Richard Lawrence - The Mammoth Book of Space Exploration and Disasters

A cloud of tiny, luminous particles swarmed past the window.

“Ahhhhhhhh!” he exclaimed, to the tape recorder. “Beautiful lighted fireflies that time,” explaining, “it was luminous that time.” Banging repeatedly on the hatch, he was rewarded with explosions of cloud after cloud of luminous particles from the spacecraft.

“If anybody reads,” Scott explained excitedly, “I have the fireflies. They are very bright. They are,” he announced with triumph, “capsule emanating!” He quickly explained the cause and effect that proved his finding: “I can rap the hatch and stir off hundreds of them. Rap the side of the capsule: huge streams come out.”

He would yaw around the other way to get a better view, he reported. With his photometer handy, Scott estimated that the fireflies might register at a nine on the device and proposed to find out. “I’ll rap,” he told Woomera, now out of range. “Let’s see.”

The official NASA history of Project Mercury notes that:

Until Aurora 7 reached the communication range of the Hawaiian station on the third pass, Christopher Kraft, directing the flight from the Florida control center, considered this mission the most successful to date; everything had gone perfectly except for some overexpenditure of hydrogen peroxide fuel.

This overexpenditure was traced to a spacecraft system malfunction that went undiagnosed until after the flight.

At 04 22 07, Hawaii Capcom established ground communications.

Carpenter responded: “Hello, Hawaii, loud and clear. How me?”

But the signal from Aurora 7 was weak, so for half a minute pilot and Hawaii Capcom struggled with communication frequencies.

Carpenter asked: “Roger, do you read me or do you not, James?”

Capcom replied: “Gee, you are weak, but I read you. You are readable. Are you on UHF-Hi?”

Carpenter confirmed: “Roger, UHF-Hi.”

Reading off the flight plan, the capcom immediately told Scott to reorient the capsule and go to autopilot – the old ASCS. Scott replied six seconds later: “Roger; will do,” and, complying, at 04 22 59, repeated:

“Roger; copied. Going into orbit attitude at this time.” Retrosequence, as both Scott and capcom were aware, was fast approaching. With retro-rockets to be fired at 04 32 30 – ten minutes away – the flight plan called for equipment stowage and retrosequence checklists to begin at 04 24 00, allotting two minutes for these tasks, and then one more minute until LOS. Hawaii Capcom’s sense of urgency was evident:

“Roger, are you ready to start your pre-retrosequence checklist?”

Carpenter confirmed: “Roger, one moment.”

The Navy adage, “Aviate, Navigate, Communicate,” always in that order, was never more apt – now for the first time in space. In the grip of this instinct, Scott was properly engrossed with a critical retrosequence maneuver. He finally explained to Hawaii Capcom:

“I am aligning my attitudes. Everything is fine.”

Anticipating the capcom’s request, he said: “I have part of the stowage checklist taken care of at this time.”

Stowage is important. You can’t have equipment flying around the cramped compartment during entry. More important still, however, is aligning the spacecraft. Twice more, at 04 25 11 and 04 25 55, the Hawaii Capcom prompted Scott to begin the pre-retrosequence list.

Capcom asked: “Aurora 7, can we get on with the checklist? We have approximately three minutes left of contact.”

Carpenter confirmed: “Roger, go ahead with the checklist. I’m coming to retroattitude now, and my control mode is automatic, and my attitudes [are] standby. Wait a minute. I have a problem in—”

Thirty-three seconds passed. Scott confirmed the “problem.”

Carpenter reported: “I have an ASCS problem here. I think ASCS is not operating properly. Let me – emergency retrosequence is armed and retro manual is armed. I’ve got to evaluate this retro – this ASCS problem, Jim, before we go any further.”

Thirty seconds of silence ensued, for good reason. The automatic pilot was not holding the capsule steady for retrosequence. Again, at retrofire (an event that determines your landing point three thousand miles away) the capsule’s pitch attitude must remain steady 34 degrees, nose down. Yaw angle, too, steady at zero degrees. These two attitudes, in conjunction with a precisely timed retrofire, precisely determine the capsule’s landing point. At retrofire, two-thirds of the impulse, or thrust, delivered to the capsule at 34 degrees, nose down, tends to slow the capsule down; the remaining third tends to alter the capsule’s flight path downward. If yaw and pitch attitudes, together with the timing of retrofire, are correct, then both events – the reductions in speed and altitude – would send Aurora 7 homeward along the predetermined reentry path, somewhere in the waters southeast of Florida.

Mindful of these contingencies, the Hawaii Capcom, Jim, replied: “Roger,” told Scott he was standing by, and squeezed in two critical retrosequence items – the pilot was to switch off the emergency drogue-deploy and emergency main fuses. Scott replied:

“Roger, they are. Okay, I’m going to fly-by-wire, to Aux Damp, and now – attitudes do not agree. Five minutes to retrograde, light is on. I have a rate of descent, too, of about 10,12 feet per second.”

Hawaii Capcom did not hear and transmitted: “Say again? Say again?” He had a rate of descent, Scott repeated, “of about twelve feet per second.” The capcom asked: “What light is on?” Things were happening quickly. Scott replied only, “Yes, I am back on fly-by-wire. Trying to orient.” With only a minute until LOS, the Hawaii Capcom finally proposed a run through the checklist. Carpenter finally said: “Okay. Go through it, Jim,” and then, prompting, once more, “Roger, Jim. Go through the checklist for me.”

Approaching the most critical moment of the flight, Hawaii Capcom and the pilot of Aurora 7 used the remaining minute of voice contact to report back and forth on the arming of various squib switches, the periscope levers, up or down? Manual fuel handles (as backup for the ASCS) – were they in or out? Finally:

“Roll, yaw, and pitch handles are in.”

Capcom transmitted: “Transmitting in the blind… We have LOS. Transmitting in the blind to Aurora 7. Make sure all your tone switches are on, your warning lights are bright… Check your face-plate is closed.”

With Aurora 7 nearing reentry, Kraft learned with as much dismay as the pilot himself that the spacecraft’s ASCS was not, in the best traditions of astronaut understatement, “operating properly.”

Scott had in fact noticed the symptoms, now and then, of a malfunctioning pitch horizon scanner, and was puzzled, at times, by some instrument readings. He reported them as the anomalies they were. But the intermittent nature of these instrument failures made repeated checking of little value. The view out the window was a very good backup, and it was impervious to failure.

It was clear at Mercury Control that day that Kraft’s indignation, simmering since the second-orbit incident over Hawaii, was now compounded by the man’s genuine anxiety. Speaking of MA-7 Kranz explains: “A major component of the ground team’s responsibility is to provide a check on the crew.” And the ground, Kranz says, “waited too long in addressing the fuel status and should have been more forceful in getting on with the checklists.” A thoroughgoing attitude check during the first orbit would probably have helped to diagnose the persistent, intermittent, and constantly varying malfunction of the pitch horizon scanner. By the third orbit it was all too late. MA-7’s fuel problems dictated drifting flight. A third-orbit attitude check, particularly in yaw, would have used prodigious amounts of fuel – at reentry, an astronaut’s lifeblood.