Space station marks 15 years of astronaut life

Astronauts have circled the Earth on board the International Space Station for 15 years on Monday, a milestone for an orbiting space lab that some say deserves to win the Nobel Peace Prize.

With operations expected to last another decade, the world's space agencies are now looking to the outpost to provide key data on how future space pioneers may withstand the rigors of venturing further, perhaps even to Mars.

"We do a lot of experiments up here but I think the most important experiment is the space station as an orbiting vehicle that keeps humans alive in space for long periods of time," said NASA astronaut Scott Kelly, during a live press conference with the station's crew to mark 15 years of continuous habitation.

Along with Russian cosmonaut Mikhail Kornienko, Kelly is spending one year at the ISS so scientists can study the effects of long-term spaceflight on the body and mind.

Any trip to Mars would likely last years, raising the issue of harmful radiation, but also how to nourish astronauts for long periods and how to maintain healthy crew psychology.

"The space station really is a bridge," US astronaut Kjell Lindgren told the media conference. "It is a test bed for the technologies we need to develop and understand in order to have a successful trip to Mars."

Caption: Representative image of International Space Station

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