ISS Photography By Scott Kelly

The goal aboard the orbiting laboratory is to understand better how the human body reacts and adapts to the harsh environment of space. Data from the 12 months will help inform current assessments of crew performance and health and will determine better and validate countermeasures to reduce the risks associated with future exploration as NASA plans for missions around the Moon, asteroids and ultimately Mars.
Health studies
The International Space Station has developed exercise equipment, including treadmills and resistance devices to limit muscle atrophy in a low gravity environment. Weightlessness causes body fluids in astronauts to accumulate in the upper half of the body, leading to facial edema and unwelcome side effects. Studies on astronauts have suggested that weightlessness leads to vision problems due to increased intracranial pressure changing the shape of the eyeball.