The last shuttle pad abort after main engine ignition was on my second flight, STS-68, on Aug. 18, 1994. My crew (Baker, Wilcutt, Wisoff, Bursch, Smith, and me) was to operate Space Radar Lab 2 for 11 days, and we were keyed to go. In fact, I’d flown SRL-1 just 4 months earlier, in April on STS-59, and I was eager to put my recent experience into practice.
Video here. At T-6 seconds, Endeavour’s three main engines rumbled into life. I was strapped into my center seat on the middeck, just to the right of classmate Jeff Wisoff, as we felt the orbiter rumble and shake under the thrust of a million pounds of liquid-fueled thrust. Out the hatch window I could see the gantry apparently sway — it was actually Endeavour “twanging” under the thrust. I mentally counted: 5…4…3…2…1…waiting for the giant kick from the boosters’ ignition.
Instead, the Master Alarm blared in our headsets as the three main engines fell silent. Instead of liftoff, we were left swaying atop the orbiter as the launch team announced an RSLS (redundant sequence launch sequencer) abort – an automatic shutdown due to some as-yet unknown problem. Terry Wilcutt declared “Right engine down”, and he and Mike Baker swung into their abort checklists. Jeff and I threw off harness straps and prepared to roll out of our seats, onto the middeck’s back wall (the temporary “floor”) and heave the hatch open for an emergency egress. We might even have to hit the slidewire baskets for an escape to the blast bunker a quarter mile — and a long zip down the slide wire — away.
Launch control soon verified we had no fire and no explosion risk. The engines had shut down at T-1 second, due to an overheating LOX turbopump on SSME #3. Its discharge temperature had violated redline limits; had we launched with that violation, we might have lost an engine right after liftoff, sending us into a very hairy Return to Launch Site abort.
Wisoff and I had readied the hatch for opening, then settled in on intercom to wait for the ground crew to come out and open up from the White Room. We debated (in colorful terms) how long our mission delay would be — “We should have been gone!” Jeff lamented. When the ground crew arrived, I was sitting morosely on my middeck seat back, munching a peanut butter and jelly sandwich the crew quarters staff had packed for orbit. We eventually launched six weeks later, on September 30.
I wrote about this episode in Chapter 8, “The Only Man Available,” in Sky Walking. Not a distinction I relished, but the pad abort does show how well the shuttle’s automatic safety systems did work.