"Beautiful land, Mark, and congratulations on a great mission," Mission Control radioed when Discovery came to a safe stop.
"Great to be back," Kelly replied.
Discovery's mission spanned 14 days, 217 orbits and 5.7 million miles, and was described by NASA as being about as smooth as it gets.
Kelly and his crew accomplished everything they set out to do in orbit. They delivered and installed Japan's Kibo lab, now the space station's biggest room and most sophisticated science workshop, and dropped off a new pump that the two Russians on board used to fix their toilet.
The space station also got a new American resident who took the place of astronaut Garrett Reisman, returning home after 95 days in space.
Reisman's wife, Simone Francis, was waiting at the Kennedy Space Center. Over the past week, Reisman described in quite romantic terms how much he missed her, calling her "my favorite Earthling" and "doll face."
Although the mission itself unfolded almost flawlessly, Discovery left behind a battered launch pad on May 31. Some 5,300 bricks flew off the flame trench when Discovery blasted away, most likely because they were not attached properly to the underlying concrete wall when the pad was built in the 1960s for the Apollo moon shots.
NASA managers are confident the launch pad can be fixed in time for the next shuttle flight in October, by Atlantis to the Hubble Space Telescope.
The next time a shuttle flies to the space station, now three-quarters complete, isn't until November. That's because NASA needs to have a shuttle ready to rush to Atlantis' aid in case of serious damage to its thermal shielding. Atlantis' astronauts will not be able to get from Hubble to the space station for shelter.
NASA had no such rescue plan in place when Columbia took off in 2003 on a solo-flying research mission. In any event, mission managers had no idea Columbia's left wing was severely damaged at liftoff, and the shuttle shattered during re-entry. All seven on board were killed.
Shades of Columbia briefly surfaced Friday when Discovery's astronauts spotted something floating away from their spaceship. It turned out to be a little metal clip that broke off the rudder, and engineers ascertained within just four hours that its absence posed no danger for Discovery's re-entry.