NASA has taken a big step towards the relaunch of its shuttle fleet with the delivery of a new, Improved Shuttle External Tank to the Kennedy Space Centre in Florida. The tank is due for deployment on the May "Return to Flight" mission to the ISS, dedicated mainly to "testing and evaluating new procedures for flight safety" aboard space shuttle Discovery.

NASA has spent 23 months making improvements to the 47m-long tank following the 2003 Colombia disaster - caused by a lump of insulating foam from the fuel tank breaking off during launch and punching a hole in the shuttle's wing. Superheated gas entered the rupture during re-entry, causing the vehicle to disintegrate.

External tank project manager, Sandy Coleman, said: "Our team of contractors and civil servants has worked hard developing, testing and implementing improvements that will reduce the risk to the orbiter during liftoff and ascent. This will be the safest, most reliable tank NASA has ever produced." ®

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