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Film ‘The Martian” gets it really wrong about ionising radiation

text-relevantHere Are The Biggest Health Risks To Humans In Space, Gizmodo MADDIE STONE12 OCTOBER 2015 “…….Radiation  And now we get to my One Big Problem with the science of The Martian. OK, we get it: Mark Watney has an extraordinarily sunny disposition and bowels of steel. (Seriously, who can eat protein squares for two years straight and still, you know, fertilize the potatoes?) But nothing can save Watney from the inconvenient truth that Mars has no ozone layer. That means the surface is awash in ultraviolet radiation — the same stuff we use to sterilize hospital clean rooms. And UV loves to rip, shatter, and mutate DNA. As far as we can tell, all life forms are susceptible to its burn.

text ionisingGiving Mark Watney cancer on Mars probably wouldn’t have made too much sense from a narrative perspective. But radiation is something we worry about on the ISS and it’s certainly something we’ll have to consider if and when we send humans to Mars.

There are a few types of harmful radiation zipping about in outer space. There’s UV, which is several hundred times stronger in orbit than it is beneath Earth’s atmosphere. During Kelly’s year in space, he’s soaking up roughly the same amount of extra radiation (0.16 sieverts) that a regular cigarette smoker does over the course of a year. (For comparison, 1 sievert of radiation is associated with a 5.5 per cent increase in the risk of fatal cancer, and the background daily radiation dose on Earth is on the order of 10 micro-sieverts, or 0.00001 sieverts.)

That’s not great, but it’s also not that bad. The radiation danger gets a lot worse when you leave the protection of Earth’s magnetosphere.

During the trip from Earth to Mars, astronauts will be exposed to other flavours of radiation: namely, high energy subatomic particles from the sun, the Milky Way galaxy and beyond. It’s these solar energetic particles and galactic cosmic rays that we’re most worried about, because they ravage biological tissue very quickly. As an instrument aboard the Curiosity Rover recently revealed, even the shortest round-trip from Earth to Mars could dose our astronauts with 0.66 sieverts of radiation — the equivalent of a whole-body CT scan every five or six days.

Certain materials, including aluminium and polyethylene plastics, can block or slow down radiation, but Shelhamer warns that shielding ourselves could backfire. Slowing down a high-energy cosmic ray could afford it more opportunity to collide with other particles and create dangerous secondary particles. “A particle of galactic radiation might be better off going fast…. if it’s moving slowly, it has the opportunity to create more damage,” he said. “It’s a very tricky situation, and we don’t have a good handle on the extent of the risk and what can we do about it.”

If one thing is clear, it’s that our ability to safely put humans on Mars — no less keep them alive on the radiation-riddled surface — depends very much on whether we can solve this problem.

The Biggest Danger to Humans in Space……“As the Chief Scientist whose job is to oversee this whole thing, the thing that concerns me most is the one danger that we haven’t yet thought of,” Shelhamer said. “What’s the biggest risk? It’s the radiation that causes a mutation in a pathogen when your immune system is compromised, and the medication on board doesn’t work because your metabolism has shifted. It’s the interaction of factors nobody considered.”…..

References

Effects of Prolonged Spaceflight on Human Skeletal Muscle. NASA, 2015.

Gifford, S. Calculated Risk: How Radiation Rules Manned Mars Exploration. Astrobiology Magazine, 2014. http://www.gizmodo.com.au/2015/10/here-are-the-biggest-health-risks-to-humans-in-space/

October 14, 2015 - Posted by | 2 WORLD, radiation

1 Comment »

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