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#51
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Musk plans for mars
Fred J McCall wrote:
Rob wrote: wrote: "Astronauts flying to Mars are in danger of long-term brain damage and dementia from the onslaught of radiation in galactic cosmic rays, according to a new study. The paper, published today in Nature's Scientific Reports, raises alarm for NASAÂ’s future plans in long-term space travel." Aren't people who stay on earth in the same danger? There are lots of things that can cause this, including posting on usenet newsgroups, reading too many studies, or even just living. The Earth's magnetic field shields most of that away from us (which is why we have Van Allen belts around the planet). Go beyond the Van Allens and you are outside that protection. But brain damage and dementia can result from the above causes as well. |
#52
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Musk plans for mars
Rob wrote:
Fred J McCall wrote: Rob wrote: wrote: "Astronauts flying to Mars are in danger of long-term brain damage and dementia from the onslaught of radiation in galactic cosmic rays, according to a new study. The paper, published today in Nature's Scientific Reports, raises alarm for NASA?s future plans in long-term space travel." Aren't people who stay on earth in the same danger? There are lots of things that can cause this, including posting on usenet newsgroups, reading too many studies, or even just living. The Earth's magnetic field shields most of that away from us (which is why we have Van Allen belts around the planet). Go beyond the Van Allens and you are outside that protection. But brain damage and dementia can result from the above causes as well. True, but that's rather like saying that since we can be injured in many ways there is no point in trying to avoid injury. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
#53
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Musk plans for mars
Le 11/10/2016 à 12:29, Fred J. McCall a écrit :
However, shielding is not that difficult. In principle. In practice we just do not know. No shielding has been tested in interplanetary space till now. The crew needs to be shielded on Mars too, but that could be easier if they went underground. A deep cave and you should be OK. But you shouldn't go out for extended periods since Mars offers no shielding from radiation from cosmic rays. The ultra thin atmosphere is no protection at all, and there is no planetary magnetic field. You have to stay as much as possible in the cave. Planet too small, gravity is one third of what is on earth. Consequences in terms of bone loss are unknown but probably not very good. Look, I am not at all against humans going out of the earth, to the contrary. But I see no need to sacrifice people just... for what? What can humans do that they couldn't do safely from earth? OK, driving rovers without a 15-30 minute time lag is a reason, maybe a valuable reason. But in that case is better to live in orbit rather than in a cave... Artificial gravity is easier to do in space than on the surface of mars. Better conditions are easier to realize in a station orbiting Mars than trying to scrap a living in the surface. Short trips to the surface could be done of course, but for the bulk of exploration just staying in orbit would be easier. Induced radioactivity because of cosmic rays bombardement during eons makes the surface of Mars slightly radioactive, and besides, it is stock full of substances that are very toxic for humans. Mars dust is very sticky, probably electrically charged. All those problems are avoided in orbit. Machines do not care about those hazards, resist very well decades of Mars conditions without any problems. Humans have a machine roving around in Mars since January 2004 and it is *still roving around*. Only problems are a stuck wheel and the flash memory that gave up the ghost some months ago. TWELVE YEARS! That proves that toasters have quite a good price/science ratio. Humans are very fragile, as you know. But it would be nice to go there, of course. As a thrill, or for scientific reasons, to study a planet and the biology there. All NASA missions point to a biology in Mars, and that will be surely one of the big discoveries of this century. But humans in Mars could swamp what that subterranean microbial life could tell us about ourselves. It is a second ecology. It seems that life in Mars was very similar to life on Earth since a microbiologist discovered formations that are identical to fossil formations in Earth. When Mars was wet and had an atmosphere, the microbes were very similar since they produced similar fossils. Mars is full of secrets, let's explore it wisely. Developing a technology that carries people to Mars will be done, but it will take decades. Biology will give us the solution. Genetic engineering of a space suit skin, redesigning the DNA repair machinery so that radioactivity and cosmic ray damage doesn't affect us as much would allow for less shielding. To design a body that can live in Mars easily. That will take some time. |
#54
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Musk plans for mars
jacob navia wrote:
Le 11/10/2016 à 12:29, Fred J. McCall a écrit : However, shielding is not that difficult. In principle. In practice we just do not know. Of course we do. We know what the radiation environment looks like. No shielding has been tested in interplanetary space till now. But we know the radiation environment and the shielding properties of various materials. This is NOT a hard problem. It just takes mass. The crew needs to be shielded on Mars too, but that could be easier if they went underground. A deep cave and you should be OK. Also a shallow cave. Or a trench with a few meters of dirt mounded over it. Or... But you shouldn't go out for extended periods since Mars offers no shielding from radiation from cosmic rays. The ultra thin atmosphere is no protection at all, and there is no planetary magnetic field. The "ultra thin atmosphere" is quite a lot of protection, actually, and eliminates over 60% of the radiation. You have to stay as much as possible in the cave. Not so much. Planet too small, gravity is one third of what is on earth. Consequences in terms of bone loss are unknown but probably not very good. You can't equate total ignorance and then assume bad news. Look, I am not at all against humans going out of the earth, to the contrary. But I see no need to sacrifice people just... for what? What can humans do that they couldn't do safely from earth? OK, driving rovers without a 15-30 minute time lag is a reason, maybe a valuable reason. But in that case is better to live in orbit rather than in a cave... But 'in orbit' gives you a much worse radiation environment to deal with, you have no hope of in situ use of resources, etc. Artificial gravity is easier to do in space than on the surface of mars. Better conditions are easier to realize in a station orbiting Mars than trying to scrap a living in the surface. Short trips to the surface could be done of course, but for the bulk of exploration just staying in orbit would be easier. No, because you want PEOPLE doing the exploring. A couple humans on the surface with a small vehicle can explore more than a rover can do in years. Induced radioactivity because of cosmic rays bombardement during eons makes the surface of Mars slightly radioactive, Not enough to care about. and besides, it is stock full of substances that are very toxic for humans. So is Earth. Mars dust is very sticky, probably electrically charged. All those problems are avoided in orbit. Machines do not care about those hazards, resist very well decades of Mars conditions without any problems. Well, no. Your 'sticky dust' problem, if it exists, is a problem for MACHINES, not people. Humans have a machine roving around in Mars since January 2004 and it is *still roving around*. Only problems are a stuck wheel and the flash memory that gave up the ghost some months ago. And humans on site with a vehicle could accomplish more in a matter of weeks than the toaster has in its whole existence. TWELVE YEARS! That proves that toasters have quite a good price/science ratio. Humans are very fragile, as you know. It proves no such thing. If humans cost 100x but return 1,000x data, humans are a better deal. But it would be nice to go there, of course. As a thrill, or for scientific reasons, to study a planet and the biology there. Or just to live. You know, like we do in North America. All NASA missions point to a biology in Mars, and that will be surely one of the big discoveries of this century. But humans in Mars could swamp what that subterranean microbial life could tell us about ourselves. It is a second ecology. It seems that life in Mars was very similar to life on Earth since a microbiologist discovered formations that are identical to fossil formations in Earth. When Mars was wet and had an atmosphere, the microbes were very similar since they produced similar fossils. So nothing new, then. You can't argue it both ways. Either there's something new, in which case we'll be able to tell it from Earth life when we find it, or there's nothing new and we don't need to worry about contaminating it. Mars is full of secrets, let's explore it wisely. Developing a technology that carries people to Mars will be done, but it will take decades. For some value of 'decades' that's approximately equal to between one and two. Biology will give us the solution. Genetic engineering of a space suit skin, redesigning the DNA repair machinery so that radioactivity and cosmic ray damage doesn't affect us as much would allow for less shielding. To design a body that can live in Mars easily. That will take some time. Which is why we won't wait for any such silly thing. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
#55
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Musk plans for mars
JF Mezei wrote:
On 2016-10-11 23:42, Fred J. McCall wrote: The "ultra thin atmosphere" is quite a lot of protection, actually, and eliminates over 60% of the radiation. I read that lack of magnetic field was a far greater problem in terms of providing protection from radiation. True. If Mars had a magnetic field like Earth's there would be orders of magnitude less surface radiation. Could a Mars colony dig deep to get geothermal energy ? Or has Mars cooled to a point where its core is no longer molten ? They could always drill to get geothermal energy, regardless of whether the core is still molten or not. Temperature will always increase with depth. However, that's a lot of trouble to go to. Solar and nuclear are more likely power sources. Solar cells could probably be produced locally. Nuclear fuel would probably have to be imported. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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