Mission to Mars: The Radiation Problem

NASA wouldn’t opt to expose astronauts to a 19 percent increased risk of cancer, but there’s no telling what a reality TV show would do

No one is going to Mars until scientists figure out how to shield travelers from deadly radiation. (NASA/NSSDC)

Would you go on a mission to Mars? The Dutch startup company Mars One is planning to establish the first Mars colony in 2023, starting with four individuals and adding more people every two years, funded by turning the whole endeavor into a reality TV show.

It’s just the latest plan to colonize the Red Planet, but I’m doubtful it will happen. There’s the expense, for sure, and the trials of trying to convince anyone to go on a one-way journey with just a few other strangers (what if you don’t get along? It’s not like you can leave). And then there’s the radiation problem.

Out in space, there are gamma rays from black holes, high-energy protons from the Sun, and cosmic rays from exploding stars. Earth’s atmosphere largely protects us from these types of radiation, but that wouldn’t help anyone traveling to Mars. They would be exposed to dangers that include neurological problems, loss of fertility and an increased risk of cancer.

NASA scientists calculated in 2001 that a 1,000-day Mars mission would increase the risk of cancer somewhere between 1 and 19 percent. If the risk is on the lower end, then the outlook for Mars might be pretty good, but if it’s higher, then NASA, at least, wouldn’t send people (there’s no telling what a reality TV show might do). A 2005 study found even more to worry about—the radiation would be high enough to cause cancer in 10 percent of men and 17 percent of women aged 25 to 34 if they were to go to Mars and back.

The easy solution would seem to be to shield the vessel that carries the humans to Mars, but no one has figured out how to do that. When the thin aluminum currently used to build spacecraft is hit with cosmic rays, it generates secondary radiation that is even more deadly. Plastic might work—the shields on the International Space Station are made of plastic—but it’s not 100-percent effective. One scientist has suggested using asteroids to shield a vessel traveling between Earth and Mars. But somehow I don’t think Mars One is going to make that one work within a decade.

Or they could just send old people—a solution proposed a couple of years ago by Dirk Schulze-Makuch of Washington State University and Paul Davies of Arizona State University. “This is not a suicide mission. The astronauts would go to Mars with the intention of staying for the rest of their lives, as trailblazers of a permanent human Mars colony,” Schulze-Makuch and Davies wrote in the Journal of Cosmology. Loss of fertility wouldn’t be an issue for older astronauts and the radiation wouldn’t increase their lifetime cancer risk too much (since they’re already near the end of their lives).

That may be a solution more suited to NASA than Mars One, however, since television casting departments would probably want someone more like Snooki than Snooki’s grandma.

Editor’s note: In other Mars news, NASA is preparing for the August 5 landing of its massive unmanned science laboratory, Curiosity. The seven minutes between when the rover hits the top of the atmosphere and when it touches ground are the riskiest moments of the whole mission. The video below shows a few of the hundreds of things that need to go just right:

Team members share the challenges of Curiosity's final minutes to landing on the surface of Mars
About Sarah Zielinski
Sarah Zielinski

Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.

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