It springs antifreeze leaks, suffers electrical and steering failures, and has survived a fire and a catastrophic collision. It's been driven hard, and it's rapidly growing obsolete.
If it were a car, its jittery owner would have junked the 11-year-old vehicle long ago. But it's Russia's Mir space station, and the owner is loath to get rid of the world's only orbiting human habitat.
Still, Mir operates 250 miles above the Earth, in the blood-boiling vacuum of space. The urgent questions remain: Is it still safe to fly, or even worth repairing?
For the Russians, Mir is one of the last remnants of a once-mighty space program.
Despite six harrowing months for Mir crews, the Russians are hanging onto it. With an electrical splice here and a hull patch there, they say, it will be fine.
But some Americans are nervous. U.S. astronauts are regular passengers aboard Mir. Anticipating danger, NASA gave Astronaut Michael Foale extra fire-fighting training before joining the current crew.
Rep. F. James Sensenbrenner, a Wisconsin Republican who is chairman of the House Science, Space and Technology Committee, suggests it may be time to send Mir to the scrapheap.
The National Aeronautics and Space Administration plans to spend $470 million over the next five years to put astronauts aboard Mir. They're supposed to train to operate the planned international space station Alpha, a joint U.S.-Russian venture.
Without NASA's support, Russia's space program might not survive. Still, NASA says Mir's fate is strictly Russia's business.
"It's their spacecraft, their systems -- they're the ones who will make the ultimate judgment as to whether or not their Mir space station is safe enough to keep up in orbit," says Rob Navias, a NASA spokesman at Johnson Space Center.
"As far as we're concerned, we think the spacecraft meets the criteria for safe passage."
Some of those familiar with Russia's space program concede that life-support equipment has been faulty and some cosmonauts fumble-fingered after long, fatiguing stays in space. But the craft itself is sound, they insist.
The biggest threat to the crew is the catastrophic loss of cabin pressure. And that's not likely to happen, short of another collision.
"As long as they have life support, a spacecraft where they can escape, and a spacecraft that's under control, they are perfectly safe," says Charles Vick of the Federation of American Scientists. "There is no real danger."
A Soyuz escape capsule stands ready to evacuate crew members. Mir orbits Earth 16 times every 24 hours, and three of those orbits take it over the emergency landing zone in Kazakstan.
There is no precedent for abandoning a crippled vehicle in space. After an explosion in 1970, Apollo 13 astronauts used the craft's lunar lander as a temporary lifeboat. But they returned to Earth, as planned, in the command module.
Roald Sagdeev, the former chief of Soviet space science who is now a professor at the University of Maryland, didn't always agree with Mir engineers while they were building a Mir module for his Institute of Space Research back in the 1980s.
'Airtight, solid, reliable'
But, he says, the basic structure of the Mir is "airtight, solid, reliable."
Mir was launched in 1986, with an expected life of five years. At first, it was loaded with Soviet-era electronics that were below Western standards. During the past few years, though, much of that equipment has been upgraded.
Russians, Sagdeev points out, have more experience in space than Americans. Before Mir, the Soviets operated six smaller space stations.
And Mir has a much better safety record than NASA's chief project, the space shuttle. Seven astronauts died when the shuttle Challenger exploded in 1986.
"The last fatality [in a Soviet spacecraft] was in 1971," Sagdeev notes, referring to three cosmonauts who died on re-entry. "Who else has such a track record?"
NASA's only experience running a space station came between May 1973 and February 1974, when a succession of crews operated the glitch-plagued Skylab. It served as a working space station for just 3,900 orbits over 171 days -- compared to Mir's 11 years and more than 64,000 orbits.
Russia's experience will be vital, he says, to operating Alpha.
Sagdeev says the current crisis on Mir is an opportunity to increase cooperation between Russian and U.S. space officials.
The Russians, he says, should let NASA participate in analyzing and deciding how to respond to problems and emergencies.
"I don't want to criticize Russian scientists," he says. "They are trying to do a heroic job in salvaging the station, but more openness and cooperation would help them."
Vick, of the Federation of American Scientists, says that Mir shouldn't be blamed for most of its troubles.
Take the June collision between the Mir and the Progress, an unmanned cargo craft the size of a bus. Progress was loaded with trash, and scheduled to be cast off to burn up in the Earth's atmosphere.
