STS-124 and Expedition 17 crew members wave to the camera after bidding farewell to one another, 10 Jun 2008

The astronauts on board the U.S. space shuttle Discovery have said goodbye to the crew of the International Space Station, and are preparing to return to Earth following their mission to the orbiting outpost.

Crews closed the hatches between the shuttle and the space station Tuesday ahead of Wednesday's undocking. Other duties called for conducting a series of leak checks before the astronauts go to sleep.

The astronauts arrived at the space station last week to deliver and attach a $1-billion Japanese laboratory. They also tested a robotic arm that will help with science experiments outside the station.

Discovery's commander, Mark Kelly, says his crew's mission was a great success. The shuttle is expected to land in the United States on Saturday.

Astronaut Garrett Reisman will be on board as the shuttle returns to Earth. Reisman spent the last three months aboard the space station. His replacement, Greg Chamitoff, will remain on the station for the next six months.

Some information for this report was provided by AP and Reuters.