Spaceflight missions of extended duration result in astronaut deconditioning, including a decrease in muscle mass and performance, reduced aerobic capacity, and losses in bone density, in addition to a host of other physiological changes. However, well-structured countermeasures systems, including exercise and nutrition, help to mitigate these losses. Mars One astronauts will be well prepared with a scientifically valid countermeasures program that will keep them healthy, not only for the mission to Mars, but also as they become adjusted to life under gravity on the Mars surface.
A great example of the effectiveness of in-flight exercise countermeasures in maintaining astronaut health and performance is illustrated by American astronaut Shannon Lucid’s 188 day stay aboard the Russian MIR space station, during which time she relied heavily upon the use of exercise countermeasures. When her mission came to an end, she was able to walk unassisted within 24h.
When Mars One astronauts arrive on Mars (62% less gravity than Earth), they would theoretically be stronger compared to an astronaut returning to Earth’s gravity after a mission of similar duration.
A recent study of International Space Station (ISS) astronauts, with mission durations ranging from 4-6 months, showed a maximum loss of 30% muscle performance (and maximum loss of 15% muscle mass). However, we intend even to lower these numbers. With recent and emerging scientific research of effective long-duration countermeasures, Mars One will take advantage of the ~10 years prior to the launch of the first colonization mission to observe and select the most suitable astronauts and countermeasures to ensure a safe and successful mission.
Astronauts will suffer a loss of bone density; however, the problem can be mitigated with appropriate and well-designed countermeasures, including but not limited to exercise and pharmaceuticals. Continued research and advancements in this area will surely produce even more effective countermeasures within the ~10 year period of preparation prior to the first Mars One launch. Once on the Mars surface, astronauts will be able to take advantage of the force of gravity (albeit, less than that of Earth) to assist them in the reconditioning and adaptation process, which will result in bone remodeling that will help to strengthen the astronauts’ bones.