Pursuant to a congressional request, GAO reviewed the National Aeronautics and Space Administration's space station program, focusing on: (1) the Department of Defense's (DOD) potential use of the space station for national security purposes; (2) the program's total cost; and (3) other existing and planned space stations.

GAO found that: (1) DOD has not identified or planned any research that would require the space station's unique environment; (2) the space station's design is not suitable for many DOD activities conducted on the space shuttle, but some shuttle-based research could benefit from the space station's capabilities; (3) space shuttle upgrades, such as long duration orbiters and Spacehab, could meet potential DOD research needs; (4) the space station's total estimated cost is at least $118 billion, but program costs may increase due to design changes and other research and development activities; and (5) Russia plans to upgrade its existing space station in 1994 and build a new more capable station in the future.