Summary: NASA has estimated that it will cost $1.3 billion annually to operate the international space station. However, this amount does not include all funding requirements for space station operations. NASA does not prepare budget estimates on a full-cost basis because it has not completely implemented its full cost accounting system. Additional items that will have to be paid for in the future include upgrading obsolete systems and operating an alternative propulsion module. Also, NASA has not estimated the cost to run an alternative propulsion module being bought to provide reboost if Russia is unable to deliver that equipment. Items that GAO found were being funded in other NASA budget lines include space shuttle flights, civil service personnel, principal investigations, and space communications. These are estimated to cost $2.5 billion in 2004. When NASA implements full cost accounting in 2001, some costs now in other NASA budget lines will be included in the space station budget. In commenting on GAO's draft report, NASA said that shuttle flights should be allocated to the overall cost of operating the space station using a marginal cost of $84 million per flight rather than an average cost of $435 million. GAO believes that the average cost per flight more accurately represents the resources NASA will spend to run the space station. Moreover, there is a high degree of uncertainty in NASA's estimate for the cost to run the space station from 2005 to 2014. Not enough information exists to determine the amount that NASA funding requirements could be reduced by international partners' contributions toward common operating costs.
