Riding Rockets

“Throttle up.” The air was thinning and the aerodynamic pressure decreasing. The three Rocketdyne beauties at our backs were once again spiraling to full power. What a rush it was to feel the buildup of thrust, just like jamming the throttles of a fighter into the afterburner detents. I suspect every shuttle pilot would have loved to snatch the controls from the autopilot and manually throttle the engines to full power. How many times in your life would you have 1.5 million pounds of thrust wrapped around your fingers?

The prayers flying from the souls of everybody in the cockpit were identical, that God would continue to smile upon the SSMEs. We most feared these engines, and for good cause. There had been many SSME ground-test explosions and premature shutdowns. We were also strapped to two SRBs, each burning nearly 5 tons of propellant per second, but nobody gave a second thought to them. No engineer had ever come to a Monday morning meeting to explain away a SRB ground-test failure. The SRBs had always worked. But even as we scorched the prayer line with our pleas for flawless SSME function, both SRBs were betraying us. A primary O-ring at different joints in each tube had failed to seal as the motors had ignited. Tentacles of flame from the combustion area had wiggled between the segment facings. Like something alive and trapped, the gas had been wild to escape. It had reached the leak points and started to consume the O-ring rubber. The leak on the left-side SRB was bad enough for hot gas to actually get past the primary O-ring. Though we wouldn’t know it until after theChallenger disaster, we had just experienced the first case of what the Thiokol engineers would later define as “blow-by.” Hot gas had penetrated into the space between the primary and backup O-rings. Had our leak continued moments longer, the primary and backup O-rings would have been consumed and history would have recorded theDiscovery disaster instead ofChallenger. It would have been Zoo Crew’s names etched in an Arlington Cemetery monument. But the leak hadn’t continued. Inexplicably the primary O-rings had resealed.

The clock was approaching T+2 minutes and the Gs rose to 2.5. An invisible hand pushed me deeper into the seat. I reached forward, drew my hand back, then reached forward again. The veterans had warned it was tough to maneuver an arm under G-loads and it was a good idea to practice in case an ascent emergency later required a reach for a switch.

“You see that?” At Hank’s question I was reminded of Judy’s warning about not ending any sentence with the wordthat. Needless to say, my ears perked up.

Mike replied, “Yeah, it looks like foam from the tank is flaking off.”

Mike and Hank continued a brief discussion about the particles that were racing past the windows, sometimes striking them. There was no concern in their voices and I quickly dismissed their comments. The ET insulation foam was so light I couldn’t imagine it would damage any part of the vehicle. Nineteen years later a briefcase-size chunk of foam ripping from the gas tank would doomColumbia.

“P-C less than fifty.” Hank relayed the message on his computer screen that the chamber pressure inside the SRBs had fallen to less than 50 pounds per square inch. A loud metallic bang shook the cockpit and a flash of fire whipped the windows as the boosters separated from the ET. Both SRBs tumbled away to parachute into the ocean.

The sudden loss of 6 million pounds of thrust accompanied by dead silence caught me by surprise. Had all three of the SSMEs also shut down? I leaned to my left and stared at the engine status lights and for several heartbeats I expected to see them illuminate in a deadly red glow. But the lights remained off, the radios quiet. I swallowed back my heart. Apparently I had been asleep in training when somebody had described SRB separation and the quiet, velvet smoothness that followed. There was nothing wrong with the vehicle.Discovery had put most of the atmosphere behind her. There was no air to grip the machine or rattle us with shock waves. And the SSMEs were as finely tuned as a Rolex. They continued to deliver nearly 1.5 million pounds of thrust 100 feet behind our backs without a whisper of noise or ripple of vibration. The ride became as smooth as a politician’s lie.

Hank’s altitude and velocity tapes scrolled upward as the sky faded to abysmal black. Sunlight was streaming through the windows and yet the sky was utterly dark. It was my first real space experience, something I had never and could never experience as an earthling…simultaneous night and day, simultaneous high noon and deep midnight.