Scott Kelly did not mutate into a genetic alien during his year living aboard the International Space Station. You might have gotten that impression last year, though, when several news outlets reported that 7 percent of the astronaut’s genes had changed over the course of his mission.
Scott Kelly and Russian cosmonaut Mikhail Kornienko spent 340 days aboard the space station in 2015-16. This was and is still the longest consecutive spaceflight on the ISS. But Scott and Mikhail weren’t just trying to get their names into the record book; The length of the mission provided a vital test for future long-duration missions to Mars and beyond. A trip to Mars would take several months to a year, and NASA is curious to see what toll that amount of time in space takes on the human body.
NASA and its international partners commonly keep astronauts aboard the space station for six-month missions, but even half a year in space takes a toll. Astronauts commonly report diminished eyesight that doesn’t return to normal upon their return home. Bones can become more brittle in microgravity. Muscles atrophy. It’s harder to get to sleep in space. And scientists are worried that prolonged missions could have wide-ranging impacts on human biology, from altering the levels of beneficial bacteria in the gut to diminishing the power of the immune system.
NASA is still experimenting on Scott and comparing the changes in his body to those of astronauts who have spent shorter times in space. The basic question is: Does added time in space cause even more disruptions?
As a test subject, Scott Kelly is a bit special. Perhaps you’ve heard of his identical twin brother, Mark Kelly. Mark was also an astronaut, and he now advocates for gun control alongside his wife, former Rep. Gabrielle Giffords.
The Kellys went to NASA and pointed out that since they have the same DNA, Mark Kelly might make for an interesting control for the tests. NASA liked the idea and put out a call for outside researchers to submit proposals to study differences in the Kelly twins.
In all, there are ten research projects in what NASA is calling the “Twin Study,” ranging from testing the cognitive abilities of the Kelly twins to assessing changes to how their genes are expressed to looking for signs of change in their metabolisms.
It’s not a perfect control, but because the researchers have data from multiple points in time for each twin, there is some validity. If Scott’s levels on any of these tests vary wildly from Mark’s over that course of time, then perhaps those changes can be attributed to the time Scott spent in space.
But even a year later, it’s still hard to draw concrete conclusions about what aspects of spaceflight led to these changes. Here’s why: Genes turn “on and off” all the time, and these cycles are influenced by “basically everything,” Ran Blekhman, a genetics researcher at the University of Minnesota, says. Stress, diet, exposure to pathogens, physical activity, and even loneliness could potentially tweak the way genes are turned on and off. Many genes also run on a circadian rhythm, meaning they cycle on and off regularly on a 24-hour cycle. Heck, there was even a study that found meditation altered gene expression.
All this noise makes the work that goes into identifying meaningful changes in gene expression (like the ones the make the difference between a cancerous cell and a healthy cell) and what exactly caused those changes very difficult, painstaking work. And if there are changes, it will be hard to attribute them to any one aspect of spaceflight. They could be due to living in microgravity, a lack of exercise or disturbed sleep, or a diet of freeze-dried foods. They could also just be the result of random chance.
So what can we learn from this twins study?
Andy Feinberg is a molecular biologist at Johns Hopkins University involved in the Kelly twins study, studying the methylation of the Kellys’ genes. The plan, he says, is for all the researchers involved in the twin study to draft an academic paper, have it peer-reviewed, and then, hopefully, accepted to an academic journal.
Feinberg cautions that the genetic tests in the twin studies are not designed to yield definitive conclusions about the impact spaceflight has on our genetics. You could never do that with just one subject and one control. “You could form a hypothesis from that, but you couldn’t prove anything,” he says.
And overall, the researchers aren’t just looking at genetics. They’re looking at measures of cognitive function, immune function, metabolism, and vital signs. Across all these studies, the data may hint at a comprehensive story about how space impacts health, a hypothesis to test in future missions.
What’s underappreciated but perhaps more important, Feinberg says, is that this twins study is a way for scientists to refine their methods for conducting biological tests on astronauts. For instance, he says he and his colleagues spent some time in the “vomit comet” - NASA’s airplane that mimics the effects of zero gravity - so that they could develop rigorous blood drawing procedures for the astronauts to collect samples.
“Just figuring out how to do these things is a big deal,” he says. Even if the results only yield a hypothesis to test in the future, that’s okay. The work of getting human beings ready for interplanetary travel is “intergenerational,” he says. This study is just one small step. So, scientists may not learn a huge amount about how space impacts the way our genes work from Scott and Mark Kelly. But they’ll have a better idea of how to answer that question in the future.
In the meantime down here on Earth, it appears Scott has been enjoying retirement, spending plenty of time with his family and working hard to share the word of his book, Endurance - I would know as much, since I was privileged to have dinner with him at a private CSLUB event earlier this month.
What do you say when sat in the presence of an American hero and NASA’s most “alien-blooded” astronaut? Furthermore, how could you not wonder what experiences in his life today could ever hold a candle to his year in space?
So that’s what I asked him: After traveling for unprecedented time in space and enduring the effort it took from you to reach that goal, could you talk about something in your life that continues to challenge you today?
Scott responded: “I’ve got two kids.
Both very different, both great. But you know, as a parent, you want the best for your kids. But you always want to support them, and do whatever you can to make them happy and successful. But other challenges? I don’t know, I’m figuring that out. And hopefully I’ll find that someday.”
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Citation: Rovira, Lia N. "What Can Be More Challenging Than a Year in Space? Scott Kelly Tells SkyFeed." SkyFeed. 27 March, 2019. Web article. Resnick, Brett. "Scott Kelly's Genes and NASA's Twin Study on Him, Explained." Vox. 21 March, 2018. Web article.