The shuttle is to land this morning at the Kennedy Space Centre at Cape Canaveral, Florida, at 4.46 local time, having descended from more than 220 miles and a speed of 17,500mph. Its approach from the south-west will take the shuttle over Nicaragua and Cuba before touching down.
"It's time to come home," Discovery's commander, Eileen Collins, said yesterday. "And keep working on getting the shuttle better and ready to fly in the future again." Perhaps not surprisingly, Nasa officials said they expect no problems with re-entry. But as a result of the break-up of the shuttle Columbia in February 2003 on its return, officials are aware of the anxiety surrounding Discovery's journey.
Wayne Hale, Nasa's deputy shuttle programme manager, said: "It's been an outstandingly successful mission. We accomplished everything that we set out to do and more." But he added: "Flying a re-entry from 17,500 miles per hour to stop in this 100-ton glider that has got one shot at a runway is not what normal, sane people would normally call safe."
On Saturday morning, the shuttle separated from the international space station with which it has been docked for the past week and conducted a "victory lap" around the station that allowed the crew to photograph the orbiting facility. On Sunday, the crew made final checks and practised their return on a flight simulator. Otherwise their day was deliberately kept "light".
LeRoy Cain, the flight director, said the weather forecast looked good for the landing but should officials decide there was a problem Discovery had an opportunity to try again at 6.21am. Nasa may also consider landing at two other runways, Edwards Air Force base in California and White Sands missile range in New Mexico. Officials strongly prefer landing in Florida to avoid the need to transport the shuttle back to Cape Canaveral.
Keith Cowing, a former Nasa scientist who now runs the NasaWatch.com website, said officials were confident and Nasa hoped to use the boost of a safely completed mission to announce it had solved the problem of falling debris from the external tanks and that the next shuttle flights - scheduled for September - could go ahead. Experts said that Discovery's mission had been almost flawless, despite the concern about the continuing problem of falling debris which led to Columbia's demise in 2003. At present, all future flights are suspended until the problem is solved.
Most of the 13-day mission was spent resupplying the space station and replacing a gyroscope that stopped in 2002. The crew also restored power to another gyroscope which stopped in March and unloaded the station's rubbish. Last week a crew member, Stephen Robinson, made a spacewalk to remove insulation padding dangling from the underside that engineers feared could cause overheating.
One person anticipating a safe return is Cdr Collins' 77-year-old mother Rose Marie, in Elmira, New York. She said: "It's kind of scary ... I'll have my rosary beads in my hand. [But] I have a lot of confidence in Eileen. If anybody can do it, she can."Reuse content