By AMERICAN HEART ASSOCIATION NEWS
Amid major efforts by the United States, other countries and private companies to send people to Mars, a recent study suggests deep space travel may dramatically increase the risk of later dying from cardiovascular problems. To protect the health of astronauts, NASA this month launched a new research institute.
NASA has a variety of programs that examine how radiation exposure could affect astronauts’ biological systems and how to protect against damage. The latest got its official start Oct. 1 after the agency awarded The Center for Space Medicine at Baylor College of Medicine in Houston up to $246 million to initiate a new institute to find innovative approaches to keeping astronauts healthy during long space flights. Called the NASA Translational Research Institute, it is slated to last for a minimum of six years but as long as a dozen.
“The Translational Research Institute will look for game-changing technologies in areas of science that will jump-start ways to solve the risks of going into space,” said Graham Scott, Ph.D., associate professor at the Center for Space Medicine at Baylor and chief scientist at the NASA-funded National Space Biomedical Research Institute.
He said the new institute’s specific activities are still being determined but that “theoretically, we are looking for countermeasures to problems.” For example, he said that research could look at ways to deflect radiation so it doesn’t become a problem. Scott said it could take astronauts between six and nine months to reach Mars.
“You don’t want them to have a heart attack or stroke when they are in space,” he said.
A study published this summer posed that exposure to deep space radiation beyond Earth’s protective magnetosphere could have an adverse effect on blood vessels. The Apollo astronauts on lunar missions died from cardiovascular problems at four to five times the rate of astronauts who only flew in low-Earth orbit or never flew at all, the study found.
“The findings were surprising. I don’t think that anyone expected the Apollo astronauts’ results would be so different from the others,” said Michael D. Delp, Ph.D., dean of the College of Human Sciences at Florida State University and lead author of the study published in Scientific Reports.
Twenty-four astronauts flew into deep space as part of NASA’s Apollo program which ran from 1961 to 1972. For the study, Delp and his team examined the death certificates of seven of the eight dead Apollo astronauts. One died after the analysis was completed. Their causes of death were compared with those of 35 astronauts who only flew within the Earth’s orbit and 35 who never flew at all.
Three, or 43 percent, of the Apollo astronauts died from cardiovascular problems, including Neil Armstrong, the first person to walk on the moon. In contrast, only 11 percent of the astronauts who flew low-orbit Earth missions and 9 percent of the non-flight astronauts died from heart problems.
Some key experts dismissed the findings because of the study’s very small sample size and design. For example, it didn’t consider whether the Apollo astronauts had health conditions like high blood pressure that could lead to a cardiovascular incident. NASA funded the study and in a statement said, “With the current limited astronaut data referenced in the study, it is not possible to determine whether cosmic ray radiation affected the Apollo astronauts.”
Others were more blunt: “The conclusions are unfounded and the data are of little use for understanding this problem,” said Benjamin Levine, M.D., a professor of cardiology at UT Southwestern Medical Center, Cardiovascular Team Lead for the National Space Biomedical Research Institute and advisor to NASA’s flight surgeons on cardiovascular issues.
The issue of space radiation accelerating atherosclerosis, or hardening of the arteries, is important and may be one of the most important risks to middle-aged astronauts during long-duration space missions, said Levine, Harry S. Moss Heart Chair of Cardiovascular Research at Texas Health Presbyterian Dallas. But he worries the study will send a message that deep space travel is too dangerous just as NASA and others are gearing up to send people to Mars. NASA is preparing to send a manned mission to Mars during the 2030s.
“The effect of space radiation on vascular health should be studied carefully and comprehensively in the context of exploration class missions into deep space which will last years,” said Levine, who chairs the American Heart Association’s Council on Clinical Cardiology committee on exercise, cardiac rehabilitation and secondary prevention.
“Sending people to Mars safely is an important issue that cannot be answered by studies involving mining of uncontrolled data on small numbers of retired astronauts,” he said.
Delp acknowledges the study’s limitations and said he hopes to work with NASA to access the astronauts’ health information to conduct more scientifically rigorous research. However, he said the results shouldn’t be ignored.
The study also looked at the effects of weightlessness and intense radiation on mice for a period equivalent to 20 human years. It found that the radiation, and not the weightlessness, damaged the animals’ arteries.
“This is a bit of caution,” said Delp. “We need to explore what is happening.”