Discovery‘s crew early on Tuesday made final preparations for a predawn return to Earth that will mark the conclusion of the first space shuttle flight since the 2003 Columbia disaster.
The seven astronauts closed the payload area’s massive baydoors in preparation for the homebound journey that initially had been scheduled for Monday.
The crew have admitted they would have the deaths of their Columbia colleagues on their minds during their return to Earth.
But they were were upbeat as mission control at the National Aeronautics and Space Administration (Nasa) woke them to the Beatles’ Good Day Sunshine.
”We sure hope that we get our feet on the ground today,” mission specialist Wendy Lawrence told mission control.
Nasa cancelled plans to land Discovery in Florida on Tuesday because of stormy weather and told the crew to aim instead for a touchdown across the country, in California.
Unstable weather at Cape Canaveral prompted mission control’s decision to send Discovery to the backup touchdown site at Edwards Air Force Base in the Mojave Desert, especially after small pockets of thunderstorms popped up close to the landing strip.
”How do you feel about a beautiful clear night with a breeze down the runway in the high desert of California?” mission control radioed.
”We are ready for whatever we need to do,” replied commander Eileen Collins.
The shuttle’s first opportunity to land at Edwards would be at 12.12pm GMT.
The directions to redirect toward California came just minutes after controllers told Collins the weather seemed to be clearing in Florida and they hoped to get the crew to the Kennedy Space Centre.
Conditions then took a turn for the worse.
Collins was understanding. She said her crew was familiar with Florida storms and was ”not surprised at all.”
”I’ve been in your shoes many times so I understand,” Collins told Mission Control.
Nasa instructed the astronauts to continue landing preparations and begin drinking large amounts of fluids, which are necessary for re-entry because bodily fluids are lost in the weightless environment of space.
Collins said earlier she had no worries about the return to Earth as the orbiter was in great shape.
Nasa managers also hailed the ”return to flight” mission as a complete success.
But Discovery will be grounded with the other two remaining shuttles in the fleet because its mission revealed that Nasa had failed to resolve the problems with debris falling off during lift off that had doomed Columbia.
The mission was largely designed to test changes made to the shuttle since the Columbia disaster, including improvements meant to prevent insulating foam from breaking off during launch.
The crew carried out emergency repairs in orbit, and there were concerns that a tear to a thermal blanket just outside Collins’s cockpit could pose a new danger. But Nasa officials said the return would be safe.
They also said the orbiter suffered no significant damage when foam insulation fell off its external fuel tank as the shuttle blasted into orbit on July 26.
The same problem doomed Columbia, as the debris hit the orbiter’s left wing, causing a crack that eventually allowed superheated gases to penetrate the structure upon re-entry into the atmosphere.
As it plunges through the atmosphere, the shuttle’s speed drops from nearly 29 000km per hour in orbit to about 350kph at touchdown.
The mission had been scheduled to last 12 days, but an extra day was added so the crew could transfer as much material and provisions as possible to the International Space Station, amid uncertainty over the date of the next shuttle flight.
The crew also retrieved waste and equipment to clear out space in the cramped orbiting lab.
During the mission, Stephen Robinson became the first astronaut to carry out a spacewalk under the shuttle, to extract two protruding pieces of fiber that risked overheating during re-entry.
In another two spacewalks, Robinson and Japanese astronaut Soichi Noguchi tested repair techniques adopted after the Columbia tragedy and replaced one of the space station’s four gyroscopes. – Sapa-AFP