Mission Control ordered the astronauts, on their way back from the International Space Station, to remain in orbit until Monday afternoon.
RG: Well, like I said in the presentation, I wanted to be an astronaut way before that, back in 1969, when I was a little kid, watching the moon landing.
Along the way the astronauts would be bombarded by cosmic radiation and risk being baked by unpredictable solar flares.
In a space-age first, the astronauts also appeared by way of a video link in front of a Senate appropriations subcommittee on space, whose chairwoman is Barbara A. Mikulski, Democrat of Maryland, a space and Hubble supporter.
Officials will also run an anonymous survey to get other suggestions, including ideas for improving the way the astronauts' office is run.
After the first moon landing, it became commonplace for people to ask, "If they can land a man on the moon, why can't they figure out how to fix (insert type of problem)?" The subtext of the celebration is to suggest that some of the can-do spirit — and, perhaps, a few glasses of Tang, the breakfast drink of the astronauts — could go a long way toward helping solve the current difficulties.
But the M.R.I. scans also revealed little ripples in the back of the eyes of some of the astronauts, distorting their vision in a way that "would be more disconcerting to us," Dr. Kramer said.
The NASA administrator, Sean O'Keefe, has spoken publicly in some detail about the problems of a manned landing on Mars, saying the nation would have to develop new methods of propulsion and electricity generation in space and a way to protect the astronauts from large radiation doses.
Risk is part of the challenge, inherent in why drivers are revered, in the same way people admire the astronauts who went to the moon.
