Richard Lawrence - The Mammoth Book of Space Exploration and Disaster

NASA officially revised its re-entry bulletin to: “Skylab re-entered the atmosphere at altitude of 10 kilometres at 2:37 a.m. (Eastern Australian time) at 31.80 S and 124.40 E – just above the tiny Nullarbor Plain town of Balladonia.” Burning pieces of Skylab were scattered over an area 64 kilometres wide by 3,860 kilometres along the flight path.

The Soviet Union gave up trying to go to the moon in 1971, after which their efforts consisted of a series of orbiting space stations. The official reason was research for a mission to Mars, but the real reason was observation of US missiles and launches. General Yuri Glaskov flew on a Soviet space station during the 1970s. He explained: “It’s very easy to see your missiles, the way they’re installed we could look right down on them.”

From 1971 to 1982 the Soviets sent up seven manned space stations, the Salyut stations. Salyut means “Salute” in honour of the heroes of the Soviet space program such as Gagarin and Korolev. It was traditional for cosmonauts to visit their memorials before launching. The main Soviet space effort was concentrated on long-stay scientific missions.

In June 1985 cosmonauts revived the Salyut 7 space station after TsUP had decided to abandon it, but reversed its decision. Bryan Burrough personally interviewed the two cosmonauts who arrived at the space station and translated the Russian language transcripts. Burrough:

Frozen and empty, the station had drifted without power for eight months when two cosmonauts, Vladimir Dzhanibekov and Viktor Savinykh, approached in their Soyuz and managed a difficult manual docking with the station, which was in free drift. The temperature inside the station was well below zero when the two men, wearing fur-lined jumpsuits and oxygen masks, clambered inside with flashlights. Every surface was coated with frost and icicles. Working with ventilation to clear their carbon dioxide, the men grew cold and sleepy, repeatedly retreating to their Soyuz to rest and regain strength. As they worked to resuscitate the station over the next several days, patching burst pipes and thawing water supplies, headaches plagued them. Eventually they managed to revive several of the station’s dead batteries and from there gradually switched on all the station’s major systems. It took weeks to slowly resurrect Salyut 7 but by the time Dzhanibekov and Savinykh finished, they had shown that the Russians could almost literally bring a space station back from the dead.

On 28 January 1986, the Space Shuttle Challenger exploded 73 seconds after launching from Kennedy Space Center. After the explosion, the crew module separated intact from the fireball before going into a two-minute free fall from 50,000 feet and plunging into the sea. A gas leak in the right booster rocket was blamed for the explosion.

Challenger was carrying seven crew members, including a New Hampshire schoolteacher. They had no parachutes and no way to jettison the hatch. All seven members of the crew were killed. They were Francis R. Scobee, commander; Michael J. Smith, pilot; three mission specialists, Judith A. Resnik, Ellison Onizuka and Ronald E. McNair; payload specialist, Gregory Jarvis of Hughes Aircraft; and payload specialist, S. Christa McAuliffe. McAuliffe, a New Hampshire teacher, was the first Space Shuttle passenger/observer to participate in the NASA Teacher in Space Program and had intended to teach planned lessons during live television transmissions.

McAuliffe was selected by NASA in 1984 from among more than 11,000 teachers who applied for the Challenger mission and took a leave of absence that fall to train for it.

It was the 25th mission in the Space Shuttle program and was designated mission 51-L.

NASA managers had been anxious to launch the Challenger for several reasons, including economic considerations, political pressures, and scheduling backlogs. The previous shuttle mission had been delayed a record number of times due to foul weather and mechanical factors. NASA wanted to launch the Challenger without any delays so the launch pad could be refurbished in time for the next mission, which would be carrying a probe that would examine Halley’s Comet. If launched on time, this probe would have collected data a few days before a similar Russian probe would be launched.

There was probably also pressure to launch Challenger so it could be in space when President Reagan gave his State of the Union address. Ronald Reagan’s main topic was to be education, and he was expected to mention the shuttle and the first teacher in space, Christa McAuliffe.

On 3 February 1986 President Reagan ordered a Commission to report on the Space Shuttle Accident (Executive Order 12546). The Commission reported:

The shuttle’s solid rocket boosters are key elements in the operation of the shuttle. Without the boosters, the shuttle cannot produce enough thrust to overcome the earth’s gravitational pull and achieve orbit. There is a solid rocket booster attached to each side of the external fuel tank. Each booster is 149 feet long and 12 feet in diameter. Before ignition, each booster weighs 2 million pounds. Solid rockets in general produce much more thrust per pound than their liquid fuel counterparts. The problem is that once the solid rocket fuel has been ignited, it cannot be turned off or even controlled. So it was extremely important that the shuttle’s solid rocket boosters were properly designed. Morton Thiokol was awarded the contract to design and build the solid rocket boosters in 1974. Thiokol’s design is a scaled-up version of a Titan missile which had been used successfully for years. NASA accepted the design in 1976.

The booster is comprised of seven hollow metal cylinders. The solid rocket fuel is cast into the cylinders at the Thiokol plant in Utah, and the cylinders are assembled into pairs for transport to Kennedy Space Center in Florida. At Kennedy Space Center, the four booster segments are assembled into a completed booster rocket. The joints where the segments are joined together at Kennedy Space Center are known as field joints. These field joints consist of a tang and clevis joint. The tang and clevis are held together by 177 clevis pins. Each joint is sealed by two O-rings, the bottom ring known as the primary O-ring, and the top known as the secondary O-ring. (The Titan booster had only one O-ring. The second ring was added as a measure of redundancy since the boosters would be lifting humans into orbit. Except for the increased scale of the rocket’s diameter, this was the only major difference between the shuttle booster and the Titan booster.) The purpose of the O-rings is to prevent hot combustion gases from escaping from the inside of the motor. To provide a barrier between the rubber O-rings and the combustion gases, a heat-resistant putty is applied to the inner section of the joint prior to assembly. The gap between the tang and the clevis determines the amount of compression on the O-ring. To minimize the gap and increase the squeeze on the O-ring, shims are inserted between the tang and the outside leg of the clevis.

During the night, temperatures dropped to as low as 8°F. This was much lower than had been expected. Safety showers and fire hoses were turned on to keep the water pipes in the launch platform from freezing. Some of this water had accumulated, and ice had formed all over the platform. There was some concern that the ice would fall off of the platform during launch and might damage the heat-resistant tiles on the shuttle. The ice inspection team thought the situation was of great concern, but the launch director decided to go ahead with the countdown. Safety limitations on low temperature launching had to be checked and authorized by key personnel several times during the final countdown. These key personnel were not aware of the teleconference about the solid rocket boosters that had taken place the night before. At launch, the impact of ignition broke loose a shower of ice from the launch platform. Some of the ice struck the left-hand booster, and some ice was actually sucked into the booster nozzle itself by an objective effect. Although there was no evidence of any ice damage to the Orbiter itself, NASA analysis of the ice problem was wrong. The booster ignition transient started six hundredths of a second after the igniter fired. The aft field joint on the right-hand booster was the coldest spot on the booster: about 28°F. The booster’s segmented steel casing ballooned and the joint rotated, expanding inward as it had on all other shuttle lights. The primary O-ring was too cold to seal properly, the cold-stiffened heat-resistant putty that protected the rubber O-rings from the fuel collapsed, and gases at over 5000°F burned past both O-rings across seventy degrees of arc. Eight hundredths of a second after ignition, the shuttle lifted off. Engineering cameras focused on the right-hand booster showed about nine smoke puffs coming from the booster aft field joint. Before the shuttle cleared the tower, oxides from the burnt propellant temporarily sealed the field joint before flames could escape. Fifty-nine seconds into the flight, Challenger experienced the most violent wind shear ever encountered on a shuttle mission. The glassy oxides that sealed the field joint were shattered by the stresses of the wind shear, and within seconds flames from the field joint burned through the external fuel tank. Hundreds of tons of propellant ignited, tearing apart the shuttle. One hundred seconds into the flight, the last bit of telemetry data was transmitted from the Challenger.