S121-E-07702 (15 July 2006) --- After almost nine days of cooperative work onboard the International Space Station and Space Shuttle Discovery, the STS-121 and Expedition 13 crews bid farewell to each other prior to the undocking of the two spacecraft. Pictured are astronauts Jeffrey N. Williams, Expedition 13 NASA space station science officer and flight engineer; Lisa M. Nowak and Michael E. Fossum, STS-121 mission specialists; European Space Agency (ESA) astronaut Thomas Reiter, Expedition 13 flight engineer; and Mark E. Kelly, STS-121 pilot. Undocking of the two spacecraft occurred at 5:08 a.m. (CDT) on July 15, 2006.