NASA: Ice won't threaten Shuttle launch
Last hurdle cleared
NASA has decided to go ahead with plans to resume Shuttle flights next month, judging that the risk of the Discovery being damaged by ice falling from its fuel tanks is "acceptable".
After a day spent reviewing the engineering analysis of the risk posed by falling ice, Shuttle program manager Bill Parsons said that he saw no major technical issues that would cause the Shuttle to miss its launch window of 13-31 July. The final decision about returning to flight will be taken after a "readiness review" later this week.
The question of ice build-up posing some kind of threat to the safety of a launch is one that was raised, as many safety questions have been, by the falling piece of foam insulation which damaged Columbia's wing before its last flight. That mission ended in tragedy when the shuttle broke-up on re-entry, costing the lives of all seven astronauts on board.
The Shuttle Discovery was originally scheduled to return to flight between 22 May and 3 June, but as the deadline approached, engineers began to wonder if the ice that builds up on the outside of the cryogenic fuel tanks could do as much damage as a falling piece of foam.
In late April, NASA administrator Michael Griffin confirmed that the launch date would be delayed while the risk from ice was studied. Engineers also added an extra heater to a particularly vulnerable area near the oxygen tank's feedlines.
NASA officials have not yet quantified the risk posed by falling ice, saying that the variables are too complex to boil it down to a single number without further study. Despite this uncertainty, John Muratore, manager of the space shuttle engineering and integration office told reporters: "I believe our concerns are put to bed and we're ready to go fly." ®
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