A human mission to Mars has been the subject of science fiction since the 1880s, but over the past decades it became the goal of national space programmes. The potential missions come with several key physical challenges, including threats from cosmic rays, adverse fallout from prolonged weightlessness, and the psychological effects of isolation.
A recent study has revealed what could be a disconcerting discovery for the future generation of astronauts embarking on long spaceflights.
Research suggests that lengthy weightlessness can shrink the heart, with even a long-term programme of low-intensity exercise in space falling desperately short of counteracting the side effects for the heart, according to a paper published in the American Heart Association’s journal Circulation.
As long-term suspension in water is similar to zero gravity or the condition of weightlessness in space, especially in a ‘prone swimmer’, the research compared data from retired astronaut Scott Kelly’s almost year-long stint aboard the International Space Station (ISS) from 2015 to 2016 and that of endurance swimmer Benoît Lecomte.
The latter swam 1,753 miles (2821 kilometres) across the Pacific Ocean over 159 days, from June 5 to November 11, 2018. The marathon athlete averaged nearly six hours daily, during a journey which started at Choshi, Japan and was due to end in California.
After his support boat was damaged, the mission was prematurely wrapped up.
Kelly, throughout the 340 days in space, exercised six days a week, one to two hours per day, using a stationary bike, a treadmill and resistance activities.