Lunar orbiter shows plastic can protect space travellers from radiation

Plastics may be the protection of choice against cosmic radiation on flights to Mars.
Radiation has been on the minds of would-be space pioneers lately, accounting for yet another obstacle that needs to be overcome on the road to Mars and beyond. However, after the bad news that the trip to Mars would exceed safe radiation levels, there is now a bit of good news.

Scientists from the University of New Hampshire and the Southwest Research Institute released a report this week with findings from NASA's Lunar Reconnaissance Orbiter (LRO) that suggest another substance might be better than the usual aluminum for shielding against radiation — good old plastic.

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Aluminum always been the go-to choice for building objects designed for space. It's fairly light (at least compared to other metals), which means it costs less in fuel to launch. It's also pretty cheap, easy to shape, and it doesn't react with oxygen because it's coated in a handy oxide layer. Unfortunately, it's also pretty crummy at protecting against high-energy cosmic rays unless you layer it up, and when you do that, you cancel out the benefits of using a lightweight material and your ship becomes too expensive to launch.

Artist's conception of NASA's LRO above the Moon. CRaTER is visible at the bottom left corner of the spacecraf …The paper released this week reports observations from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER, to its friends), which is on-board the LRO.

Cary Zeitlin, the lead author of the paper, said in a release that "this is the first study using observations from space to confirm what has been thought for some time — that plastics and other lightweight materials are pound-for-pound more effective for shielding against cosmic radiation than aluminum."

This wasn't a complete surprise. Ground-based tests using particle accelerators and computer models suggested as much, but this is the first time the experiments had been tested in space, and according to the press release, Zeitlin said they've "gained a lot of confidence in the conclusions [they] drew from that work", adding that "anything with high hydrogen content, including water, would work well."

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This 'traditional' kind of radiation shield isn't the only game in town when it comes to ideas for how we might protect future astronauts as they head off on deep space missions. Other candidates are so-called "active shields" which rely on magnetic or electric fields to deflect particles, like on the Enterprise, and expanding on what Zeitlin said about 'anything with lots of hydrogen', some people have suggested using water, food, and even the astronaut's own waste to line the walls.

Let's hope that last one comes with an air freshener.

(Images courtesy: Mars Inspiration, NASA)


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