The space adventure of the STS-126 mission astronauts ended successfully on Sunday with Endeavour’s perfect landing at Edwards Air Force Base in California, after two weeks of hard work for both them and the astronauts on the International Space Station.

The Endeavour crew had the crucial mission of preparing the International Space Station for additional permanent residents, but also for an extended period without incoming supplies. The ISS is expected to host six crew members, instead of just three, and become less shuttle-depended, now that it has its own regenerative life support system.

The space shuttle arrived at the International Space Station carrying a payload of equipment and supplies, including the necessary tools to expand the station’s capacity from a three-bedroom one-bath residence for three astronauts, to a five-bedroom two-bath residence for six astronauts. As lead shuttle flight director Mike Sarafin pointed out early in the mission, establishing a six-person crew on the International Space Station is the best way to celebrate its 10th anniversary.

The STS-126 mission featured four spacewalks and intensive repair work on the station’s Solar Alpha Rotary Joints, which were cleaned and lubricated in order to allow the solar arrays to track the sun. The mission specialists also replaced 11 of the trundle bearings (one bearing was replaced in June, during the STS-124 mission).

Apart from some incidents, which included astronaut Heidemarie Stefanyshyn-Piper’s accidental loss of a tool bag, and some unfortunate problems with the urine recycling system, the work performed during the 16-day journey ended well.

Endeavour and its crew, including flight Engineer Greg Chamitoff, who was replaced on ISS by Flight Engineer Sandra Magnus, arrived at the Edwards Air Force Base on Sunday, although the initial objective was to return to the Kennedy Space Center in Florida. This occurred due to unfavorable weather conditions, NASA said.

The STS-126 mission may have just ended, but NASA is already looking forward to the next mission on the International Space Station, which is scheduled to launch in February 2009. The goal of the mission is to deliver the final set of solar arrays for the station’s complement of electricity-generating solar panels, which will provide the space station with enough power to accommodate the expanded crew of six.

Kwatsi Alibahuro, lead space station flight director for the mission, explained that although they are able to do a lot of things in the current power configuration, there are still other elements that need to be placed into orbit. “We don’t have the Columbus module and the Kibo module completely full of experiments, the way we expect to have it in coming years. So we need additional power capability to be able to expand the science capability.”

In addition to Discovery Commander Lee Archambault, the STS-119 mission will include Pilot Tony Antonelli, and Mission Specialists Richard Arnold, Joseph Acaba, John Phillips, and Steve Swanson, as well as Koichi Wakata of the Japan Aerospace exploration Agency, who will remain aboard the station, replacing astronaut Sandy Magnus.