Former astronaut Mark Kelly (left) poses with his identical twin brother, astronaut Scott Kelly (right). As part of NASA’s Twins Study, Scott spent nearly a year in space, while Mark stayed here on Earth. This gave researchers a chance to study the health effects of long-term spaceflights. (Credit: NASA) Scott and Mark Kelly are identical twin brothers. Though that alone does not make them unique, what does is the fact that they are also both astronauts. In order to take advantage of the Kellys’ unique situation, NASA scientists decided to conduct a detailed study on the twins, aimed at unraveling how nature versus nurture plays out in space. As part of NASA's Twins Study, researchers collected biological samples from each of the Kellys before sending Scott to the International Space Station for a year starting in March 2016. Meanwhile, his brother Mark, who retired as an astronaut in 2011, remained on Earth to serve as the control subject. By analyzing how each twins’ biological markers evolved during the mission, the researchers learned a great deal about how the human body reacts — both physically and mentally — to extended periods of spaceflight. The NASA Twins Study is made up of ten distinct research projects, which all focus on different aspects of the human body. And last month, after nearly two years of study, the ten separate research teams confirmed their preliminary findings (which were initially released in 2017), as well as presented details on their postflight follow-up results. Later this year, the findings for each of the various projects will be integrated together and released as one summary paper, which will be followed by several companion papers focusing on the individual studies. In the meantime, here is a summary of the most recent findings for each of the research projects that were carried out as part of the Twins Study.
#1 - Telomeres get longer during spaceflight
Telomeres are the caps that shield the ends of our chromosomes, protecting DNA strands from damage and degradation. In a study led by Susan Bailey of Colorado State University, researchers tracked the length of each twins’ telomeres before, during, and after Scott’s yearlong spaceflight. The researchers found that Scott’s telomeres significantly increased in length while he was in space, which was not the case with his Earth-bound brother Mark, whose telomeres remained relatively stable. Previous research has shown that longer telomeres are associated with fewer age-related problems. Though Scott’s telomeres were found to lengthen while he was in space, postflight measurements showed that the telomeres underwent rapid shortening within about 48 hours of landing back on Earth. Eventually, they returned to their preflight lengths. The team believes that the temporary lengthening of Scott’s telomeres could be a side effect of his rigorous exercise routine and restricted, low-calorie diet.
