JOHNSON SPACE CENTER, Texas -- Their incredibly successful mission nearly over, shuttle Endeavour's astronauts readied their spaceship for Wednesday evening's ride home.

The seven crewmen accomplished everything they set out to do in orbit. They added another room to the international space station, assembled a giant robot, tested a gooey patch for shuttle thermal tiles, inspected a jammed solar-wing joint, dropped off a shuttle inspection boom and swapped out station residents.

All that remained was re-entry and touchdown, and the weather looked as though it would cooperate.

As has become customary during their 16-day flight, Gorie and his crew got an early start Tuesday on Endeavour's flight systems checkout. Everything tested fine.

Endeavour was returning much lighter than when it blasted into orbit in the early hours of March 11.

The shuttle delivered to the space station the first section of Japan's Kibo lab, a 14-foot, 18,500-pound storage compartment. The actual lab will arrive in May aboard Discovery. Endeavour also ferried up a 12-foot, 3,400-pound robot named Dextre - complete with 11-foot arms - that was provided by Canada.

It took three spacewalks to put Dextre together outside the space station.

The orbiter is scheduled to land at Kennedy Space Center, Fla., on Wednesday.