Nasa scientists are continuing to search for evidence of damage to the space shuttle Discovery after it was hit by debris shortly after take-off on Tuesday. Prior to docking with the International Space Station the craft performed manoeuvres to allow its entire surface to be photographed. Concerns were first raised when a small piece of insulating foam was seen peeling off and striking one of the wings. Nasa says there are eleven signs of potential impact but nothing that will endanger Discovery’s journey home. But after the Columbia disaster in 2003, the experts are leaving nothing to chance and NASA is preparing for the worst. The evidence is not complete yet, but if continued examination of the shuttle reveal further faults, the crew will be stranded on the International Space Station.The nine astronauts in total can only survive for a month with the combined air and supplies on board both vessels which means a rescue mission and that means using the last remaining shuttle, Atlantis. The question NASA has to face is how does it fly a rescue shuttle if it knows the shuttle is flawed? A crew of four specially trained astronauts have been preparing for such a scenario over the last six months. If the same fuel tank foam problem occurs when Atlantis takes-off, NASA will face another crisis – how to bring 13 astronauts back to earth without a shuttle. The answer is likely to come from Russia by way of its small Soyuz cargo crafts. But as they are not designed for such procedures, it would be a long and extremely risky operation.