As humanity extends its reach into space, seldom in the annals of 20th-century exploration have events converged to focus on a frontier as they are doing now.
The promise - and perils - are seen in a stunning range of missions under way. This Friday, a robotic rover will land on Mars and begin gathering soil samples on a planet that scientists believe could harbor microbial life. Last Friday, a spacecraft whizzed past a coal-black asteroid and provided scientists with a series of dramatic snapshots. Tomorrow, the space shuttle embarks on a mission to study the formation of metals and gardening under microgravity conditions.
But for the moment, it is in the confines of an aging space station circling Earth, where astronauts are working in the dark with flashlights in their mouths, that the notion of frontier resonates most.
"These guys are real heroes," said Frank Culbertson, a manager of the Shuttle-Mir program at a briefing yesterday. "They've shown that with perseverance and support [from the ground], you can get through some very serious situations. This is giving us a better understanding of the risks and what it takes to manage and deal with them."
The two Russian cosmonauts and one NASA astronaut are trying to repair the stricken Russian space station after a supply ship collided with Mir last Wednesday, punching a hole in the structure. The Mir crew awaits badly needed supplies that are expected via a Russian Progress resupply ship that is scheduled to launch between July 5 and July 8.
BUT as living conditions return "more to normal," Mr. Culbertson says "you're seeing a reduction in the [crew's] alarm level and increase in the capability of the station to support life."
Still the crew has raised warning flags about the plans to restore power. The supply vessel punched a hole of unknown size and location in Spektr, Mir's newest science module. The collision also damaged a solar panel and severed power and solar-panel control cables running from the Spektr to the rest of the station.
Russian controllers currently expect to have the cosmonauts modify and install a new hatch between Spektr and the station's hub that will allow cables to pass through without depressurizing the rest of the station. Because they will be working inside the airless module to splice power and control cables, they must wear bulky space suits designed for use outside Mir. Space on board is tight. In the wake of the collision, no one is certain about what chemicals may have been released in Spektr or what jagged edges there may be to snag a space suit.
When NASA officials at Russia's Star City began to explain the plan to astronaut Michael Foale and asked him to come up with a list of things for the cosmonauts to retrieve on Spektr, he said, "Look, I can come up with a list, but the idea of them going much further than the entry way is incredible." On Friday, one of the cosmonauts expressed similar concerns, saying it would be impossible for someone in a pressurized space suit even to fit through the hatch.
The terse rely came back from mission control in Moscow: "That's what the training session is for," referring to on-orbit simulations planned to prepare the crew for the repair effort.
To some aerospace specialists, the Russians' penchant for patching stems from a different design approach than NASA's. Mir and Columbia's aborted April science mission illustrate the contrast, they say. NASA cut short Columbia's flight when a fuel cell malfunctioned, even though the orbiter can operate with less than its full array of fuel cells. Russian officials have kept Mir going despite fires, a balky life-support system, and modules that have been occupied for years beyond their design life.
"The Russians are very pragmatic.... They design robust, simple systems that can be repaired by someone without an engineering degree and with simple tools," says Charles Kauffman, an engineer at the University of Michigan. "We go to extremes with redundant devices."
For all NASA's emphasis on safety, the US space program has lost 10 astronauts between Apollo 1 and Challenger. The Russians, he says, have lost three.
"Expanding the limits of aviation has always been risky. Maybe what's happening on Mir isn't desirable, but it certainly is very valuable. How they solve this thing will be very useful for the International Space Station or an eventual manned mission to Mars."
THE run of problems on Mir has prompted some people to call for an end to sending US astronauts to the station. James Oberg, an analyst of the Russian space program, says that NASA has learned a great deal from its flights to MIR. But recent events, he says, have shown that even the station's handlers can't be sure about the reliability of key components. "It's more than risky to keep men there, it's reckless," he says. Losing a Mir crew could sink cooperative efforts between the US and Russia.
Canceling reservations for the last two US astronauts scheduled to work aboard Mir "would not be a major loss to the program," says John Logsdon, a space expert at George Washington University. But a decision to scratch the final two tours has potential consequences for the partnership, he adds. "If we decide to pull out but the Russians keep a crew aboard, we're casting a vote of no-confidence on their judgment," he says.
For now, NASA will continue the missions. "There's useful activity that can be done once we complete repairs, says Culbertson. But if we reach the point where it's not productive, and certainly if it's not safe, we'll bring people home."
* Neela Banjeree contributed to this report from Moscow.