Most missions to the International Space Station (ISS) range from 160 to 180 days, but this month Russia and NASA will launch a joint year-long mission designed to more fully test the stress of space travel on the human body. ISS veterans Scott Kelly (US) and Mikhail Kornienko (Russia) have been training for two years for this daunting mission, with departure slated for March 27, 2015, 3:42 p.m. EST. from the historic Baikonur Cosmodrome.

While the space station Mir hosted four cosmonauts for over a year each in the 1980s and 90s, (and Valery Polyakov racked up a 437 day 18 hour stay aboard Mir from January 1994 to March 1995), the ISS has yet to achieve that honor, nor has an any NASA astronaut stayed in space for longer than the average six month mission.

For the One-Year Mission, researchers all over the world have planned a slate of studies to test the astronauts in seven medical and psychological areas of concern. Most of the studies represent real problems for astronauts recovering from extended space travel, and thus would be concerns for future manned flights to Mars.

When returning from space, astronauts face difficulties, such as walking upright, decreased bone density, and changes in ocular fluids and pressure. The investigations will address the safety of astronauts on extended missions, in regards to their fatigue and fine motor control, however, the research may also benefit sufferers of certain diseases on Earth.

The extended stay will also allow Kelly and Kornienko to participate in more research studies than previous ISS participants. And because both men have logged about 180 days in space already, the studies can also be compared to physical data gathered previously. Additionally, Kelly's identical twin brother Mark, also a NASA astronaut, will act as a control for Scott in several twin studies.

"As [Konstantin] Tsiolkovsky said, the Russian space scientist, the humankind cannot stay in the cradle forever, so we have to leave Earth, and the function of the ISS is to learn as much as we can about life in space...It’s impossible to do it with one country alone," said Kornienko when asked what the significance of cooperative space travel was to him before ISS Expedition 23/4.

The Baikonur Cosomodrome is significant historically, launching both Earth's first satellite and first man in space. Soon it will add the credit of launching Earth's first year-long visitors to the ISS.

Below is NASA's video explaining the significance of the One-Year Mission.

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