Shuttle leaves space station for Monday landing

CAPE CANAVERAL, Fla, April 17 (bdnews24.com/Reuters) - Space shuttle Discovery left the International Space Station on Saturday, wrapping up a 10-day stay to deliver supplies and spare parts before NASA retires its shuttle fleet later this year.

Pilot Jim Dutton gently pulsed Discovery's steering jets to back out of its berthing slip at 8:52 a.m. EDT/1252 GMT as the two spaceships sailed 217 miles/350 km over New Guinea in the southwest Pacific Ocean.

"Thanks for your hospitality," shuttle commander Alan Poindexter radioed to the station crew. "We enjoyed every minute of it."

In addition to delivering new experiment racks, a fourth sleeping berth and a darkroom for the US Destiny laboratory, Discovery astronauts made three spacewalks to install a new ammonia cooling system on the station, though a valve problem remains to be resolved before the new gear can be turned on.

NASA considered adding an extra day to Discovery's visit so spacewalkers Rick Mastracchio and Clay Anderson could venture outside for a fourth outing and install a spare nitrogen tank. The nitrogen is needed to pressurize the coolant, which dissipates heat from the station's electronics.

Flight directors decided to let the shuttle depart on time and have the station astronauts or a future shuttle crew make the repairs. The station has two cooling loops. Both will need to be operational beginning in about a month, when the shifting angle of the sun causes extra heating on the station.

Discovery's departure leaves NASA with just three more shuttle missions to the station before the ships are retired.

The White House wants to end NASA's planned follow-up mission to fly astronauts to the moon and instead refocus the agency on research and technology demonstrations that will culminate in a crewed mission to an asteroid in 15 years and then a mission to Mars in the 2030s.

In the meantime, Russia will fly astronauts to and from the station until a commercial US firm develops capability to launch people into orbit, an effort that President Barack Obama wants to support with a five-year, $6 billion stimulus.

The only new crewed spaceship in NASA's immediate future under Obama's plan is a revamped Orion capsule that instead of going to the moon would serve as a station lifeboat.

Discovery is due back at the Kennedy Space Center on Monday, the same day that sister ship Atlantis is scheduled to be rolled out to the launch pad to begin preparaions for its final flight on May 1