An American astronaut and Russian cosmonaut launched into space Friday to attempt something their two countries have never done together before: a one-year mission on the International Space Station that could help one day send humans to Mars.

The epicone-year space missionlaunched NASA's Scott Kelly and cosmonaut Mikhail Kornienko into orbit aboard a Russian Soyuz space capsule at 3:42 p.m. EDT (1942 GMT) today (March 27) from the Baikonur Cosmodrome in Kazakhstan, where it was early Saturday morning local time. Also flying on the Soyuz is cosmonaut Gennady Padalka, a crewmember who will live and work aboard the orbiting outpost for about six months, the usual length of time people spend on the station.

"A year in space starts now," NASA spokesperson Dan Huot said at launch.You can check out avideo of the history-making launchas well. [The One-Year Space Mission: Full Coverage]

It should take Padalka, Kelly and Kornienko about 6 hours to reach the space station. If all goes according to plan, the three crewmembers will link up with the space laboratory at around 9:36 p.m. EDT (0136 March 28 GMT), and you canwatch the docking live on Space.comvia NASA TV starting at 8:45 p.m. EDT (0045 March 28 GMT). The hatches between the two spacecraft are scheduled to open at 11:15 p.m. EDT (0315 March 28 GMT), allowing the three space fliers to enter the station. The hatch opening will also air live on Space.com at that time.

Scientists will usehealth and other datacollected from Kelly and Kornienko during their yearlong mission to learn more about how long-duration spaceflight affects the human body. While researchers know a lot about what happens to people who live in space for six months, they don't know how the body changes with a longer stay in microgravity.

Acrewed Mars mission a huge goal for NASA in the future could take 500 days or more, according to the space agency. Therefore, learning more about the potential problems astronauts could experience during a long mission is important for NASA officials.

Kelly's identical twin brother (and former NASA astronaut) Mark Kelly will participate in experiments on the ground to help scientists monitoring his brother in space. The Kelly twins will be monitored before, during and after Scott's spaceflight for a number of experiments chosen by NASA officials.

"Today, we launch an American astronaut and a Russian cosmonaut to live and work in space for an entire year the longest continuous stretch an American astronaut will have been in space," NASA administrator Charles Bolden wrote in aSpace.com-exclusive op-ed. "It's an important stepping-stone on our journey to Mars, and will give us detailed medical data recorded throughout the one-year expedition."

Kornienko and Kelly have been training for this yearlong mission for about two years, but this won't be the first time the astronauts have flown to space.

Before this mission, Kelly logged 180 days in orbit during two space shuttle flights and one previous space station mission. By the end of this mission (scheduled to last about 342 days, just shy of a year), Kelly will have logged 522 days in space, according to NASA.

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US, Russian astronauts begin one-year space mission