Podcast Episode
Researchers sent twenty-four mice to the International Space Station in March 2023, where they spent nearly a month living under different gravity conditions using a specialised centrifuge system built by the Japan Aerospace Exploration Agency. The animals experienced microgravity, one-third Earth gravity, two-thirds Earth gravity, or full Earth gravity for up to twenty-eight days. Twenty-three returned alive for analysis.
This places the protective threshold at around sixty-seven percent of Earth's gravity, well above what either Mars or the Moon can offer. Mars sits at roughly thirty-eight percent, and the Moon at just seventeen percent.
Former NASA chief scientist Mark Shelhamer noted that scientists still have no certainty about whether lunar or Martian gravity is sufficient to prevent the deconditioning of bones and muscles. Meanwhile, University of Michigan researcher Lori Ploutz-Snyder pointed out that her own human studies using parabolic flights identified a similar threshold between fifty and seventy-five percent gravity, lending weight to the mouse findings.
Mars Gravity Too Weak to Protect Human Muscles, ISS Mouse Study Reveals
March 15, 2026
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A new study published in Science Advances found that gravity must reach at least sixty-seven percent of Earth's level to fully preserve muscle function. With Mars sitting at just thirty-eight percent, the findings raise serious questions about long-term human habitation of the Red Planet.
Space Mice Reveal a Gravity Problem for Mars
A landmark study published in Science Advances has delivered a sobering finding for anyone dreaming of life on Mars: the Red Planet simply does not have enough gravity to keep human muscles healthy.Researchers sent twenty-four mice to the International Space Station in March 2023, where they spent nearly a month living under different gravity conditions using a specialised centrifuge system built by the Japan Aerospace Exploration Agency. The animals experienced microgravity, one-third Earth gravity, two-thirds Earth gravity, or full Earth gravity for up to twenty-eight days. Twenty-three returned alive for analysis.
The Critical Threshold
The results identified a clear tipping point. At one-third gravity, roughly comparable to Mars, the mice retained their muscle size but lost grip strength and experienced changes in muscle fibre composition. At two-thirds gravity, however, the animals showed no deterioration whatsoever: no loss of strength, no changes in fibre type, and no signs of atrophy.This places the protective threshold at around sixty-seven percent of Earth's gravity, well above what either Mars or the Moon can offer. Mars sits at roughly thirty-eight percent, and the Moon at just seventeen percent.
What This Means for Space Exploration
The findings pose direct challenges for NASA's Artemis lunar programme and its ambitions to send astronauts to Mars in the 2030s. Astronauts aboard the ISS already exercise two hours daily yet can still lose up to forty percent of their muscle mass after five months.Former NASA chief scientist Mark Shelhamer noted that scientists still have no certainty about whether lunar or Martian gravity is sufficient to prevent the deconditioning of bones and muscles. Meanwhile, University of Michigan researcher Lori Ploutz-Snyder pointed out that her own human studies using parabolic flights identified a similar threshold between fifty and seventy-five percent gravity, lending weight to the mouse findings.
The Road Ahead
Whether artificial gravity systems, advanced exercise protocols, or pharmaceutical interventions can bridge the gap remains an open question. The study's authors stressed that understanding the molecular mechanisms behind gravity-induced muscle changes is urgently needed before humans attempt extended stays on Mars.Published March 15, 2026 at 12:11am
