Can We Protect Planetary Explorers From Cosmic Rays?

The superhero team in Fantastic Four gained their powers from exposure to cosmic rays while aboard an experimental spacecraft. Real-life astronauts are not so lucky.

In truth, galactic cosmic rays (GCR) don’t bestow otherworldly abilities. Their gift is an increased risk of cancer. While this isn’t a concern within Earth’s magnetosphere, which deflects radiation, astronauts on a mission to Mars could hit NASA’s cumulative, career-long radiation limit in as few as 150 days. It could take up to 260 days to reach the Red Planet, let alone return. According to Kerry Lee, operations lead of NASA’s Space Radiation Analysis Group, there’s no easy solution to this problem. Adding multiple layers of armorlike passive shielding might work, but it would make a spacecraft too massive to launch.

Lee’s favored approach is to surround the ship with a protective magnetic field. But the superconducting magnets would need to be kept colder than space itself, requiring a huge amount of power. And while nuclear reactors could supply that energy, they also emit radiation themselves. Ultimately, NASA might have to patch together various partial solutions. “Maybe the answer isn’t to shield the crew completely, but to use a small shield in addition to faster propulsion,” says Lee. Astronauts might sleep behind physical barriers, work within a limited magnetic field, and spend less time in transit in order to reduce their overall GCR exposure. Whatever design NASA lands on doesn’t have to be as elegant as its ­sci-fi equivalents. It just has to work.

This article was originally published in the July 2015 issue of Popular Science, as part of our Weird Science feature. Check out the rest of the feature here.