Scott Kelly spent nearly a year in space, while Mark stayed on the planet as a contrast. The results of this study are now finally published. As part of the research, Scott Kelly lived on the International Space Station for 340 days in 2015 and 2016. And his brother, also a retired astronaut, experienced his normal life on the ground. Of course, the idea is that identical twins have 100% identical genes, and they are a good window to understand the impact of the space environment on the human body.
In this case, 10 research groups conducted in-depth research on the different aspects of the physiology of the Kelly brothers during space flight and within six months after Scott Kelly returned to Earth. The data collected will help inform the space missions of the coming decades, including future astronaut diets, exercise mechanisms, and health and safety measures, as humans will return to the moon and eventually to Mars.
One of the most interesting findings is related to Scott Kelly's telomeres. These parts of DNA are located at the end of the chromosome, protecting the DNA from damage when the cell divides, somewhat like small plastic fragments at the end of the lace. As they get older, they naturally get shorter - but scientists notice that Scott Kelly's telomeres actually grow longer in space. Within a few days of returning to Earth, they contracted sharply and then returned to an average length within six months. At the same time, Mark's telomeres remained stable throughout the test.
Another important finding is that flu vaccines work in space. Scott Kelly was the first person to vaccinate in space and found that his immune system should respond as such. This indicates that future vaccination will be an important procedure.
The gene expression between Scott and Mark is also different. Although space seems to have changed genetic activity to a higher level than usual, more than 90% of these changes have returned to normal on Earth. Interestingly, about 7% of people last longer than six months. These gene expression changes can be correlated with many other findings in the study. NASA studied radiation exposure and observed DNA damage.
Scott's cognitive ability seems to have remained relatively unchanged during his space years, but interestingly, his cognitive speed and accuracy have dropped after he returned to Earth six months later. However, NASA said that this may be due to re-adapting to the gravity of the Earth and the pressure of busy work afterwards.
In addition, Scott's gut microbiome is quite different during the space travel period than before. This is most likely due to the very different foods that astronauts must eat, including mainly freeze-dried food. What is not known is whether these changes may be long-term, but fortunately the study found that the microbiome returned to normal within six months. These data help inform the changes in the astronaut's diet and promote healthier gut bacteria.
Among the many other health effects observed by Scott, the team found evidence of thickening of the carotid wall and elevated levels of protein AQP2 - which may play a role in astronaut-reported vision problems - folic acid and other epigenetic changes.
The data collected through this comprehensive study will undoubtedly continue to be tracked in the coming years. Not only does it help inform future space missions, it can also bring more general health benefits to people on Earth, including new treatments for diseases.
The study was published in the journal Science.