As NASA [Images] engineers conduct a series of tests to determine how best to repair a torn heat-resistant blanket on the space shuttle Atlantis, two astronauts are gearing up for a planned spacewalk.

Atlantis astronauts Patrick Forrester and Steve Swanson, will likely use a sewing kit, reserved usually for spacesuits to repair a peeled-back thermal blanket near the spacecraft's tail, NASA managers said.

The shuttle astronauts' 11-day mission was extended Monday by two days to allow time to fix the thermal blanket, which peeled during launch last week.

With this delay, Indian American astronaut Sunita Williams will spend an extra two days in space.

No decision has been made on when the repair, which covers a 4-by-6-inch area over an engine pod, will be made.

"They have several different solutions to put the blanket down and keep it down," John Shannon, NASA's deputy shuttle program manager told reporters here at NASA's Johnson Space Center during a mission briefing.

The thermal blankets are used to protect the shuttle from searing heat during re-entry.

Engineers don't think the intense heat could burn through the graphite structure underneath it and jeopardize the spacecraft.

During the six-and-a-half-hour spacewalk, the astronauts will finish rigging a massive rotary joint that will slowly turn a newly installed set of solar arrays to keep them face-on to the sun.