Planets

Epic One-Year Space Station Mission Complete

US astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko returned to Earth Wednesday after spending almost a year in space in a ground-breaking experiment foreshadowing a potential manned mission to Mars.

US astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko returned to Earth Wednesday after spending almost a year in space in a ground-breaking experiment foreshadowing a potential manned mission to Mars.

NEWS: U.S. Astronaut Coming Home After Epic Stay in Space

"We have landing," Russian Mission Control confirmed after the trio touched down southeast of the settlement of Dzhezkazgan in central Kazakhstan at 11:27 p.m. EST.

Kelly and Kornienko, who both spent 340 days in space, returned with Russia's Sergei Volkov, who was stationed at the ISS for over five months.

The "one-year crew" mission saw Kelly break the record for the longest single stay in space by a US astronaut, while Kornienko is now fifth on the list for lengthiest mission by a Russian cosmonaut.

The pair's near year-long stay in space -- which started on March 27 last year -- was the longest by any astronauts aboard the ISS and seen as a vital chance to measure the effects of a prolonged period in space on the human body.

NEWS: Scott Kelly, NASA's 1-Year Space Twin, Returns Today

Kelly was also part of an experiment comparing his development and changes in space with his identical twin brother -- Mark -- back on Earth.

"Spaceflight is the biggest team sport there is, and it's incredibly important that we all work together to make what is seemingly impossible possible," Kelly said when handing over command of the ISS to fellow NASA astronaut Tim Kopra on Monday.

In his year aboard the space station Kelly has been an avid Internet poster, capturing stunning views on his Instagram page and tweeting regularly to nearly a million followers while traveling some 143 million miles (230 million kilometers).

In one particularly eye-catching stunt the bald-headed astronaut posted a short video of himself dressed up in a gorilla suit and floating through the ISS in pursuit of a colleague.

PHOTOS: Calluses to Klingons, ISS Astronaut Tells All

"Needed a little humour to lighten up a year in space," he wrote on Twitter on Feb. 23, when he posted the video.

"Go big, or go home. I think I'll do both."

Expedition 46 Commander Scott Kelly of NASA rests in a chair outside of the Soyuz TMA-18M spacecraft just minutes after he and Russian cosmonauts Mikhail Kornienko and Sergey Volkov of Roscosmos landed in a remote area near the town of Zhezkazgan, Kazakhstan on Wednesday, March 2, 2016 (Kazakh time).

Scott Kelly is a NASA astronaut working for a year in space on the International Space Station. Does he have the stuff of "The Martian,"

the highly anticipated Matt Damon movie to be released on Oct. 2

, chronicling the life of a stranded astronaut on the surface of Mars? While Kelly certainly isn't on his own in space, much of the work he is doing would be useful for a trip to Mars. Here are some of the things the astronaut is working on that Mark Watney (Damon's character in "The Martian") would appreciate.

MORE: NASA's Ultimate Space Twin Experiment

The sun goes through an 11-year cycle of activity, and we are just past the peak of one of those cycles. The solar peak is a time when the sun unleashes more flares and coronal mass ejections (charged particles). When these particles hit the Earth's magnetic field, they can produce spectacular auroras.

But they also can give astronauts a higher dose of radiation.

The space station monitors radiation levels for astronauts close to Earth; in fact, one of the reasons Kelly was selected for this mission was he did not exceed the lifetime radiation levels allowed for astronauts. Radiation is expected to jump for those travelling outside of Earth's magnetic influence. Mars doesn't have much magnetic field to speak of, and the Curiosity mission is monitoring radiation levels on the surface to get more information for future human missions.

MORE: Killer Radiation: How to Protect Martian Astronauts

Working in space is a harsh business. You're busy all the time, you're stuck in a small environment with several people, and your family and friends are far away. NASA keeps close tabs on its astronauts' psychological health through measures such as doctor calls with astronauts, and

having the astronauts keep journals

during their missions. This will especially be important for Mars, as astronauts will need to be even more self-sufficient due to the time delay in communications between planets. NASA has

an ongoing comm delays study

for astronauts doing simple tasks; these tasks and their effects on astronauts will be studied as the station work continues.

MORE: Space Radiation May Harm Astronauts' Brains

Microgravity is hard on your body. NASA has its astronauts exercise for a couple of hours a day, which seems to help counteract bone loss for missions of six months. But what about a year, or longer? That's part of what Kelly's mission is supposed to answer. Bones aren't the only things to worry about, either. Muscles shrink, eye pressure increases, your sense of balance changes. Even your immune system may be affected, something that

NASA is also looking at

in detail. So while we think of astronauts as boldly doing spacewalks and experiments on station, understand that they are also part of the experiment. Their very health is being watched for the benefit of future space missions.

MORE: Space Missions Turn Astronauts' Hearts Spherical

While Watney develops a certain affection for potatoes, Kelly recently posted a picture of himself looking pretty pleased next to a floating pile of fruit. It turns out that little comforts do go a long way for astronaut morale, and any nutritionist would tell you that a varied diet of healthy foods is good for you -- not just the freeze-dried stuff the Apollo astronauts survived on during their missions. NASA has an experiment in place to see how well

astronauts are meeting nutritional requirements for their work on station

, and also for their long-term health.

MORE: Real NASA Space Tech in 'The Martian'

Astronauts are very tied to shipments from Earth right now in terms of eating ... but that is changing in a small way.

Thanks to an experiment called Veggie

, astronauts got to taste some food grown aboard the space station this summer. Lettuce, of course, does not an entire meal make. But as the movie Contact (1997) reminds us, it's through "small moves" that we learn about science. The hope is eventually this experiment will translate into a better way of harvesting crops beyond Earth. For Mars, we're even wondering how viable the soil could be to support plants.

MORE: 'Smart' LED Farming Could Make Space Veg Viable

"#ILookLikeAnEngineer on @space_station. Also a scientist, medical officer, farmer & at times a plumber," Kelly wrote with this image in August. What's more, he has to do all those things in a small space. Since every pound hoisted to space costs money, astronauts are accustomed to working in claustrophobic quarters. But NASA, concerned about its astronauts' efficiency and happiness, also has an

experiment that is supposed to look at how best to construct a living space for astronauts

. That way, the habitats designed for Mars will be suitable for long-term living.

MORE: Why 'Space Madness' Fears Haunted NASA's Past

During a recent Twitter chat, Kelly was asked if he wanted to go to Mars. He said yes, as long as he could return. Getting to Mars and back will take hundreds of days of transportation, let alone the time on the surface. The gravity on Mars is less than 40% what we experience here on Earth. And unless spacecraft design changes substantially, the astronauts will be in microgravity on the way there and back. NASA has an experiment to see

how well (or badly) astronauts work on the surface shortly after landing

, an experiment that Kelly is participating in. This will be important not only for returning to Earth, but seeing how well a crew can get adapted to Mars after being in microgravity for the transit.

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