Astronauts Scott and Mark Kelly are twins. And they're taking part in one of the most ambitious genetic studies ever to see how time in space might affect genetics.
The brothers are the perfect candidates for a genetic study: They're almost genetically identical, and one spent nearly a year in space while the other stayed on Earth.
The official results of the study aren't out yet, but initial results are showing interesting differences between the twins.
One difference was in the telomeres — the protective bits at the end of our chromosomes. After his year in space, Scott's telomeres were longer than his brother's. They have since returned to normal. His microbiome changed, too. In fact, nearly everyone working on the study is finding differences.
The study found Scott's gene-expression signature had changed. Gene signatures are the way genes in a cell combine to express a certain trait. Changes in the gene-expression signature aren't uncommon, but the changes in Scott's seemed to be larger than normal.
Scott also exhibited a decrease in DNA methylation — a change in a chemical marker that can effect gene expression. His brother saw an increase during the same period. Scientists working on the project aren't sure what this means yet.
Long-term exposure to microgravity can really wear on a person's body. This study could help NASA come up with ways to lessen those effects on long term missions — like the one they want send to Mars sometime in the 2030s.