President Barack Obama, First Lady Michelle Obama, daughters Sasha and Malia, and Marian Robinson, stand on the viewing platform where they would have watched the launch of the Space Shuttle Endeavor at the Kennedy Space Center in Cape Canaveral, Fla., April 29, 2011. The launch was delayed due to an electrical heating problem.

President Barack Obama, First Lady Michelle Obama, daughters Sasha and Malia, and Marian Robinson, stand on the viewing platform where they would have watched the launch of the Space Shuttle Endeavor at the Kennedy Space Center in Cape Canaveral, Fla., April 29, 2011. The launch was delayed due to an electrical heating problem.

President Barack Obama and the First Family arrive at the Towway Landing Zone at the Kennedy Space Center in Cape Canaveral, Fla., April 29, 2011.

President Barack Obama and the First Family arrive at the Towway Landing Zone at the Kennedy Space Center in Cape Canaveral, Fla., April 29, 2011.

President Barack Obama is given an "I’m an Obamanaut" bumper sticker at NASA operations at the Kennedy Space Center in Cape Canaveral, Fla., April 15, 2010.

President Barack Obama is given an "I'm an Obamanaut" bumper sticker at NASA operations at the Kennedy Space Center in Cape Canaveral, Fla., April 15, 2010.