The release of the report on the Columbia (search) disaster Tuesday opens the door for a new space shuttle mission by next spring.

But even NASA (search) officials concede their goal of launching the space shuttle Atlantis (searchsometime between March 11 and April 6 may be too lofty a target.

NASA Administrator Sean O'Keefe will have the final word on timing, but he will be advised by a task force that will review whether the shuttle improvements from the Columbia accident report have been carried out. NASA will present a return-to-flight plan to Congress next week.

Four crew members are already training in Houston on mock-ups of the Atlantis and the international space station. They are commander Eileen Collins, pilot James Kelly, Japanese astronaut Soichi Noguchi and mission specialist Stephen Robinson. Other crew members will be named later.

The next mission's responsibilities are still uncertain, but it could include bringing back the next two-man crew on the space station. Astronaut Michael Foale and Russian cosmonaut Alexander Kaleri are scheduled to be launched to the space station in a Russian Soyuz vehicle in October.