The shuttle Discovery has moved away from the International Space Station while Nasa braced for the first landing since the crew of Columbiadied minutes before they were due to touch down in February 2003.
"We are going to be pretty darn happy to get to wheels stop and see this good crew step off," said lead flight director Paul Hill. "It'll be a huge sense of accomplishment having gotten through the last two years and demonstrated that we still know how to do this very difficult and dangerous business."
After 13 days in orbit, Discoveryis due back at the Kennedy Space Centre in Florida early tomorrow morning.
The mission is Nasa's first since the Columbiaaccident. Columbiawas damaged during liftoff by a piece of foam insulation that fell off the fuel tank and struck the ship's wing. As the ship plunged through the atmosphere for landing 16 days later, superheated gases blasted inside the damaged wing, melting the structure and dooming the crew.
A major goal of Discovery'smission was to test how well the newly designed fuel tank worked and practice using a suite of imaging and data analysis techniques to assess the shuttle's condition while it was in orbit. Though the fuel tank shed much less debris than on previous flights, several large pieces still broke away during launch, prompting Nasa to halt future missions until the problems can be readdressed.
After a nine-day service and resupply mission at the space station, the seven shuttle astronauts boarded Discoveryand closed the hatch. Pilot Jim Kelly gently pulsed the ship's thrusters to ease away from the station, then looped the space freighter around the outpost while his crewmates snapped pictures to document the station's condition. Bidding the station crew a final farewell, Mr Kelly then fired the shuttle's jets to leave the station's orbit, the first step toward the trip back home.
While at the station, Discoveryastronauts Soichi Noguchi and Steve Robinson conducted three spacewalks, which were mostly devoted to maintenance work on the station and installing a storage platform on its exterior.
The third walk included an unprecedented repair by Mr Robinson on the shuttle's belly as he plucked out two cloth strips protruding from the heat shield. Discoverytransferred tons of cargo to and from the space station, stocking it with food, water and other supplies, and carting off trash and unneeded equipment that had piled up since the last shuttle visit in 2002.