GAO Faults NASA on Shuttle Alternative Effort

At a May Senate hearing, Griffin acknowledged the shuttles may not be up to making 28 flights in five years. He said shuttle program engineers and managers are considering dropping some of the missions.

A new cargo-only module could be employed to replace the lost shuttle missions, Griffin said. The agency is currently evaluating 26 proposals from companies interested in ferrying cargo to and from the space station. International partners Japan and Europe are developing automated cargo haulers that can launch on rockets. Currently, Russia's Progress automated cargo spacecraft are the only means of resupplying the outpost while the U.S. shuttles are grounded.