The U.S. space agency, NASA, says a decision is close on how to exchange the international space station crew while the U.S. shuttle fleet is grounded.
The moratorium on shuttle flights during the Columbia disaster probe is putting the spotlight on Russian Soyuz rockets to serve the station. NASA head Sean O'Keefe says the 16 nations participating in the space station program are discussing how to staff the outpost through the end of the year in the absence of regular shuttle resupply flights. He told reporters that a decision is imminent on when to replace the current three-man U.S.-Russian crew, and whether to dispatch another team of equal size or to send only two crewmembers to reduce demand on supplies.
"We're looking at all those options and we'll be looking at a conclusion here within a matter of a few days, as a matter of fact, in terms of which preferred direction we want to go," he said.
The current station crew was to be exchanged next month with a three-member replacement crew flown up on the shuttle Atlantis. Columbia's disintegration on February 1 caused NASA to halt shuttle flights temporarily.
The outpost has enough supplies for its crew to survive through the end of June. If shuttles remain grounded, a Russian Soyuz, rocket would have to carry out the crew exchange and bring up new cargo. A Soyuz can carry three people and was the vehicle that flew the first crew to the station in 2000.
A likely time for a station crew swap would be April, when the Russian space agency had planned to send up a new Soyuz to replace the one already attached to the station as an emergency escape vehicle.
A Soyuz seems almost certain to carry out the exchange if it occurs in the next few months. Mr. O'Keefe says shuttles will not fly until the independent investigating board determines the cause of the Columbia accident. Board chairman Harold Gehman said Tuesday that finding will require long and careful analysis because his panel is examining thousands of debris pieces, everything done to Columbia since its last mission last year, and NASA's management, safety, and technical practices.
"There is a ton of work left to be done in this area. We are just at the beginning of this analytical work. We are still receiving information from private citizens and the U.S. government," he said.
If U.S. space shuttles are grounded into next year, the U.S. would continue its dependency on Russian rockets to supply and staff the space station. But a legal constraint exists.
Russian space agency chief Yuri Koptev says he needs money from the United States or the other station partners to finance construction of the extra spacecraft needed for the task. But U.S. law forbids extraordinary payments to the Russian space agency for the station unless Washington confirms that Moscow has not provided Iran with missile or weapons technology in the previous year.
Whether the European, Canadian, and Japanese space agencies fill the Russian space agency's funding gap is undecided. News reports quote the European space agency's top representative in Moscow as saying the question has been discussed.
NASA administrator O'Keefe says he is confident the 16-nation partnership will solve the problem.
"Every member I see and have talked to [is] dedicated to the objectives of the international space station. We will work this together as a partnership maintaining this capability."