to get into the correct position for placing the feet into a restraint. Once there, Mattingly glanced towards where the spacecraft was pointed and caught sight of the Moon with most of its disk illuminated by the Sun.
''Oh, man. Man, the old Moon's out there. Okay, going after the pan camera. Okay, here comes the hard cover - gone.'' He threw the outer metallic cover of the pan camera cassette away then removed the soft, inner cover that had been velcroed in place, throwing it off into space. ''Soft cover has gone. Okay, I'm going after the hook.'' He attached a tether to the magazine as the Sun beat down from his right making him glad he was wearing Young's LEVA. ''Boy, that old visor of yours -that outer visor on the glare shield really comes in handy.''
Mattingly continued removing the giant cassette. ''The pip-pin is out, and I'm throwing it away. Okay, get my feet out. There's one. There's two. Okay.'' As soon as his feet came free, he involuntarily rotated as if he was doing a handstand on the spacecraft and had to pull himself back in with his hands. With the magazine tethered to his wrist, he manoeuvred across the module towards Duke in the hatch and passed the heavy object across for Duke to send it through to Young inside.
When Ron Evans got his opportunity to go outside his CSM America and retrieve
the film cassettes, no one could have been happier about it than he was. Throughout his EVA, he hummed and chatted with a boyish delight in what he was doing. Working away outside the spacecraft, he waved at the camera. ''We see you waving,'' informed Houston.
''Hey, this is great!'' said Evans, his voice up an octave in the joy of being outside of the cramped cabin where he had been for over 10 days. ''Talk about being a spaceman? This is it!''
Evans took a look at the damage the SM skin had sustained during the flight. ''Okay. Beautiful! Hey, the paint on here - it's a silver paint and it's just got little blisters on it. You just kind of peel it off with your fingers.'' Then he described his position between the two worlds. ''I can see the Moon back behind me! Beautiful!
The Moon is down there to the right - full Moon. And off to the left, just outside the hatch down here, is a crescent Earth.'' Looking at Earth, he noticed how the atmosphere scattered the sunlight towards the night side, extending the crescent. ''But the crescent Earth is not like a crescent Moon. It's got kind of like horns, and the horns go all the way around, and it makes almost three-quarters of a circle.''
Having manoeuvred into the correct position, he tried to settle into the golden slippers. ''Okay, I'm having a little trouble, right now, just torquing down to get my foot in the foot restraint, for some reason. Okay, the right one's in. And the left one's in. Hey, pretty stable right here. Let go of both hands? See?''
Happy as he could be, he went after the radio sounder's cassette. ''Okay, let's try the old cassette. We'll push down on it until it goes past centre. Ah-ha! I think that was more than [the expected] two pounds of force to come out, but it came out. And I've got the film.''
He brought the cassette to Schmitt and then returned for the panoramic camera's film, all the time revelling in the experience.
''Houston, this is - Let's see, when you're EVA, they use your name, don't they?'' He wasn't simply '17' now.
''Okay, Ron,'' humoured Houston. ''Yes, sir, we'll use it, Ron.'' ''Houston, this is Ron, okay?'' announced a gleeful Evans. ''You hear me okay, I guess, huh?''
''Roger, Ron,'' replied Houston. ''Read you loud and clear.'' ''Okay,'' laughed Evans. ''Oh, this is great, I'll tell you!''
''Yes, we thought it was Mr. America.'' With a pun on the name of the CSM, Houston was gently mocking him, but in his happiness he took it in good heart.
''Well, it is. Something like that. Oh, boy! Beautiful Moon! Full Moon down there. I can see the engine bell sitting back here. That's a pretty good-sized thing, too. And, of course, the VHF antenna is still sticking out there.''
Evans held up the panoramic camera's thermal cover for Houston to see. ''Can you see that? The thing I'm holding up. It's the cover that's on the outside of the pan camera. It's a thermal cover, see, that covers up the cassette.'' ''Roger. Yes, we see it, Ron,'' confirmed Houston.
''Whooooee!'' laughed Evans as he tossed the cover past the camera's field of view.
Houston noticed. ''We just saw that cover.''
Humming away to himself, Evans attached the magazine to his wrist and pulled it free.
''Out she comes. Nice and easy. This is a heavy son of a gun. Not heavy up here; it just has a lot of momentum to it. Once she starts pulling in one direction, it just takes a lot of force to stop it.''
As he hand-walked his way along the handholds, he noted how the heavy object moved. ''Hey, it's just kind of coming along with me. I'll just let her do that. Hey, she's just floating there. That's good. Nice and slow, because you don't want that thing banging around too much up there, I don't think. That's the way it ought to be done, isn't it?''
Evans passed the cassette to his colleagues and returned to the SIM bay for the
mapping camera cassette. As he did, he found he was becoming used to the mechanics of getting around in space, and decided to go back down to the SIM bay, aiming his feet directly for the restraint. ''You know, I'll just go backwards down there.'' He hummed away to himself as he shimmied down the spacecraft.
''That's an unorthodox way to enter the SIM bay, but it works. Once you get your feet in there, you almost feel like maybe they might come out, you know,'' he laughed. ''So I'm not sure you really trust them. The right foot's in good and tight. Hello, Mom!''
''We see you, Ron. Looking great,'' called Houston. The MOCR were enjoying Evans' show as much as he was enjoying giving it. He then called to his children.
''Hello, Jan. Hi, Jon. How are you doing? Hi, Jaime. Let's see, I'm supposed to rest, though, aren't I? What would you like to know about the SIM bay? Looks great.''
When compared to the light-hearted and longer EVAs by Mattingly and Evans on the later flights, Al Worden's foray to the SIM bay on Apollo 15 was a quick, ^^^^^^^^^^^^^^^^^^^^^^^^^ efficient affair where, although he
- ' enjoyed the experience, he wasted
• little time on enjoying the view.
^ ? However, as he started to bring the
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