NASA Found 7% of Scott Kelly’s Gene Activity Stayed Altered After 340 Days in Space
Updated
Updated · spacedaily.com · May 20
NASA Found 7% of Scott Kelly’s Gene Activity Stayed Altered After 340 Days in Space
2 articles · Updated · spacedaily.com · May 20
Six months after Scott Kelly returned from a 340-day ISS mission, about 7% of his gene expression still had not returned to preflight baseline, with the most persistent changes tied to immune function, DNA repair, bone formation and mitochondria.
NASA’s twin study could isolate those effects unusually well because Kelly’s identical twin, Mark, stayed on Earth while both brothers were tracked with matching biological and cognitive tests over multiple years.
Telomeres—normally a marker of biological aging—lengthened unexpectedly in orbit, then fell below pre-mission levels within 48 hours of landing, alongside chromosomal abnormalities that persisted for years.
Cognitive testing also showed slower reaction time, accuracy and risk calibration during the mission’s final months, with performance still measurably below Kelly’s preflight baseline months after return.
The findings suggest long-duration spaceflight perturbs interconnected systems rather than a single organ, raising concern for Mars-class missions that would face longer exposure and higher radiation beyond Earth’s magnetosphere.
If space permanently alters human genes, what is the single greatest biological risk facing the upcoming Artemis II crew?
Are new countermeasures enough for a Mars mission, or is our biology the ultimate barrier to deep space travel?
Persistent Genetic Changes in Astronauts: What the NASA Twins Study Means for Long-Duration Space Missions
Overview
The NASA Twins Study, published in 2019, provided unique insights into how the human body responds to long-duration spaceflight by comparing astronaut Scott Kelly, who spent 340 days on the International Space Station, with his identical twin Mark Kelly, who stayed on Earth. The study closely tracked changes in Scott’s body, revealing widespread shifts in gene expression, especially in genes related to immune function and DNA repair. These changes were most pronounced during the second half of the mission. While most gene expression changes returned to normal after six months back on Earth, about 7% persisted, highlighting potential long-term health effects of space travel.