Introduction: Being Human on Mars
How does living on Mars change the human body? This question intrigues not only science fiction writers but also scientists. Mars is a far cry from the comfort zone we’re used to on Earth; its gravity is about one-third, the atmosphere is thin and mostly filled with carbon dioxide, cosmic radiation levels are high, and temperature fluctuations are extreme. What kind of changes does this environment induce in the human body? Especially during prolonged stays, what effects might it have in terms of adaptation and intergenerational changes?
Although we don’t have a direct dataset examining the effects of living on Mars on human physiology, our experiences in low Earth orbit and observations from the International Space Station (ISS) help us make some educated guesses. One of the most notable studies in this area is NASA’s “Twins Study,” which delved into the genetic and physiological impacts of spaceflight. Yet, Mars’s unique gravity and environmental conditions raise many new questions and uncertainties beyond these predictions.
When considering the potential changes living on Mars might bring to the human body, comparing Mars conditions with life at high altitudes on Earth can provide valuable insights. People living at high altitudes show physiological adaptations for oxygen transport, while Mars’s low gravity, radiation, and enclosed living spaces require us to ponder how these factors interact. The example of astronauts growing taller on the ISS can be helpful in understanding the effects of gravity on the skeletal system. In this article, we’ll explore the anatomical and physiological changes in humans who stay on Mars for extended periods, separating known data from speculation.
Weakening Gravity: Bones, Muscles, and the “Mars Body”
Gravity on Mars is only about one-third of Earth’s, which could have significant effects on the human skeletal and muscular systems. In microgravity environments, astronauts can experience a loss of bone mineral density at a rate of 1% per month. For long missions, this indicates substantial clinical bone loss. However, Mars’s 0.38 g environment is not microgravity, so data from the ISS cannot be directly applied to Mars. The actual impact on Mars remains unmeasured, and therefore interpretations rely on modeling and animal experiments.
Muscle atrophy, loss of muscle strength, and functional changes in certain muscle groups associated with long-term space missions also draw attention. There’s no definitive answer on how much Mars’s low gravity will mitigate these changes. Thus, less muscle mass or a different distribution of muscle strength might be a possible outcome, but it’s not inevitable.
One predicted anatomical change is thinner bones and postural differences. This is a theoretical prediction about how low gravity might shape the human skeleton in the long term. However, it’s more accurate to understand the direction and potential consequences of change rather than making definitive statements.
Countermeasures like exercise and artificial gravity have been developed to prevent such changes. The resistance exercise devices used by NASA on the ISS aim to reduce muscle and bone loss in astronauts. However, whether these measures will…