Mars Explorers Face Huge Radiation Problem 283
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."
And once you get there... (Score:4, Informative)
http://mars-one.com/en/faq-en/19-faq-health/185-will-the-astronauts-suffer-from-radiation [mars-one.com]
However, I would still go. I mean, if we can actually get people to Mars, we shoudl have no problem getting around the radiation problem.
Re:wait... (Score:4, Informative)
risk low compared to mission as a whole (Score:5, Informative)
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.
Re:Hitch a ride: (Score:4, Informative)
Given that attaining suitable velocity to get there in a reasonable timeframe with manageable fuel loads is probably one of the big issues of Mars travel, how does hitching a ride become advantageous? The differential velocity between you and the space rock would be way too high to dock, and even if you could 'grapple' it, you would likely slow it down too much.
To match its speed to board it would require just as much energy as accelerating yourself to the required travelling velocity in the first place.
Maybe a grapple with a winch could be a solution so that you can grab it while the velocity difference is high and apply a braking force to the winch mechanism until your speed matches. Then you could slowly wind yourself in. Would have to be a very long winch though. We'd probably have space elevator tech as a prerequisite to this.
Re:Okay (Score:5, Informative)
Best source I can find is this [space.com] 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.
Re:wait... (Score:4, Informative)
Re:Lead Lining? (Score:5, Informative)
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.
Re:use water (Score:4, Informative)
Certainly.
Now, calculate that your average human requires approximately 2 liters of water daily for proper renal function (though they often do drink less, and it is unhealthy.) Also factor in the scarcity of the material on mars, and the feasibility of sustainable agricultural activities without that large quantity of water.
Now, let's also think about the secondary particles generated when heavy and complex lead neuclei are exposed to iron neculei traveling at near C, and the subsequently exponential impact that this secondary radiation will have as the shielding becomes more and more radiological from constant exposure.
In other words, yes, water has serious issues. You still have to bring it with you if you are really serious about a martian colony. There is no discussion there. You HAVE to take it. It isn't optional. Since you already have to tae it with you, using the absurd cost to orbit it as a canard is moot. Adding the water AND the lead will always cost more than launching just the water.
The water does not have the same problem with producing dangerous secondary radiation, and does not become radioactive itself at near the same rate as will the lead rad shield. The water is already required, and is not optional.
Why not just use the water, then?
You can resolve the "water expands, dumbass!" Problem by freezing it already prior to launch. This also makes it much safer to transport in the event of a micrometeorite puncturing the containment vessel, and believe it or not, ice can be quite insulating, and can serve other functions for regulating the capsule's environment.