The Columbia space shuttle almost certainly suffered a devastating puncture which allowed hot air inside the left wing, US investigators say. Columbia broke up upon re-entry on 1 February with the loss of its crew of seven in a disaster which has raised questions about the future of the International Space Station. NASA scientists studying debris at the Kennedy Space Center in Florida now say the disintegration occurred after its left wing was punctured in some way. It is the first time the US space agency has hinted that the tragedy was probably not caused by the loss of a heat-resistant tile as originally thought.