30 years on from Challenger, NASA remembers the fallen
Winter is the killing season for US astronauts
On the clear and cold morning of January 28, 1986, the space shuttle Challenger lifted off from Cape Canaveral bearing seven crew. Minutes later they were all dead, and NASA is holding an official day of remembrance for them, and the crews of Apollo 1 and Shuttle Columbia.
"Every year at this time, we take a moment to reflect as the NASA Family on the very broad shoulders on which we stand: the shoulders of those men and women at NASA who gave their lives so that you and I could continue to reach new heights for the benefit of all humankind," said NASA administrator Charlie Boden.
The Challenger disaster was the worst failure in NASA's history, particularly as the flight was so high-profile. Payload specialist and teacher Christa McAuliffe had been selected in a nation-wide competition to be the first Space Teacher, and had become a national celebrity. Her parents were in the grandstands to watch the launch.
The flight had been delayed for days, but blasted off at 1139 EST (1639 UTC) in what looked like a clean launch. But 58 seconds into the flight, one of the O-rings on one of the shuttle's solid rocket booster failed, due to being hardened by the sub-zero temperatures, and this triggered a cascade of failures that doomed the spacecraft.
The O-ring failure allowed a plume of superheated gas to escape from the right-hand-side solid fuel booster, and this burned through both the strut holding the rocket in place and the external liquid hydrogen fuel tank of the shuttle.
73 seconds into the flight and 48,000 feet (15 km) up, the booster strut failed and the rocket pivoted, slamming into the exterior fuel tank and rupturing it, mixing the liquid hydrogen and oxygen fuel which then ignited. "Uh-oh," Pilot Michael Smith was heard to say on the shuttle's flight recorder.
There was really very little he could have done. Once ignited, solid-fuel boosters burn continuously until depleted and, while the shuttle could jettison its external tanks, the speed of the spacecraft at that time made a safe landing very unlikely.
"Flight controllers here looking very carefully at the situation," mission control said at the time. "Obviously a major malfunction. We have no downlink. We have a report from the flight dynamics officer that the vehicle has exploded."
The shuttle survived the fuel tank explosion but was subjected to a 20G turn and began to break up due to the extreme aerodynamic forces. It continued to rise to around 65,000 feet (20 km) before falling back towards the ocean in pieces, with the crew compartment largely intact but unpressurized.
The central crew module was hardened for safety and at least some of the astronauts survived the initial event. Three of the shuttle's emergency oxygen supplies were activated and instrument settings in the recovered cockpit showed that Pilot Smith had been trying to get electrical power restored after the accident.
But in the unpressurized cabin, the crew would have quickly been rendered unconscious. A supposed transcript of the crew crying and praying during descent did the rounds after the crash, but was determined to be a fake.
After nearly three minutes of freefall, the capsule hit the sea travelling at 207 mph (333 km/h) and the 200G impact was not survivable. It was March before the last of the bodies could be recovered from the sea floor.
"The crew of the space shuttle Challenger honored us by the manner in which they lived their lives," said President Ronald Reagan in an address to the nation later that day.
"We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and slipped the surly bonds of earth to touch the face of God."
The coincidental killing time
It's a bad time of year for the American space program. January 27 marked the 49th anniversary of the Apollo 1 disaster, when Gus Grissom, Ed White, and Roger Chaffee burned in their crew module after an uncontrolled oxygen fire broke out.
Meanwhile, February 1 marks the 13th anniversary of the Columbia shuttle disaster, when another seven astronauts died after a damaged heat shield on the left wing caused the spacecraft to break up on reentry.
The timing of these tragedies is coincidental, but NASA still feels each loss keenly. As part of Thursday's day of remembrance for all three events, the crew of the International Space Station held a minute's silence.
"These brave women and men are forever a part of a story that is ongoing," said President Obama in a statement.
"It is a story that we bring human beings to Mars and out into our solar system – and beyond. It is a story made possible by their sacrifice and heroism. May America always carry forward the bravery of those we have lost, and may we harness it to make today's impossibilities tomorrow's realities." ®