While you might think that NASA and other space agencies have made great strides in investigating the final frontiers of space, it turns out that there are far too many limitations for what humans are able to do. Astronauts and cosmonauts train for the better part of the lives, learning technical information and perfecting the physical attributes needed to live in space. But when it comes down to mission time, they only have a few months in space-at best. Considering that new missions to Mars will look towards taking human journeys far deeper into space than anyone has been before, NASA's new experiment is looking into how long exposure to zero-gravity will affect humans. And they're using a familiar method of testing their hypotheses-twins.

With the launch today, Mar. 27, NASA astronaut Scott Kelly and Russian Cosmonaut Mikhail Kornienko bid adieu to Earth and will say hello to the International Space Station, where they will begin a one-year mission in space. Though they will be accompanied by the rotating crew of the ISS the goal of the mission will be to test the limits of human research, space exploration and the human spirit.

"Long exposure to a zero-gravity environment can affect the human body in multiple ways. Some physical symptoms can include changes to the eyes, muscle atrophy and bone loss" NASA spokesperson said in a press release issued today. "Human psychology is also an important area of study, as the effects of living in isolated and small spaces will be important to understand ahead of future human missions to Mars."

"Research collected from the one-year mission can help NASA and the international partners reduce risks and better understand how to ensure astronauts will thrive on longer missions."

While most expeditions to the space station only last between four and six months on average, researchers hope that by logging in more than twice the normal tour time they will be able to better understand how the human body will react to much longer spaceflight. 

Current mission plans of sending astronauts to Mars, which could take 500 days or longer just in transit, primarily focus on keeping astronauts in an artificially induced coma to conserve energy and resources throughout the trip. But as with any sedentary lifestyle, researchers fear that the long spaceflight may take a major toll on the bodies of their test subjects. So to better view just how a body will react in space, versus here on Earth, they have turned to one of the oldest tricks in the book-researching twins.

What's the crux to NASA's new study?

"While Scott Kelly is in space, his identical twin brother, retired NASA astronaut Mark Kelly, will participate in a number of comparative genetic studies. Some of these experiments will include the collection of blood samples as well as psychological and physical tests" NASA spokesperson says. "These tests will track any degeneration or evolution that occurs in the human body from extended exposure to a zero-gravity environment."

"The new twin studies are a multi-faceted national cooperation between universities, corporations and government laboratory expertise."