The STS-135 mission to be flown by Space Shuttle Atlantis later this year will bring down the curtain on the 30-year shuttle program. After this final flight, the United States will have to do without a spacecraft fleet of its own for a number of years. Until NASA decides where it stands on further manned space activities, the International Space Station will remain the only such program running. By retiring the Shuttles the Americans will be unable to independently transport crews and cargo to the Station, and will have to rely for this capability on their ISS partners. Russian Progress ships will shoulder the main burden of resupplying the Station, because the European Space Agency’s ATV Automated Transfer Vehicle and its Japanese equivalent HTV have so far been launched but once a year.
On the one hand, the Western partners consider their respective ISS segments to be largely completed; as for the routine tasks of keeping the Station in food, fuel and other supplies, these are not going to be compromised by the retirement of the shuttle. Prior to the final flight of Atlantis the ISS orbit will be raised to 400 km to compensate for drag. In the future Progress and ATV resupply craft will be using their engines to raise the ISS orbit as required.
