13 thoughts on “Radiation”

  1. Not only are there implications for spaceflight, but potentially big implications for Mars colonization. Mars offers limited protection from radiation, maybe it is enough to enable colonies or settlers to have a better chance of success. Also, doesn’t the in transit mars rover have a radiation meter recording doses in transit? If it is on the rover, will it continue to function on the surface? (-assuming a safe landing). If the radiation risks during transit are also lowered by this study, the spaceships carrying people can be made with less shielding, which will greatly reduce cost and transit time of getting to Mars safely.

  3. One problem on Mars is ambient neutrons, resulting from cosmic ray spallation of atmospheric constituents. It’s difficult to shield against neutrons, and they induce radioactivity. I don’t know the details, but it is somewhat alarming.

    1. Neutrons can be stopped by water or a thick sheet of styrofoam. In the nuke plants we depend upon water to moderate and shield neutrons.

  4. One problem with space radiation is that it is different in character from gamma photons- the energetic particle does strong local damage along its track, while gammas produce much more even damage. A single gamma can damage a cell, while a cosmic ray primary kills an entire column. The same total energy delivered by charged particles is much more damaging, and isn’t what our radiation repair mechanisms evolved to repair. It may still be a major problem.

  5. The beneficial or at least non sickening effects of chronic low level radiation doses is called hormesis and discussion of it is verboten in nuclear power training classes by NRC decree. The Linear No Threshhold (LNT) theory is the official ideology.

    I would bet spaceflight with it’s much higher dose rates on a chronic basis, punctuated by high acute doses on a frequent but irregular basis will still not be a good thing for humans to experience. Better shielding will still be needed both in space and on the ground on the moon or Mars.

  6. I keep coming back to ice. How many feet of ice on the exterior to reduce cosmic radiation to near ‘ground levels’?

    1. Way too much, and it would have to be insulated and kept frozen, making for another parasitic house load.

  7. Biotech is advancing faster than the snail’s pace of getting Mark 1 humans to Mars so I expect cell repair tech to exist long before we face the space rad boogeyman.

  8. Joe Wooten, I owe you a plate of barbecue for saying “hormesis,” which is the word I’ve been trying to think of all day since downloading/skimming the study.

  9. The study lends strong reinforcement to the vast difference between how scientists thought life around Chernobyl would react versus how it thrived.

    I’m not sure how it would affect spaceflight beyond LEO where the shielding would have to protect against severe proton events and other occurances that are potentially lethal in hours or days. Given the three week duration of the mouse study, it perhaps suggests that the shielding could be reduced somewhat so that the safe exposure level during major radiation events is several hundred times greater than we would’ve previously prefered.

    Perhaps someone who has been crunching numbers and running radiation shielding calculations could convert this into a revised estimate of shielding mass (as a percentage reduction).

  10. I just did some quick research on radiation for a post and was amazed at what I found. It really is an overblown issue.

    Less than 0.1 Sv in a year has no measurable cancer risk and the average dose for a year on mars is only 0.08 Sv. Sunburn is the biggest problem which humans have built in detectors for. About every nine months they will have to take shelter from a solar event that would be 20 times less than radiation poisoning if it happened in a few seconds but they will have all day to get out of it.

    I am absolutely amazed at how this issue is overblown.

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