NASA Study Finds 7% of Gene Activity Still Altered 6 Months After Spaceflight

2 articles · Updated · spacedaily.com · Aug 4

Six months after landing, about 7% of Scott Kelly’s gene activity still had not returned to its preflight pattern, NASA-backed research found, showing some spaceflight effects can outlast a mission by months.
Months in microgravity drive roughly 2 liters of fluid toward the head, cut blood volume early, and erode bone by about 1% to 1.5% a month; calf muscle can shrink around 15% despite daily exercise.
Vision remains a top concern because headward fluid shifts can swell the optic nerve and flatten the back of the eye, leaving some astronauts needing stronger glasses after return.
NASA said most changes from space-station-length missions do reverse, but the persistent minority matters for Mars, where crews would face years in space, higher radiation and no in-flight medical backup.