Exercise and onboard ultrasounds helped keep astronauts' hearts stable during six-month missions

An international team published findings in Circulation based on onboard echocardiograms performed by 13 crew members during six-month spaceflights. Initial imaging showed modest, reversible changes in heart chambers as the body adjusted from Earth's gravity to weightlessness. Continuous exercise and strength training mitigated these effects, stabilizing cardiac structure after the first months and restoring normal function upon return.

Simulated exposure to three-eighths Earth gravity, the level expected on Mars, produced no greater cardiovascular strain than upright posture on Earth. The study underscores the importance of robust in-flight fitness equipment for future Mars missions, which will involve two six-month microgravity trips and an extended stay on the Red Planet. Researchers highlighted that, while equipment failures have caused past NASA fatalities, a cardiovascular event remains a plausible medical emergency for middle-aged astronauts.