NASA should be able to assemble the "complete US core" of the International Space Station with the existing funding, plus the European and Japanese modules. After that, it has to go back to Congress and the allies asking for more money, and to do that, it needs a definitive plan. The key limit at this point is that the lifeboat on the station can only hold three people, so the crew is limited to three (temporarily expanded for a couple of days whenever a Space Shuttle visits). What is needed is either another cheap lifeboat, or (what NASA and the Europeans really want) a dedicated crew service vehicle, a sort of mini-shuttle that could be used to carry crewmen to the station and provide them a way down if things go wrong. NASA has enough money for five shuttle flights a year, which just barely supports any kind of science program on the station (which cannot do much with the three-man crew).--Stephen V Cole