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#31
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Another problem with longer flights
On Thu, 29 Jan 2009 22:59:24 +0100, in a place far, far away, jacob
navia made the phosphor on my monitor glow in such a way as to indicate that: Pat Flannery wrote: jacob navia wrote: There are serious hints of living beings in Mars, If by "beings" you mean bacteria... If there are bacteria, there is surely something that eats those bacteria. Why? Then, there are surely others that eat the bacterial eaters. The bacteria could be at the base of a food chain. They could also be at the top. |
#32
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Another problem with longer flights
On Thu, 29 Jan 2009 19:49:49 -0500, in a place far, far away,
"Jonathan" made the phosphor on my monitor glow in such a way as to indicate that: "jacob navia" wrote in message ... In any case we need to explore more with robots first. Imagine sending people only to find out that they can't establish anything there... What a waste of time! You just confirm what I am arguing :-) This research certainly means the debate between robots and humans as explorers has ended. Nonsense. The winner is obvious. Only to the illogical. |
#33
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Another problem with longer flights
Rick Jones wrote: That presumes Europa started thawed and then froze right - with the ice expanding inwards as well as outwards? Otherwise, since water expands when it freezes, if it started frozen and had its core thawed by tidal (?) forces there might not be as much pressure. I wasn't thinking of it generating pressure by squeezing the water (which is pretty much incompressible anyway, but simply from the weight of ice on top of the water... the gravity is far lower than that of Earth (about 1/6 ours, like the Moon) but that means if you have a ice shell six miles thick over you it will generate the same amount of pressure as it you were around one mile deep in the ocean. Military subs tend to operate at a maximum depth of 1,000 -1,300 feet, so that means if the ice crust on Europa is over around a mile thick, you are going to have a very hard time building a habitat under it or venturing outside of it in any sort of diving suit. Unfortunately, no one knows just how thick the ice is, with estimates ranging from around 700 feet to around 19 miles: http://en.wikipedia.org/wiki/Europa_(moon) If the lower estimate is correct, you could swim around in it in conventional scuba gear, as it would be like if you were around 100 feet deep on Earth. If the upper estimate is right, then it would mean that you could only move around in it in some sort of deep submergence vehicle, as it would be equivalent to being three miles deep in the ocean on Earth. Since the truth probably lies between these two extremes, it's pretty unlikely you are going to be doing much swimming in the cold Europian seas unless you are wearing some sort of a atmospheric diving suit with propellers on it, and probably even that wouldn't be tough enough. Which is just as well, as Europian Sono-Squids, though not as dangerous as Titanic Titanian Methane Muskies, are still nothing to be trifled with - particularly given they have a average IQ approaching that of Einstein, and a hunger as rapacious as that of a six-year-old at the movies. They would look upon human divers in hard suits entering their realm as simply witless snack food that had delivered itself into their hands like so many salted-in-the-shell peanuts and gnaw on them as they discussed the finer nuances of the thirteen body problem. :-) Pat |
#34
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Another problem with longer flights
jacob navia wrote: Pat Flannery wrote: jacob navia wrote: There are serious hints of living beings in Mars, If by "beings" you mean bacteria... If there are bacteria, there is surely something that eats those bacteria. Then, there are surely others that eat the bacterial eaters. The bacteria could be at the base of a food chain. Or they could be the only link in the food chain, as they appear to all live deep underground if they exist - an area that has been notably free from the evolution of large sophisticated lifeforms on Earth, although I'm sure Edgar Rice Burroughs (Burrows?) could have come up with some pretty frightening things living underground on Mars, probably with eight legs and under the control of some blind albino race of cave Martians, whose voluptuous women don't even realize that their skimpy brassieres are on inside out. Pat |
#35
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Another problem with longer flights
Pat Flannery wrote:
Rick Jones wrote: That presumes Europa started thawed and then froze right - with the ice expanding inwards as well as outwards? Otherwise, since water expands when it freezes, if it started frozen and had its core thawed by tidal (?) forces there might not be as much pressure. I wasn't thinking of it generating pressure by squeezing the water (which is pretty much incompressible anyway, but simply from the weight of ice on top of the water... But water ice expands right? I was thinking more along the lines of the ice forming a shell that sort of pulled away from the water beneath it. Or if you will the water pulling away from the shell as it contracted relative to the ice. I dunno, call it a Dysan sphere made of ice? (OK, _LOTS_ of handwaving . In otherwords is the ice actually supported by the water, or does it simply form a hard shell around the water with its own structure supporting it? rick jones They would look upon human divers in hard suits entering their realm as simply witless snack food that had delivered itself into their hands like so many salted-in-the-shell peanuts and gnaw on them as they discussed the finer nuances of the thirteen body problem. :-) Or discovered how this new food didn't really sit will with their digestive systems -- portable adj, code that compiles under more than one compiler these opinions are mine, all mine; HP might not want them anyway... feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
#36
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Another problem with longer flights
Rick Jones wrote: But water ice expands right? I was thinking more along the lines of the ice forming a shell that sort of pulled away from the water beneath it. Or if you will the water pulling away from the shell as it contracted relative to the ice. I dunno, call it a Dysan sphere made of ice? (OK, _LOTS_ of handwaving . All the cracks in it would probably rule out any sort of sub-ice voids of any major size, but who knows? Or discovered how this new food didn't really sit will with their digestive systems All joking aside, if the waters of Europa really are quite salty and full of minerals as has been speculated, that could make them electrically conductive enough for creatures living in them to use sensory organs based on some form of electrical conduction to detect things in their environment, as well as sound detection (which would work very well indeed, as there would be no wave noise to contend with). Without having to deal with storms, and only having thermal upwelling rather than strong currents to contend with, animals in such a environment might be very fragilely built and of quite large size. Pat |
#37
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Another problem with longer flights
Pat Flannery wrote:
All joking aside, if the waters of Europa really are quite salty and full of minerals as has been speculated, that could make them electrically conductive enough for creatures living in them to use sensory organs based on some form of electrical conduction to detect things in their environment, as well as sound detection (which would work very well indeed, as there would be no wave noise to contend with). I seem to recall that one of the reasons it was/is popular for submarines to hide under the Arctic ice was it was very noisy. Given the cracks and tidal forces on Europa couldn't it be pretty noise too? rick jones -- The glass is neither half-empty nor half-full. The glass has a leak. The real question is "Can it be patched?" these opinions are mine, all mine; HP might not want them anyway... feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
#38
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Another problem with longer flights
On Jan 27, 7:02*am, jacob navia wrote:
In any trip for humans beyond the moon (mars and beyond) artificial gravity is a necessity. Space.com reports: [1] quote Astronauts that spend long months aboard the International Space Station lose bone strength faster than previously thought and have a higher risk of breaking their hips later in life, a new study reports. A survey of 13 space station astronauts found that their bone strength dipped by at least 14 percent on the average during their half-year stays aboard the orbiting laboratory. Three of the astronauts lost up to 30 percent of their bone strength during their long-duration spaceflights, putting them on par with the bone strength of older women with osteoporosis on Earth, the study reported. end quote If in only 6 months trips they lose 14% of their bone strength, in a trip of 2 years (the minimum time for a Mars trip) the strength of their bones would disminish in such a measure that it would be a one way trip only. They could not resist earth gravity when they come back. This means that artificial gravity is a must for any trip that takes more than 2-3 months. Note that the risk of breaking their bones much later in life increases since apparently is very difficult to get the lost strength back. This is another big problem with humans in space and with human spaceflight. [1]http://www.space.com/scienceastronomy/090126-astronauts-bone-strength.... -- jacob navia jacob at jacob point remcomp point fr logiciels/informatiquehttp://www.cs.virginia.edu/~lcc-win32 Why do you folks keep excluding cosmic and secondary/recoil radiation? ~ BG |
#39
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Another problem with longer flights
On Jan 29, 1:59*pm, jacob navia wrote:
Pat Flannery wrote: jacob navia wrote: * There are serious hints of living beings in Mars, If by "beings" you mean bacteria... If there are bacteria, there is surely something that eats those bacteria. Then, there are surely others that eat the bacterial eaters. The bacteria could be at the base of a food chain. *We know now, that Europa has an ocean below * the ice. This means that we could establish a submarine settlement in * there (if there is no life or if the life there is not incompatible * with ours). The same in Enceladus. The water pressure might be pretty high, as some estimates put the ice cover as being many miles thick. Pat Most literature I have read put the ice cover as a very thin layer of ice, since there was some dark liquid oozing out of the cracks in many photographs sent by the Galileo spacecraft. An impact crater in the ice hints also to a thin layer. In any case we would not know anything about Europa if the robot Galileo wouldn't have been there in the first place. In any case we need to explore more with robots first. Imagine sending people only to find out that they can't establish anything there... What a waste of time! You just confirm what I am arguing :-) -- jacob navia jacob at jacob point remcomp point fr logiciels/informatiquehttp://www.cs.virginia.edu/~lcc-win32 Robots will cost us 0.1% of whatever a human outfitted expedition would demand. However, the one-way human mission has terrific potential. Put those one-way tickets up for grabs on eBay, and see how much our NASA gets offered (minimum bid $100M). ~ BG |
#40
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Another problem with longer flights
Rick Jones wrote: I seem to recall that one of the reasons it was/is popular for submarines to hide under the Arctic ice was it was very noisy. Given the cracks and tidal forces on Europa couldn't it be pretty noise too? It could be, but I would think it would be less so than in the arctic due to lacking anything like summer thawing and winter freezing. A lot of noise in the polar oceans is probably due to icebergs toppling over or fracturing and ice flows grinding together. Still, ice fracturing can make a very weird and loud noise*. We hear a lot of that come early spring on our local reservoir as the ice starts to melt, and I didn't think of that problem in regards to under-ice noise on Europa. * Which is hard to describe - it sort of resembles the sound made by a saw used as a musical instrument by bending it back and forth rapidly. What it really resembles is the sound made when that guy punches one of The Dirty Dozen in the top of his steel helmet in the latrine fight scene in the movie "The Dirty Dozen". :-) Pat |
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