Identical twin astronauts volunteer for unique study

When astronaut Scott Kelly embarks on a one-year space station stint next spring, his twin brother will offer more than his usual moral support. Retired astronaut Mark Kelly will join in from Earth, undergoing medical testing before, during, and after his brother’s American-record-setting flight.

It’s part of an unprecedented study of identical twins, courtesy of the Kellys and NASA. Researchers hope to better understand the effects of prolonged weightlessness by comparing the space twin with the Earth-bound twin.

The 50-year-old Kelly brothers represent a scientific gift, said Craig Kundrot, deputy chief scientist for the human research program at NASA’s Johnson Space Center in Houston.

“Not only are they the same genetically, but one is an astronaut, one’s a retired astronaut,” Kundrot said. “So they’ve followed very similar career paths. After Scott’s mission is done, he’ll have 540 days of spaceflight (in four missions). Mark will have 54. So exactly a 10-fold difference. That’s just an uncanny opportunity that we’re taking advantage of.”

NASA has selected 10 proposals for the twin study, involving the immune system, gut bacteria, reaction time, fluid shift in space and its potential connection to visual impairment, DNA and RNA molecular science, and hardening of the arteries, among others. The researchers will receive a combined $1.5 million from NASA over three years.

Stanford University sleep specialist and immunologist Emmanuel Mignot said he felt lucky the Kellys were “willing to be the guinea pigs for this thing.”

“No one really knows what happens to the immune system in space for a long period of time and, sooner or later, people are going to need to confront this issue,” Mignot said.

That’s the whole point of Scott Kelly and Russian cosmonaut Mikhail Kornienko’s one-year mission: to identify physical challenges that need to be overcome before astronauts venture to Mars and beyond.

Scott Kelly, who is divorced, lives in Houston. For his 19- and 10-year-old daughters, the trip “still seems kind of far out there,” he said. His 74-year-old father “seems OK with it,” he added.

Mark Kelly, also a retired Navy captain with two daughters, is married to former congresswoman Gabrielle Giffords, who survived a 2011 assassination attempt—while her brother-in-law was on the space station. Mark commanded NASA’s next-to-last shuttle flight four months after the shooting, then left NASA. They live in Tucson, Arizona.

The twin study will unite the brothers in a new way.

“It’s a way for us to participate in a space flight together, which we never have done before,” Scott said. And “it keeps him involved in something that he feels very passionate about.”

Mark said he’d spend an entire year in space—“absolutely”—if the circumstances were different.

The next best thing is having his twin up there, while he’s down here, doing his part for NASA, he said.

The Associated Press contributed to this report.