Fifteen years after President Reagan directed NASA to develop a new space station, and almost a year after the first component was launched into space, the complex project continues a lifelong pattern of making itself up as it goes along. The latest: NASA still hasn't figured out what it will cost to operate the orbital facility year by year once its $63 billion development and construction phase is over in, perhaps, 2004, according to congressional investigators.

The U.S. space agency has estimated that the station's annual operating costs will average $1.3 billion, or $13 billion over a 10-year lifetime. But a report by the General Accounting Office, the watchdog arm of Congress, concludes that this estimate falls billions of dollars short because it omits a number of items; was developed for a different, earlier design; and does not reach far enough into the future.

One of the big selling points for the project was its international aspect. But nobody can say at this point how much NASA's costs would be reduced by any contributions from partners such as the European Space Agency and most particularly the struggling Russians. "The full impact on operations if Russia is unable to fulfill its obligations is not known at this time," the GAO said.

NASA's space station budget does not now include the costs of upgrading obsolete systems or operating an alternative propulsion module, which would be needed to prevent the facility from falling out of orbit if Russia defaults on that obligation.

And some costs properly attributed to the space station, such as civil service workers and space shuttle flights, are listed elsewhere in the NASA budget.

The investigators noted that NASA officials are working on a new, improved 10-year funding profile.