Keeping astronauts healthy in space is challenging. When they are on long missions, like those on the International Space Station (ISS), they exercise for two hours daily to prevent muscle loss. Understanding the gravity level at which muscle deterioration starts is essential for successful missions to the Moon and Mars.
A recent study in Science Advances explored this. Researchers looked at how different levels of artificial gravity affected mice aboard the ISS. They found that when gravity drops below 0.67 g (67% of Earth’s gravity), muscle deterioration begins. This is a crucial finding, and it could help guide future human missions.
Lori Ploutz-Snyder, a kinesiology expert from the University of Michigan, notes the value of using mice for these experiments. While not humans, they allow scientists to study muscle changes over time in a controlled environment.
In this study, 24 mice were launched into space in March 2023. They experienced three gravity levels: 0.33 g, 0.67 g, and 1 g for up to 28 days. When the mice returned, researchers examined their muscle strength and signs of atrophy. Even at 0.33 g, the mice maintained some muscle strength, though their muscle fiber composition changed. At 0.67 g, there was no loss of muscle strength or fiber changes.
This study raises concerns for astronaut health on the Moon and Mars, where gravity is lower—approximately 0.17 g on the Moon and 0.38 g on Mars. Knowing how much gravity is needed to maintain muscle health is vital for long stays in these environments.
Earlier research by Ploutz-Snyder suggested a similar gravity threshold of 0.5 g to 0.75 g in humans. More studies are needed to determine if these findings align for both species. She believes this is a solid basis for future experiments.
Mark Shelhamer, a former chief scientist for NASA’s Human Research Program, is also encouraged by the results. He acknowledges that they are a significant step toward understanding how gravity impacts astronaut health.
Understanding these thresholds will be crucial for future missions, especially as NASA aims to establish a lunar base and send astronauts to Mars through the Artemis program. This knowledge could also help scientists design effective exercise programs for long-duration missions.
Ploutz-Snyder hopes future research will explore how gravity levels affect bone health differently, how exercise might affect these thresholds, and the practical applications of this information. This research could pave the way for human habitation on the Moon, Mars, and beyond.
For more on NASA’s plans for lunar habitats, check out the Artemis program.
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astronaut health,international space station,microgravity
