“We basically did a countdown, a mock countdown, and filled the tank with propellants like we normally would during a launch countdown, but at T minus 31 seconds, that’s when we called it, we cancelled the test.”
Discovery moves into the Vehicle Assembly Building on Wednesday morning after its 3.4 mile roll back from Launch Pad 39A.
Photo credit: NASA/Frank Michaux
During the mock fill-up, scientists measured the tank for stresses and strains. The shuttle engines burn liquid hydrogen and oxygen, and those fuels are so cold that they can shrink the aluminum fuel tank by half an inch. After completing the fill-up, then draining the tank, engineers didn’t spot any new cracks. But they want to make sure by bringing the shuttle indoors for a set of x-rays.
“Now what we have to do build up platforms so they can reach the area where they want to do the x-ray scans and then on the backside of the tank where we aren’t able to scan at the pad, they’ll actually scan inside to make sure there aren’t cracks on the other side of the tank as well.”
The danger is that a crack could dislodge a piece of insulating foam during liftoff. If the foam strikes the shuttle, it could damage the shuttle’s heat shield. That’s what happened to Space Shuttle Columbia, which burned up when re-entering earth’s atmosphere in 2003.
Technicians will work on the x-rays through the holidays, but will get Christmas and New Year’s Day off.