If humankind will someday travel to and live on Mars, much will be owed to the scientific groundwork laid by astronaut Scott Kelly’s year on the International Space Station (ISS). After more than 340 days in space, Kelly is scheduled to return to Earth on March 1 at 11:25pm ET. Marking the occasion, PBS and Time have partnered to present A Year in Space, a two-part documentary tracking his entire mission. The first part (March 2 at 8pm ET, check local listings) follows Kelly’s extensive training, his launch into orbit, and his life aboard the ISS. Part 2 airs in 2017 and follows Kelly’s reentry, and how his mind and body readapt to life on Earth. Using Scott’s earthbound identical twin brother Mark as a comparison, scientists hope to learn how to overcome the challenges of human interplanetary travel.
Physical Effects Of Spaceflight
Telomeres Cosmic rays may cause damage to sections of DNA called telomeres that are believed to play a role in aging.
Microbiome Essential bacteria that live in the gut, skin, mouth and elsewhere are affected by space travel.
Fluid Shift With no gravity to push bodily fluids down, space travelers experience higher pressure in their upper bodies. Changing cranial pressure can affect vision.
Musculoskeletal Atrophy Weightlessness causes certain muscles to lose mass. Without gravitational stress, bones lose density and weaken in a condition known as spaceflight osteopenia.
Photo: Courtesy of Marco Grob for TIME