NASA is racing the clock for a space shuttle flight — and desperately hoping it never gets off the ground. Not Endeavour — scheduled to lift off next week with a crew of seven, including schoolteacher-astronaut Barbara Morgan — but sister shuttle Discovery, which is being readied for launch at short notice. Discovery will mount a rescue mission if Endeavour flies into trouble and its crew has to be brought back.
After Columbia disintegrated during re-entry into Earth’s atmosphere in February 2003, scientists developed several methods for repairing stricken shuttles. These include wing sensors to detect impacts, a redesigned fuel tank to prevent debris from heat shields damaging it, and a lengthened robot arm to scan the shuttle’s skin for damage. Nasa, however, is still not confident about fixing an orbiting shuttle and wants marooned astronauts to take refuge on the half-built international space station (ISS) and wait for a rescue crew. They could then ride home in reclining seats, which lessen the effects of returning to Earth’s gravity and allow the rescue ship to carry 11 people instead of the normal seven.
But a rescue mission is so risky that Nasa may as well fly the shuttle unmanned for some of the 15 more missions needed to complete the ISS. Shuttle designers of 30 years ago had in mind a reusable spacecraft that would lift off, go into orbit, and carry out the entire re-entry and landing sequence automatically (except for flipping the landing gear switch: this was left manual so that pilots didn’t feel redundant).
By 2010, shuttles will have been replaced by the crew exploration vehicle, Orion, which uses the same main engines, solid rocket boosters, and external tank. But it perches atop the launcher, above any debris that might fall off. Its conical shape is considered the safest for re-entering Earth’s atmosphere. It can carry three astronauts and cargo for the ISS or a crew of four for a lunar mission. Enhanced electronics, life support, propulsion, and heat protection systems should help Orion take up from where Apollo left off.