In a remarkable journey through space, identical twin brothers Scott and Mark Kelly have redefined our understanding of human biology under extraterrestrial conditions. As American astronauts, they participated in NASA’s historic Twins Study, which began in 2015, allowing researchers to explore the significant effects of living in space on the human body.
The groundbreaking study involved Scott Kelly spending 340 days aboard the International Space Station (ISS), while his brother Mark remained on Earth. This experimental design capitalized on the brothers’ identical genetic makeup, providing a unique opportunity to measure the physiological changes Scott underwent during his extended mission.
Launched in March 2015, Scott’s mission focused on understanding how the human body adapts to the harsh environment of space. According to NASA, “The mission’s goal was to understand how the human body reacts and adapts to the harsh environment of space.” Over the course of his time in orbit, nearly 400 experiments were conducted, exploring various aspects of human health, which will inform future space missions, including those aimed at Mars.
The experiment asked how a human being might respond after an extended period in microgravity. Both brothers underwent numerous health assessments before, during, and after the mission. These assessments included blood tests, stool samples, urine and saliva analysis, and cognitive and physical performance tests.
Interestingly, the results of the study were surprising and illuminating. Post-mission evaluations revealed that Scott Kelly did not experience significant long-term health problems as a result of his extended stay in space—a crucial finding for NASA’s aspirations for future long-duration flights. Scott’s immune system returned to normal quickly after landing, indicating that the human body possesses a remarkable ability to adapt.
However, there were unexpected results regarding Scott’s biological markers. One intriguing discovery was that Scott’s telomeres, which typically shorten with age and are indicators of biological aging and risk factors for diseases, actually lengthened during his time in space. This finding surprised scientists at NASA, leading to a re-evaluation of what long-term exposure to space environments might mean for astronauts.
Reflecting on the findings, Steven Platts, deputy chief scientist with NASA’s Human Research Program, articulated the implications of the research, stating, “The results we’ve seen… show the resilience and robustness of the human body.” He emphasized the adaptability of human biology, noting, “We’ve evolved here on Earth in a one-(gravity) environment, we grow up, we train, we do everything here, and yet, when we go into space… our bodies adapt and continue to function and by and large, function extremely well.”
Platts further explained that most changes observed in Scott returned to baseline levels shortly after his return to Earth. “Changes that were seen in Scott, the vast majority of them came back to baseline in a relatively short period when he returned to Earth. And those that did not are markers of things we already knew were likely to happen,” he added, reinforcing the idea that the findings will help guide biomedical research for future long-duration missions.
Overall, the results of the Twins Study provide a hopeful outlook for upcoming space explorations. NASA’s mission to deepen our understanding of human adaptability is not just relevant for astronauts, but potentially opens doors for all kinds of health advancements on Earth, especially as space agencies prepare for future journeys to Mars and beyond.
As Scott and Mark Kelly’s story encapsulates, the quest for knowledge continues to push humanity forward, unlocking new insights about ourselves and our place in the universe.
