NASA began planning for a year-long mission aboard the ISS following a Russian announcement for a similar mission. The primary goal of the year-long expedition aboard the orbiting laboratory was to better understand the effects of spaceflight on the human body. In November 2012, Kelly was selected for a one-year mission to the ISS, but was medically disqualified the following day due to his vision worsening in microgravity. Kelly appealed to NASA, and was reselected for the mission along with cosmonaut Mikhail Kornienko.