Can Astronauts Survive Rigors of Long Space Journeys?
As the United States considers a manned mission to Mars by the mid-2030s, ongoing research is beginning to raise doubts about the ability of human astronauts to survive such a multi-year journey in zero gravity without severe and possibly permanent physical or psychological damage.
One of the most pressing concerns, researchers say, would be the effect on their vision, as acceleration on launch followed by long exposure to weightlessness has been shown to change the shape of astronaut eyeballs, swell the optic nerves and cause blurred vision — problems that have been found to persist long after return to Earth and normal gravity. Cosmic radiation exposure is another concern for long-voyage astronauts, who would be without the protection the Earth’s atmosphere provides, and bone loss has been found to be progressive and continuous throughout long periods spent in weightless conditions.