NASA astronaut Scott Kelly and cosmonaut Mikhail Kornienko share inside look at life in space

On Tuesday, AOL.com caught up with NASA astronaut Scott Kelly and cosmonaut Mikhail Kornienko LIVE from the International Space Station.

Kelly and Kornienko are now eight months into a unique mission for which they're spending one full year aboard the International Space Station -- that's twice as long as the time in space spent by the typical ISS crew member.

"A year is a really long time," Kelly told AOL.com. "I feel like I've lived my whole life up here."

Photos from Scott Kelly and Mikhail Kornienko's year in space so far:

The goal of the One-Year Mission is to better understand how spending long periods of time in the harsh and stressful environment of space impacts the human body and mind. Learning about the long-term effects of weightlessness and living in a microgravity environment will be key to NASA's future goal of getting people safely to Mars.

Kelly spoke about how astronauts and cosmonauts train to be mentally prepared for such a long stay away from home. "I think NASA and ... our partner agencies have a pretty good selection process for deciding who they're going to send up here as astronauts and cosmonauts ... We also do some training in ... team living, teamwork, leadership, followership ... critical skills to have for operating in such a challenging environment. For most of us ... when we get here, we're pretty well prepared for ... staying mentally strong during this type of mission.

"Occasionally you might get ... I wouldn't say depressed, but you might not feel 100% at times, and I think it's important to put the whole thing in perspective and understand the importance of what you're doing ... and [remember] eventually I'll be home someday, so that helps a little bit."

Although a year is certainly a long time to spend in space, Kelly is optimistic about the mission and the work his team is doing. "We're still able to do our work and do it with enough enthusiasm and energy to get the job done. I guess that's something I've learned a little bit since I've been here."

Kornienko explained that astronauts and cosmonauts do have techniques for countering the physical impact of living in a microgravity environment. "Of course there are changes in the body -- for example [changes] related to the musculoskeletal system -- and we are counteracting this by doing physical exercises. We have a good gym on the station."

Kornienko, however, has noticed a puzzling change in his vision. "I noticed for myself, I have better near vision. I'm not sure [why] ... the scientists [on the ground] will tell me later." Kornienko is not the first to experience vision changes after living in space.

The data Kornienko and Kelly are collecting during their year in space will ultimately be used to help prepare future space travelers for a journey to Mars. For the first time in four years, NASA is accepting applications for astronauts.

Kelly weighed in on what it's going to take future astronauts to make the ambitious journey to Mars. "For the person that goes to Mars ... certainly an operational type of background will be important," Kelly explained.

According to Kelly, the ideal candidate for a Mars mission needs to be a "jack–of–all–trades."

"On the space station, we're it. If something breaks, whether it's the electrical system, or the hardware that removes the carbon dioxide from the atmosphere, we have to fix it. If there's a science experiment, we are the ones that conduct it. Computer problems — we have to take care of those too ... Fortunately right now we have a doctor on board, but if he gets sick, one of us has to be his doctor."

"What is [also] critical is team work, and being able to work as part of a team, and it's a diverse team ... It will probably be an international effort [to get to Mars], and getting along with and working well with your international colleagues will be very important."

Kelly recently broke the record for the most time spent in space by an American, and he still has several months to go before he and Kornienko return to Earth in March 2016. Kelly also just completed his second spacewalk on November 6, spending almost eight hours floating outside the International Space Station (tied only with a tether) to perform critical maintenance tasks.

Check out the full interview above.

Stunning images Scott Kelly has shared so far form his #YearinSpace:

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