Riding Rockets

An October 1, 1985, interoffice Thiokol memo contained this plea: “HELP! The seal task force is constantly being delayed by every possible means.” In his last paragraph, the memo’s author, R. V. Ebeling, obliquely highlights the major problem of the operational STS…not enough people. “The allegiance to the O-ring investigation task force is very limited to a group of engineers numbering 8–10. Our assigned people in manufacturing and quality have the desire, but are encumbered with other significant work.” He finished his memo with the warning, “This is a red flag.”

Another indication of the crushing workload being borne by the Thiokol engineers is found in an October 4, 1985, activity report by Roger Boisjoly. “I for one resent working at full capacity all week long and then being required to support activity on the weekend…” The operational shuttle program was devouring people.

Astronauts remained ignorant of the O-ring bullet aimed at our hearts. It was never on the agenda of any Monday meeting. None of the memos being circulated at Thiokol made it to our desks. But there were other things happening in the Golden Age of which we were aware—terrifying near misses.

On April 19, 1985, asDiscovery landed from STS-51D at KSC, the brake on the inboard right-side wheel locked on, resulting in severe brake damage and the blowout of the tire. Unlike large aircraft, which have engine trust-reversers to aid in stopping the machine, the shuttle is completely dependent on brakes…and it lands 100 miles per hourfaster than airplanes of comparable size. (A deployable drag chute was added in 1992.) When a shuttle touches down, it is a hundred tons of rocket, including several tons of extremely dangerous hypergolic fuel, hurling down the runway at 225 miles per hour. While the shuttle runways at KSC and Edwards AFB, at 3 miles in length, are sufficiently long for stopping, they are only 300 feet wide. A perfectly landed shuttle is only 150 feet from an edge, an eye blink in time at those speeds. It was a minor miracle thatDiscovery didn’t experience directional control problems as a result of the blown tire and careen off the runway.

STS-51F experienced the second engine-start pad abort of the shuttle program. While not really a near miss, pad aborts have the potential to become dangerous. Afterward, I watched that crew put on their Right Stuff, no-big-deal faces for the press, just as we had done following our 41D pad abort. Astronauts are great actors.

STS-51F also became the first shuttle mission to perform an ascent abort whenChallenger ’s center SSME shut down nearly three minutes early. It was later determined that the malfunction was due to two faulty engine temperature sensors. There had been nothing wrong with the engine. With only two SSMEs, the crew was forced into an Abort to Orbit (ATO). Fortunately, this was the safest of aborts. The shuttle had been high enough and fast enough at the time of the engine failure to limp into a safe orbit on its two remaining engines. Had the engine failure occurred earlier, the crew would have faced a much more risky 15,000-mile-per-hour, thirty-minute TAL to a landing at Zaragoza, Spain.

Having experienced both an engine-start abort and a powered-flight abort, the 51F crew had gone through ten lifetimes of heartbeats. After they returned, astronauts joked that a cocked, loaded gun pointed between the eyes of any of them would not have elicited the slightest fear response. The mission had desiccated their adrenal glands.

STS-61C (Congressman Nelson’s flight), the last mission prior to theChallenger disaster, experienced a pair of bizarre and dangerous malfunctions even before it was launched. During a January 6, 1986, countdown attempt, a temperature probe inside one ofColumbia ’s propellant pipes broke off and was swept into a valve that controlled fluid flow to an SSME. Unknown to anybody, the valve was jammed in the prelaunch open position. Engineers in the LCC noted the temperature sensor was not responding, but erroneously assumed it was due to an electronic malfunction. It had not occurred to anybody that the probe might have actually broken free and was floating around inColumbia ’s guts. The countdown continued using a backup temperature sensor. The mission was ultimately scrubbed for other reasons and the valve jam was discovered in the countdown reset. HadColumbia launched, there was a good chance the jammed valve could have caused a turbo-pump to overspeed and disintegrate during the engine shutdown sequence at MECO. The resulting shower of hot steel inside the engine compartment would probably have trashed the vehicle hydraulic system, dooming the crew on reentry.