“ … We have a Go for main engine start … ”
The preparations proceeded remarkably smoothly for the second attempt to launch Shuttle Discovery on her maiden voyage, STS-41D. As described in yesterday’s AmericaSpace history article, a problematic backup computer had been replaced and tested and showed no discrepancies. The countdown moved crisply: built-in holds at T-20 minutes and T-9 minutes were passed and, at 8:39 a.m. EDT, with five minutes to go, Pilot Mike Coats reached down and switched on Discovery’s three Auxiliary Power Units (APUs). The trio of hydraulic pumps hummed perfectly to life. “The meters showed good pressure,” recalled Mike Mullane, who was seated directly behind Coats. “Discovery now had muscle.” The computers automatically commanded a final series of checks of the main engines and the elevons on the wings. With two minutes to go, the astronauts closed their visors. Commander Hank Hartsfield shook Coats’ hand and wished them all good luck, reminding them to stick to their training and keep their eyes focused on the instruments. Thirty-one seconds before liftoff, the Ground Launch Sequencer (GLS) handed over primary control of the countdown to the shuttle’s computers. In the darkened middeck, Judy Resnik and Charlie Walker clasped hands. The Solid Rocket Boosters (SRBs) underwent their final nozzle steering checks, and at 10 seconds a flurry of sparks from hydrogen burn igniters gave way to a familiar low-pitched rumble.
“ … seven, six, five … we have main engine start … ”
Inside Discovery’s cabin, the astronauts felt the immense vibration as turbopumps awoke, liquid oxygen and hydrogen flooded into the engines’ combustion chambers and they roared to life … and then, suddenly and shockingly, were arrested by the blaring sound of the master alarm. Something had gone badly awry. “Then there’s this grinding,” remembered Walker. “I cannot describe it. It sounded like … imagine in your mind the hand of God comes out of the sky, reaches down and twists the launch tower and structure outside the vehicle. It sounds like the place is being ripped apart!” Two of the main engines—No. 2 and 3, closest the aft body flap—had blazed to life, but the No. 1 engine, directly at the “top” of the pyramid, had failed to ignite. “The vibrations were gone,” wrote Mullane in his 2006 memoir, Riding Rockets. “The cockpit was as quiet as a crypt. Shadows waved across our seats as Discovery rocked back and forth on her hold-down bolts.” From the pilot’s seat, all Coats could hear was the screeching of disturbed seagulls outside. Two red lights on the instrument panel indicated that the No. 2 and 3 engines had indeed shut down, but the indicator for the No. 1 engine remained dark.
Instantly, Coats, whose responsibility as pilot was to monitor the engines during ascent, jabbed his finger onto the button to shut it down. The status indicator did not change; it remained dark. Downstairs, Walker’s eyes were focused intently on the procedures for “Mode 1 Egress,” the instructions for opening the side hatch and evacuating the vehicle. Meanwhile, on the roof of the Launch Control Center (LCC), the astronauts’ families were watching the unfolding drama … and they were perplexed both by what they could see and what they couldn’t. “A thick summer haze had obscured the launch pad,” wrote Mullane. “When the engines had ignited, a bright flash had momentarily penetrated that haze, strongly suggesting an explosion. As that fear had been rising in the minds of the families, the engine-start sound had finally hit … a brief roar.” The sound echoed off the walls of the gigantic Vehicle Assembly Building (VAB) and was gone. Within seconds, it became clear what had happened.
“ … we have a cutoff … we have an abort by the on-board computers of the orbiter Discovery … ”
Over the intercom, the astronauts heard the worrisome words “RSLS Abort,” meaning a “Redundant Set Launch Sequence.” This pointed inevitably to a main engine problem, which had forced their automatic shutdown by the General Purpose Computers (GPCs). Intuitively, the crew knew that safeguards existed to prevent the SRBs from igniting—if that had happened, it would have killed them all—but they also knew that only a few seconds existed on the countdown clock. “A couple of seconds in the world of electronics is a lifetime,” said Mullane, “and I’m sure that all the safety devices had rotated to prevent [the solids] from igniting … but in the back of your mind, you’re thinking What happens if those ignite?” The situation was by no means under control. As if the indication that the No. 1 engine might still be burning was not enough, Launch Control now told the crew that there was a fire on the pad and the suppression equipment had been activated.
The decision over whether to unstrap and make an emergency evacuation of the orbiter was now in the hands of Discovery’s commander, Hank Hartsfield; downstairs, on the middeck, Judy Resnik had unstrapped and was peering through the window in Discovery’s side hatch. She could see no fire. The astronauts would have to run across the access arm to a set of seven baskets which would whisk them from the pad to safety. Listening to the communication loop, Hartsfield elected to sit tight. It was a decision which probably saved their lives. Hydrogen burns “cleanly,” invisible to the human eye, and it had already begun to ignite combustible materials on the pad surface. Subsequent inspections would reveal scorched paint all the way up the launch pad structure, as far as the crew access arm. “The flame may have been as high as the cockpit,” Mullane continued, “but … we would not have seen it. We could have thrown open the hatch and run into a fire.” Years later, Walker would praise Hartsfield for not having ordered a Mode 1 Egress that day. In his conversations with the launch director after the abort, Hartsfield realized that a lot of doubt also existed over the reliability of the slide-wire baskets and that had informed their judgment to keep the crew aboard the orbiter.
At the press site, Mark Hess’ commentary continued: “We have an indication two of our fire detectors on the zero level; no response … They’re side by side, right next to the engine area … The engineer requested that we turn on the heat shield firewall screen between the engine valve and Discovery’s three main engines … ”
From the flight engineer’s seat, Steve Hawley injected a spark of humor into the proceedings. “Gee,” he said, in his thick Kansan drawl, “I thought we’d be a lot higher at MECO!”
There had been a Main Engine Cutoff, but not at the edge of space; Discovery remained firmly shackled to Earth. T-zero had not been reached and so the SRBs had not been commanded to ignite. Hawley’s joke “broke the ice and got everybody laughing,” said Mike Coats, but did little to dissipate a pervasive sense of gloom that their mission had been aborted just four seconds before liftoff. Gloom is often associated with bad weather and rain, and when the 41D crew finally saw the light of day and made their way out of the orbiter, they did so in a torrential downpour … not of rain, but of the waters of the fire suppression system. The entire gantry was soaked, drips from every pipe and platform, the white room ankle-deep in water. As Mike Coats walked out of the elevator at the base of the pad, it was like walking beneath a waterfall. “We got completely soaked to the skin,” he explained years later. “Then we got in the astronaut van, which was air-conditioned and very cold. As we were driving away, there’s a window in the back of the van and all of us were looking back at the shuttle on the launch pad, shivering and soaking wet, like drowned rats.”
As well as being cold, wet, and disappointed, the crew was also exhausted. “After a launch abort,” Mullane told the oral historian, “you could take a gun and point it right at somebody’s forehead, and they’re not even going to blink, because they don’t have any adrenaline left in them; it’s all been used up.” Mike Coats took his wife and children to Disney World, where, later that afternoon, they found themselves, ironically, queuing for the Space Mountain ride. Replacement of the troublesome main engine would require a return to the VAB and that prompted a delay until August 1984 at the earliest; Discovery was destacked and returned to the Orbiter Processing Facility (OPF) by 17 July.
The lengthy down time forced NASA to make a number of uncomfortable decisions about the schedule for the remainder of the year. “Payloads were stacking up,” Mullane wrote. “Every day a communications satellite wasn’t in space meant the loss of millions of dollars of revenue to its operators.” The focus was on combining the payloads of two missions into one and deleting the other from the manifest, thereby providing for the minimum distortion of the launch schedule and maintaining NASA’s commitment to its commercial customers. Mission 41F had been due to launch on 9 August and was cancelled; its entire payload—with the exception of SPARTAN—would be shifted onto 41D.
Since 41F included the second Syncom (4-2) military communications satellite as part of its payload, that also ended up on 41D, with peculiar the result that the second numerical Syncom actually launched ahead of the first. (Syncom 4-1 was ultimately launched in November 1984.) Hartsfield’s crew retained the Office of Aeronautics and Space Technology’s OAST-1 payload, but lost the Large Format Camera, which moved onto Mission 41G, the dedicated Earth resources flight, in October. In Steve Hawley’s mind, training for this change was not a big deal, for the crew had already spent months working on OAST-1, Syncom deployment procedures, and deployment procedures for the Payload Assist Module (PAM)-D booster. By early August, Discovery was back on Pad 39A, with launch anticipated at the end of the month. With the SBS-4, Telstar-3C, and Syncom 4-2 communications satellites and OAST-1 in her payload bay, she would be carrying the heaviest load—at 41,180 pounds (18,680 kg)—ever taken into orbit by the shuttle at that time.
It would be an ambitious mission—a mission which a future AmericaSpace article will explore in greater depth. It would also inaugurate a remarkable career for Discovery, which, in time, would earn its place as the leader of NASA’s shuttle fleet and accomplish a string of phenomenal successes in our exploration of the frontier of space.
This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next week’s article will focus on STS-4, the final test flight of Columbia, which landed on Independence Day in 1982, supposedly bringing the shuttle’s operational testing to an end. However, in the minds of the astronauts, it underlined the reality that the shuttle could never be truly a routine vehicle.