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#31
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Discussion on sci.space.science
Alain Fournier wrote:
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. Surface gravity on Mars is lower by a factor of 2.64 than that of Earth. That means you need 2.64 times the mass of atmosphere to create the same air pressure. -- Mvh./Regards, Niels Jørgen Kruse, Vanløse, Denmark |
#32
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Discussion on sci.space.science
On Aug/12/2018 at 10:09 AM, Niels Jørgen Kruse wrote :
Alain Fournier wrote: 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. Surface gravity on Mars is lower by a factor of 2.64 than that of Earth. That means you need 2.64 times the mass of atmosphere to create the same air pressure. Right. I should have thought of that. Alain Fournier |
#33
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Discussion on sci.space.science
JF Mezei wrote on Sat, 11 Aug 2018
22:12:03 -0400: "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 is marginal out at Mars anyway. Plan on nuclear. -- "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 |
#34
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Discussion on sci.space.science
On 8/1/2018 7:43 PM, Alain Fournier wrote:
Jeff Findley and I have been having on sci.space.science a discussion about water on Mars and terraforming Mars, that I appreciate very much. Nobody else is contributing to the discussion, possibly because some of you have given up on sci.space.science. So if you haven't checked on sci.space.science for a while, I encourage you to go check it out. And if you want to contribute to the discussion, that would be great. Alain Fournier I don't want to sound snarky, but given the fact that NASA won't even consider strong LEO gravity lab proposals pitched by Rand Simberg and the SSI, for eventual ISS commercialization strategies, just so we can find out if humans can live on Mars for more than a few years at a time before succumbing to strange physiological conditions heretofore unheard of, I find this whole issue, well, just not worth a discussion. Sorry and a bit ****ed. Not a good time for pie in the sky with me. Dave |
#35
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Discussion on sci.space.science
On 8/14/2018 12:25 AM, David Spain wrote:
Not a good time for pie in the sky with me. Dave It doesn't help that on every clear night this month I can look up in the east and see Mars, shining right back at me. It seems more remote than ever. I hope Musk is successful. I hope it's not a graviational death trap. Somebody should tell NASA it'd be better to know instead of relying on hope and faith. Dave |
#36
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Discussion on sci.space.science
In article , says...
On 8/1/2018 7:43 PM, Alain Fournier wrote: Jeff Findley and I have been having on sci.space.science a discussion about water on Mars and terraforming Mars, that I appreciate very much. Nobody else is contributing to the discussion, possibly because some of you have given up on sci.space.science. So if you haven't checked on sci.space.science for a while, I encourage you to go check it out. And if you want to contribute to the discussion, that would be great. Alain Fournier I don't want to sound snarky, but given the fact that NASA won't even consider strong LEO gravity lab proposals pitched by Rand Simberg and the SSI, for eventual ISS commercialization strategies, just so we can find out if humans can live on Mars for more than a few years at a time before succumbing to strange physiological conditions heretofore unheard of, I find this whole issue, well, just not worth a discussion. Sorry and a bit ****ed. Not a good time for pie in the sky with me. I agree with you and I've been there. Right now my opinion is that NASA has become a boat anchor when it comes to crewed space exploration. They spend orders of magnitude more time and effort "naval gazing" while thinking about theoretical crew safety than they do actually flying crew. We're very close to flying commercial crew but the certifications are what's holding things up. Every little thing they object to causes some sort of redesign and "fix" which draws out the schedule. But, at the same time, terraforming will take hundreds or thousands of years. Not something we're ever going to watch live on YouTube like a rocket launch. All of us here will no doubt be long gone when the first Kuiper belt object is dropped on Mars. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#37
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Discussion on sci.space.science
In article , says...
On 8/14/2018 12:25 AM, David Spain wrote: Not a good time for pie in the sky with me. Dave It doesn't help that on every clear night this month I can look up in the east and see Mars, shining right back at me. It seems more remote than ever. I hope Musk is successful. I hope it's not a graviational death trap. Somebody should tell NASA it'd be better to know instead of relying on hope and faith. We could test this by connecting a tether between a BFS and a BFS tanker and spin them in LEO for a year or so. This would test out long term life support, power, propulsion, and other systems while also serving as a Mars gravity test. Or we just go and see how people actually react to Mars gravity. My guess is that Musk would choose this option. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#38
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Discussion on sci.space.science
On Wednesday, August 15, 2018 at 7:16:13 AM UTC-4, Jeff Findley wrote:
But, at the same time, terraforming will take hundreds or thousands of years. Not something we're ever going to watch live on YouTube like a rocket launch. One website article I found said more like 100,000 years. All of us here will no doubt be long gone when the first Kuiper belt object is dropped on Mars. Just how do you go about "dropping a Kuiper belt object on Mars?" An object 1/4 mile in diameter would probably be in the billions of tons. Where will the energy be found to transfer that to a Mars solar orbit perigee, then accelerate it up to Mars solar orbit speed, then decelerate it to Mars surface at a speed that won't create a massive crater on the scale of the one out in Arizona? How many hundreds or thousands of such objects would be needed? |
#39
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Discussion on sci.space.science
On Aug/15/2018 at 4:05 PM, Scott M. Kozel wrote :
On Wednesday, August 15, 2018 at 7:16:13 AM UTC-4, Jeff Findley wrote: But, at the same time, terraforming will take hundreds or thousands of years. Not something we're ever going to watch live on YouTube like a rocket launch. One website article I found said more like 100,000 years. All of us here will no doubt be long gone when the first Kuiper belt object is dropped on Mars. Just how do you go about "dropping a Kuiper belt object on Mars?" An object 1/4 mile in diameter would probably be in the billions of tons. Where will the energy be found to transfer that to a Mars solar orbit perigee, then accelerate it up to Mars solar orbit speed, then decelerate it to Mars surface at a speed that won't create a massive crater on the scale of the one out in Arizona? Why not have another crater on Mars? And why not slam the objects at high speed into Mars. When the thing hits the surface, it will decelerate. Yes you will lose a little mass that will escape because of the energy released on impact. You just bring in more objects to compensate. How many hundreds or thousands of such objects would be needed? Many thousands. Alain Fournier |
#40
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Discussion on sci.space.science
Jeff Findley wrote on Wed, 15 Aug 2018
07:18:37 -0400: Or we just go and see how people actually react to Mars gravity. My guess is that Musk would choose this option. Musk will almost certainly 'just go', but he'll 'just go' in a way that lets him find his way before any disasters occur and given BFR he'll always have a way to bring a small settlement home. -- "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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