CAPE CANAVERAL, FL - MAY 16: NASA space shuttle Endeavour lifts off from Launch Pad 39A at the Kennedy Space Center on May 16, 2011 in Cape Canaveral, Florida. After 20 years, 25 missions and more than 115 million miles in space, Endeavour is on its final flight to the International Space Station before being retired and donated to the California Science Center in Los Angeles. Capt. Mark E. Kelly, Gabrielle Giffords's husband, will lead mission STS-134 as it delivers the Express Logistics Carrier-3 (ELC-3) and the Alpha Magnetic Spectrometer (AMS-2) to the International Space Station. (Photo by Joe Raedle/Getty Images)