One-year spaceman sees mission as 'steppingstone' to Mars

[...] this mission — which began with a launch last March — is all about Mars.

(It will be Tuesday night in the U.S.) The astronaut will ride a Soyuz spacecraft back with two Russians, including Mikhail Kornienko, his roommate for the past year.

The 52-year-old brothers joined forces to provide NASA with a potential gold mine of scientific data: one twin studied for a year in orbit — twice the usual space station stay — while his genetic double underwent similar tests on the ground.

While a handful of Russians have spent longer in space, the record being a 438-day flight, those expeditions date back to the 1980s and 1990s aboard the Mir space station, rustic if not rickety compared with the current space station.

Kelly's vision has degraded a bit as it did during his last mission, a normal outcome for some astronauts because of increased pressure inside the skull in weightlessness.

The real question mark — and Kelly's biggest concern — is the possible lingering effects of space radiation.

Johnson Space Center physiologist John Charles puts the psychological side of long-duration spaceflight right up there with radiation, as well as in-flight medical care and even food preservation and packaging for the long haul.

Kelly points out that crew quarters on Mars-bound craft will be much tighter than the space station — and nothing like the spaceships of science fiction.

NASA will need to improve privacy on Mars missions, he said, if it hopes to combat crew stress and fatigue.