EVA PREPARATIONS

The checklist for donning and checking the accoutrements required to venture out onto the surface was lengthy and excruciatingly detailed. First, each man unstowed his PLSS from its mount on the side wall and stood it on the floor by the forward hatch, then the bags containing the extravehicular gloves and helmet augmentation were retrieved and deposited on the floor next to the backpacks. Next, Armstrong retrieved the OPS packages from the stowage compartment on the side wall. In the event of the primary oxygen supply failing during the moonwalk, the OPS – which would be mounted on top of the PLSS backpack – contained sufficient oxygen to facilitate an emergency ingress and switch back to the cabin’s supply. Finally, he retrieved the remote control units containing status displays for the PLSS and radio system that were to be worn on the chest, and the light-blue deeply treaded rubber overshoes for firm traction outside in the weak lunar gravity. After Aldrin assisted Armstrong to put on his overshoes, Armstrong did so for Aldrin. Aldrin transferred his PLSS to the circular cover of the main engine of the ascent stage, added the OPS, then turned around and reversed up against the backpack. Armstrong helped him to fasten the waist and shoulder harnesses, which clipped to rings on the suit, attach the chest unit to the shoulder harnesses, and run the oxygen umbilicals from the PLSS to the sockets on the front of the suit. Aldrin then helped Armstrong to do likewise. The next step was to conduct a communications check with the portable radios. Aldrin disconnected his cabin communications umbilical and plugged in the one from his PLSS, and Armstrong did the same. As the backpacks projected 10 inches to the rear, they greatly reduced the scope for movement in the cramped cabin. On Earth the backpack weighed 120 pounds but on the Moon it was only 20 pounds. However, it retained its inertia and if it were to even nudge against the lightweight structures it would deliver a significant impact.

“Houston,” Collins called, “could you enable the S-Band relay at least one way from Eagle to Columbia, so that I can hear what’s going on?”

“There’s not much going on at the present time,’’ McCandless noted, “but I’ll see what I can do about the relay.’’

As part of the PLSS communications checks, the crew switched to VOX, and although this enabled people to listen in, the terse to and fro was not particularly illuminating for anyone without a checklist. McCandless participated only when addressed.

As 108 hours approached, Public Affairs Officer Jack Riley announced, “We do not at this time have a good estimate for the start of the EVA.’’ The astronauts were 30 minutes behind on the checklist, and slipping further. Jan Armstrong, on the floor in front of the television, laughed. “It’s taking them so long because Neil is trying to decide about the first words he’s going to say when he steps out on the Moon.’’ In the Collins home there was impatience rather than tension. Pat Collins sat with a plate of lasagne in the company of Clare Schweickart, Barbara Gordon and Mary Engle. Rusty Schweickart was attempting to follow the preparations by listening to the squawk box, but the astronauts’ commentary was not particularly informative. Noting that her husband had requested a one-way relay to enable him to listen in to transmissions between Eagle and Houston while on the near side of the Moon, Pat suspected that he would be on the far side when the moonwalk started, and therefore miss it. Joan Aldrin was relaxing, listening to Duke Ellington records. On breaking off, she said to Audrey Moon, “I’ve thought sometimes, privately, and may even have said so to Buzz, that he was so caught up in the mechanics of all this that he really hadn’t realised the significance of what he was doing; but now I really think he did!’’ She settled down to a plate of buffet nibbles and awaited developments.

Advancing through the preparations, Aldrin inserted the circuit breaker for the television system. “Houston, are you getting a signal on the television?’’ he asked. The MESA compartment was still in its stowed position, denying illumination to the camera inside, but the system was transmitting.

“The data we’re receiving looks good,’’ said McCandless, “and we’re getting synchronisation pulses and a black picture.’’

With the Sun low in the east, the 23-foot-tall vehicle was casting a very long shadow, and the ladder on the forward leg was facing westward. “You’ll find the area around the ladder is in a complete dark shadow,’’ Armstrong pointed out, “so we’re going to have a problem with the television, but I’m sure you’ll be able to see the lighted horizon.’’

“We request that you open the television circuit breaker,’’ McCandless called. “It’s been on about 15 minutes now, with the MESA closed.’’ Houston wanted it switched off to preclude the camera overheating in the insulated compartment. Aldrin was to have pulled the circuit breaker immediately following the test, but had missed a step on the checklist.

“Do we have a Go for cabin depress?’’ Armstrong asked.

When there was no response, Aldrin quipped about VOX letting Houston listen

A diagram of the Extravehicular Mobility Unit.

in, “They hear everything but that!” He made the call himself just in case there had been a fault with Armstrong’s radio. “Houston, this is Tranquility. We’re standing by for a Go for cabin depress.’’ Actually, the delay was because Charlesworth was polling his flight controllers. McCandless ought to have replied to Armstrong with a ‘Standby’.

“You’re Go for cabin depressurisation,’’ McCandless replied finally.

In fact, they were currently some 22 minutes behind their 108:00 estimate, and had just received permission to proceed with the final phase of the preparations; it would be another half hour before they would be ready to start the depressurisation of the cabin. With the moonwalk imminent, the Apollo 12 LM prime and backup crews of Pete Conrad, Al Bean, Dave Scott and Jim Irwin joined McCandless. Gene Kranz returned and sat with Charlesworth to watch the telecast on one of the wall screens.

Having configured the cabin for exposure to vacuum, Armstrong and Aldrin were able to finish suiting. Once the cooling system had been checked, the water umbilical was run from the PLSS to the suit to circulate water through the liquid coolant garment. The umbilical to the cabin’s oxygen system was removed, and the OPS umbilical was plugged into the vacant sockets. After he had applied an anti-fogging agent to the inside of Aldrin’s ‘bubble’ helmet, Armstrong slipped it over Aldrin’s head and locked it into position. He followed up with the polycarbonate shell incorporating the visor assembly that provided an inner and outer visor. The outer visor had a gold coating to reflect the harsh glare from the Sun which, in the absence of an atmosphere, was not only bright but also full-spectrum. Aldrin then repeated the procedure for Armstrong. Finally, they donned their extravehicular gloves, which had coverings of woven steel-fibre and rubberised finger tips for a modicum of dexterity. Taken together with the PLSS, OPS, helmet augmentation, extravehicular gloves and overshoes, the suit was described in NASA-ese as the extravehicular mobility unit. Aldrin wore a watch over the gauntlet-like sleeve of the right glove, but Armstrong decided to leave his watch inside as an emergency backup to the spacecraft’s event timer. A checklist for the external activities had been stitched onto the gauntlet of each left glove, listing that man’s specific tasks. Owing to uncertainty regarding the metabolic rate of an astronaut working on the lunar surface, and the fact that no one knew for certain how long the coolant water would last, the duration of the moonwalk had been set conservatively. However, the ‘clock’ on the life – support system started when the PLSSes were activated to pressurise the suits prior to depressurising the cabin.

‘‘Now comes the gymnastics,’’ Armstrong observed.

Aldrin carefully reached down and opened the valve built into the waist-high forward hatch, and then they monitored the pressure meter, which was initially at 4.8 psi. The depressurisation was slowed by the bacterial filter incorporated into the valve to protect the lunar environment from terrestrial biota, lest this be sampled, returned to Earth and misinterpreted as evidence of lunar life. As the pressure decreased, the rate of decrease slowed as it took time for the remaining gas molecules to find their way to the vent valve. ‘‘It sure takes a long time to get all the way down, doesn’t it?’’ mused Aldrin. When the pressure fell below 0.2 psi he tried the hatch, but it would not budge.

‘‘Neil, this is Houston. What’s your status on hatch opening?’’ McCandless called 10 minutes into the procedure.

‘‘Everything is Go here. We’re just waiting for the cabin to blow enough pressure to open the hatch. It’s about one-tenth on our gauge now,’’ Armstrong replied. Fifteen seconds later, he announced, ‘‘We’re going to try it.’’ But even at 0.1 psi, the 32-inch-square hatch would not open. Aldrin suggested that they also open the overhead valve, but they decided to wait. The cabin had vented sooner in altitude chamber tests, but as a chamber never establishes a perfect vacuum this had not given an accurate time measurement. As the hatch was only a thin metal cover of little rigidity, Aldrin carefully peeled back one of its corners to break its seal. Ice crystals formed as the residual air rushed out. Aldrin then readily hinged the hatch in towards his feet. “The hatch is coming open,” Armstrong announced.

“The valve’s in Auto,” Aldrin confirmed as he set the hatch valve to enable it to be operated from the outside.

The final task was to install the lunar equipment conveyor (LEC). This was a long nylon tether with a hook at each end to enable it to be linked into a loop and run around a pulley on a fixture located in the cabin. It had additional hooks on it to attach equipment for transfer to or from the surface. For Armstrong’s egress, the tether was hooked to the tie-down strap of his neck-ring as a safety precaution. With the hatch open wide, Armstrong faced aft and, with one hand leaning on the cover of the ascent engine, carefully lowered himself until he was kneeling on the floor with his feet in the hatch. Then Aldrin provided cues to help him to reverse out. With the bulky PLSS on his back it was a tight fit, but the hatch was already as large as the vehicle’s design could accommodate. Rusty Schweickart called to those in the Collins home that the hatch was finally open. Listening to Aldrin assisting Armstrong out, Schweickart remarked, “Don’t bump into anything! Just find the ladder, Neil!’’ When CBS anchorman Walter Cronkite wondered why Armstrong was taking so long, Schweickart muttered that it was “because he doesn’t have eyes in his rear end’’. Armstrong reversed out across the porch more or less flat on his stomach until his boots were at the far end, then he grasped the side rails and pushed himself up onto his knees. Aldrin pushed a bag of packaging through the hatch, and Armstrong dumped it over the side. By this point, they had been living off their PLSS resources for 25 minutes.

“Houston, I’m on the porch,’’ Armstrong announced.

Fifteen seconds later, Aldrin started the Maurer 16-millimetre camera that he had earlier installed on the bracket in the top-right corner of his window. Since he had no viewfinder, he adjusted it as best he could to view Eagle’s shadow, with a little of the illuminated lunar surface to each side. Armstrong entered the frame 30 seconds into the sequence.

“Stay where you are a minute, Neil,’’ called Aldrin. In preparation for his own egress, Aldrin partially closed the hatch to enable him to cross to the left-hand side of the cabin, and he did not want Armstrong to snag the tether on the hatch.

“Can you pull the door open a little more?’’ Armstrong prompted, when told he could continue.

“All right,’’ said Aldrin, and he opened the hatch fully, into the space where he had previously been standing.

As Armstrong prepared to descend the ladder, Columbia passed ‘over the hill’ and, deprived of his relay, Collins’s eagerness to hear what Armstrong would say as he stepped onto the lunar surface was frustrated.

In case Armstrong had forgotten to deploy the MESA, Aldrin asked, ‘‘Did you get the MESA out?’’

“I’m going to pull it now,” Armstrong replied. He located the D-ring alongside the porch using his left hand, and tugged it. The pallet on the front-right quadrant of the descent stage hinged down until just short of horizontal. “Houston, the MESA came down all right.’’

“Roger,” replied McCandless. “And we’re standing by for your TV.’’

“The television circuit breaker is in,’’ reported Aldrin. The transmission was by the high-gain antenna.