The NASA space shuttle Discovery rides atop a Boeing 747 as it flies over Washington D.C., capital of the United States, April 17, 2012. The space shuttle on Tuesday left Kennedy Space Center in Florida to Smithsonian National Air and Space Museum's Udvar-Hazy Center in Virginia where it will be displayed as a museum relic. [Xinhua]

People watch as the NASA space shuttle Discovery rides atop a Boeing 747 and fly over Arlington of Virginia to Washington D.C., capital of the United States, April 17, 2012. The space shuttle on Tuesday left Kennedy Space Center in Florida to Smithsonian National Air and Space Museum's Udvar-Hazy Center in Virginia where it will be displayed as a museum relic. [Xinhua]

The NASA space shuttle Discovery rides atop a Boeing 747 as it flies over Washington D.C., capital of the United States, April 17, 2012. The space shuttle on Tuesday left Kennedy Space Center in Florida to Smithsonian National Air and Space Museum's Udvar-Hazy Center in Virginia where it will be displayed as a museum relic. [Xinhua]

U.S. space shuttle Discovery aboard a modified jumbo jet flies over Washington D.C., the United States, April 17, 2012. The most traveled US space shuttle, Discovery, left for Washington D.C. and will become a museum relic. [Xinhua]

U.S. space shuttle Discovery aboard a modified jumbo jet flies over Washington D.C., the United States, April 17, 2012. The most traveled US space shuttle, Discovery, left for Washington D.C. and will become a museum relic. [Xinhua]