Twin study reveals space surprises
Nearly a year in space put astronaut Scott Kelly’s immune system on high alert and changed the activity of some of his genes compared to his Earthbound identical twin Mark, researchers say.
Scientists don’t know if the changes were good or bad, but the results of the unique study, released at a science conference yesterday, are raising new questions for doctors as the US space agency aims to send people to Mars.
Tests of the genetic doubles gave scientists an opportunity to track details of human biology, such as how an astronaut’s genes turn on and off in space compared to at home.
One puzzling change was that Kelly’s immune system was hyperactivated.
‘‘It’s as if the body is reacting to this alien environment sort of like you would a mysterious organism being inside you,’’ said geneticist Christopher Mason of New York’s Weill Cornell Medicine, who helped to lead the study. He said doctors were now looking for that in other astronauts.
Since the beginning of space exploration, Nasa has studied the toll on astronauts’ bodies, such as bone loss that requires exercise to counter. Typically, they’re in space for about six months at a time. Kelly, who lived on the International Space Station, spent 340 days in space and set a US record.
‘‘I’ve never felt completely normal in space,’’ the now-retired astronaut said, citing the usual congestion from shifting fluid, headaches, difficulty concentrating due to extra carbon dioxide, and digestive complaints from microgravity.
But this study was a unique dive into the molecular level, with former astronaut Mark Kelly on the ground for comparison.
A number of genes connected to Scott Kelly’s immune system became hyperactive, Mason said. He also spotted a spike in the bloodstream of another marker that primes the immune system. Yet at the same time, Kelly’s blood showed fewer of another cell type that is an early defence against viruses.
The good news: almost everything returned to normal shortly after Kelly got back on Earth in March 2016. The immune-related genes, however, ‘‘seemed to have this memory or this need to almost be on high alert’’ even six months later, Mason said.
A human mission to Mars, which Nasa hopes to launch in the 2030s, would take 30 months, including time on the surface.
Kelly, who turns 55 next week, said he would be willing to go to Mars. A trip that long ‘‘wouldn’t be worse than what I experienced. Possibly better. I think the big physical challenge, radiation aside, will be a mission where you are in space for years’’. –AP