Space Shuttle Discovery flies final mission

Media from around the world photograph crews at the Kennedy Space Center in Cape Canaveral, Fla. Saturday morning, April 14, 2012 as they work on preparations to attach the space shuttle Discovery to a modified Boeing 747, not pictured, that will ferry the spacecraft to the Smithsonian National Air and Space Museum in Washington.

News media crews document work on attaching the space shuttle Discovery to a modified 747 that will ferry the shuttle to the Smithsonian in Washington, using the Shuttle Mate Demate device at the Kennedy Space Center in Cape Canaveral, Fla., early Sunday morning, April 15, 2012.

Crews at the Kennedy Space Center work on attaching the space shuttle Discovery to a modified 747 that will ferry the shuttle to the Smithsonian in Washington, using the Shuttle Mate Demate device in Cape Canaveral, Fla., early Sunday morning, April 15, 2012.

Space shuttle Discovery atop a 747 carrier jet taxi's down the runway before leaving the Kennedy Space Center, Tuesday, April 17, 2012, in Cape Canaveral, Fla. Discovery is being transported to the Smithsonian National Air and Space Museum in Washington.

Space shuttle Discovery atop a 747 carrier jet departs the Kennedy Space Center, Tuesday, April 17, 2012, in Cape Canaveral, Fla. Discovery is being transported to the Smithsonian National Air and Space Museum in Washington. (AP Photo/John Raoux)

Space shuttle Discovery atop a 747 carrier jet departs the Kennedy Space Center, Tuesday, April 17, 2012, in Cape Canaveral, Fla. Discovery is being transported to the Smithsonian National Air and Space Museum in Washington.

The Space shuttle Discovery, mounted on top of a modified 747, flies over the Atlantic Ocean as it makes a low pass over Cocoa Beach, Fla. for the final time heading to Washington D.C. and the Smithsonian. On Thursday, it will be towed to its permanent installation at the Smithsonian's annex in northern Virginia.

US space shuttle Discovery sitting atop NASA's 747 shuttle carrier aircraft flies over Washington monument in Washington,DC on April 17, 2012 as it arrives from Kennedy Space Center in Florida to be displayed at the National Air and Space museum near the US capital.