In space, on a space station, gravity is a fraction of the Earth’s. In space, radiation exposure is potentially hundreds of times greater than it is while you’re underneath the protection of the planet’s atmosphere. One astronaut named Scott Kelly, after nearly one full year in space, came back to Earth two inches taller than before he left as a rocket man to spend 340 days living on the International Space Station (twice as long as any other American astronaut before). Scott has a twin brother who stayed on the ground, and he was about two inches taller than him when he got back home. (In space, the lack of strong gravity causes the spaces in between an astronaut’s spinal discs to get larger.) However, he quickly began “shrinking” back down to his normal size right after his space capsule’s touch down.
One of the things that NASA researchers are most interested in monitoring in Scott Kelly now that he’s back down to Earth is how prolonged radiation exposure may have affected him during his near-year in space. Astronaut exposure to radiation while living on the ISS is about 20 times as intense as it is to people on the Earth, but during a human mission to planet Mars (which NASA is looking to launch) the radiation exposure to a human body could be at least 300 times greater than while earthbound.
Kelly has noted that NASA scientists are most curious about his heart, blood vessels, bones, central nervous system, and brain. He’ll be examined annually for many years to come after his prolonged time in space so that the scientists can get a good indication of what his body went through while he was aboard the ISS. Needless to say, this ongoing research is intended to help prepare astronauts for a future spaceflight to Mars. NASA has plans to send a human crew of astronauts to the red planet around the year 2030.
One of the things of paramount concern to scientists other than radiation exposure in space is how the heart can shrink while a human is “out there.” Kelly says, “Just like the bones and muscles, the heart is designed to work in one gravity here on Earth, so when you put the heart in space it operates differently and changes shape.”
Right after coming back down from his time in space, Kelly reported that his muscles and joints ache (likely from him being unused to the usual gravitational stress on Earth). His skin has become sensitive enough for him to feel a burning sensation just from sitting down (which may be due to radiation exposure). Kelly first noticed the aches in his joints and muscles when he got back to his home after touch down and jumped into his pool.
Yet another effect of spending prolonged time in space is mild vision loss. Scientists want to study Kelly’s eyesight in the coming months and years, especially since they’re presently not sure why time in space weakens one’s eyesight. “The majority of astronauts have to change their eye glasses while in space. They bring eye glasses with them and typically change a few months into the mission,” Kelly says.
“I thought it would probably be a little different, but it’s more than just a little different. Coming back to gravity is harder than going to no gravity,” Kelly said when asked about coming back from space.
Doug Wheelock, a NASA astronaut and the incoming director of NASA’s office at Russia’s Star City space exploration headquarters, says NASA is looking to send perhaps ten more astronauts like Scott Kelly to spend a prolonged time in space in order to prepare for the future Mars missions.
[Photo: Krill Kudryavtsev/AP Images]