By James Wray Apr 29, 2005, 14:15 GMT
The agency has concerns that ice forming on the top of the shuttle's external fuel tank could cause foam insulation to break off during a launch. Engineers have been examining the possibility of this happening and planning possible solutions. It is thought they may opt to install a heater to stop the build up of ice, but this would involve the shuttle having to be moved back to its hanger and take many days if not weeks to complete.
If, as expected, a delay is announced then it most likely the launch will not take place until mid-July due to NASA's desire for a daylight launch. This is to ensure they can get high quality photos during the launch to check for any foam coming loose and for any resulting damage.
It was foam breaking off from an external fuel tank during launch and damaging the wing that caused the disaster on Columbia in 2003.
The announcement is expected to be made later today.
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