SPACE CENTER, Houston (AP) – NASA Chief Michael Griffin said Friday he hasn’t given up on launching another space shuttle later this year, despite suspending flights until the space agency can stop foam insulation from snapping off and threatening the spacecraft.

He said he has set up a “tiger team” to try to solve the problem as quickly as possible. “We don’t expect this to be a long drawn-out affair,” he said by telephone from Washington in a briefing with reporters in Houston.

Like other NASA officials, he said “we made a mistake” in not addressing the area of the external fuel tank where a piece of foam broke off shortly after Discovery’s launch on Tuesday. That insulation chunk came from a different spot on the huge fuel tank than the foam piece that ultimately brought down Columbia.

“Do I take responsibility? Absolutely,” he said. “We’ll fix this.”

The launch windows later this year are very limited, however. The first is Sept. 9-24, and the second is a couple of days in November. That is based on the Earth’s orbit and the hours of daylight a shuttle could be launched so it could be photographed to watch for problems.

Griffin said he was not willing to give up on this year.

In addition, he told reporters there were not just one, but perhaps four, pieces of foam that were bigger than NASA was willing to allow break from the fuel tank during launch.

It was a large piece of foam that doomed Columbia on its launch in 2003 by hitting the shuttle’s wing.