The loss of the shuttle Columbia won't strand two Americans and a Russian orbiting on the International Space Station. But an extended grounding of NASA's fleet could threaten the station's long-term viability - and provide critics with ammunition in their fight to kill the $100 billion program.
The three astronauts who arrived in orbit in November have an evacuation capsule docked to the station - a Russian-made Soyuz that can return them to Earth at any time, NASA officials said.
An unmanned Russian Progress cargo ship was scheduled to lift off today from Baikonur Cosmodrome in Kazakstan on a routine supply mission. Even without it, the astronauts have enough food, water and air to last until June, shuttle program manager Ron Dittemore said yesterday.
But the cash-strapped Russian space agency says it can't pay for many more Soyuz flights - it was counting on U.S. space shuttles to take over in the long term. If NASA, as expected, cancels all shuttle flights until it makes sure its three surviving orbiters are safe, the space station might have to go dormant.
"It's a great blow to the whole space program," Sergei Gorbunov, director general of the Russian Aviation and Space Agency, told the Russian NTV network last night.
The space station is a 16-nation project administered by the U.S., Russian, European, Japanese and Canadian space agencies. It depends heavily on Russian expertise and employs thousands of engineers and scientists in Moscow.
But NASA critics have long viewed it as a boondoggle that relies on old technology and doesn't produce enough scientific benefits to justify the cost.
"It's always been a target," said one of those critics, Roy Williamson, a research professor at George Washington University's Space Policy Institute. When the shuttle program was created 30 years ago, one of its main justifications was its ability to supply a permanent space station.
Columbia did not visit the station on its last voyage, but its sister ship Endeavour delivered the station's three current tenants in November. The shuttle Atlantis was scheduled to deliver supplies and scientific equipment in March, while Endeavour was scheduled to haul up a framework of external trusses and solar arrays in May.
The Columbia disaster is expected to bring an intense examination of both the space station and NASA's overall budget.
"There's no doubt there will be a lot of scrutiny of that agency," Williamson said.
Cost concerns at NASA are not new. NASA Administrator Sean O'Keefe, a former ranking official at the White House Office of Management and Budget, made cost control and financial management a top priority when he took over the space agency on Jan. 15, 2001.
He was also directed to resolve cost overruns, especially on big-ticket programs such the space station. Testifying in Congress during his confirmation hearing, O'Keefe said the agency had done a good job putting the first part of the station into space but had poorly managed the costs, estimated to be $4.8 billion over budget.
To rein in costs, O'Keefe put the space station on two years' probation, restricted the shuttle fleet to four supporting flights a year, and froze the space station crew size at three.
For the time being, everything will be on hold while NASA officials sort out safety issues.
"Right now, certainly there is a hold on future flights until we get ourselves established and understand the root cause to this disaster," NASA's Dittemore said at a news conference in Houston.
The current crew aboard the space station, known as Expedition Six, is scheduled to return in March. The crew is composed of NASA astronauts Ken Bowersox and Don Pettit and Russian Soyuz commander Nikolai Budarin.
The Soyuz capsules they rely on for emergency transportation are replaced every six months or so when their certified life in orbit ends.
A 1996 agreement obligates the Russian Aviation and Space Agency to provide 11 Soyuz capsules for the space station. The three-seat craft can also be used to deliver astronauts, but each capsule is good for only one round trip.
It was Soyuz capsules that transported U.S. tourist passenger Dennis Tito in April 2001 and South African tourist cosmonaut Mark Shuttleworth a year later.
Because of Russia's budget problems, the United States, which already provides most of the space station's funding, would have to pay for any replacement spacecraft as well.
The are only enough Soyuz and Progress cargo vehicles to service the station for one year, Gorbunov said.
The last Soyuz is scheduled to arrive at the station in November 2005, with a return to Earth planned about May 2006.
NASA had hoped to expand the space station during five shuttle flights this year. But if the shuttles are grounded, expansion will be impossible.
Even with a ramped-up program to build replacement craft, it could take two years to build new vehicles - meaning the station might have to be abandoned for a period, Russian experts say.
With no permanent crew aboard, the space station can operate in a "dormant" mode as long as occasional maintenance is performed by visiting astronauts. Officials said NASA had already been considering a "de-manning" contingency plan before yesterday's disaster.
But engineers say the longer the station is vacant, the greater the chances that it will deteriorate to an uninhabitable state.
Wire reports contributed to this article.