Russian cosmonauts restored several key computers aboard the International Space Station yesterday, resolving a problem that had bedeviled flight and ground crews from the U.S. and Russia for four days.
Still, the orbiting craft's Russian-operated computer system - apparently knocked out by a power glitch when an American solar panel array was connected this week - reminded the world that the lofty ambitions of manned space exploration can rise or fall on technology as mundane as a power cable or a software malfunction.
The downed computers also provided fresh ammunition to critics who call the $100 billion manned station, launched in 1998, a boondoggle that relies on old technology and doesn't produce enough science to justify its cost.
"It is vastly cheaper, 10 to a hundred times cheaper, to do things robotically in space," said Robert Park, a University of Maryland astronomer.
Cosmonauts Fyodor Yurchikhin and Oleg Kotov had to make the fix by hand yesterday, when they used a cable to bypass a power switch and got two out of three computer connections running, according to Lynette Madison, a NASA spokeswoman in Houston.
The space station needs only one working connection to operate computers that control orientation and oxygen production.
The cosmonauts planned to watch the computers for the next several hours to make sure that they were functioning properly. "They're up and operational, and this is good news for all," Madison said.
The computers oversee life support systems, keep the craft properly positioned, point its solar power arrays at the sun, and shift the station to avoid occasional space junk, officials said.
Help from shuttle
With the computers down, the space shuttle Atlantis' thrusters were able to help the station stay in place while the spacecraft are docked. After the shuttle leaves in several days, the space station's gyroscopes and thrusters on three Russian spacecraft docked at the station can help maintain control in a pinch.
If the computers falter again, a Russian cargo ship's trip to the station can be moved up next month to deliver new ones. Even without a working oxygen-production system, enough oxygen is stored on board to last almost eight weeks.
The bottom line, officials said, is that the station is on track to be completely constructed by 2010.
The jointly managed effort, an orbiting platform for scientists here and in Europe, has experienced problems before - including glitches with both American- and Russian-run computers. "It's had all kinds of technical problems, and it's designed to be fixed," said John M. Logsdon, director of the Space Policy Institute at George Washington University.
This week's glitch has been unusually confounding, though.
Nikolai Sevastyanov, president of the Russian space and rocket company Energia, told reporters yesterday that the failure of six onboard computers was caused by an surge in the power supply that occurred when U.S. astronauts installed new solar panels.
"The breakdown in the electricity network occurred when the astronauts switched on the panels on the U.S. segment," he said, according to the Russian news agency Interfax. "A static signal went through the station exceeding the permitted norms."
Both the regular and the standby power sources failed, he said. A reboot of the entire system, which the Russians tried overnight Thursday, had not solved the problem.
The glitch was an example of how, as space exploration becomes more ambitious, the technological demands on workers will intensify - and will have to be met, experts said.
"You're going to have to see these things coming and deal with them," said Tom Jones, the Baltimore-born astronaut and consultant on space issues who visited the space station in 2001. "The space station doesn't come home, so you have to do it in flight - and while you're doing other things as well. ... That's what you have to learn how to do if you want to live in space permanently."
A fix for the Russian computer system was complicated because the Russian ground control crew, unlike its U.S. counterpart, lacks a 24-hour satellite link to the onboard system, Jones said.
"The Russian controllers who wrote the software for the system are in Moscow, and Moscow doesn't have tracking satellites like we do. They rely on ground stations," Jones said. "They have to sort of try their troubleshooting during a pass, and if it doesn't work, they have to wait."
Yesterday American astronauts attempted unsuccessfully to address one suspected cause of the problem by unhooking a connector that went online just before the computer glitch started.
Even if no fix had become apparent, the worst-case scenario would have taken months to develop, experts said.
"The slowly developing worst-case situation is the station drifts out of attitude, you can't keep the solar arrays pointed at the sun, the batteries can't recharge, you lose power," Jones said. "And at some point, you have to shut down everything, and you have to evacuate the station."
Evacuation of the station would have been considered a major setback but likely would not stop efforts to complete it. Construction has been in progress for nine years, with 16 nations invested in a project that's jointly administered by the U.S., Russian, European, Japanese and Canadian space agencies.
"It's 65 percent built, you've got billions of dollars of European and Japanese equipment sitting on the ground waiting to be moved up there," Logsdon said.
When finished, the station will be larger than a five-bedroom house, weighing 1 million pounds and measuring 361 feet from end to end.
Most scientists agree that it's an impressive engineering feat. But each U.S. president since Ronald Reagan has set different priorities for the space station over the years, leading to confusion about the orbiting lab's job among scientists and the public, according to UM's Park.
"It never had a mission, or if it had a mission, it kept changing under different presidents," he said.
Space station supporters still consider it a unique, if underfunded, testing ground for studying the effects of microgravity on fluids, metals, viruses and other microscopic life forms.
"It's the only place we can do microgravity research and look at things like cell growth and the effects of weightlessness on cells," said Laurence R. Young, a professor of astronautics and health sciences at the Massachusetts Institute of Technology. "My hope is that what we'll see is a resurgence of funding under subsequent administrations."
Research money cut
President Bush made a return to the moon and eventual manned space flight to Mars part of his long-term goals for NASA in 2004. He pledged to finish construction of the space station but has since cut back funding for scientific research on board.
"For all practical purposes, NASA has removed the capacity for any scientific research," said Joseph Alexander, an astronomer and former director of the National Academy of Sciences' Space Science Board.
Alexander and other experts say the space station also is ideal for trying out technologies that will help astronauts avoid the health problems associated with extended periods in space - such as a trip to Mars.
But a National Academies report last year found that current NASA funding levels don't provide enough crews and equipment to fulfill that mission.
"If you're going to send astronauts to the moon and Mars and have humans in space for extended periods, you have to understand the risks of doing that, and the only place we have to do that is the space station," Alexander said.
With existing technology, a trip to Mars will take at least nine months in each direction, exposing crews to health problems brought on by weightless environments, Park said.
Some astronauts returning from the space station after relatively brief stints of three to six months have experienced cardiovascular problems that make them susceptible to fainting when they stand up, said Kenneth M. Baldwin, a professor of physiology and biophysics at the University of California Irvine.
They recover, but with current technology a round trip to Mars would last at least 18 months. The effects of long space flights on bone density, muscle and cardiovascular health remain largely unexplored, Baldwin said, adding that the space station remains the best place to test interplanetary fitness equipment.
Sun reporter Erika Niedowski and the Associated Press contributed to this article.