Hail storm damage grounds Atlantis

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A sudden, explosive thunderstorm Monday battered the shuttle Atlantis' external fuel tank with wind-driven, golf ball-sized hail, causing extensive damage to the tank's protective foam insulation. NASA managers said today engineers will have to move the shuttle back to the Vehicle Assembly Building for repairs, delaying launch on a space station assembly mission from March 15 to late April. With wind gusts as high as 62 mph at launch complex 39A Monday, early estimates indicated some 7,000 visible hail dings or blemishes in the orange insulation, mostly around the top of the external tank. John Chapman, external tank program manager at the Marshall Space Flight Center, said today not all of those dings will require repairs. But initial estimates have identified "hundreds" of sites that will require sanding to smooth over or foam "pours" to fill in deeper pits. In addition, at least three so-called ice-frost ramps on the upper part of the tank were damaged and two dozen or so shuttle tiles showed signs of minor surface damage. "This constitutes, in our evaluation, the worst damage that we have ever seen from hail on the external tank foam," shuttle Program Manager Wayne Hale told reporters today. "We have had hail a number of times in the past, hail is not unusual in Florida. ... But usually the hail is quite small and rarely causes damage. "This was large, wind-driven, damaging hail. It is very clear a number of these areas need to be repaired. There is not access on the launch pad so we will be required to move the space shuttle back from the launch pad to the Vehicle Assembly Building." Launch director Mike Leinbach said today the 3.2-mile trip from pad 39A to the VAB likely will get underway Sunday morning. Once the shuttle is back in the cavernous VAB, where engineers can position access platforms around the tank, Hale said a more accurate assessment of the damage will be made. In the meantime, "we do not believe we can make the launch window for the March launch of Atlantis," Hale said. "We have a fairly high degree of confidence we can repair this at the Kennedy Space Center. Most likely that would lead us to a launch of Atlantis and her crew ... after the Russian Soyuz changeout."