13 Astronauts’ Hearts Passed a Simulated Mars Test — SkimNews
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- Northwestern Medicine monitored 13 astronauts for approximately six months aboard the International Space Station with UT Southwestern Medical Center and UTHealth Houston, collecting echocardiograms before, during and after each mission.
- Astronauts’ hearts initially declined in cardiac filling, stroke volume and other cardiovascular measures during the first two weeks in space, then gradually approached prelaunch levels as the missions continued.
- NASA’s Exercise Countermeasures program had astronauts exercise up to two hours daily, including 30–45 minutes of endurance training and 60–75 minutes of resistance work; researchers called exercise crucial in microgravity.
- The simulated Martian-gravity test tilted each returning astronaut 22 degrees from a lying position, shifting blood toward the lower body; heart performance then matched preflight standing measures, with no significant cardiovascular strain.
- Circulation published the 2026 exploratory observational study, described as the first investigation of cardiac response to simulated Martian gravity after an extended period of spaceflight.
Why it matters: For NASA planners, the finding adds cardiovascular evidence for six-month missions: all 13 study astronauts’ hearts matched preflight standing performance in a 22-degree postflight gravity simulation after up to two hours of daily exercise. The small, simulated setting informs planning but does not demonstrate readiness for an actual Mars landing.
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