If the tank is shipped without the ramp, and if the upcoming tests confirm it's not needed to prevent a catastrophic failure, NASA will be clear to launch the shuttle Discovery next spring as planned on the second post-Columbia mission. In so doing, the agency will eliminate a potential source of impact debris and put to rest recent concern about cracks in the foam ramps.
But PAL ramps cannot be added at the Florida spaceport and if the tests show the pressurization lines and cable tray do, in fact, need shielding, the tank would have to be shipped back to Lockheed Martin's Michoud Assembly Facility near New Orleans for additional work. And that would put the next shuttle flight on indefinite hold.
In that case, engineers would have to reapply the long ramp, either manually or robotically spraying on foam insulation to build a sort of dam to smooth the flow of supersonic air over the externally mounted components.
More important, and potentially time consuming, they also would have to develop new application techniques or change the composition of the foam - or both - to prevent hard-to-see cracks from forming after the tank is loaded with supercold rocket fuel.
And those issues will be present in the near term if shuttle managers decided to ship a tank with PAL ramps in place.
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