CAPE CANAVERAL, Fla. - Shuttle Atlantis and five astronauts are scheduled to blast off from Kennedy Space Center tonight on what arguably is the most critical - and definitely the most expensive - International Space Station construction mission to date.
The job at hand: Delivering the $1.38 billion U.S. Destiny laboratory to the frontier outpost, where it is supposed to serve as both a central hub for scientific research and a crucial linchpin for future station construction.
And while senior NASA officials hate to contemplate the upshot of a launch accident, they know the loss of Atlantis, its crew and the lab could sound a death knell for the $60 billion station construction project -- and perhaps the agency's human space flight program.
"It's hard for me to imagine a scenario where we would lose the laboratory completely and still be in the business that we're in," said NASA space station project manager Tommy Holloway.
"How would that happen? We lose the shuttle. Well, if we lose the shuttle, we have bigger problems."
Coming 15 years and 76 flights after the 1986 Challenger disaster, the launch of Atlantis and its four-man, one-woman crew is set for 6:11 p.m. EST (23:11 GMT). (Look here for the latest update on the countdown.)Tucked snuggly in the shuttle's cargo bay is the Destiny lab, a can-shaped aluminum module that weighs 32,000 pounds (14,400 kilograms), stretches 28 feet (8.5 meters) from end to end and cost as much as NASA's Hubble Space Telescope to build.
"It is, I believe, probably the most expensive thing we will be launching" as part of the station construction project, Holloway said.
With as much pressurized space as the fuselage of a large business jet, the Destiny module is designed to be outfitted with equipment that will enable researchers to conduct experiments in a wide variety of scientific disciplines.
Just as important, though, is the fact that Destiny is supposed to serve as a new central nerve center for the station, providing command and control for the entire outpost.
What's more, the U.S. lab is supposed to furnish future European and Japanese research facilities with electrical power and cooling as well as crucial carbon dioxide removal and oxygen generation services.
And NASA has no substitute lab waiting in the wings.
Why?
"It's fairly simple -- $1.38 billion," Holloway said.
In an era of tight budgets, the American space agency cannot afford to build backups for the myriad major station components that are to be pieced together like giant Tinker Toys in orbit over the next five years.
"The resources that it would have taken to be in a full backup capability would not double the cost of the program, but [it] certainly would have added a 40-, 50- or 60-percent increase in the cost," Holloway said.
"And I have to tell you in terms of the scope and the complexity of this big job that we're doing, we need all the money that we've got to do what we've got [to do]. And we don't have the flexibility to have all the backups."
An internal NASA document, meanwhile, spells out the consequence of losing the lab during a launch accident. Penned prior to the late 1998 launch of the station's first building block, the document presages "significant impact to the station."
Some 30 months would be required to either build a replacement or outfit another American station component - most likely a U.S. habitation module - with critical systems the lab now is equipped with.
In the meantime, two extra Russian Progress space freighters would have to be launched to the station every year to provide additional fuel that would be needed to keep the outpost from making a destructive dive back through the atmosphere.
The reason: Four dome-shaped gyroscopes designed to greatly reduce the amount of fuel now being used to keep the station properly positioned in orbit cannot be activated in the absence of crucial lab control systems.
Periodic "reboosts" also would be required during all U.S. space shuttle visits to the station to help make up for the inability to spin up the so-called Control Moment Gyroscopes, or CMGs, which were delivered to the outpost last October.
At the same time, NASA's highly choreographed, step-by-step outpost assembly plan would be put on indefinite hold, bringing to a standstill a near-global project that involves 100,000 workers from 16 nations on four continents.
"Assembly cannot be continued until the lab is replaced due to critical systems located in the lab," the NASA document says.
"If we lost the lab, we would be severely set back," Holloway acknowledged. "We would have to think about restructuring the architecture of the station and downsizing for a period of time until we could replace it... I think we would be scrambling to maintain and reestablish a plan."
The future of the station construction project, consequently, will be riding along with Atlantis and its crew when NASA attempts to launch its 102nd shuttle mission tonight.
NASA's own statistics, meanwhile, say there is a one-in-438 chance that any given shuttle mission will be doomed by a catastrophic launch failure. Agency officials, as a result, say the odds of losing the lab are low.
Said Holloway: "We don't expect in our wildest imaginations to have to deal with that."
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