NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko are gearing up for launch March 27 to kick off a record one-year stay aboard the International Space Station, an orbital marathon both men say is crucial for planning future flights beyond Earth orbit and, eventually, to Mars.

While four cosmonauts logged flights longer than one year between 1987 and 1999, the upcoming flight will be a first for the international lab complex and the first to focus on the long-term biological effects of the space environment using state-of-the-art medical and scientific research equipment and procedures.

"If we're ever going to go beyond low-Earth orbit for longer periods of time, spaceflight presents a lot of challenges to the human body with regard to bone loss, muscle loss, vision issues that we've recently realized people are having, the effect on your immune system, the effect of radiation on our bodies," Kelly said Thursday during a news conference in Paris. "Understanding those effects are very important.

"If a mission to Mars is going to take a three-year round trip, we need to know better how our body and our physiology performs over durations longer than what we've previously on the space station investigated, which is six months. Perhaps there's a cliff out there with regards to some of these issues that we experience and perhaps there aren't. But we won't know unless we investigate it."

A veteran of three previous space flights, including a shuttle mission to the Hubble Space Telescope and a 159-day stay aboard the station in 2010-11, Kelly is the twin brother of Mark Kelly, a retired astronaut who flew four shuttle missions and who is married to former congresswoman Gabrielle Giffords.

Kornienko also is a station veteran, logging 176 days aboard the outpost in 2010.

Astronaut Scott Kelly, left, and cosmonaut Mikhail Kornienko strike a pose during training for launch next year on a record year-long mission aboard the International Space Station.

NASA

"The last long-time space mission was on the Mir (space) station and it brought major data for investigations and research about how humans will feel during long-term flights into space," he said. "I hope that our mission will be an opportunity for others who will follow in our footsteps and take space exploration further."

Excerpt from:

Space station team eager to begin record year-long flight