SPACE CENTER, Houston (AP) _ With the space shuttle fleet grounded by the Columbia disaster, Russian spacecraft will be used to exchange crew members aboard the International Space Station, NASA officials said.
The next crew to live on the station will have two members instead of the usual three and will be launched in late April or early May. The crew _ one American and one Russian _ will deliver a fresh Russian Soyuz, the space station's lifeboat.
The station's current crew _ Americans Kenneth Bowersox and Donald Pettit and Russian Nikolai Budarin _ would return to earth after being in orbit since November. Station crews normally are exchanged on shuttle flights.
Since last week, two U.S. astronauts and two Russian cosmonauts have been training in Russia for the two slots. The crew, set to be the seventh to live on the station, will be chosen in mid-March, said NASA spokesman Rob Navias.
Once the new station crew members arrive, they will work with the current residents for four to six days on handover procedures before Bowersox, Pettit and Budarin return to Earth.
The two American astronauts training are C. Michael Foale and Edward Lu, and the two Russian cosmonauts are Alexander Kaleri and Yuri Malenchenko. Lu, Kaleri and Malenchenko were originally the three-person crew set to replace the space station's current residents. Foale had been picked to be the commander of the eighth resident crew.
``Based on the normal Soyuz rotation (about every six months), if shuttles are not flying by mid-October, we will do another two-man rotation using (another) Soyuz,'' Navias said.
The 16 nations involved in the program decided Wednesday to go with a two-person crew because only a limited number of supplies, particularly water, can be delivered to space station Alpha while the shuttle fleet is down. Russian Progress vehicles, cargo ships that are launched and dock automatically at the station, cannot alone deliver enough supplies to maintain a three-person crew, Navias said.
The station currently has enough fuel to stay in orbit for another year but future Progress vehicles will deliver additional fuel. Assembly of the station has been halted. Scientific experiments will continue but on an altered basis with the two-person crew.
``It was the unanimous belief of the partnership that it was very important to keep the station manned to maintain the capability onboard, to deal with any unexpected systems issues and to press on with the science program that may be available to be conducted under the circumstances,'' Navias said.
NASA Administrator Sean O'Keefe told the House Science committee on Thursday that the Russians have agreed to build enough spacecraft to send four Progress ships to the space station this year and five in 2004 to keep Alpha resupplied.
While no timeline was discussed for the shuttle's return, officials have planned for a worst case scenario of going 18 months to two years with two-man crews. ``As long as Soyuz and Progress vehicles are produced ... you could stay with a two-man crew (rotation) indefinitely,'' Navias said.