Richard Lawrence - The Mammoth Book of Space Exploration and Disaster

Haise was on watch when:

Just as Haise approached the right-hand window, a chillingly familiar bang-whump-shudder shook the ship. He shot his hand out, braced himself against the bulkhead, and froze in mid-float. The sound was essentially the same as Monday night’s bang, though it was unquestionably quieter; the sensation was essentially the same as Monday night’s shudder, though it was unquestionably less violent. The locus of the event, however, was utterly different. Unless Haise was mistaken – and he knew he wasn’t – this disturbance had not come from the service module, at the other end of the Aquarius-Odyssey stack, but from the LEM descent stage below his feet.

Haise swallowed hard. This should be the helium burst disk blowing: if the ground has told you to expect a venting and a moment later your ship bangs and rocks, chances are the two are connected. But viscerally, Haise – the man who understood Aquarius better than anyone else on board – knew this wasn’t true. Burst disks didn’t sound this way, they didn’t feel this way, and, floating cautiously up to his porthole and peering out, he also saw that they didn’t look this way. Just as Jim Lovell had discovered vented gas streaming past his window more than forty hours ago, Haise, the LEM pilot, was alarmed to see much the same thing outside his window now. Drifting up from Aquarius’s descent stage was a thick white cloud of icy snowflakes, looking nothing at all like misty helium streaming from a burst disk.

“OK Vance,” Haise said as levelly as he could, “I heard a little thump, sounded like down in the descent stage and I saw a new shower of snowflakes come up that looked like they were emitted from down that way. I wonder,” he said somewhat hopefully, “what the supercritical helium pressure looks like now.”

Brand froze in his seat “OK,” he said. “Understand you got a thump and a few snowflakes. We’ll take a look at it down here.”

The effect of this exchange on the men in Mission Control was electric.

“You copy that call?” Dick Thorson, at the CONTROL console, asked Glenn Watkins, his backroom propulsion officer.

“Copied it.”

“How’s that supercrit look?”

“No change, Dick,” Watkins said.

“None?”

“None. It’s still climbing. That wasn’t it.”

“CONTROL, Flight,” Gerry Griffin called from the flight director’s station.

“Go, Flight,” Thorson answered.

“Got an explanation for that bang?”

“Negative, Flight.”

“Flight, Capcom,” Brand called.

“Go, Capcom,” Griffin answered.

“Anyone know what that bang was about?”

“Not yet,” Griffin said.

“Anything at all we can tell him, then?” Brand asked.

“Just tell him it wasn’t his helium.”

As Brand clicked back on to the air-to-ground loop and Griffin began polling his controllers on the flight director’s loop, Bob Heselmeyer at the TELMU station began scanning his console. Looking past the oxygen readouts, past the lithium hydroxide readouts, past the CO 2and H 2O readouts, he noticed the battery readouts, the four precious power sources in Aquarius’s descent stage that, working together, were barely providing enough energy for the exhausted, overtaxed ship. Gradually, the readout for battery two – just like the too easily recalled readout for Odyssey’s O 2tank two – had slipped below what it should be and was failing steadily.

If the data were right, something had arced or shorted in the lunar module’s battery, just as it had arced or shorted in the service module’s tank on Monday night. And if there had been a short, the battery, like the tank would soon go off line killing fully one quarter of a power supply that Houston and Grumman were rationing down to the last fraction of an amp. The numbers on the screen were too preliminary to be conclusive – too preliminary even for Heselmeyer to pass them on to Griffin. And if Heselmeyer didn’t pass them on to Griffin, Griffin couldn’t pass them on to Brand, and Brand couldn’t pass them on to Haise.

At the moment, that was probably just as well. Standing at his window and looking out at the growing cloud of flakes surrounding the bottom of his LEM, Fred Haise had more than enough burdens of command.

It was battery two in the LEM which had four batteries, each one designed to compensate for loss of power in any of the others. The damaged battery was still working despite the small explosion.

The astronauts were still wearing their bio-medical sensors. Lovell pulled his off because they were becoming uncomfortable and to conserve power. When the Capcom found out he just said “OK”.

Houston wanted Odyssey to be powered up because the systems were sensitive to the cold. Capcom told Lovell that the explosion was a minor one in battery two in the LEM and that a burn for realignment of the re-entry angle was required.

Meanwhile the crew were beginning to experience health problems and had decided to drink as little as possible when the capsule began to become cluttered with bags of urine. Venting helium was eroding the re-entry angle.

Lovell regarded both his crewmates and reflected on what he ought to do next, but before he could reach any conclusions, his thoughts were interrupted. From beneath the floor came a dull pop, then a hiss, then another thump and vibration ratted through the cabin. Lovell leapt forward toward his window. Below the cluster of thrusters to the left of his field of vision, he could see a far too familiar cloud of icy crystals floating upward. For an instant Lovell was startled, and then just as quickly he knew what the sound and the vent were.

“That,” he said, turning to his crewmates, “was the end of our helium problem.”

They re-established the PTC roll.

At 8 pm on Thursday, 16 April the re-entry angle was beginning to decay again. The Atomic Energy Commission was concerned about a fuel rod in the LEM which should have been left behind on the moon, in the descent stage. Although the LEM would be jettisoned in space it would eventually fall to earth, so the Atomic Energy Commission wanted to ensure that it fell into the deepest water possible.

The food supplies in Odyssey had frozen solid. They had to decide the best way to handle the separation of Odyssey and Aquarius.

When the time came to jettison the service module, they decided Jim Lovell and Fred Haise would stay in the LEM, while Jack Swigert would scramble up into the command module. Moments before separation, Lovell would fire the LEM’s thrusters for a single pulse, pushing the whole spacecraft stack forward. Swigert would then press the button that fired the service module’s pyrotechnic bolts, cutting the huge, useless portion of the ship loose. As soon as he did, Lovell would light his thrusters again, this time in the opposite direction, backing the LEM and its attached command module – with Swigert aboard – away from the drifting service module.

Easier, but no less elegant, was the procedure for jettisoning the LEM. Before a lunar module was released on a normal mission, the astronauts would close the hatch in both the lander itself and the command module, sealing off the tunnel from the cockpits of either ship. The commander would then open a vent in the tunnel, bleeding its atmosphere into space and lowering its pressure to a near vacuum. This would allow the twin vehicles to separate without an eruption of air blowing them uncontrollably apart.

During the flight of Apollo 10 last spring, the controllers had experimented with the idea of leaving the tunnel partially pressurized, so that when the clamps that held the vehicles together were released, the LEM would pop free of the mother ship, but in a slower, more controlled way than it would if the passageway between the two spacecraft was fully pressurized. This method, the controllers figured, would come in handy if a service module ever lost its thrusters. Now, a year later, a service module had done just that and the flight dynamics officers were glad they had the maneuver tucked away in the contingency flight-plan books. Yesterday, the procedure had been explained to Jack Lousma, and the Capcom had proudly relayed it up to Lovell.