by Sixstrings » Fri 07 Nov 2014, 01:13:58
$this->bbcode_second_pass_quote('MonteQuest', 'D')ue to radiation, any child conceived and born in space is likely to be born sterile.
Okay, fine.
Colony orbiting Jupiter, within its massive magnetosphere, no problems with radiation.
Or, again, undersea colony on Europa and protected by the ice cap.
As for Mars -- all you need is martian soil covering the habitat and that's as good as the Earth's magnetosphere. For the travel there, in open space, you'd need a crew section with water shielding for the crew to go into, in the event of a coronal mass ejection headed their way.
It's not just heavy lead that protects from radiation. Soil does too. And water. And food. And ice. You could have water and waste water tanks surrounding crewed areas, and the foodstuffs, for example.
$this->bbcode_second_pass_quote('', 'R')adiation Fears Shouldn't Hold Back Mars Colonization
Mars One aims to establish a permanent human settlement on Mars in 2023, requiring no return mission.
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For the study, Cary Zeitlin of the Southwest Research Institute and his colleagues calculated radiation exposure for a 360-day return trip to Mars to be 662 plus or minus 108 millisieverts(mSv), equivalent to the radiation of about 10,000 chest X-rays. The researchers determined that value using measurements from NASA's Mars Science LaboratoryRadiation Assessment Detector (RAD), onboardthe spacecraft while the Curiosity rover traveled to Mars in 2012. [Photos: Mars One Wants You as a Martian Colonist]
This finding from RAD indicates that for a human traveling to and living on the Red Planet, the risk of a fatal cancer resulting from radiation exposure lies within the currently accepted risk for low-Earth-orbit astronauts.
Radiation exposure during space travel
In transit to Mars, the Mars One crew will be protected from the other source of radiation — solar particles — by the structure of the spacecraft, which will provide 10 to 15 grams per square centimeter (2.3 to 3.4 ounces per square inch) of shielding, equivalent to 4 to 6 inches (10 to 15 cm) of water.
That level of protection will not suffice in the case of coronal mass ejections, solar flares and other sources of solar particle events.
Taking their cue from an onboard solar-flare forecasting and radiation measurement system the crew will retreat to a dedicated radiation shelter located in a hollow water tank, where shielding will increase to a total of 40 grams per square cm (9 ounces per square inch).
Assuming the exposure levels the RAD experienced, Mars One's crew will be exposed to 386 plus or minus 63 mSv of radiation on its 210-day journey to Mars in 2022, which is equivalent to 58 percent of the total exposure of a 360-day return trip, as calculated by the recent Science study. [Could Radiation Harm Astronauts Traveling to Mars? (Video)]
Radiation exposure on Mars
On Mars, radiation exposure is considerably less than the exposure in space. Thanks to the shielding provided by the planet itself and its atmosphere, Mars' surface receives 30 microsieverts (0.03 millisieverts) of radiation per hour during solar minimum, according a NASA technical paper entitled "Space Radiation Cancer Risk Projections for Exploration Missions: Uncertainty Reduction and Mitigation."
The research, conducted by Francis Cucinotta, chief scientist at the NASA Space Radiation Program and his colleagues, found that the exposure is reduced by about 50 percent during solar maximum because solar particles actually decrease galactic rays.
The Mars One habitat will be covered by a necessary layer of soil that provides shielding even against galactic cosmic rays. Sixteen feet (5 meters) of Martian soil provides the same protection as the Earth's atmosphere — equivalent to 1,000 grams per square cm(227.6 ounces per square inch) of shielding. The Mars One habitat can support a soil layer 36 feet (11 m) thick. If the settlers spend, on average, two hours per day outside the habitat, their individual exposure adds up to 22 mSv per year.
NASA radiation exposure graphPin It Graph showing NASA ten-year career effective dose limits based on three percent excess lifetime risk of fatal cancer.
Credit: Adapted from NCRP Report NO. 132 (2000)View full size image
Radiation exposure limits
The world's space agencies have put in place radiation exposure limits for astronauts over their careers. The agencies restrict the astronauts to serve low-Earth-orbit missions and do not consider the longer durations and different conditions of interplanetary missions.
NASA low-Earth-orbit radiation exposure limits were designed to keep the risk of radiation-induced fatal cancer below 3 percent, according to the National Council on Radiation Protection and Measurements report 132. The limits depend on the sex and age of the astronaut.
According to that report, young females are most susceptible to radiation-induced fatal cancer and therefore have the lowest allowed exposure. For International Space Station (ISS) operations, NASA uses the 3 percent risk with a confidence level applied to it, resulting in doses about three times lower than the acceptable limits, according to National Council on Radiation Protection and Measurements report 142.
Considering a scenario where an inhabitant receives the upper limit of radiation of 449 mSv during the 210 day transit to Mars, for a female inhabitant younger than 35, the exposure amounts to about 3 percent risk for her lifetime (not including NASA ISS confidence levels). Risks are lower for women departing at a higher age, and especially for male colonists. On Mars, the risk can be managed by monitoring each crew member's radiation exposure and limiting the surface exploration time of those who are most at risk.
http://www.space.com/21813-mars-one-colony-space-radiation.html