The Mammoth Book of Space Exploration and Disasters

Another item on my schedule was to throw a switch to try out an ingenious system for controlling the attitude of the capsule in case the automatic pilot went out of action or we were running low on fuel in the manual control system. We have two different ways of controlling the attitude of the capsule – manually with the control stick, or electrically with the auto-pilot. In the manual system the movement of the stick activates valves which squirt the hydrogen peroxide fuel out to move the capsule around and correct its attitude. We can control the magnitude of this correction by the amount of pressure we put on the stick. The auto-pilot works differently. It uses an entirely different set of jets – to give us a backup capability in case one set goes out – and a separate source of fuel. But the automatic jets are not proportional in the force that they exert. This gave the engineers an idea: they created a third possibility, which they call “fly-by-wire”, in which the pilot switches off the automatic pilot, then links up his manual stick with the valves that are normally attached to the automatic system. This gives him a new source of fuel to tap if he is running low, and a little more flexibility in managing the controls. The fly-by-wire mode seemed fine as far as I was concerned, and another test was checked off the list of things we were out to prove.

We were on our way down now and I waited for the package which holds the retro-rockets on the bottom of the capsule to jettison and get out of the way before we began our re-entry. It blew off on schedule and I could feel it go, but the green light which was supposed to report this event failed to light up on the instrument panel. This was our only signal failure of the mission. I pushed the override button and the light turned green as it was supposed to do. This meant that everything was all right.

Now I began to get the capsule ready for re-entry. Using the control stick, I pointed the blunt end downward at about a 40° angle, and switched the controls back to the auto-pilot so I could be free to take another look through the periscope. The view was still spectacular. The sky was very dark blue; the clouds were a brilliant white. Between me and the clouds was something murky and hazy which I knew to be the refraction of various layers of the atmosphere through which I would soon be passing.

I fell slightly behind in my schedule at this point. I was at about 230,000 feet when I suddenly noticed a relay come on which had been activated by a device that measures a change in gravity of 0.05G. This was the signal that the re-entry phase had begun. I had planned to be on manual control when this happened and run off a few more tests with my hand controls before we penetrated too deeply into the atmosphere. But the G forces had built up before I was ready for them, and I was a few seconds behind. I was fairly busy for a moment running around the cockpit with my hands, changing from the auto-pilot to manual controls, and I managed to get in only a few more corrections in attitude. Then the pressure of the air we were coming into began to overcome the force of the control jets, and it was no longer possible to make the capsule respond. Fortunately, we were in good shape, and I had nothing to worry about so far as the capsule’s attitude was concerned. I knew, however, that the ride down was not one most people would want to try in an amusement park.

In that long plunge back to earth, I was pushed back into the couch with a force of about 11 Gs. This was not as high as the Gs we had all taken during the training programme, and I remember being clear all the way through the re-entry phase. I was able to report the G level with normal voice procedure, and I never reached the point – as I often had on the centrifuge – where I had to exert the maximum amount of effort to speak or even to breathe. All the way down, as the altimeter spun through mile after mile of descent, I kept grunting out “OK, OK, OK,” just to show them back at the Control Centre how I was doing. The periscope had come back in automatically before the re-entry started. And there was nothing for me to do now but just sit there, watching the gauges and waiting for the final act to begin.