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Cosmic Rays Could Kill Astronauts Visiting Mars
jvchamary writes "Given the recent stream of reports of 10th planets and the relative success of the NASA Discovery mission, it might again be time to get excited at the prospect of visiting the Red Planet. Unfortunately, New Scientist reports that Astronauts traveling to Mars would be exposed to so much cosmic radiation that 10% would die of cancer."
So how would this be a limiting factor for a government that still subsidizes tobacco farmers? What if we only sent smokers? TFA article says that 10% would get fatal cancer sometime in their lives. Really, how is this different from those who self select themselves for a much increased risk of cancer through smoking?
If brevity is the soul of wit, then how does one explain Twitter?
2.2 Sieverts is 220 rems. that's like 8-10 times previous estimates. And you've got to wonder about quotes like this:
Others suggest more radical solutions might be needed. "Radiation exposure is certainly one of the major problems facing future interplanetary space travellers," says Murdoch Baxter, founding editor of the Journal of Environmental Radioactivity. "Unless we can develop instantaneous time and space transfer technologies like Dr Who's TARDIS."
Wasn't mini-magnetospheric plasma propulsion supposed to offer robust shielding, in addition to efficient travel?
---If you can't trust a nerd, who can you trust?
So even if they cannot solve the cosmic radiation problem entirely, there is a possibility that could get them safely to Mars and back. Of course first we'd need that Moon base I've been reading about in SF stories written as far back as forever...
Seriously, though, does anyone know just how much material is needed to block these rays? Specifically, if a space habitat were constructed (along the lines of an O'Neill cylinder, for instance), how many meters of rock would we require on the outer surface to make the place long-term habitable?
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~ |rip/\/\aster /\/\onkey
Basically, yeah - we have several miles of comparatively dense atmosphere (or the entire bulk of the earth) protecting us from cosmic rays. Future Mars astronauts will pretty much have a few layers of tinfoil.
Still, it is possible to design ships which will shield passengers from the worst of the rays, but these tend to be prohibitively heavy (= prohibitive amounts of fuel) because of all the additional shielding.
The best alternative I've seen yet were plans to build a ship where all the water and other supplies were stored around the outsides of the ship, and the actual crew living compartment was a small space right in the middle - this uses water and fuel (the bulkiest of the supplies) as additional shielding, but it still carries a much elevated risk of irradiation and/or cancer than staying put on earth.
Everything in moderation, including moderation itself
I know you're joking, but I think a number of slashdot readers are thinking, "yeah, why can't they just shield them".
I'm not sure I see the point of even going to Mars in the first place; like Kennedy's moon trip, going to Mars will get us nothing. Things are just too impractical to get anything useful done on either planet. The futurists all argue, "well, SOME day it'll be practical". Wasn't this the same group that predicted we'd have, ten years ago, flying cars, transporters, faster than light travel, etc?
Please help metamoderate.
Again, I'm reminded of stories of voyages of discovery from 200 years ago. The crew sailing with Captain James Cook actually fared better than most, according to Wikipedia:
At that point in the voyage, Cook had lost no men to scurvy, a remarkable and unheard-of achievement in 18th century sea-faring. He forced his men to eat such foods as citrus fruits and sauerkraut -- under punishment of flogging if they did not comply -- although no one yet understood why these foods prevented scurvy. Unfortunately, he sailed on for Batavia, the capital of the Dutch East Indies, to put in for repairs. Batavia was known for its outbreaks of malaria, and, before they returned home in 1771, many in Cook's crew would succumb to the disease, including the Tahitian Tupaia, Banks's secretary Herman Spöring, astronomer Charles Green, and the illustrator Sydney Parkinson.
Would it be that much worse to be afflicted with cancer in the 2000's than with malaria in the 1700s? At least we have morphine now.
The suggestion that brain ailments might afflict spacefaring explorers strikes a familiar chord as well:
Cook returned to Hawaii in 1779. On February 14 at Kealakekua Bay, some Hawaiians stole one of Cook's small boats. Normally, as thefts were quite common in Tahiti and the other islands, he would have taken hostages until the stolen articles were returned. However, his stomach ailment and increasingly irrational behaviour led to an altercation with a large crowd of Hawaiians gathered on the beach. In the ensuing skirmish, shots were fired at the Hawaiians and Cook was speared to death.
Another factor to keep in mind is the motivation of the sailors. For one thing, conditions at home didn't offer much better chance at longevity. But perhaps more importantly, Captain Cook believed in the medicinal value of large quantities of beer:
The custom of allowing British seamen the regular use of fermented liquor is an old one. Ale was a standard article of the sea ration as early as the fourteenth century. By the late eighteenth century, beer was considered to be at once a food (a staple beverage and essential part of the sea diet), a luxury (helping to ameliorate the hardship and irregularity of sea life) and a medicine (conducive to health at sea).
It sounds like we won't be exploring Mars until we have a population of would-be explorers that is 1) worse off here than in space, 2) led by a captain with a penchant for the lash, and 3) drunk off their arse.
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.
Sounds like good materials for shielding has had some research and progress (http://www.materialisations.com/materialisations/ Shielding/) but still has a long way to go.
This is a really alarmist article but its actually great people are finally get out of the multidecade fixation on LEO and thinking about these things again.
The first reason you want a moon base is to study, learn to deal with and minimize the radiation exposure.
"Short of hauling up lead plates, I don't know what they'll do."
Put the crew compartment inside a water tank, since you are going to need the water anyway.
Build shields out of lunar regolith since its gravity well is smaller, though you need to have fuel and a vehicle to get it from the moon to the vehicle. It would give the people at the moon base something useful to do.
When they get to Mars bury the habitat, and give them shielded rovers. At least gravity is 1/3 that of earth so they weight wont be as bad on the tires as it would on Earth.
Make the mission to Mars a one way trip, send permanent colonists, not tourists like Apollo. The round trip mission adds a lot of complexity in radiation, G tolerance if you return to Earth and 1G, and fuel for a return trip. For a permanent colony the challenge is finding and harvesting resources you need on planet like water, oxygen, hydrogen for rover fuel. Plus you need nuclear power plants which are heavy which is part of building reliable supply heavy lift supply train from Earth for everything you can't find on planet.
In Kim Stanley Robinson's seminal work on Mars colonization, Red/Green/Blue Mars he used a cheat, gene therapy to repair the radiation damage with the added bonus it cured cancer and provided virtual immortality if you could afford the treatment.
@de_machina
Hey, don't laugh - certain types of tumors can cause gynecomastia. A friend of mine knows someone that this is happening to (they haven't found the cause yet), and it's not a pleasant experience for him to say the least.
"It felt almost as good as stealing cars from grandma." -- Margaret Thatcher, probably.
10% extra, albeit annoying, is nothing when weighed against the excitement of being on a manned mission to Mars.
The easy solution would be to take some digging and tunneling equipment then use that to create an underground Mars station....thus using the billions of tons of existing rock & dirt to sheild you. You could also take melting aparatus and make an under-ice cave in the new lake.
One thing this and most other articles fail to mention is that radiation exposure on the Martian surface is about 75% of that in space. The thin Martian atmosphere offers little protection, and when particles get through and strike atoms in the soil they create a scatter of secondary radiation, some of which scatters upward.
One of NASA's Design Reference Missions to Mars involves a total mission duration of 900 days with a 500 day stay on the surface. This mission would expose the crew to more than their allowable lifetime radiation dosage. Another mission profile involves a 435-day duration. Both of these missions involve a year's round trip travel time, and virtually doom the crew to early cancer deaths after their return to Earth.
Gaseous Core Nuclear Rockets would make Mars missions truly feasible. For reasons discussed in detail here, here and here, among other places, GCNR rockets would get a mission to Mars and back in 270 days, with 7 months travel time and 60 days on the surface. Additionally, the GCNR rocket would have huge carrying capacity, enough for the craft to carry a foot-thick water shield in a double hull. Such a ship would reduce the crew's total radiation exposure to about 1/5 of the 435-day mission and 1/10th of the 900 day mission. The water layer would also act as a giant passive heat sink, eliminating the need for a complex refrigeration system. It would also be a self-sealing micrometeorite shield -- the outer few inches of water would freeze, and if a micrometeorite punctured the hull the escaping water would refreeze over the hole immediately.