After an hours-long crawl, the space shuttle Discovery reached its launch pad on Saturday, in preparation for a May 31 liftoff to add the main piece of a huge Japanese research complex to the international space station.
With the shuttle in position, NASA will conduct a practice launch countdown with the seven-member crew next week. The mission is the third of five planned for this year.
Discovery's crew, led by Mark Kelly, includes five first-time fliers and two veterans. Kelly has made two previous spaceflights, and lead spacewalker Michael Fossum has flown once.
The crew includes Japan's Akihiko Hoshide, who will oversee the setup of Kibo, the Japanese Aerospace Exploration Agency's primary contribution to the space station. Also aboard will be pilot Ken Ham, spacewalker Ron Garan, mission specialist Karen Nyberg and space station flight engineer Greg Chamitoff.
Chamitoff will remain behind on the station, replacing astronaut Garrett Reisman, who began his stint as a member of the station's live-aboard crew during the last shuttle mission in March. Reisman will be returning to Earth in Chamitoff's place.
NASA delivered the storage compartment for Kibo during the March flight, setting the stage for this month's mission. Discovery is bringing up the lab's workspace module, along with its robotic-arm system. Kibo's experiments will focus on space medicine, biology, Earth observations, material production, biotechnology and communications research.
A final segment of the elaborate lab, an exposed back porch for microgravity research experiments, is due to arrive next year.
Ten shuttle flights to go
NASA is planning 10 more shuttle flights to the multibillion-dollar space station before it retires the fleet in 2010. The space agency also plans a final servicing call to the Hubble Space Telescope this fall.
The shuttles, which began flying to space in 1981, are being retired due to safety issues raised by 2003's Columbia tragedy. NASA is funding the development of a new spaceship, called Orion, which will be capable of traveling to the moon as well as low Earth orbit. However, there will be a gap between the shuttle fleet's retirement and Orion's debut.
NASA estimates the country will need to depend on other space transports to ferry station crew members to and from the station for about five years while the new ships are under construction. For now, the Russian Soyuz craft is the only alternative, but NASA is also supporting private-sector spaceship development projects that may become available.
NASA's post-shuttle options have become a subject of renewed debate in the wake of last month's bone-jarring landing of a Soyuz crew returning from the space station. NASA managers have acknowledged that the Soyuz capsule's separation system apparently malfunctioned during the descent. An investigation into the hard landing is continuing.
This report includes information from Reuters and msnbc.com.