NASA Administrator Michael Griffin, left, and Associate Administrator for Space Operations William Gerstenmaier, right, look on as Space Shuttle Program Manager Wayne Hale speaks from NASA's Marshall Space Flight Center during a media briefing about the space shuttle program and processing for the STS-121 mission, Friday, April 28, 2006, at NASA Headquarters in Washington. At left on screen is Ken Welzyn, External Tank Chief Engineer. Photo Credit (NASA/Bill Ingalls)
