Discovery astronauts wrap up space station work

The crew have used the shuttle's robotic arm to scan Discovery for possible damage caused during liftoff and Nasa analysts found nothing that would prevent the spaceship from safely flying home on Monday.

But for the first time in a shuttle mission, the astronauts will conduct another safety check Friday before they pull out of the International Space Station to ensure that Discovery's heat shield was not cracked by space particles during just the second flight since the 2003 Columbia tragedy.

They will make one last inspection after they undock from the ISS Saturday.

"We are going to look at it one more time," Discovery pilot Mark Kelly told CBS News television from the ISS. "But based on what we have seen so far and on what the risk is, I think all of us feel really comfortable."

Before the inspection, the astronauts finished putting ISS trash and unused equipment into a container that they prepared to transfer into the shuttle's payload bay.