One NASA astronaut and two Russian cosmonauts have begun their one year mission in space after blasting off in a Soyuz TMA-16M rocket towards the International Space Station last March 27.

American Scott Kelley along with Mikhail Kornienko and Gennady Padalka are now at the ISS for the Year in Space mission.

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Their spacecraft was launched from the Baikonur Cosmodrome in Kazakhstan at 3:42 p.m. ET Friday afternoon and took six hours to reach the ISS. They now join the Expedition 43 crew of commander Terry Virts, Roscosmos' Anton Shkaplerov and ESA's Samantha Cristoforetti.

Padalka will spend six months in the space station. Kelly and Kornienko, however, will remain there for an entire year and will return to Earth via a Soyuz TMA-18M in March 2016.

Their one year stay in space will help scientists understand how the human body and mind can withstand longer periods of spaceflight.

According to NASA, this knowledge is pivotal for human journeys into deep space, including the voyage to and from Mars that could potentially last for more than 500 days.

Researchers on Earth will also monitor Scott Kelley's twin brother, Mark Kelley, and both will undergo a series of tests to track their physical and psychological health.

As scientists study one twin in space and the other brother on Earth, NASA says they'll track any degeneration or evolution that can happen to the human body exposed to a zero gravity environment. This data will also be shared with Roscosmos and will be another important step in reducing costs and increasing efficiency for future space station research.

The One Year Mission and the Twin Study project will involve a total of 400 experiments also designed to benefit NASA's planned mission to Mars. The experiments will cover sleep monitoring and cognitive performance tests and the immune system's response to a zero gravity environment along with vision, muscle mass and metabolism.

The 51 year-old Kelley will spend the longest time in space, twice as long as any US astronaut. The previous record was held by NASA's Michael Lopez-Alegria who spent eight months on the ISS. Kelly's 522 days in space will beat this record.

Padalka will also establish a new world record for the most cumulative time spent by any human in space as he has already logged more than 710 days at the Russian Mir space station and three missions on the ISS.

TagsAstronauts Begin One Year Mission in Space; NASA Studies Twins in Space and Earth, NASA, NASA twin study, NASA astronauts one year in space, ISS, scott kelley