As humans prepare for longer missions to the moon and Mars, scientists are trying to understand how space affects the human body. One of the biggest concerns is space radiation - high-energy particles from the sun and distant galaxies that can pass through spacecraft and into bodies.
Unlike Earth, which is protected by a magnetic field and atmosphere, space is not. This means astronauts are exposed to radiation that could harm their health during and long after their missions end.
Dawn Bowles, a researcher at Duke University, is collaborating with NASA to study how space radiation affects the heart.
Originally trained as a virologist, Bowles was among nine principal investigators recruited by NASA into its Space Radiation Element program to mitigate the harmful effects of space radiation on astronauts' health.
"Astronauts who are going to be traveling to Mars or who are going to be living on the moon are going to be continually hit, bombarded with this kind of radiation. It is a serious risk for human health."
Dawn Bowles
Her team conducts its research at a unique facility at Brookhaven National Laboratory in New York, home to the NASA Space Radiation Laboratory .
"It's a really neat, nifty, unique thing that NASA has developed," she said. "They actually can simulate as closely as possible what the radiation environment looks like in space here on Earth."
Trying to understand the cardiovascular risk of space radiation exposure from astronaut data has been challenging due to the lack of data. Only 24 Apollo lunar astronauts have traveled beyond low Earth orbit (LEO) into the complex space radiation environment. Of those individuals who have traveled further, the amount of time spent there has been less than 50 days.
Bowles explained: "Astronauts who are going to be traveling to Mars or who are going to be living on the moon are going to be continually hit, bombarded with this kind of radiation. It is a serious risk for human health."
Although astronauts have spent extended periods of time in space aboard the International Space Station, they remain within the protective environment of a magnetic field, known as the magnetosphere, and are not exposed to significant amounts of radiation.
As a result, other studies that have examined the cardiovascular effects of space radiation on astronauts have been unable to generate firm conclusions.
Studies in animals have shown that radiation can lead to stiffening of the arteries, damage to the heart's structure, and changes in how the heart beats.
"We've identified that there might definitely be a problem, at least in animal models," said Bowles. "We're doing additional studies to understand the mechanisms behind this problem and whether we can remedy it."
Clues from the Lab and from Space
Bowles and her team use advanced tools to study how radiation affects tissues at the molecular level. "We do a lot of very advanced molecular omics - genomics, transcriptomics, proteomics," she said, referring to the study of DNA, RNA and proteins. "We try to look at the tissues or cells very holistically."
In addition to exploring ways to protect astronauts from radiation damage, Bowles' team is investigating whether existing medications could help. "We have a paper under review where we analyzed our data to see if there were any drugs that could be repurposed," she said. "NASA's just looking at ways to do this as economically as possible. If something already exists, why not use it?"
While her team hasn't yet studied dietary changes, she believes their data could be used to explore that too.
"NASA really invests in these deep characterizations because these data sets go into their repository," she said. "There's a whole group of scientists at NASA doing data mining to gain new insights." That information, Bowles noted, can be made available for other scientists to evaluate.
Though the research is focused on space, it could also benefit people on Earth. "There's personnel in the medical field, like interventional cardiologists, who are exposed to low levels of radiation over time, who might develop similar cardiovascular effects," Bowles noted. "Maybe we can find something protective for the heart for a patient undergoing cancer treatment. There is potential for saving human lives."
Does Radiation Affect People Differently?
There's still much to learn, especially about how radiation affects different sexes and species. "Most early studies were done with male mice," Bowles said. "Now we're doing studies with both sexes to see if there are differences."
She added that they are also adding another component to the study - microgravity or weightlessness to better mimic the full space environment.
Bowles' research, until now, has been funded by NASA. Despite funding uncertainties, Bowles remains optimistic.
"I'm very blessed to be able to work in an exciting field like this," she said. "We're uncovering biological mechanisms and responses that no one's really looked at before. It's all new ground and it's very exciting."
