|
Post by ka9q on Jan 25, 2011 18:51:29 GMT -4
Is this the "awash with deadly radiation" wording once again? I guess it would be correct to say that the radiation is deadly within a short time to a human in shirtsleeves or the like. But so is the deserts on earth. A couple of days unprotected and you are dead - killed by radiation of photons from the sun no matter the Belts. Am I correct? Yeah, pretty much. Actually, if you were exposed to space without any protection the vacuum would kill you far more quickly than the Deadly Radiation. The same structure that protects you against the vacuum of space will also protect you against the vast majority of the radiation. Most of the charged particles trapped in the earth's magnetosphere have very low energies and are easily stopped by even a thin spacecraft hull. Some trapped solar particles, along with cosmic ray particles from outside the solar system, are so energetic that no practical amount of shielding can stop them. The CTs constantly rant about them, but they fail to understand that they're such a small fraction of the total particle population that the dose rate through the Apollo hull was entirely tolerable for a week-long trip to the moon. The only thing left (and which some CTs eagerly point to) is the risk of a major coronal mass ejection from the sun hitting the earth/moon system. But we know that none of these happened during any Apollo mission. These solar events are a serious risk for long-term missions outside the earth's magnetosphere. A moon or Mars base can mitigate the problem by building a "storm shelter" with local material, but a spacecraft in an interplanetary cruise could be in trouble. The problem is being actively worked on, and the CTs often point to this as "proof" that Apollo was impossible. Which is, of course, a complete misrepresentation of their work.
|
|
|
Post by PhantomWolf on Jan 25, 2011 19:58:52 GMT -4
Some trapped solar particles, along with cosmic ray particles from outside the solar system, are so energetic that no practical amount of shielding can stop them. The CTs constantly rant about them, but they fail to understand that they're such a small fraction of the total particle population that the dose rate through the Apollo hull was entirely tolerable for a week-long trip to the moon. They also fail to realise that these extremely high energy particles are likely to go right through the crew too. The ones that were an issue are the ones that were high enough energy to get though the CSM, but not high enough to get through both the CSM wall and the crew. Those particles pass their energy off to the crew they hit, doing damage to their cells, the really high energy ones that just fly straight through without stopping don't impart enough energy to do serious damage and so can be igmored for the most part.
|
|
|
Post by lukepemberton on Jan 25, 2011 22:01:48 GMT -4
Those particles pass their energy off to the crew they hit, doing damage to their cells, the really high energy ones that just fly straight through without stopping don't impart enough energy to do serious damage and so can be igmored for the most part. Now that is a really interesting point, and one I once tried to explain to several HBs. It's actually the 'slow movers' that do the most biological damage. The problem with the HBs view of Galactic Cosmic Rays is that all particles are equal. They simply are not. There's a small issue of cross section of interaction and it varies with the energy of the particle. I add this is not a geometric cross section either, it's related to quantum processes and fundamental forces. Brookhaven have a facility that researches this area. I'm not overkeen on wiki quotes with no citation, but I can't find the orginal paper right now. Seach this article on Brookhaven. en.wikipedia.org/wiki/Health_threat_from_cosmic_rays
|
|
|
Post by lukepemberton on Jan 25, 2011 22:39:35 GMT -4
These solar events are a serious risk for long-term missions outside the earth's magnetosphere. A moon or Mars base can mitigate the problem by building a "storm shelter" with local material, but a spacecraft in an interplanetary cruise could be in trouble. The problem is being actively worked on, and the CTs often point to this as "proof" that Apollo was impossible. Which is, of course, a complete misrepresentation of their work. That frustrates me. They take such work out of context, claiming that NASA are still researching radiation protection, and this means the Apollo missions were fake. Yes, NASA are still researching this area - for a long voyage and because astronauts are spending longer time in space on the ISS. Not because they have not solved the radiation problem for a short lunar mission. In the event of a solar storm comparable with the 1972 storm, there is no question that astronauts caught on the moon would have become seriously ill. Even if they had been in the CM at the time, they would have probably received a dose that made them ill, but it would have not been a lethal dose. It's all explained here by my evil paymasters The hoaxers fallback position is to quote the Comprehensive Flare Index (CFI) and state that 'major' flares occurred during the missions. Major is hardly a quantitative term for a start. Jay explained why this data is worthless by itself to our favourite antipodean. The CFI describe H-alpha emissions, not proton solar events (SPEs). SPEs have an exact definition, and there was not a single SPE on the Earth-Moon system during the Apollo missions. Certainly not one that was comparable to the 1972 storm. The antipodean in question likes to quote the importance index of CFI flares as burning proof, citing that flares with higher importance than the 1972 storm occurred during the Apollo missions. As I have pointed out though, he also showed data that illustrated an SPE that correlates with H-alpha data of higher importance than some Apollo flares and the 1972 flare; but the SPE he showed would be attenuated by the shielding offered by the CM. So yes, you can have 'whackingly huge' H-alpha emissions, but they are only accompanied by low energy protons that can be attenuated readily. Even when they use the data, the do not understand it, and certainly cherry pick from it. Quoting Mauldin's book - Prospects for Interstellar Travel - is an other of their favourite fall backs, and another of my bugbears.
|
|
|
Post by ka9q on Jan 26, 2011 4:28:57 GMT -4
They also fail to realise that these extremely high energy particles are likely to go right through the crew too. The ones that were an issue are the ones that were high enough energy to get though the CSM, but not high enough to get through both the CSM wall and the crew. Although the very high energy particles don't deposit energy at the same rate as low energy particles (especially those that are completely stopped) I don't think you can completely disregard them either. It's just that there aren't very many of them. Fortunately. It is interesting that most of the Apollo lunar astronauts are still alive in their late 70s and early 80s despite having been exposed to small but measurable amounts of a rather esoteric form of radiation not ordinarily encountered on the earth even by nuclear technicians. Of the 24 men who've flown to the moon without necessarily landing, 6 have died. One from an accident (Conrad); two from heart attacks (Irwin and Evans); and one from pancreatitis (Roosa). That leaves only two cancer deaths (Shepard from leukemia and Swigert from bone cancer) that could conceivably have been due to their exposures to energetic particle radiation. But 13% of all humans die from cancer, so one would certainly expect some cancers among the Apollo astronauts by now even if they'd never flown in space at all. So while the sample size is small, this still says that small amounts of this radiation aren't drastically more lethal than we thought at the time.
|
|