Does NASA consider this problem solved?
Shuttle Surface More Vulnerable Than Suspected
By JOHN SCHWARTZ
Published: January 20, 2005
The space shuttle's skin is turning out to be even more fragile than NASA engineers thought, its scientists and engineers say.
Impact tests and analysis performed as part of the return-to-flight effort show that pieces of insulating foam that weigh less than half an ounce can cause small cracks and damage to the surface coating on the heat-resistant panels on the leading edge of the wing, agency officials said in interviews this week.
They said the foam pieces could, under the heat of re-entry into the atmosphere, lead to the kind of damage that destroyed the shuttle Columbia two years ago.
John Muratore, the manager of systems engineering and integration for the space shuttle program, said the agency had figured out how to keep pieces even that small from hitting the orbiter by refining the process of applying the foam to the tank.
After this analysis, which Mr. Muratore estimates as costing about $50 million, the action taken by NASA should limit the size of pieces of foam that are still expected to pop off the tank to less than a hundredth of a pound, so "we have margin in here," he said....
http://www.nytimes.com/2005/01/20/science/space/20foam.html