STS-121 was NASA's second and final Return to Flight mission and the 115th flight of the Space Transportation System program. The primary goal of this 13-day mission was to perform routine maintenance and resupply the International Space Station. Other important goals achieved included testing new procedures that will increase the safety of the Space Shuttle, and repairs on Station.

Orbiter:
Discovery (32)

Crew:
Steve Lindsey, Commander
Mark Kelly, Pilot
Michael Fossum, Mission Specialist 1
Lisa Nowak, Mission Specialist 2
Stephanie Wilson, Mission Specialist 3
Piers Sellers, Mission Specialist 4
Thomas Reiter (ESA), Mission Specialist 5/Expedition 13 Flight Engineer (up)

Launch:
July 4, 2006, 1:38 p.m. CDT

Landing:
July 17, 2006, 8:07 a.m. CDT

Payload:
Leonardo MPLM; ISS-ULF1.1