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Mars Explorers Face Huge Radiation Problem
astroengine writes "A radiation sensor inside NASA's Curiosity Mars rover shows that even under the best-case scenario and behind shielding currently being designed for NASA's new deep-space capsule, future travelers will face a huge amount of radiation. The results, based on Curiosity's 253-day, 348-million-mile cruise to Mars, indicate an astronaut most likely would exceed the current U.S. lifetime radiation exposure limit during one round trip mission. "Even for the shortest of missions we are perilously close to the radiation career and health limits that we've established for our astronauts," NASA's chief medical officer Richard Williams told a National Academy of Sciences' medical committee on Thursday."
From the article:
Current U.S. standards limit an astronaut’s lifetime radiation exposure to 1 Sievert, or 1,000 milliSieverts, which equates to about a five percent chance increase in developing a fatal cancer.
A new study shows that with currently available propulsion technologies and similar shielding to Curiosity’s, astronauts on even the shortest roundtrips to Mars would get radiation doses of about 662 millisieverts and that doesn’t include radiation dosages for any time spent on the Martian surface.
Sounds like a rather low risk compared to that of the mission as a whole.
Best source I can find is this article, which lists the surface radiation as around .7 millisieverts a day, or around the same as low Earth Orbit (Mars atmosphere is extremely thin, so it doesn't give as much protection as Earth's does from cosmic rays). This is vastly more than people are exposed to on Earth, and could definitely pose long-term health risks for a colony or other one-way mission.
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
The heaviest material? Really compatible with space travel fuelled by some of the world's most expensive fuel at great expense. Part of the problem of space is not that "we can't do that", it's that "it's so FECKING expensive to do it the way we would on Earth".
There's nothing stopping us shipping an entire biodome up to Mars, with enough food for a million people. It's just a question of weight (and, thus, cost). The point of the very first manned Mars mission is going to be to get there, not to prove we can start industry there. As such, things like huge amounts of lead are a luxury we can ill afford.
That, and most of the radiation that's damaging can actually be stopped by a bit of aluminium foil. The problem isn't that we *couldn't* shield from it, it's that we can't afford to. And pioneers often have to suffer for the title of being "first", I'm afraid (e.g. Madame Curie).
The bigger problem is the legality over what is basically a health and safety issue that, if we'd worried about it in the past, we'd never have let anyone go up Everest, fly to the Moon, etc. etc. etc.
These people are going to get irradiated. There's nothing practical that we can do to stop that. Many of the Apollo astronauts had eye problems related to radiation exposure in later life, it's just a simple fact of going outside the Van Allen belts (and, hell, flight attendants probably get more radiation in a year than ANYONE who works in a radiology department).
We just have to make sure they understand the risk. But I'm sure that Scott understood the risk of the Antarctic, that Hillary understood the risk of Everest, and so on. There will be people more than willing to do it. And in 100 years time, in any luck, space travel could be commonplace to the point where we finally do "solve" most of those problems through finally getting the money / incentive to actually prevent them. But at the moment, it's just a legal issue to make sure these people understand just how much simple things (like invisible radiation) can scupper their lives on a remote planet.