Riding Rockets

Of one thing I was certain. IfAtlantis ’s wounds were mortal, our fortress cockpit would protect us long enough to watch death’s approach. Certainly it would last long enough for us to see multiple warning messages as various systems were affected by the heat. We would probably live to experience the out-of-control tumble and breakup of the vehicle. Even after our fortress was penetrated by the incandescent heat, death would not be immediate. Our pressure suits would protect us from the loss of cockpit air. Only when the fire penetrated the fabric of our LESes would we die. If we were lucky, unconsciousness would come before the heat began to consume our flesh.

I kept returning to MCC’s assessment for comfort. It was hard not to yield to their conclusion that we were going to be fine. I had never been associated with any teams as good as those that manned the MCC. But ifChallenger had proven anything, it was that great teams do fail. A lot of very smart people had mishandled the O-ring issue that killed theChallenger crew. Were they now mishandling our heat-shield damage? Would anAtlantis presidential commission report end up containing the statement, “The crew radioed that the damage to their heat tiles looked serious, but in Houston their concerns were dismissed”?

The anxiety was exhausting and I finally gave in to Hoot’s solution. The day before, as he floated to the windows to do some sightseeing, he said, “No reason to die all tensed up.” I would do my best to relax and enjoy the sights.

Chapter 35

Riding a Meteor

“Fifty seconds.” Hoot gave the time remaining until the OMS deorbit burn. I floated behind Jerry Ross and watched the countdown on the computer displays. As the burn execute time neared, I tightened my grip on Jerry’s seat. The one-quarter G of the thrusting OMS engines was trivial but it was enough to put anything unrestrained on the back wall, me included.

Astronauts have great faith in the OMS engines. They are the essence of simplicity. They have no spinning turbo-pumps to worry us, not even an igniter to fail and jeopardize our lives. The fuel and oxidizer are pushed into the combustion chamber by helium pressure, and their chemical composition causes them to ignite on contact. No spark needed. Getting stuck in orbit would ruin your whole day, so having a deorbit engine that was as foolproof as possible eased one of our perennial worries.

At time-zero the cockpit shuddered under the hammer of the two engines. Small bits of food crumbs, which had escaped our cleanup, drifted to the back wall. Hoot and Guy watched the computer displays of helium pressures, temperatures, and other indications of engine performance. They were all nominal.

The burn, and its acceleration on our bodies, ended. We were back in weightlessness. Hoot checked the residuals, which indicated the error of the maneuver. They were negligible. Whatever fate awaited us, we were now irrevocably committed. The OMS deorbit burn had clipped 200 miles per hour from our speed and changed our orbit so its low point was into the Earth’s atmosphere. There was no way we could climb back up to the temporary sanctuary of orbit.

According to the checklist I should have been strapped into the mid-deck seat, but there was nothing to do or see down there, so I had asked Hoot if I could hang out on the flight deck and shoot some video of the early part of reentry. I would get into my seat before the Gs got too high.

During the next twenty-five minutes we fell across the Indian Ocean, across the darkened continent of Australia, and shot into the night sky of the great Pacific basin. In our dive toward perigee,Atlantis gained back the velocity lost in the deorbit burn and added more. Shuttles achieved their peak speed on reentry, not ascent. The ride was as smooth and silent as oil on glass. The machine was on autopilot, with only her rear thruster jets active. Those were holdingAtlantis ’s nose 40 degrees high and presenting her wounded belly to the approaching atmosphere. Her aerodynamic control surfaces, the elevons on the wings and rudder on the tail, wouldn’t be able to hold her in attitude until we were much deeper into the atmosphere. If the rear thrusters failed, we would slowly drift out of attitude, tumble, and die. But an RCS system failure was far down on our lists of worries. The thruster jets were just smaller versions of the OMS engines, using a simple blow-down helium pressure feed system with propellants that burned on contact.

Hoot called the descent. “Mach 25.1…340,000 feet…Guidance looks great.” We were slightly faster than 25 times the speed of sound and at an altitude of 64 miles. Our little green bug was tracking perfectly down the center energy line. We were on course for Edwards AFB, still 5,000 miles away.