NASA Astronaut Scott Kelly, twin brother of Tucsonan Mark Kelly (a retired astronaut and husband of Gabby Giffords), has made it through the first six months of his year in space. NASA notes:

“I think the legacy of this mission will be based on the science of having us in space for a year,” remarked Kelly in a recent interview. “The great data we collected, what we learned about being in space for this long and how that will help our journey to Mars someday.”

In their almost six months in orbit, Kelly and Kornienko have participated in a range of scientific experiments focusing on seven key areas of human research.

One of the most ambitious studies undertaken so far is Fluid Shifts, which studies what happens when fluids shift into the upper body during weightlessness. This shift may cause changes in vision through increased intracranial pressure and is a major issue that scientists are looking to resolve before humans begin exploring beyond Earth’s orbit. The study uses the Russian Chibis device to draw fluids back into the legs while measurements of the subject’s eyes are taken to track any changes. NASA and Roscosmos are already looking at continuing the Fluid Shifts investigation with future space station crews beyond the one-year mission.

Kelly seems to really enjoy using the cameras aboard the space station. IO9 has rounded up 51 of his best photos here.

Here's a video that explains the mission: