Photographers look on as space shuttle Discovery (above) is approached by a NASA 747 aircraft being towed into the Mate Demate facility at Kennedy Space Center in Cape Canaveral, Florida April 15, 2012. Discovery was later mated with the aircraft and is expected to be flown to its final home at The Smithsonian National Air and Space Museum Steven F. Udvar-Hazy Center in Chantilly, Virginia on April 17. REUTERS/Joe Skipper (UNITED STATES - Tags: SCIENCE TECHNOLOGY TRANSPORT) Spaces Shuttle Discovery, Kennedy Spaces, Florida April, Capes Canaveral, April 15, Kennedy Space Center, Space Shuttle Discovery, Spaces Center, Spaces Museums
The space shuttle Discovery, attached to a modified NASA 747 aircraft, makes a final flyby before heading for it's final home at The Smithsonian National Air and Space Museum Steven F. Udvar-Hazy Center in Chantilly, Virginia, from the Kennedy Space Center in Cape Canaveral, Florida April 17, 2012. REUTERS/Pierre Ducharme (UNITED STATES - Tags: SCIENCE TECHNOLOGY TRANSPORT)
On it's final mission, the Space Shuttle Discovery rides atop a NASA modified 747 plane over Washington April 17, 2012.
The space shuttle Discovery, riding atop a NASA 747 transport jet, does a final fly-by over the White House as tourists an Washingtonians watch and take pictures in Washington, April 17, 2012.
The Space Shuttle Discovery, mounted on the Shuttle Carrier Aircraft, flies over the Lincoln Memorial in Washington, Tuesday, April 17, 2012.
The space shuttle Discovery, sitting atop a 747 carrier aircraft, lands at Dulles International Airport in Chantilly, Va., Tuesday, April 17, 2012.
Discovery, the longest-serving orbiter will be placed to its new home, the Smithsonian's National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Va. (AP Photo/Manuel Balce Ceneta)
The Space Shuttle Discovery is seen above the Washington suburbs before heading to retirement at the National Air and Space Museum. (AFP Photo/Mandel Ngan)
BOSTON - APRIL 15: Two explosions went off near the finish line of the 117th Boston Marathon on April 15, 2013.
Thurgood Marshall, center, argued the Brown v. Board case against segregated schools, with George E.C. Hayes (left) and James M. Nabrit, two other lawyers who also led the fight for integrated classrooms. Marshall later became the first African-American Supreme Court justice.