The main task for the morning hours was to place the Italian-made Raffaello module back in the shuttle cargo bay. It was used to ferry in food, supplies and spare parts to the ISS and now is crammed with waste and equipment, clearing out some space in the cramped orbiting lab.

"We are in really good shape. The vehicle is in pristine condition. All tests are good, we are ready to go. De-orbit is not a risk free activity. Our big risk now would be weather," Paul Hill, lead shuttle flight director, told a briefing in Houston, Texas, ahead of undocking expected at 0724 GMT Saturday.

"When we undock, we are going to fly around the space station, they'll fly a full loop all around the space station with windows to the space station, snapping pictures all the way around. We are doing it to take pictures of the space station, snap some pictures from some angles we haven't seen since the last orbiter was there" in 2002, Hill said.

The shuttle was expected to land early Monday at Kennedy Space Center near Cape Canaveral. The touchdown time, weather permitting, has been set for 0846

NASA could leave the shuttle in orbit an extra two days if weather conditions interfere. It also could order a landing at Edwards Air Force Base in California.

The reentry phase, which starts about an hour before landing, will be a highly nervewracking moment for NASA two and one half years after Columbia burned up on reentry killing its seven astronauts on February 1, 2003. During the landing, "You only get one shot at it since we are only a big glider," Hill explained.

"Before I go in (the mission control) building, I assume I'll have a thought or two about the 107 crew," he said referring to the flight number of the Columbia mission.

"During de-orbit, I'm sure I'll have a thought or two about Rick Husband and his crew. At wheel stop, I'm sure all of us are going to think a lot about the 107 crew, as well as the 114 crew we are going to be very happy to see on the ground," he added.

Before that mission officials will check data to confirm Discovery is in good shape; it has new detectors to pinpoint any abnormal temperature rise on reentry.

The features were built into the wings of the shuttle after the Columbia disaster. Discovery is the first shuttle to dock at the ISS since the 2003 Columbia disaster.

NASA has warned it is not going to run new shuttle missions until it had solved the problem with foam insulation which tore off the fuel tank on launch July 26. The same kind of damage spelled death for Columbia's crew of seven in February 2003.

Much of Discovery's 13-day mission was dedicated to inspections to try to make sure that debris from the fuel tank had not damaged the shuttle so that it could make a safe return to Earth.

But according to internal NASA documents published Thursday in The New York Times, the space agency was warned in December 2004 that the way in which insulation was applied to the external fuel tank was still a risk -- despite 200 million dollars having been spent to solve the insulation woes.

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