The mission marks the end of service for Discovery, which has a storied service record that includes the deployment of the Hubble Space Telescope and the two return-to-flight missions after both the Challenger and Colombia disasters. Needless to say, Discovery was a workhorse for NASA and her retirement is both a milestone for the program and an emotional day for the flight crews and program employees that worked with her. Said launch director Mike Leinbach at a news conference yesterday: "There's still a certain amount of disbelief that it's really her final launch. It's difficult to accept emotionally. But rationally, we all know it's coming to an end, and we need to get on with it."