NASA’s Study of Astronaut Twins Creates a Portrait of What a Year in Space Does to the Human Body

Embark on a journey through the cosmos, as we delve into NASA's groundbreaking study on astronaut twins. Discover the profound effects a year in space can have on the human body, unraveling mysteries that could shape the future of space exploration.

NASA has big plans for human spaceflight

The space agency’s proposals to send long-term, crewed missions to the moon and eventually, land astronauts on Mars will require significant advances in rocket and spaceflight hardware.

• But along with new technology, scientists are grappling with another crucial question: Can the human body sustain itself during that much time in space?
• To study the influence of microgravity, radiation and confinement in long-duration spaceflight, NASA selected twins Scott and Mark Kelly for a unique mission.

Spaceflight’s Influence on the Mind

In one potentially concerning result, a team studying cognition found that Scott’s performance on a series of cognitive tests declined in the post-flight period.

• Even though Scott’s in-flight measures were stable, his “cognitive efficiency,” or his speed and accuracy in completing the test battery, dropped once he got back to Earth.

The Space Explorer’s Body

Throughout the rest of Scott’s body, researchers observed other changes related to spaceflight.

• Urine samples from Scott’s time aboard the ISS contained high levels of collagen, a structural protein.
• Looking at this measure along with physiological changes-like those observed in Scott’s eyeballs and vascular system-could be a sign that the body was restructuring.

A Question of Aging

One of the ten teams, led by Susan Bailey, a professor of radiation and cancer biology at Colorado State University, focused on telomeres, the “caps” that protect the ends of DNA strands on Earth.

• On Earth, these caps get depleted over the course of a lifetime as each round of DNA replication wears away at them, but in space, they actually increased during the mission.
• The team hoped to analyze the activity of telomerase, an enzyme that normally gets switched off in most adult body cells, to see if it somehow was activated while Scott was in space.

Gene Expression in Space

Researchers also studied Scott’s genome to see if gene expression changed during flight, as it tends to do in stressful situations.

• After the mission’s end, 90 percent of the modified gene expressions returned to their pre-flight baseline-a good sign that the body can bounce back after a long mission.

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