MARCH 4, 2016--On March 2, astronaut Scott Kelly returned from a year living on the International Space Station. Meanwhile, his twin brother Mark, a retired astronaut, has been going about his daily life here on Earth. The brothers met at NASA’s Johnson Space Center in Houston to participate in a twin study that will evaluate how the human body changes during a year in space. Mark Kelly will serve as a control in the study.
GUMC Update sat down with Albert J. Fornace, Jr., MD, who holds the molecular cancer research chair at Georgetown Lombardi, to discuss his work on cosmic radiation and potential health concerns for Scott Kelly.
A .22 caliber bullet versus a cannon ball
Fornace’s lab received a grant from the NASA Human Research Program to study the effect of cosmic radiation on gastrointestinal cancers, with the ultimate goal of gauging risks for astronauts and making recommendations to NASA about how to lower those risks.
To understand Scott Kelly’s risk of developing GI cancer as a result of his year in space, it is important to understand the difference between traveling to the International Space Station and venturing into “deep space,” Fornace explained.
The Earth’s magnetic core protects earth dwellers and to some extent astronauts from cosmic radiation, as long as astronauts stay within Earth’s magnetosphere. The International Space Station is within Earth’s magnetosphere – but a mission to Mars, for example, would expose astronauts to more harmful levels of cosmic radiation.
“If you think of the kind of x-rays or gamma rays you might be exposed to on Earth, an analogy would be to that of a .22 caliber bullet,” said Fornace. “A lot of these particles in deep space, like iron particles and silicon particles, they’re like cannonballs. So if the cell gets hit with a .22 caliber bullet, it’s not good, but if it gets hit with a cannonball, it's very different.”
Fornace studies the effect of those cannonballs, or at least the effect on mice. His team exposed mice to simulated cosmic radiation by using the cyclotron, a type of particle accelerator, at NASA’s Space Radiation Lab at Brookhaven National Laboratory on New York’s Long Island. After being exposed to the particles, the mice developed more cancerous tumors compared with gamma rays.
Fornace said that Kelly has gotten “substantially more radiation in space than he would have on Earth,” but less than he would have in deep space for the same length of time. While Kelly’s risk of cancer due to his time in space is probably relatively low, a better understanding of the effects of space radiation should help delineate the risk with more certainty and perhaps identify targets for cancer prevention.
Cosmic radiation is hardly the only thing astronauts have to worry about in space. One of the most well-known and consequential effects of space travel is weightlessness.
“When you’re on a roller coaster dropping down a steep track and your feet feel funny and your heart feels like it’s in your throat – that’s the way astronauts feel all the time,” said Fornace. “You’re falling, but instead of hitting something, you’re falling indefinitely.”
Besides being uncomfortable, weightlessness presents health concerns for astronauts, including weakened bones and muscles, and changes in eye pressure. Getting accustomed to gravity again after a whole year in a zero gravity environment will likely be Kelly’s major short-term health challenge, according to Fornace. Longer-term health effects remain to be seen.
So can we go to Mars?
John Holdren, director of the White House Office of Science and Technology Policy, told the Los Angeles Times this week that the twins study “is absolutely essential if we’re ever going to send people to Mars.” But is it enough?
In terms of the risk of radiation, Fornace pointed out that the International Space Station is a far cry from going on a mission into deep space. And of course, the study would be stronger if there were ten sets of twins instead of just one.
Still, the twins study is revolutionary in that humans, not mice, are the subjects. Fornace believes it has the potential to point researchers in the right direction.
“The twins study can certainly serve as an indicator of areas that could be a concern,” he said. “It could raise some red flags.”
Leigh Ann Renzulli
Video: Learn more about cosmic radition. Did you know that traveling in high-altitude planes exposes us to cosmic radiation?