The stakes are literally sky high: Nothing less than the future of the international space station. That's what many believe is riding on Wednesday's launch of a long-delayed Russian command module called Zvezda.

The Zvezda service module in this artist's impression. But what are NASA's plans if it doesn't reach orbit? Photo: NASA

The Zvezda module will serve as the station's central command center, providing crew quarters, power distribution, data management and propulsion during the initial years of assembly.

Scheduled for launch early Wednesday atop a Russian heavy-lift Proton rocket, Zvezda is expected to dock with the international space station July 26. If the automatic docking sequence fails for any reason, two cosmonauts will be standing by for launch to Zvezda aboard a Soyuz rocket to carry out a manual linkup.

But if the module is lost in a launch mishap or because of a catastrophic problem in orbit, completion of the space station would be delayed by at least three years, according to internal NASA planning documents.

And that does not take into account the inevitable political fallout in a presidential election year.

"My assumption is that NASA would fiddle around with contingency plans until a new president is in place and at that point, there would be an agonizing reappraisal of where we're going with the space station," said John Pike, a space policy analyst with the Federation of American Scientists.

"In the interim, I would assume Congress would spend the rest of the year doing a rain dance about how we shouldn't be working with the Russians on the international space station. ... They would lay the political foundation to predispose the next president to kick the Russians off the station."

The Clinton Administration required NASA to invite the Russians to participate in the project in 1993 as a foreign policy objective, a way to keep Russian rocket scientists employed in a peaceful pursuit in the wake of the Cold War.

For NASA, it's a sort of Catch-22: Without the Russians, it's not clear the station could maintain its current level of congressional support.

"For the last eight years or so, the political center of gravity has been that it was only the cooperation with the Russians that saved it," Pike said of past opposition to the space station. "The Russians got brought in and ... they've had more than enough votes.

"But if you were to kick the Russians off," Pike said, "the project reverts to being a science project. The thing can't be sold as a science project politically."

Politics aside, the loss of Zvezda would force NASA to launch a shuttle mission as soon as possible to upgrade the Russian-built NASA-financed control module called Zarya to increase its orbital lifetime. The shuttle crew also would boost the station to a higher, more stable altitude.

The Interim Control Module seen in computer graphic form. Photo: NRL.

NASA's $100 million interim control module, an unmanned propulsion system being built by the Naval Research Laboratory, would be launched next spring, according to the agency's contingency plan, probably in the April 2001 timeframe.

All spacecraft in low-Earth orbit are subjected to the effects of friction with atoms and molecules in the extreme upper atmosphere, which acts to lower the vehicle's altitude. The space station must be periodically reboosted to maintain a stable orbit.

Without Zvezda, the station would have to rely on the unproven interim control module. The ICM, attached to the aft docking port of the Zarya module, is designed to provide periodic reboosts for up to three years.

Once the ICM is in place, NASA likely would continue station assembly through the next five shuttle missions while accelerating development of life support systems and a more capable propulsion module to replace the ICM.

Here is the breakdown for near-term flights in the event Zvezda is lost for any reason:

Flight STS-106: Equip Zarya with upgraded systems to extend orbital lifetime; launch date TBD

ICM:Provide station reboost capability; launch date: April 2001

STS-92/ISS 3A: Z1 truss; control moment gyroscopes; KU-band communications system; pressurized mating adapter

STS-97/ISS 4A: P6 solar array truss; radiators

STS-98/ISS 5A: U.S. laboratory module, Destiny

STS-102/ISS 5A.1: Lab outfitting; first multi-purpose logistics module

STS-100/ISS 6A: Second MPLM; UHF antennas; station robot arm

The station would remain in this configuration until a U.S.-built propulsion module could be built and launched to provide extended reboost capability. The station could not support full-time crews until NASA could completed development of its own life support systems.