Riding Rockets - Mike Mullane [181]
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.
The atmosphere had thickened enough to become an obstacle to our hypersonic sled. Compression againstAtlantis ’s belly heated the air to a white-hot glow now visible from the front windows. I wondered what was happening underneath us. I had visions of molten aluminum being smeared backward like rain on a windshield. None of our instruments or computer displays showedAtlantis ’s skin temperature. Only Houston had that data. I wondered if they would call us if they saw it rising. I hoped not. Such a call would definitely have us all tensed up as we died. Even Hoot wouldn’t be able to laugh away that MCC call. I looked at our displays and meters, not sure which would be the first to reveal a heat-shield problem. They were all in the green. Hoot would later tell me his eyes were never long from the elevon position indicators, certain a left-right split in those instruments would be the first hint the right wing was melting.
With the nominal displays I was happy to consider that our worries might have been misplaced. Maybe we had been alarmists. Maybe the damage was minor, as MCC had indicated. I still couldn’t believe that, but I prayed it was the case. I would have no problem offering the flight director, the CAPCOM, and everybody else an apology for having questioned their judgment.
“Three hundred ten thousand feet…still holding Mach 25…some Gs starting