Latest Mystery In Quest To Solve Insulation Problems

It's one step forward, two steps back lately for NASA, as officials announced Tuesday they have still not figured out what caused the loss of insulating foam from the external fuel tank on this summer's flight of Discovery -- although a new problem found with another tank may provide a clue.

A series of nine hairline cracks found on another tank, originally meant to be used on Discovery's flight, may provide scientists with a clue of how the expansion and contraction of the fuel tank's ultra-thin metal skin is transferred to the foam coating -- and, if those cracks are big enough to cause a breach in the insulating covering.

"We're trying to come to grips with what that means," said shuttle program manager N. Wayne Hale Jr, in a Los Angeles Times story.

While the cracks -- which appeared after the tank was filled with supercooled liquid hydrogen and liquid oxygen this summer -- point to a new issue to be addressed, NASA has made several positive gains in dealing with other potential areas of concern.

As had been extensively reported in Aero-News, scientists have found several areas on the external tank where the chances of a foam breach have, at least, been minimized. NASA also believes it has solved two problems that crept up during the Discovery flight: a fraying insulating blanket under the commander's window, and two protruding spacer strips between tiles on the shuttle's underside.

One hundred insulating blankets found to have weak stitching have been replaced on Discovery, and its sister ship Atlantis. A new method of applying adhesive to the tile gap fillers is also currently being tested.

Some NASA officials have played down the possibility that the cracks in the tank's insulation were related to the problem of falling foam, including NASA's External Tank Manager John Chapman.

"We haven't found any Eurekas or smoking guns," he said.

Nor has NASA found the one surefire way to guarantee Discovery will be able to launch next May, as was originally planned. The timetable was intended to utilize the proper launch window to allow Discovery to dock with the ISS, and bring home its current crew.

"We're not driving to a calendar, to a date set arbitrarily," Hale said.

FMI: www.nasa.gov