CAPE CANAVERAL, FL - MARCH 09:  In this handout image provided by NASA, NASA Astronauts and STS-133 mission crew members, from left, Mission Specialists Nicole Stott, Michael Barratt, Pilot Eric Boe, Commander Steve Lindsey, Mission Specialists Alvin Drew, and Steve Bowen pose for a photograph in front of the space shuttle Discovery after they landed at Kennedy Space Center after returning for the last time from a space flight to the International Space Station on March 9, 2011 in Cape Canaveral, Florida.  Discovery flew 39 flights over its 27 years of service and will be sent to a museum. Two remaining shuttle missions are planned before the program ends.  (Photo by Bill Ingalls/NASA via Getty Images)