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The space shuttle Discovery lifts off from launch pad 39A at the Kennedy Space Center in Cape Canaveral, on Florida March 16, 2009 - Source: Reuters
The NASA space agency has cleared the space shuttle Discovery for launch, after a prolonged debate about whether its fuel tank was safe enough for flight.
In the end, the vote was unanimous to proceed with launch at 5.36pm on Tuesday, New Zealand time.
Discovery is scheduled to spend 13 days in orbit on a mission to deliver supplies and spare parts to the International Space Station.
Foam falling off the shuttle's fuel tank during launch has been an ongoing safety issue since the 2003 Columbia accident, in which seven astronauts were killed.
The shuttle was hit by a falling chunk of foam that damaged its heat shield.
The ship broke apart as it flew through the atmosphere for landing 16 days later.
Several redesigns of the tank have greatly reduced the amount of foam shed during launch, but concerns remain.
During last month's launch of shuttle Endeavour, the tank lost foam from a new area.
Because the tanks are not retrieved, NASA has not been able to determine what caused the foam loss.
Engineers suspect a problem with the adhesive used to bond the insulation to the metal tank.
Technicians drilled nearly 200 samples out of Discovery's tank to test whether its foam was properly applied, then patched the holes.
Some engineers had pushed for additional tests, which would have delayed launch until October. Managers decided no more tests were necessary.
However, the Discovery pilots will fire their ship's steering rockets longer than usual after reaching orbit to provide more light for photographing the tank after it is jettisoned.
NASA has six missions remaining to outfit the station before the shuttle fleet is retired.
After that, the station will be serviced by smaller Russian, European and Japanese vehicles which cannot carry bulky experiment racks and heavy spare parts.
