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JF Mezei wrote on Thu, 16 Aug 2018
15:56:48 -0400: On 2018-08-16 15:46, Fred J. McCall wrote: You appear to have forgotten the whole "increased atmospheric pressure" thing, Mayfly. So you are claiming it should be possible to get 14.7 PSI atmosphere on Martian ground ? Of course it's 'possible'. It's just (large-scale) engineering. or are you going for 5 PSI with pure O2 as atmosphere for humans in suits and insiude habitable volume ? This is a horrible idea for all sorts of reasons. And once again you're forgetting the whole idea that people will be OUTSIDE for some appreciable amount of time. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
#52
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"Scott M. Kozel" wrote on Thu, 16 Aug 2018
14:17:43 -0700 (PDT): On Thursday, August 16, 2018 at 4:03:53 PM UTC-4, Fred J. McCall wrote: "Scott M. Kozel" wrote on Thu, 16 Aug 2018 The Tunguska object is a mystery. As you suggested a comet-like body melts and outgasses as it comes closer to the Sun. Usually well underway within 2 astronomical units from the Sun (Mars being within that). So the questions outstanding are how did a comet get that close to the Earth without being sighted, how did it stay intact enough to cause a massive explosion in the atmosphere. Visibility varies based on comet composition. It got so deep because it didn't soak up enough heat to reach critical temperature until it was so deep. One theory is that it was a rocky object that came into the atmosphere at a nearly flat angle and at extremely high velocity (70,000 mph or more) and traveled several miles in the atmosphere and completely disintegrated in a multi-megaton explosion to where no significant meteorite remained. That scenario probably passes the physics test. Like I said it is still a mystery among scientists that have studied it. Several good theories but no conclusion. "No one knows for sure" doesn't equate to "my niche hypothesis is correct". No, but that is one of the theories. So is that it was a big natural gas explosion and nothing from space was involved at all. That doesn't make it likely and it doesn't explain a lot of things, like the observed noctiluminescence. And the word you want is 'hypothesis', not 'theory'. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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On Friday, August 17, 2018 at 12:49:19 AM UTC-4, Fred J. McCall wrote:
"Scott M. Kozel" wrote on Thu, 16 Aug 2018 On Thursday, August 16, 2018 at 4:03:53 PM UTC-4, Fred J. McCall wrote: "No one knows for sure" doesn't equate to "my niche hypothesis is correct". No, but that is one of the theories. So is that it was a big natural gas explosion and nothing from space was involved at all. That doesn't make it likely and it doesn't explain a lot of things, like the observed noctiluminescence. And the word you want is 'hypothesis', not 'theory'. I would be interested in knowing how NASA determined such a detailed "generally agreed upon theory". Size, velocity, mass, temperature, explosion height, explosion size. Actually the last 2 could be derived from the treefall patterns. |
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On Saturday, August 18, 2018 at 8:28:40 AM UTC-4, Jeff Findley wrote:
In article , says... One of the articles that I found, said that if the terraforming process went awry, that fixing the issues might make the whole process far more difficult and time consuming than it would be from starting with the virgin planet. True. There is always a chance that something might go awry. But there is also the chance something will go awry with earth's climate as well (natural cycles, man made problems, and etc.). There are no guarantees in this universe. True. The Sun could go nova and expand its envelope to beyond the orbit of Mars. |
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Le Aug/18/2018 Ã* 8:26 AM, Jeff Findley a écritÂ*:
In article , says... On 2018-08-15 20:16, Jeff Findley wrote: Nuclear fission or nuclear fusion powered rocket engine using some of the volatiles from the Kuiper belt object as reaction mass. You'd almost surely combine that with some gravity assist flybys and the like. But, as you said before, this would be a very long process. Woopty do. When you consider the low gravity of Mars, and that to increase PSI are ground level, you will need to add a HUGE amount of atmpsophere most of which will be so high as to be useless, it becomes far more efficient to just build pressurized shelters (which you need to build anyways) and just add the atmosphere needed to pressurize the shelters and energy to heat them. In the near term, shelters would be the way to go. Again, terraforming will take thousands of years. And since such a colony would have limited O2 supply, it is more likely that the CO2 would get recycled into Carbon and O2 as part of ECLSS of the habitable volumes. aka: they aren't going to dump CO2 into outside atmosphere. Surely. But, in the short term, just as surely O2 will also be produced from CO2 and H2O found locally. QUESTION: In theoretical terraforming scenario where lots of CO2 is added, with so much of atmpsphere very thin and very high, would the CO2 reflect the heat back to ground level in a significant way? Or would it trap heat at such a high altitude that ground level would see little change ? This is a detail I am not at all familiar with. The more general point is that CO2, and other added gases, will add both pressure and increase the atmospheric temperature of Mars. In the "short term" (which is still thousands of years), this would lead to an atmosphere where you could venture outside without a bulky, heavy, pressure suit. A breathing mask and eye protection would suffice. CO2 is quite transparent to visible light. Sun light will go right through and hit the ground where it will be transformed into heat. CO2 is much less transparent to infra-red radiation. So heat at ground level will have a somewhat hard time escaping to space. It will do so by heating the atmosphere a little higher which will then heat the atmosphere again a little higher etc. In the long term, plants would convert the CO2, ammonia, and other stuff humans don't like to breathe much of into O2 and biomass (that's where the carbon goes). This eventually (many thousands of years more) leads to an atmosphere where you can step outside without any protection just like on earth. Just a little more detail about humans not liking to breathe CO2. Of course we have some CO2 in our atmosphere, it isn't toxic for most people. But as about anything else the dose does matter. As you increase CO2 concentrations you increase the incidence of panic attacks. If I remember correctly at 20% CO2 100% of subjects will have a panic attack within 10 minutes. (DO NOT TRY THIS ON YOUR OWN, THIS SHOULD ONLY BE DONE WITH QUALIFIED PERSONNEL SUPERVISING, THE OUTCOME CAN BE DEATH WITHOUT YOU BEING ABLE TO DO ANYTHING ABOUT IT AFTER THE VERY FIRST SIGNS. I REPEAT DO NOT TRY THIS.) Some people have panic attacks in our regular atmosphere, the incidence just goes up as you raise the CO2 concentration. So I wouldn't recommend going out breathing the atmosphere in a terraformed Mars until CO2 levels are quite low even if the O2 levels are acceptable. Alain Fournier |
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