EVERYTHING
According to Bgr, a comprehensive study of identical twins Scott and Mark Kelly has provided groundbreaking evidence regarding how prolonged exposure to microgravity affects human biology. The research, which concluded in 2019, analyzed the physical and genetic differences between the two brothers after Scott spent nearly a year aboard the International Space Station (ISS).
Molecular and physiological shifts
While the twins remained genetically identical, the data showed that space travel significantly altered how Scott's genes were expressed. Researchers discovered that approximately 7% of his gene expression had changed even six months after he returned to Earth. While many biological markers stabilized upon his return, scientists identified 811 specific genes across multiple cell types that failed to return to pre-flight levels.
The study highlighted several key areas of impact:
- Changes in immune system activity and DNA repair mechanisms.
- Fluctuations in telomere length, which are the protective endcaps on chromosomes associated with aging.
- Physical changes including increased height and significant muscle loss.
- Persistent decreases in cognitive skills related to speed and accuracy.
Unexpected findings on cellular aging
One of the most surprising results involved Scott's telomeres. Typically, telomeres shorten as humans age; however, Scott's telomeres actually lengthened during his time in space before shortening again after he landed. Scientists noted that while longer telomeres are often associated with slower aging, the long-term significance of this specific phenomenon remains unknown.
The study also revealed that despite some improvements in certain metrics, Scott experienced a measurable decline in cognitive performance regarding speed and accuracy. These effects persisted even after his return to Earth's gravity. Because these results were based on a single pair of twins, researchers emphasize the need for broader studies to determine if these changes are universal or unique to Scott's specific physiology.
These findings serve as a vital blueprint for NASA as it prepares for multi-year missions to Mars and beyond. The data suggests that new safety protocols and medical safeguards will be necessary to protect the health of astronauts who may face these permanent biological shifts during deep-space exploration.