The next-to-the-last space shuttle mission will be led by astronaut Mark Kelly, husband of Rep. Gabrielle Giffords, D-Ariz., who is hoping to attend the Endeavor's afternoon launch at Florida's Kennedy Space Center.

Giffords, who was shot in the head at a political rally three months ago in Tucson, has been undergoing intensive rehabilitation at Houston's Memorial Hermann Texas Medical Center.

Launch director Mike Leinbach said he hopes Giffords will be able to attend the event.

"I hope she comes. That would be cool," Leinbach told reporters, noting there would be additional security procedures should doctors okay her travel to Florida.

The Endeavor's crew arrives the Tuesday before the launch, just before the countdown is scheduled to start. Liftoff is set for 3:47 p.m. Friday.

This will be Endeavor's 25th and final mission and the 134th overall for the space shuttle program. Endeavor was built to replace the space shuttle Challenger, which was destroyed during liftoff in 1986.

"The emotional aspect is very, very real," Leinbach said, referring to the end of the space shuttle program. "It's very difficult to put into words."