Astronaut Scott Kelly, who spent 340 days aboard the International Space Station, said that being in space appears to have "permanent" effects that aren't fully understood.
“The environment astronauts are exposed to while in space is unlike anything we experience here on earth. Specifically, astronauts are exposed to high levels of radiation and carbon monoxide, and a micro-gravity environment which causes loss of bone and muscle, vision impairment and effects on our immune system to name a just a few,” he wrote in his prepared remarks to the House Science, Space and Technology committee. “These are very real issues that need to be solved before the human race is able to reach destinations beyond the Earth and the Moon.”
"Exposure to the space environment has permanent effects we simply do not fully understand," he added.
The NASA project that Kelly was a part of aimed to observe the long-term effects of spaceflight on the human body. Kelly, as well as his identical twin brother, Mark Kelly, underwent medical tests—with Mark Kelly acting as the control subject on Earth.
Scott Kelly, who had previously undergone a 159–day mission to the International Space Station in 2010 and 2011, said he was surprised at how differently he felt compared upon return this time around.
Due to the absence of gravity, Kelly’s skin “did not touch anything for nearly a year,” and because of this it was “extremely sensitive and became inflamed.”
“I developed a hive-like rash on every surface of my skin that came in contact with ordinary surfaces on Earth during normal activities like sitting or lying in bed.”
In addition, the astronaut explained that his legs were swollen “due to the shift of gravity forced upon my body,” and that he developed flu-like symptoms that he believes were due to his extended time in space.
Despite effects he has experienced since his arrival back to Earth, Kelly expressed his honor to play a part in future space pioneer’s missions, as well as his belief of the need for continued spaceflight and exploration to ensure the “success and development of our nation and species.”
“We are on the cusp of a new space age,” he said. “One in which greater numbers of Americans will travel to space and go further than ever before.”