The Mammoth Book of Space Exploration and Disaster

by Richard Russell Lawrence

  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.

  Scott, meanwhile, was busy aviating and navigating. The California Capcom, Al Shepard, took over voice communications for the retrofire sequence, one minute away:

  “Seven, this is Cap Com. Are you in retroattitude?”

  Carpenter replied: “Yes. I don’t have agreement with ASCS in the window, Al. I think I’m going to have to go fly-by-wire and use the window and the [peri]scope. ASCS is bad. I’m on fly-by-wire and manual.”

  Capcom responded: “Roger. We concur.”

  But in going to fly-by-wire, Scott forgot to shut off the manual system that he’d activated during the pre-retro checklist over Hawaii as backup for the automatic system. So his efforts to control attitude during retrofire were accomplished on both fly-by-wire and manual control modes, spewing out fuel from both tanks. Halfway through his fifteen-minute flight the year before, Al himself had committed the identical error. Retrosequence was coming up.

  Capcom radioed: “About ten seconds on my mark . . . 6, 5, 4, 3, 2, 1.”

  Car
penter reported: “Retrosequence is green.”

  Green is good. Green means that everything is set right for automatic retrofire. But not in this case, because the automatic system was locked out and the gyros were caged. Scott would have to fire the retros manually, throwing switches upon Al’s count, coming up fast. Suddenly a critical intervention from Al. If Scott’s gyros were caged, Al reported, he would have to “use attitude bypass.” His gyros were off, Scott answered, and Al repeated his remark:

  “But you’ll have to use attitude bypass and manual override.”

  Carpenter reported: “Roger.”

  Then two seconds. Al counted down, “4, 3, 2, 1, 0.”

  Before, during, and after the retrofire firing, Al offered Scott two crucial observations. Because of the instrument failures, the cockpit was in a configuration never before envisioned, and Al perceived the effect it would have on the required cockpit procedure. His contribution to Scott’s safe reentry was a resounding endorsement of the decision made a few years before to place astronauts in the communication loop, as knowledgeable buffers between the ground-control people and the man doing the flying. Al’s insight at a crucial moment probably kept Scott’s landing from being even farther off target than it was.

  Carpenter continued:

  The last thirty minutes of my flight, in retrospect, were a dicey time. At the time I didn’t see it that way. First, I was trained to avoid any active intellectual comprehension of disaster – dwelling on a potential danger, or imagining what might happen. I was also too busy with the tasks at hand. Men and women who enter high-risk professions are trained to suppress, or set aside, their emotions while carrying out their duties. After the job, and after the danger has passed, is the time for emotions.

  Without the ability to detach oneself from the peril in a situation, one has no chance of surviving it. What perils did I face? They were the same perils faced by Al, Gus, and John – and later by Wally and Gordo. The retros might not fire. They might explode or not burn properly. The heat shield might not work. The drogue or the main chute might not deploy or reef properly. Thinking about all the things that could go wrong, no one would ever climb into a spacecraft. A pilot counts on all those things going right, not because he needs to believe in a fairy tale, but because he has confidence in the hardware, in the systems, in the men and women on the ground. In himself.

  Still, I do remember being surprised by the power of my detachment. It felt as though I were watching myself, with fascination and curiosity, to see how my great adventure might turn out. The rockets were supposed to fire automatically. I watched the second-hand pass the mark, and when they didn’t, punched the retrobutton myself a second later. An agonizing three seconds passed until the reassuring sound and vibration of firing retrorockets filled the cabin. I was prepared for a big boot, which never came. Deceleration was just a very gentle nudge, not at all the terrific push back toward Hawaii that John had reported feeling from his own retrofire.

  Al was still in voice range and we continued to transmit information about retrosequence. I noticed smoke in the cabin and the smell of metal. Two fuses had overheated. I was worried about the delayed firing of the retrorockets. At that speed, a lapse of three seconds would make me at least fifteen miles long in the recovery area. Al asked me if my attitudes held, and I said, “I think they are good,” but I wasn’t sure, adding that “the gyros are not quite right.”

  My visual reference was divided between the periscope, the window, and the attitude indicators. My views out the window and the periscope helped me attain the desired pitch of 34 degrees, nose down, although the attitude indicator read minus-ten. I tried to hold it there, at minus-ten degrees, a false but at least steady reading, throughout retrofire, continually cross-checking with the window and the scope. The long hours on the Mercury Procedures Trainer were paying off.

  I had commented, many times, that on the MPT you cannot divide your attention between one attitude reference system and another and still do a good job in retrofire, although it appears I pretty much nailed the pitch attitude. But the nose of Aurora 7, while pitched close to the desirable negative 34 degrees, was canted about 25 degrees off to the right, in yaw, at the moment of retrofire. By the end of the retrofire event I had essentially corrected the error in yaw, which limited the overshoot. But the damage was already done.

  In the end I was 250 miles long. The yaw misalignment alone caused the spacecraft to overshoot the planned impact point by about 175 miles. The three-second delay in firing the retrorockets added another fifteen miles to the error in trajectory. Under-thrusting retrorockets piled an additional sixty miles onto the overshoot.

  “But retrojettison,” I said to Al, changing the subject. It was a question. “Roger,” he told me, “ten seconds until retrojettison.” Right on time. I heard barely audible ignition sounds from the retrojettison rocket. I reported on my fuel supplies, now at 20 percent for manual control, 5 for automatic. My next job was to damp out any oscillations the spacecraft might develop during the next stage of reentry. But in a little more than a minute, the manual control system would be out of fuel and thus worthless. I still had the fly-by-wire system: “I am out of manual fuel, Al.”

  As always, Al was cool. I had merely reported the depletion of manual fuel.

  As it happens, Max Faget had foreseen the reentry dangers posed by an aerodynamically unstable craft. He prepared for this theoretical possibility of attitude-control failure by designing a near-perfect reentry body. The vehicle was designed, Max explains, “so that in the event the attitude control system failed, we would still make reentry.”

  Fuel starvation had rendered my attitude control system ineffective. Still, during the final stages of reentry, I remember thinking the capsule’s oscillations were being damped, or suppressed, without any control inputs I was attempting. I remember thinking Faget’s design was working: the Mercury capsule had positive aerodynamic stability – as advertised back in 1959, when we were invited to volunteer for this grand adventure. My safe reentry was virtually guaranteed.

  Aerodynamic stability is a good thing, but there were still things I could do to improve my situation. At 04 35 13.5, the capsule was oscillating between plus or minus 30 degrees in pitch and yaw, but I was able to use my fly-by-wire controls to further damp the oscillations. A postflight report noted that “by manually controlling the spacecraft during retrofire,” I had “demonstrated an ability to orient the vehicle so as to effect a successful reentry, thereby providing evidence” that human beings can “serve as a backup to malfunctioning automatic systems of the spacecraft.”

  About three seconds after reporting to Al the depletion of my manual fuel, I inquired about the next key event during reentry, called “.05g.” That’s when you feel that first gentle deceleration signaling the loss of weightlessness.

  Carpenter asked: “.05 should be when?”

  Capcom replied: “Oh, you have plenty of time. Take your time on fly-by-wire to get into reentry attitude.”

  Capcom added: “I was just looking over your reentry checklist. Looks like you’re in pretty good shape. You’ll have to manually retract the scope.”

  No, the scope had come in during a retrosequence check over Hawaii.

  Capcom continued: “Roger. I didn’t get that. Very good.”

  Carpenter commented: “Going to be tight on fuel.”

  Capcom replied: “Roger. You have plenty of time. You have about 7 minutes before .05 g so take—”

  Now I was literally dropping out of the sky and had a beautiful view of the earth below. On his own way down Al had strained for a similar view through the tiny portholes of Freedom 7. He hadn’t been able to see anything on his way down, so I treated him to a vicarious thrill – my newer version of the Mercury capsule offered a panoramic view of the earth below.

  Carpenter described: “Okay. I can make out very small farmland, pastureland below. I see individual fields, rivers, lakes, roads, I think. I’ll get back to reentry attitude.”


  Kris Stoever:

  “Roger,” Al concurred. “Recommend you get close to reentry attitude.” Listening to Scott, Al may have recalled that his own attempts at reentry sightseeing had left him behind in his work. Coming up on LOS, he reminded Scott for the last time to use “as little fuel as possible and stand by on fly-by-wire until rates develop. Over.”

  Carpenter replied: “Roger, will do.”

  With Scott now in range over Cape Canaveral, Gus read off the final stowage checklist items – reminders in case the pilot had been busy with other things. Was the glove compartment “latched and closed?” “Roger, it is,” Scott replied. He read off the face-plate check. “Negative. It is now. Thank you.” Everything else was done. Gus transmitted a weather report for the expected impact point:

  “The weather in the recovery point is good – you’ve got overcast cloud, 3 foot waves, 8 knots of wind, 10 miles visibility, and the cloud bases are at 1,000 feet.”

  Scott reported matter-of-factly on “the orange glow,” using the definite article because the glow, in that particular blazing color, had been reported by his predecessors in these fiery precincts. He also saw burning particles from the heat shield form an immense orange wake behind him and struggled against increasing G loads to switch on the auxiliary damping mode. G forces would peak in a few minutes at eleven times the normal gravitational load. The capsule steadied. Auxiliary damping worked!

  “I assume we’re in blackout now,” Scott transmitted to Gus, referring to the expected loss of voice contact that sets in at about 75,000 feet.

  “Give me a try.” Nothing. “There goes something tearing away,” Scott said, now for the voice recorder. Atmospheric drag was creating temperatures outside of close to 4,000 degrees Fahrenheit – incinerating trivial bits of the spacecraft, as expected.

  Scott continued talking, for the voice recorder, using the old Carpenter grunt perfected at Johnsville to force the words out. It took all his strength. Aurora 7 was reaching peak deceleration rates. Telemetered cardiac readings coming in at Mercury Control registered the physical effort required to produce words, observations, status reports. He never stopped, every three to five seconds bringing a new, concise transmission. The capsule was now oscillating badly.