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#21
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Discussion on sci.space.science
"JF Mezei" wrote in message ...
On 2018-08-09 16:52, Fred J. McCall wrote: It's all about time scales. Can you add enough gas fast enough and will it lose it slowly enough to be worthwhile. You don't build and then board a leaky lifeboat unless you are damned sure another boat will come in before it sinks. You do if there's no other lifeboat at all. But that's not even the point. I'll let you in on a hint. Pretty much all boats leak. It's a matter of rate. If the boat takes on 1 liter/hour and I can pump out 10 liter/hour, I'm not worried. If the boat takes on 1 liter/hour and it takes 1,000,000 liters to sink the boat, I'm not worried. Why spend the money/effort to add atmpsphere to Mars knowing that it will be lost and you'll either have to continuously add to it, or eventually leave Mars to get onto another planet? Because those times are measured in centuries and quite manageable. Much simpler to build a domed city then to terraform Mars. Upfront sure. But then... you have to maintain your dome. And here's the kicker, I can guarantee your dome WILL leak. So why build a dome if you simply know it will leak? (using your logic). And on a more basic question: assuming unlimited supply of compressed air being shipped to Mars, is it realistic to expect liveable air pressure at ground when you consider Mar's reduced gravity and how much more air your would need above you to achieve anything near 14.7psi ? You know, there's a thriving city here in the US that's a mile up... and has an average psi of 12psi. And that's not even all that extreme for human limits. If you can't achieve proper air pressure at ground, it is worth the effort to try to terraform the planet since you wouldn't be able to go outside without a space suit ? You know, last time I was in Denver, I was wearing shorts and a t-shirt. (of course the next day I nearly missed my flight due to the snowstorm.) -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net IT Disaster Response - https://www.amazon.com/Disaster-Resp...dp/1484221834/ |
#22
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Discussion on sci.space.science
JF Mezei wrote on Fri, 10 Aug 2018
13:20:08 -0400: On 2018-08-09 16:52, Fred J. McCall wrote: It's all about time scales. Can you add enough gas fast enough and will it lose it slowly enough to be worthwhile. You don't build and then board a leaky lifeboat unless you are damned sure another boat will come in before it sinks. Sorry, but that makes no sense. Why spend the money/effort to add atmpsphere to Mars knowing that it will be lost and you'll either have to continuously add to it, or eventually leave Mars to get onto another planet? Because if you can add enough gas in a few generations and it takes 100,000 years to bleed off, that's a pretty good deal. Much simpler to build a domed city then to terraform Mars. Well, no, because then you just get some little domes instead of an entire planet. And on a more basic question: assuming unlimited supply of compressed air being shipped to Mars, is it realistic to expect liveable air pressure at ground when you consider Mar's reduced gravity and how much more air your would need above you to achieve anything near 14.7psi ? If you can't achieve proper air pressure at ground, it is worth the effort to try to terraform the planet since you wouldn't be able to go outside without a space suit ? My God, do you ever bother to research anything even a little bit before you start nit picking? Here, read this for a start to educating yourself: https://en.wikipedia.org/wiki/Terraforming_of_Mars -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
#23
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Discussion on sci.space.science
On Aug/10/2018 at 2:52 PM, Greg (Strider) Moore wrote :
"JF Mezei"Â* wrote in message ... And on a more basic question: assuming unlimited supply of compressed air being shipped to Mars, is it realistic to expect liveable air pressure at ground when you consider Mar's reduced gravity and how much more air your would need above you to achieve anything near 14.7psi ? You know, there's a thriving city here in the US that's a mile up... and has an average psi of 12psi. And that's not even all that extreme for human limits. If you can't achieve proper air pressure at ground, it is worth the effort to try to terraform the planet since you wouldn't be able to go outside without a space suit ? You know, last time I was in Denver, I was wearing shorts and a t-shirt. (of course the next day I nearly missed my flight due to the snowstorm.) What you put in parentheses is important. Snow storms are much rarer in Washington D.C. than in Denver, though they are approximately at the same latitude. The main reason for that is because you have less air over your head in Denver, altitude of about 1600m, than in D.C., altitude of about 0m. More snow, isn't really the problem here, it is the cold. If you terraform Mars with less atmospheric pressure than on Earth you will likely have colder temperatures. That isn't a show stopper. But it is something that should be taken into consideration when planning what kind of atmosphere you plan to have on a terraformed Mars. Alain Fournier |
#24
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Discussion on sci.space.science
Alain Fournier wrote on Fri, 10 Aug 2018
19:33:15 -0400: On Aug/10/2018 at 2:52 PM, Greg (Strider) Moore wrote : "JF Mezei"* wrote in message ... And on a more basic question: assuming unlimited supply of compressed air being shipped to Mars, is it realistic to expect liveable air pressure at ground when you consider Mar's reduced gravity and how much more air your would need above you to achieve anything near 14.7psi ? You know, there's a thriving city here in the US that's a mile up... and has an average psi of 12psi. And that's not even all that extreme for human limits. If you can't achieve proper air pressure at ground, it is worth the effort to try to terraform the planet since you wouldn't be able to go outside without a space suit ? You know, last time I was in Denver, I was wearing shorts and a t-shirt. (of course the next day I nearly missed my flight due to the snowstorm.) What you put in parentheses is important. Snow storms are much rarer in Washington D.C. than in Denver, though they are approximately at the same latitude. The main reason for that is because you have less air over your head in Denver, altitude of about 1600m, than in D.C., altitude of about 0m. More snow, isn't really the problem here, it is the cold. If you terraform Mars with less atmospheric pressure than on Earth you will likely have colder temperatures. Actually, you get more snow in Denver because of the Rockies. Denver gets pretty warm in summer, so it's not just thinner air equating to colder temps. -- "Rule Number One for Slayers - Don't die." -- Buffy, the Vampire Slayer |
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#26
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On Aug/10/2018 at 9:14 PM, Fred J. McCall wrote :
Alain Fournier wrote on Fri, 10 Aug 2018 19:33:15 -0400: On Aug/10/2018 at 2:52 PM, Greg (Strider) Moore wrote : "JF Mezei"Â* wrote in message ... And on a more basic question: assuming unlimited supply of compressed air being shipped to Mars, is it realistic to expect liveable air pressure at ground when you consider Mar's reduced gravity and how much more air your would need above you to achieve anything near 14.7psi ? You know, there's a thriving city here in the US that's a mile up... and has an average psi of 12psi. And that's not even all that extreme for human limits. If you can't achieve proper air pressure at ground, it is worth the effort to try to terraform the planet since you wouldn't be able to go outside without a space suit ? You know, last time I was in Denver, I was wearing shorts and a t-shirt. (of course the next day I nearly missed my flight due to the snowstorm.) What you put in parentheses is important. Snow storms are much rarer in Washington D.C. than in Denver, though they are approximately at the same latitude. The main reason for that is because you have less air over your head in Denver, altitude of about 1600m, than in D.C., altitude of about 0m. More snow, isn't really the problem here, it is the cold. If you terraform Mars with less atmospheric pressure than on Earth you will likely have colder temperatures. Actually, you get more snow in Denver because of the Rockies. Denver gets pretty warm in summer, so it's not just thinner air equating to colder temps. Correct. There are many things that affect temperatures. Nonetheless, locations at higher altitudes do tend to have colder temperatures than locations at lower altitudes. And that is mostly because of thinner air. And Mars being further away from the sun than Earth, one would prefer having a "thicker blanket" to help control temperatures. Alain Fournier |
#27
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Discussion on sci.space.science
Alain Fournier wrote on Sat, 11 Aug 2018
08:57:03 -0400: On Aug/10/2018 at 9:14 PM, Fred J. McCall wrote : Alain Fournier wrote on Fri, 10 Aug 2018 19:33:15 -0400: On Aug/10/2018 at 2:52 PM, Greg (Strider) Moore wrote : "JF Mezei"* wrote in message ... And on a more basic question: assuming unlimited supply of compressed air being shipped to Mars, is it realistic to expect liveable air pressure at ground when you consider Mar's reduced gravity and how much more air your would need above you to achieve anything near 14.7psi ? You know, there's a thriving city here in the US that's a mile up... and has an average psi of 12psi. And that's not even all that extreme for human limits. If you can't achieve proper air pressure at ground, it is worth the effort to try to terraform the planet since you wouldn't be able to go outside without a space suit ? You know, last time I was in Denver, I was wearing shorts and a t-shirt. (of course the next day I nearly missed my flight due to the snowstorm.) What you put in parentheses is important. Snow storms are much rarer in Washington D.C. than in Denver, though they are approximately at the same latitude. The main reason for that is because you have less air over your head in Denver, altitude of about 1600m, than in D.C., altitude of about 0m. More snow, isn't really the problem here, it is the cold. If you terraform Mars with less atmospheric pressure than on Earth you will likely have colder temperatures. Actually, you get more snow in Denver because of the Rockies. Denver gets pretty warm in summer, so it's not just thinner air equating to colder temps. Correct. There are many things that affect temperatures. Nonetheless, locations at higher altitudes do tend to have colder temperatures than locations at lower altitudes. And that is mostly because of thinner air. And Mars being further away from the sun than Earth, one would prefer having a "thicker blanket" to help control temperatures. Some truth there, but the reason you really get that is that it's easier for ground heat to radiate away at night because there is less air and it's usually clear. That means there's less heat buildup at ground level. So Denver gets 100+ temperatures during the day (because the clear air allows more ground heating) but relatively cooler temperatures at night (because ground heat can radiate away more easily through the clear air). You can get the same effect as a thick air blanket by just having an overcast atmosphere to reflect heat back toward the ground. Snow off the mountains actually tends to moderate temperatures in Denver in winter, since that will reflect heat back toward the ground. Let the air get cold enough to clear a bit and the snow stops. -- "Rule Number One for Slayers - Don't die." -- Buffy, the Vampire Slayer |
#28
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Discussion on sci.space.science
Alain Fournier wrote:
And Mars being further away from the sun than Earth, one would prefer having a "thicker blanket" to help control temperatures. The lower gravity means the blanket is thicker than pressure would suggest. -- Mvh./Regards, Niels Jørgen Kruse, Vanløse, Denmark |
#29
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Discussion on sci.space.science
On Aug/12/2018 at 3:25 AM, Niels Jørgen Kruse wrote :
Alain Fournier wrote: And Mars being further away from the sun than Earth, one would prefer having a "thicker blanket" to help control temperatures. The lower gravity means the blanket is thicker than pressure would suggest. Thicker in terms of km. But I don't think that makes it much thicker in terms of heat retention. I could be wrong but I think that the greater scale height of Mars' atmosphere (meaning thicker atmosphere in terms of km) will make convective heat loss slower but have no effect on radiative heat loss. I also think that most of the heat loss would be from thermal radiation not from convection, especially so if the atmosphere is light (meaning low pressure at ground level). The above is mostly speculation on my part. If anyone has knowledge above speculation, I would really like you to share. Even if you have only speculation that would be cool too, just not as much. Alain Fournier |
#30
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Discussion on sci.space.science
On Aug/11/2018 at 10:12 PM, JF Mezei wrote :
"Thickening" the atmosphere with CO2 or whethever to retain heat would have a negative effect: solar panels would get less of the sun's energy. The loss of solar efficiency would be worth it if you achieved a shirt-sleeve atmpsphere on Mars. But if you still need pressurized habitats, then making the oustide less cold at the expense of reducing solar power efficiency is a trade off that designers of the habvitats will have to debate. Solar panels usually make energy from visible light. CO2 isn't very opaque for visible light. Even one full atmosphere of pressure from CO2 wouldn't reduce solar panels output much. So I don't think this is much of a problem. Alain Fournier |
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