Space travel may apparently cause genetic changes and other biological markers in astronauts, a new NASA study has found.
To conduct the study, scientists used the identical twin astronaut brothers Scott Kelly and Mark Kelly and traced out the genetic differences that came in both.
The measurements taken before, during and after Scott Kelly's space mission show changes in gene expression, DNA methylation and other biological markers that are likely to be attributable to his time in orbit.
From the lengths of the twins' chromosomes to the microbiomes in their guts, almost everyone is reporting that we see differences, said Christopher Mason, a geneticist at Weill Cornell Medicine in New York City.
The big challenge for the scientists is to differentiate between changes that are specific to physical demands of spaceflight and those many changes that might be simply due to natural variations.
But researchers believe that, since Kelly twins are just two people, the results may not be generalisable to others.
Yet the work can be seen as some of the most detailed molecular profiling ever done, involving some of the most physically demanding environments.
Scott Kelly spent 340 days in space in 2015-16, giving him a lifetime total of 520 days. Mark Kelly, also an astronaut, had previously flown in space for a total of 54 days over four space-shuttle missions between 2001 and 2011.
To test the changes after long duration spaceflight, NASA arranged to have blood and other biological samples taken from them to try and observe biological changes brought during the period.
Studies of the twins' telomeres, the caps on the ends of their chromosomes, showed that during spaceflight Scott's telomeres grew to be longer than his brother's. But this somewhere proved to be exactly opposite of what they had thought.
Scientists are now running a separate study to figure out what this means. However, levels for both men returned close to preflight levels after Scott came back to Earth.
With PTI Inputs