Smooth landing as space hero Glenn returns to Earth; Joy as Space hero Glenn comes down to Earth.
"I want to reprise a statement I made a long, long time ago," a jubilant Commander Glenn said shortly after touchdown, referring to his famous line "Zero G and I feel fine" from his 1962 space journey.
"Except this time, it is 1G and I feel fine."
As gravity reclaimed his bones, the first steps of the world's oldest astronaut after landing seemed a little shaky.
Space agency officials said balance problems were normal, even for astronauts who returned from short flights.
"They need to be a little careful, particularly when they turn corners and that sort of thing," said Mr Sam Pool of Nasa's life sciences division in Houston.
"I think that's what you were seeing in the senator."
NASA postponed a planned news conference with Discovery's crew on the orders of chief crew surgeon Philip Stepaniak.
Dr Stepaniak decided that facing the press on top of the four hours of medical tests required of Commander Glenn might prove to be "an unnecessary strain," Nasa said.
All seven crew members were doing better than expected after nine days in space and all, including Commander Glenn, were able to get off the orbiter under their own steam.
Commander Glenn's daughter, Ms Lyn Glenn, said her family's reunion was joyful. "When we saw Dad, mom said 'Look at him walk!' ... She was so happy he walked off the shuttle.
She knew that was very important to him and was happy his dream came true."
Thirty-six years after accomplishing the United States' first orbital space flight, Commander Glenn returned to space as a geriatric guinea pig. He was jabbed with needles and wired for sleep studies at night. Critics said the mission was more about rall ying support for Nasa than bona fide scientific work but nobody seemed to mind.
It gave the agency a much-needed boost before work starts later this month on the International Space Station, its most challenging construction project in outer space. Gusty winds and a potentially troublesome braking parachute failed to mar the shuttle 's return.
Flight controllers in Houston cleared Discovery to land after some last-minute discussions about high crosswinds at the landing strip. Weather forecasters at mission control and an astronaut flying a shuttle simulator aircraft at the space centre agreed it was safe to land about ten minutes before the Discovery's braking rockets fired.
Aside from the weather, the only uncertainty involved a drag chute lying exposed in Discovery's stern after its cover fell off at launch on Oct. 29.
There was a small chance that the chute, normally used at touchdown to help slow the orbiter, could have deployed without warning during the descent.
Controllers devised emergency procedures in the event of an unexpected release, but they proved unnecessary.
After touchdown, ground crews reported that the drag chute mechanism appeared undamaged and intact.