NASA: Protruding Seal On Shuttle Wing No Problem

A metal alloy seal protruding from the shuttle's port side wing is not expected to cause any significant issues during Endeavour's mission to the International Space Station or its atmospheric reentry and landing, now scheduled for 10:01 p.m. Feb. 20.

A 3.8-inch portion of the lengthy seal slipped through a flipper door than covers a cavity that holds hydraulic actuators and hinges that enable the elevons to travel 40 degrees up and 25 degrees down during ascent and atmospheric reentry and landing. A series of more than a dozen flipper doors cover the area that connects the wing with the elevons, which operate much like wing flaps on a conventional aircraft.

NASA Deputy Shuttle Manager LeRoy Cain, chairman of the Mission Management Team, said the seal serves to vent air from the cavity during ascent and reentry. The protruding seal is located far back from the leading edge of the wing -- in the "aerodynamic shadow" that does not experience high heating during atmospheric reentry and landing.

"Protrusions in general are not good," Cain said. But in this case the protuberance "is not going to pose any issue for us either structurally for the wing or from a thermal standpoint,: he said.

"Some (protuberances) are more critical than others," he added. "If it were a different piece part protruding from a different part of the vehicle, it would be a different concern for us."

A good example:

The "gap-fillers" that protruded from tiles on the underside of the orbiter on NASA's first post-Columbia test flight back in July 2005. Those protuberances were in an area that experiences high heating during atmospheric reentry. In fact they could have caused an increase in heating that could have damaged tiles and potentially burned through the shuttle heat shield.

Endeavour mission specialist Steve Robinson flew on that mission aboard Discovery and was sent out on an emergency spacewalk to retrieve the protruding gap fillers. His spacewalking partner then was Japanese astronaut Soichi Noguchi, who now is serving aboard the International Space Station.