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Explorers Will Face Dangerous Amounts of Radiation On Their Trip to Mars

New data from the Mars Trace Gas Orbiter shows just the flight there and back alone will expose astronauts to 60 percent the lifetime radiation dose

(NASA)
smithsonian.com

Traveling to Mars is the next great step in humanity’s space journey. In Hollywood, the recent movie The Martian and television series The First present reaching the Red Planet as more of a near-term logistics challenge rather than a pie-in-the-sky space dream. NASA is currently orienting itself toward a “Moon to Mars” Mission, but the technical hurdles facing a Mars mission are still massive. One of the most difficult challenges is dealing with the dose of radiation any interplanetary astronauts would face. Meghan Bartels at Space.com reports that new data from the European Space Agency (ESA) has refined our model for radiation during the journey to and from Mars, and it doesn’t look good.

The ESA’s Exomars Trace Gas Orbiter was launched in 2016 and made it into orbit around Mars after a six-month journey through interplanetary space. During its trip an instrument called the Liulin-MO dosimeter kept track of the radiation the craft experienced and has kept tabs on radiation since the TGO reached orbit. Using that data, researchers determined that any interplanetary astronaut staking the same trip would experience 60 percent of their maximum career-long radiation dose just during that trip to and from Mars, not including any time spent on the surface of the planet working and exploring.

“Radiation doses accumulated by astronauts in interplanetary space would be several hundred times larger than the doses accumulated by humans over the same time period on Earth, and several times larger than the doses of astronauts and cosmonauts working on the International Space Station,” Jordanka Semkova of the Bulgarian Academy of Sciences and lead scientist of the Liulin-MO instrument says in a press release. “Our results show that the journey itself would provide very significant exposure for the astronauts to radiation.”

The data backs up similar radiation levels detected when the Mars Science Laboratory took the same trip back in 2011 and 2012.

Sheyna E. Gifford at Astrobiology Magazine reports that we don’t think too much about radiation here on the surface of the Earth because the powerful magnetic field surrounding our planet deflects most radiation. But up in open space things are different. Astronauts are bombarded by solar energetic particles and galactic cosmic rays. A trip to Mars would be like going through a CAT scan two dozen times, which is almost 15 times higher than the radiation exposure allowed for workers at a nuclear power plant.

To protect future Mars-o-nauts, engineers need to design a shield for the galactic cosmic rays (GCRs), but that’s easier said than done. The particles are powerful.

“They rip through you like you’re cellophane,” biomedical and health informaticist Dan Masys of the University of Washington tells Sarah Scoles at Nova. So far there’s no practical method to shield ships or astronauts from the particles.

Radiation not only increases the risk of cancer, reports Scoles, but NASA has also identified dozens of other potential health problems linked to exposure, including disrupted sleep, cardiovascular and degenerative diseases, infertility, cataracts, and disrupted hand-eye-coordination. Radiation, Masys says, is a “dealbreaker” for any long-term plans for human space exploration.

Once explorers reach the surface of Mars, the radiation doesn't stop. Gifford reports that data from the Curiosity Rover shows that exposure to GCRs is about half that of being in space, but protection from solar energetic particles is spotty and unpredictable, meaning humans on the surface will continue to get a constant blast of radiation. The ExoMars 2020 mission, which will include a new Mars rover, will include a similar dosimeter that will give us even more precise data on the radiation we can expect on the surface of the Red Planet.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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