The money matter is just one of the criticisms. Some scientists believe the U.S. might have made bigger gains in space by building a permanent colony on the moon or by pushing on more rapidly to Mars. Safety is yet another concern. As at any construction site, the project can be dangerous. With so many rocket launches needed to get all the pieces into orbit, the chances are high that a major accident involving a shuttle or a Russian rocket will occur.
Some critics favor the use of robots instead of humans to explore space.
Yet another concern is the risk of relying on Russia. Given its shaky economic and political condition, some scientists question whether the Russians will be able to deliver the major parts of the station they've promised to build. Already, the Russians have fallen behind schedule on building the Service Module, the next part due to be launched. The Service Module carries the environmental controls and the life support system for the entire station. Until the Service Module is in place, no other parts can be attached.