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Robert Zubrin, founder of the Mars Society and author of "The Case for Mars" and "Mars Direct", has a Ph.D. in Nuclear Engineering. In his review of a different

Robert Zubrin, founder of the Mars Society and author of "The Case for Mars" and "Mars Direct", has a Ph.D. in Nuclear Engineering. In his review of a different article on the same topic, he writes [1]: "On a Mars mission, astronauts would receive a dose of 1 rad per month during the 6 month outbound and return transfers, and about 0.5 rad per month during 18 months on Mars, for a total of 21 Rads. (1 Gray = 100 rads)". In the paper, the animals were irradiated "at dose rates between 0.05 and 0.25 Gy/min". Zubrin writes that the huge difference in dose rates (0.01 Gy per 60 * 24 * 30 = 43200 minutes vs. 0.05 Gy per minute) makes such studies completely useless because at the lower dose rate the body can self repair and at the higher dose rate it can't. Quoting him again: "For example, if an individual were to drink one shot of vodka per second for 100 seconds, he would die. But if the same person drank one shot of vodka a month for 100 months, he would experience no ill effects at all. This is about the same ratio of dose rates as... ". 1 - http://www.marssociety.org/r-zubrin-radiation-hucksters-strike-again/ http://www.marssociety.org/r-zubrin-radiation-hucksters-stri...

Analemma_ 9y ago
> Zubrin writes that the huge difference in dose rates (0.01 Gy per 60 * 24 * 30 = 43200 minutes vs. 0.05 Gy per minute) makes such studies completely useless because at the lower dose rate the body can self repair and at the higher dose rate it can't. I think it's worth pointing out his views, but I also think people should know Zubrin is going against the grain here. Most researchers, as well as nuclear regulatory agencies, use the Linear No-Threshold model for connecting radiation exposure and risk. This is exactly what it sounds like: the model assumes that risk accumulates as a linear function of dose. Whether the LNT is true at small doses is a matter of considerable debate (it's hard to study in humans because the purported effect size is small and it's hard to do such a study ethically), but Zubrin should not talk as though the matter is settled.
- njarboe 9y ago
  Like most things where one cannot do repeated, controlled experiments, no one really knows where the truth lies apart from some vague notions. What is used as the "truth" will be a political decision. I think in the case of going to Mars, building a ship that can get there, land, and come back is the hard part. Finding out how bad or not the radiation will be on people will be found out by the people who end up going. Inform them the best we can, so they can make their own decision, monitor their radiation doses, so we can learn more about long-length, high-level radiation exposure in humans, and let people decide if they want to risk it. As long as the radiation dose is not so high to make them sick in the first few years and ruin the mission, let people take the risk if they want to. I don't see why going to another planet should have to be less risky than taking a wagon on the Oregon Trail, to allow people to try it. A safety first philosophy will not get humans living off of Earth.

Analemma_ 9y ago

> Zubrin writes that the huge difference in dose rates (0.01 Gy per 60 * 24 * 30 = 43200 minutes vs. 0.05 Gy per minute) makes such studies completely useless because at the lower dose rate the body can self repair and at the higher dose rate it can't. I think it's worth pointing out his views, but I also think people should know Zubrin is going against the grain here. Most researchers, as well as nuclear regulatory agencies, use the Linear No-Threshold model for connecting radiation exposure and risk. This is exactly what it sounds like: the model assumes that risk accumulates as a linear function of dose. Whether the LNT is true at small doses is a matter of considerable debate (it's hard to study in humans because the purported effect size is small and it's hard to do such a study ethically), but Zubrin should not talk as though the matter is settled.

njarboe 9y ago
Like most things where one cannot do repeated, controlled experiments, no one really knows where the truth lies apart from some vague notions. What is used as the "truth" will be a political decision. I think in the case of going to Mars, building a ship that can get there, land, and come back is the hard part. Finding out how bad or not the radiation will be on people will be found out by the people who end up going. Inform them the best we can, so they can make their own decision, monitor their radiation doses, so we can learn more about long-length, high-level radiation exposure in humans, and let people decide if they want to risk it. As long as the radiation dose is not so high to make them sick in the first few years and ruin the mission, let people take the risk if they want to. I don't see why going to another planet should have to be less risky than taking a wagon on the Oregon Trail, to allow people to try it. A safety first philosophy will not get humans living off of Earth.