One of space shuttle Columbia's main engines may have been leaking hydrogen fuel all the way to orbit and could have shut down abruptly if more fuel had seeped out, resulting in a never-before-attempted emergency landing, NASA said Sunday.
If it proves to be a leak, as photographs suggest, the possible engine shutdown could have caused an emergency landing within minutes of launch, either in Florida or West Africa.
Columbia made it safely to orbit Friday under the control of Air Force Col. Eileen Collins, the first woman to command a U.S. spaceship.
The shuttle, carrying five astronauts and the world's biggest and most powerful X-ray telescope, fell seven miles short of its intended orbit. A fuel leak could explain why the engines shut down one second or so early.
NASA's mission operations representative, Wayne Hale, stressed there is no proof that one or two cooling tubes in the nozzle of the right engine were cracked and leaking hydrogen. Until the shuttle returns to Earth on Tuesday night and the engine is examined, no one will know for sure, he said.
Because the three main engines are not used after propelling the shuttle into orbit, neither problem will affect the rest of Columbia's five-day flight, Hale said.
Collins and her crew conducted science experiments Sunday and chatted by ham radio with the three cosmonauts on Mir as flight controllers kept track of the free-flying Chandra X-ray Observatory and pored over shuttle engine data.