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Trip To Mars Could Damage Astronauts' Brains
Hugh Pickens writes writes "Alex Knapp reports that research by a team at the Rochester Medical Center suggests that exposure to the radiation of outer space could accelerate the onset of Alzheimer's disease in astronauts. 'Galactic cosmic radiation poses a significant threat to future astronauts... Exposure to ... equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer's disease' says M. Kerry O'Banio. Researchers exposed mice with known timeframes for developing Alzheimer's to the type of low-level radiation that astronauts would be exposed to over time on a long space journey. The mice were then put through tests that measured their memory and cognitive ability and the mice exposed to radiation showed significant cognitive impairment. It's not going to be an easy problem to solve, either. The radiation the researchers used in their testing is composed of highly charged iron particles, which are relatively common in space. 'Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them,' says O'Banion. 'One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete.'"
From the paper, you noticed that they irradiated the mice very quickly.
"using a foam tube holder positioned at the center of a 20×20 cm beam of iron ions accelerated to 1 GeV/ at a dose rate ranging from 0.1–1 Gy/min. Male mice received total doses of either 10 cGy or 100 cGy. Female mice received only a 100 cGy dose."
1Gy/min is a lot dose in a very short period. So for the female they gave all the dose in a timeframe measured in mins. At lower dose rates, cells repair the DNA damage better. I think that lower dose rates would be more likely to occur in a mars trip.
For those without much radiation background, 100cGy delivered in 1 min isn't the same as 100cGy delivered over 6 months.