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Valiant Dancer
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USA
4826 Posts |
 Posted - 01/16/2015 : 13:45:44
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Makes an interesting case for Mars colonization, but I do have a few questions that perhaps this agust body could provide insight.
In chapter 6, Zubrin claims that the PSI of Mars could be raised from what it is now (about 1 percent of the atmospheric pressure of Earth) to 35% of Earth norms (5 PSI) in 50 years by emitting the same amount of PFCs into the Martian atmosphere as we currently release into the Earth's atmosphere at a rate comprable to todays rates on Earth. This seems a little questionable.
Zubrin assumes that trapped water ice at the pole will melt and make water vapor that will not bleed off into space during that time. I am skeptical that such large scale changes could occur on a planet with such a thin atmosphere.
Any ideas on whether this is plausable or not? Or is Zubrin overstating what is possible?
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Dave W.
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26022 Posts |
Posted - 01/17/2015 : 21:04:56 [Permalink]
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I'm having trouble finding critical reviews, which is a good sign. Also, a review of the revised edition suggests that not much changed in the terraforming section of the book in 15 years.
But to this layman, to gain atmosphere, all that's needed is for more atmospheric components to be created than bleeds off into space (or gets re-captured by geology) over time. Whether Zubrin's proposed methods could do that, I don't know. But then I suppose any of them (alone or together) could work if they're cranked up high enough, but there are practical limits to consider. |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 01/26/2015 : 06:13:09 [Permalink]
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Originally posted by Valiant Dancer
In chapter 6, Zubrin claims that the PSI of Mars could be raised from what it is now (about 1 percent of the atmospheric pressure of Earth) to 35% of Earth norms (5 PSI) in 50 years by emitting the same amount of PFCs into the Martian atmosphere as we currently release into the Earth's atmosphere at a rate comprable to todays rates on Earth. This seems a little questionable. |
Without having read anything but what I've seen posted here... My first impression is that laying a foundation for an atmosphere by pumping out PFC is not such a bad idea. You'll get a heavy atmosphere thanks to the high molecular weight, which will allow you to walk around without a pressure suit, but with only an oxygen mask. It will also put less stress on structures to maintain pressurized.
Zubrin assumes that trapped water ice at the pole will melt and make water vapor that will not bleed off into space during that time. I am skeptical that such large scale changes could occur on a planet with such a thin atmosphere.
Any ideas on whether this is plausable or not? Or is Zubrin overstating what is possible?
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The ice would possibly melt, but the water vapor will certainly bleed out into space.
Since water vapor is so much lighter than PFC, and water molecules are unlikely to mix well with PFCs due to PFC's having very weak electrical dipole characteristics (and water very strong), it's not reasonable to assume that water will be contained within the atmosphere.
The water vapor will bubble up to the top of the atmosphere where it will bleed out into space. For the molecules which remains, UV-radiation will dissociate the hydrogen from the oxygen and at least the hydrogen will bleed out into space. The little of what would be left of the oxygen, who can say? Carbon dioxide seems heavy enough to remain, but it's ~40% heavier than pure oxygen.
What Mars really needs is a few trillion tons of water... |
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| Edited by - Dr. Mabuse on 01/26/2015 06:30:23 |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/27/2015 : 18:25:02 [Permalink]
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Yeah, but the calculation needed is whether water vapor can be added to the atmosphere faster than it leaves.
Oh, worse for Mars, its magnetic field is much weaker than Earth's, which means much more atmosphere is just going to be blasted away by the solar wind. |
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Valiant Dancer
Forum Goalie
USA
4826 Posts |
Posted - 01/28/2015 : 06:43:01 [Permalink]
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Originally posted by Dave W.
Yeah, but the calculation needed is whether water vapor can be added to the atmosphere faster than it leaves.
Oh, worse for Mars, its magnetic field is much weaker than Earth's, which means much more atmosphere is just going to be blasted away by the solar wind.
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Now, Zubrin has gone off into science fiction land.
Later in the book, he starts talking about igniting brown dwarf stars by using micro black holes (of the type Hawking says would have evaporated to the point they could no longer maintain singularity.) rammed into place by sending asteroids on collision courses with it.
No mention of even if this was possible what impact it would have on orbital bodies around the brown dwarf stars. (My first impression is that the orbits of these bodies would be profoundly perturbed, some would be ejected from the system and some would be sucked into the star/black hole.
I think he has a strong case for a mission to Mars, however, he gets bogged down in some old discarded hypotheses. For instance, Nemesis is related as possible even though that hypothesis was roundly discarded quite some time ago. (But close enough that Nancy Lieder took that hypothesis and added Zechariah Stitchin's fluff book and came up with Nibru/Planet X.) He suggests that a red dwarf or brown dwarf neighbor at one third of a light year (K5 to M5 stellar class) may be the Nemesis object. But he needs a bug-a-boo to impel society to take to the planets and terraforming.
I think he should have stopped at Mars. |
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Dr. Mabuse
Septic Fiend
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9688 Posts |
Posted - 01/28/2015 : 08:42:36 [Permalink]
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Originally posted by Dave W.
Yeah, but the calculation needed is whether water vapor can be added to the atmosphere faster than it leaves.
Oh, worse for Mars, its magnetic field is much weaker than Earth's, which means much more atmosphere is just going to be blasted away by the solar wind.
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That's why using PFC is actually a pretty neat idea. The C-F bond is much stronger than C-H making it much more resistant to abuse from the solar wind, and the weight makes it unlikely to be carried off out of the gravity well.
Added water vapor is lost water vapor. My concern is the limited amount of water left.
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Dave W.
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26022 Posts |
Posted - 01/30/2015 : 19:53:56 [Permalink]
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Originally posted by Dr. Mabuse
Originally posted by Dave W.
Yeah, but the calculation needed is whether water vapor can be added to the atmosphere faster than it leaves.
Oh, worse for Mars, its magnetic field is much weaker than Earth's, which means much more atmosphere is just going to be blasted away by the solar wind.
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That's why using PFC is actually a pretty neat idea. The C-F bond is much stronger than C-H making it much more resistant to abuse from the solar wind, and the weight makes it unlikely to be carried off out of the gravity well.
Added water vapor is lost water vapor. My concern is the limited amount of water left. |
Skimming around a bit, in Earth's atmosphere, water vapor rises through the air, finds itself in below-freezing temperatures, and so condenses into ice crystals which, when large enough, fall back to the surface. Would that cycle not function on Mars?
Perhaps because it doesn't get enough altitude, I've seen suggestions that water vapor doesn't get dissociated by sunlight. |
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Entering Space by Robert Zubrin
