Research Shows Space Travel Alters Human DNA Permanently

WHO:

BGR - Astronauts Scott Kelly and Mark Kelly participated in a NASA study.

Yahoo - Scott Kelly and Mark Kelly are identical twin brothers and astronauts.

WHAT:

BGR - The study revealed that Scott Kelly grew taller, lost muscle, and aged slower than Mark Kelly.

Yahoo - The age gap between Scott and Mark changed by five milliseconds during the study.

BGR - Approximately 7% of Scott's gene expression changed even six months after returning to Earth.

Yahoo - The research identified 811 genes across multiple cell types that had not returned to preflight levels six months post-mission.

WHERE:

BGR - The study took place at the International Space Station and on Earth.

WHEN:

BGR - The study was conducted between March 27, 2015, and March 2, 2016.

Yahoo - The results of the study were published in 2019.

WHY:

BGR - The study aimed to understand the physiological and molecular effects of long-duration spaceflight on humans.

HOW:

BGR - NASA monitored and collected data from both Scott and Mark Kelly throughout the year-long study.

Yahoo - The study examined changes in gene expression, immune system activity, telomere length, and mental performance.

(UPDATED June 12, 2026 21:37 UTC)

In a groundbreaking NASA study, astronauts Scott Kelly and Mark Kelly, who are identical twin brothers, were monitored to understand the effects of long-duration spaceflight on humans. The research revealed that Scott experienced changes such as growing taller, losing muscle, and aging slower than Mark, with about 7% of his gene expression altered even six months after returning to Earth. Notably, the study identified 811 genes that had not returned to preflight levels, highlighting significant physiological changes resulting from their time aboard the International Space Station.