Bill Gerstenmaier Pictures

Bill Gerstenmaier, NASA Associate Administrator for Space Operations speaks as Chris Scolese, NASA associate administrator, sits next to him (L) as they address the media after Space Shuttle Discovery landed at Kennedy Space Center, June 14, 2008 in Cape Canaveral, Florida. Discovery successfully completed a 14 day mission to the International Space Station. (Photo by Matt Stroshane/Getty .Images). (Photo by Joe Raedle/Getty Images North America)

Bill Gerstenmaier, NASA associate administrator for Space Operations addresses the media after the successful landing of Space Shuttle Endeavour at Kennedy Space Center March 26, 2008 in Cape Canaveral, Florida. Endeavour was on a 17-day mission to the International Space Station. (Photo by Eliot J. Schechter/Getty Images North America)