Author Topic: Lake Matthew - 2036  (Read 28363 times)

Offline meberbs

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Re: Lake Matthew - 2036
« Reply #180 on: 09/27/2017 07:48 AM »
incredulity at the common calculation of freezing point depression.
You started with the freezing point at -20 C rather than roughly 0 C for no apparent reason. You went on to predict around 5 times the actual freezing point change that would be expected from 0.6 M increase in concentration. If you want to recover some credibility, fixing your mistakes here would be a good place to start. (I rounded a bit to get that you were off by a factor of 5, so that you can demonstrate your understanding of freezing point depression by finding the exact answer.)

"Rambling"?
Rambling refers to being excessively long winded, sometimes covering unrelated topics. I only responded to part of what you had said in your previous post, and not really using more words than the parts of your post I quoted. So if you think my post was rambling, you should check your previous post.

Here the word "analysis" can apply.  We "broke down the topic" of target site optimization, spending time on each aspect, for each candidate site.  The integrated results improved our understanding, uniquely, and under NDA.  That's one analysis.
You put the strangest things under NDA. That sounds like something you should be publishing a scientific paper on if you had anything interesting to share. Given that the only organizations who could possibly act on that information are ones you would partner with anyway to get ground truth and enact your plan, there is nothing to lose by publishing it. On the other hand publishing could spur others to review your work or do related studies that could benefit you. And then you are still not even acknowledging the obvious things I previously mentioned that you claim as "NDA."

Another example of analysis, with all results open:  Dr. Lades analyzed the Mars Lift tether,
How is this remotely relevant? There are lots more issues that I listed and you ignored, not to mention that my post was only a partial list of things you need to address. One reason for only being a partial list is that most questions shouldn't need to be asked. If you have really gone through analysis of your plan, you would have had to have already thought through the issues and should know the major stumbling blocks better than anyone else.  You should be able to preemptively answer the most obvious questions before anyone asks.

Offline Paul451

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Re: Lake Matthew - 2036
« Reply #181 on: 09/28/2017 07:33 AM »
Quote from: meberbs
You put the strangest things under NDA. That sounds like something you should be publishing a scientific paper on if you had anything interesting to share.
Prodding for NDA material is inappropriate, and repetitive prodding, more so.  So stop.

Hiding behind claims of trade secrets is inappropriate when discussing simple, well known (or easily guessable) physical phenomena.

For example, basic crater formation has been understood since Isaac Newton. Similar materials (rock:rock) impacting cannot create a crater with a depth exceeding the diameter of the impactor in the direction of impact. To change that requires reforming the impactor to make it long and thin or to increase its density. Likewise, adding multiple levels or multiple satellite craters requires multiple impactors.

What possible trade secrets can exist in that description?

If you had a never before published method of reshaping an impactor, and/or a method of precisely controlling it during atmospheric entry, then yes that would be a potential trade secret. And meberbs acknowledged that possibility and did not ask for details about that. But simply mentioning that multiple impacts requires multiple impactors is not "prodding for NDA material". Claiming such, particularly complaining to moderators about it, is ridiculous.

Given that you have previously claimed "NDA methods" in order to avoid discussing things like your plan even using an impactor, IMO it is perfectly reasonable for everyone to be skeptical of your current claims that discussing something involves "NDA material". It's what you do.



Quote from: meberbs
You started with the freezing point at -20 C rather than roughly 0 C for no apparent reason.
Calcium chloride solution at 1.7 M freezes at -20 C.  At 2.3 M, -40 C.  So 0.6 M difference, as noted. The incredulous text was inappropriate, there and elsewhere.

Since you failed to mention the first figure, why is being asked to explain that, "inappropriate"?

(Aside: For a -20C freezing point, as meberb notes, the CaCl₂:H₂O mass ratio is 20%. For -40C, you need more than 25% CaCl₂. That is not going to apply to a large body of water, so why mention it as if applying to any significant water reservoir?)



You also completely failed to address meberbs point about your previous claim that the water in the lake would be so hot it would require cooling in order to use it for showering...

Hard, yes.  So much is hard at -60 C:  i.e., a shower:
A shower might use 40 liters at 42 C. [...]
Whereas in the Lake Matthew scheme, the shower water is not heated, but cooled.  Easier.

...but then later claiming that the water is held between 0-11C.



I believe you've also failed to explain the discrepancy between claiming that the pressure in the under-lake open-floored dome is higher than the surrounding water, and therefore keeps the water out, while also claiming that the pressure in the dome is low enough to eliminate buoyancy.

Offline Paul451

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Re: Lake Matthew - 2036
« Reply #182 on: 09/28/2017 07:34 AM »
Re: CaCl₂.

Aside 2: those figures are also close to the eutectic point of 31%. So keeping the salt in solution without it solidifying as CaCl₂6H₂O is going to be difficult, especially if its open to evaporation which raises the salinity. That belies your claim that it "can persist with little active management".



The curve to the left of the eutectic point (A) is the freezing point at that salinity, the curve to the right (between A and B) is the solidification point of the hydrate. Note how sharply the temperature necessary to maintain the liquid phase rises as the salinity increases. There's a very narrow window of salinity where there is a -40C freezing-point benefit.

Aside 3: Perchlorate measurements by Phoenix were 0.6% of regolith by mass. So you'd need to process around 50-70 tonnes of regolith for every tonne of water you want to keep as brine. Unless you have another source of chlorine.

Offline LMT

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Re: Lake Matthew - 2036
« Reply #183 on: 09/28/2017 11:25 AM »
incredulity at the common calculation of freezing point depression.
You started with the freezing point at -20 C rather than roughly 0 C for no apparent reason. You went on to predict around 5 times the actual freezing point change that would be expected from 0.6 M increase in concentration. If you want to recover some credibility, fixing your mistakes here would be a good place to start.

That's the molarity change from -20 C to -40 C, also roughly corresponding with the chart for calcium chloride that paul451 posted.  Where are you getting that "5 times" number? 

And "recover some credibility" is another inappropriate incredulity. 

Correction:  With changing solvent mass the molarity change is more accurately ~ 1 M.  So you're claiming 3x less change in freezing point.
« Last Edit: 09/28/2017 01:48 PM by LMT »

Offline LMT

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Re: Lake Matthew - 2036
« Reply #184 on: 09/28/2017 12:11 PM »
Quote from: Paul451
Hiding behind claims of trade secrets is inappropriate when discussing simple, well known (or easily guessable) physical phenomena.

If someone claimed an invention that defied known physics, under NDA, you'd suspect "hiding".  But where physical possibility is acknowledged, as with MATT, there's no such issue, obviously.   You should remove any insinuation of "hiding". 

Quote from: Paul451
For -40C, you need more than 25% CaCl₂. That is not going to apply to a large body of water, so why mention it as if applying to any significant water reservoir?

Those numbers are in rough agreement with my note on brine freezing, yes?

And surely brine concentration can be applied to Omaha Crater reservoirs.  Zero Liquid Discharge water treatment produces salt byproduct in bulk.  Moreover regolith rinsing is possible, even outdoors in summer, under the site's proposed 1.3 kPa atmospheric pressure.  These would be scalable sources of brine.

Quote from: Paul451
I believe you've also failed to explain the discrepancy between claiming that the pressure in the under-lake open-floored dome is higher than the surrounding water, and therefore keeps the water out, while also claiming that the pressure in the dome is low enough to eliminate buoyancy.

No, you've confused something there; those aren't my words.  Dome perimeter air pressure must equal water pressure for moon pool formation.   And I recall you had an incorrect understanding of buoyancy.  You might reexamine the actual F(bot) buoyancy force, to separate it clearly from the force due to air pressure.
« Last Edit: 09/28/2017 02:26 PM by LMT »

Offline LMT

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Re: Lake Matthew - 2036
« Reply #185 on: 09/28/2017 12:16 PM »
Quote from: Paul451
keeping the salt in solution without it solidifying as CaCl₂6H₂O is going to be difficult, especially if its open to evaporation which raises the salinity. That belies your claim that it "can persist with little active management".

Brines are easily managed on Earth, under evaporation.  And the reservoir would be ice-covered, with sublimation rate roughly equal to Earth evaporation rate.  That should keep that particular problem manageable.
« Last Edit: 09/28/2017 02:25 PM by LMT »

Offline Lar

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Re: Lake Matthew - 2036
« Reply #186 on: 09/28/2017 02:22 PM »
This thread was trimmed just now, but it's still problematic.

"So what's the problem?" is problematic, just to pick one example.

I'm not one to swing the machete the way some other mods do but if the tone doesn't improve, I will. Some wheat will go with the chaff. It is entirely reasonable to question assumptions and ask for clarification, and to question bonafides (up to a point). Combative responses are not helpful.
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Offline Paul451

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Re: Lake Matthew - 2036
« Reply #187 on: 09/28/2017 02:31 PM »
Quote from: Paul451
Hiding behind claims of trade secrets is inappropriate when discussing simple, well known (or easily guessable) physical phenomena.
If someone claimed an invention that defied known physics, under NDA, you'd suspect "hiding".  But where physical possibility is acknowledged, as with MATT, there's no such issue, obviously. You should remove any insinuation of "hiding".

Are you really claiming you don't know the difference between a genuine invention and an existing known physical phenomenon?

Or do you deny that you initially refused to acknowledge that your plan used an asteroid impactor because it was proprietary? Do you still claim that the idea of using a redirected asteroid to create a crater is somehow proprietary knowledge?



Quote from: Paul451
For -40C, you need more than 25% CaCl₂. That is not going to apply to a large body of water, so why mention it as if applying to any significant water reservoir?
Those numbers are in rough agreement with my note on brine freezing, yes?

Not as claimed by your molar numbers.

Quote from: Paul451
keeping the salt in solution without it solidifying as CaCl₂6H₂O is going to be difficult, especially if its open to evaporation which raises the salinity. That belies your claim that it "can persist with little active management".
Brines are easily managed on Earth, under evaporation.

On Earth, brines are not operated near their eutectic points unless you are trying to precipitate out the target salt (such as the crystallisation stage of ZLD treatment, or, hell, any salt works.) They are either at relatively low salinity (5-10%) or are intentionally over the eutectic point in order to induce precipitation; they are not trying to maintain liquid solution in open pools near the eutectic point at sub-zero temperatures in the narrow window between freezing and solidifying.

And surely brine concentration can be applied to Omaha Crater reservoirs.

Over 25% salinity by weight? In other words, around a fifth of the volume of the crater as one specific salt.



Dome perimeter air pressure must equal water pressure for moon pool formation.  And I recall you had an incorrect understanding of buoyancy, which couldn't help.  You might reexamine the actual F(bot) buoyancy force, to separate it clearly from the force due to air pressure.

As I've noted much earlier in the thread, and in other threads you hijacked, you can't just measure the mass of water above the dome and say "that's how much force is holding it down". That's not how buoyancy works. The water under the dome, or trying to get under the rim of the dome, is under an even greater mass of water (depth of the dome plus height of the dome). That difference in pressure is where buoyancy force comes from.

(And if you have a "moon pool", you certainly can't claim that the rim is somehow also sealed.)

--

{quote author=Paul451}

Aside: Please quote people properly. The site makes it easy. Failing to do so makes it difficult for people to follow threads in the future.

Offline meberbs

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Re: Lake Matthew - 2036
« Reply #188 on: 09/28/2017 03:07 PM »
incredulity at the common calculation of freezing point depression.
You started with the freezing point at -20 C rather than roughly 0 C for no apparent reason. You went on to predict around 5 times the actual freezing point change that would be expected from 0.6 M increase in concentration. If you want to recover some credibility, fixing your mistakes here would be a good place to start.

That's the molarity change from -20 C to -40 C, also roughly corresponding with the chart for calcium chloride that paul451 posted.  Where are you getting that "5 times" number?
The change in water freezing point is linear with number of ions and otherwise independent of the specific dissolved substance for reasonable concentrations. Since you had not provided a starting concentration, I simply calculated the expected freezing point for calcium chloride for a 0.6M solution.

Correction:  With changing solvent mass the molarity change is more accurately ~ 1 M.  So you're claiming 3x less change in freezing point.
Thank you for admitting this mistake. I had previously calculated as well that it is about 1 M to get from -20 to -40 C (post was lost in the thread reorganization)

Quote from: Paul451
For -40C, you need more than 25% CaCl₂. That is not going to apply to a large body of water, so why mention it as if applying to any significant water reservoir?
Those numbers are in rough agreement with my note on brine freezing, yes?
Or are you now trying to take back the admission of your mistake? 0.6M and 1M are not in "rough agreement"

Now that we established that your claims related to freezing point concentrations were inaccurate, maybe you can address some of the other issues you have been ignoring.

Offline LMT

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Re: Lake Matthew - 2036
« Reply #189 on: 09/29/2017 02:18 AM »
Are you really claiming you don't know the difference between a genuine invention and an existing known physical phenomenon?

Or do you deny that you initially refused to acknowledge that your plan used an asteroid impactor because it was proprietary? Do you still claim that the idea of using a redirected asteroid to create a crater is somehow proprietary knowledge?

Well, you've shifted from the insinuation of "hiding" to a "Do you deny / Do you still claim [some strawman]" phrasing.  Direct quote of the actual statement helps setup a question. 

Of course, if one has curiosity on NDA topics one can just ask for an NDA conversation. 

Quote from: Paul451
For -40C, you need more than 25% CaCl₂. That is not going to apply to a large body of water, so why mention it as if applying to any significant water reservoir?
Those numbers are in rough agreement with my note on brine freezing, yes?

Not as claimed by your molar numbers.

?  I corrected to 1 M delta, up above.  What molarity did you get?

On Earth, brines are not operated near their eutectic points unless you are trying to precipitate out the target salt (such as the crystallisation stage of ZLD treatment, or, hell, any salt works.) They are either at relatively low salinity (5-10%) or are intentionally over the eutectic point in order to induce precipitation; they are not trying to maintain liquid solution in open pools near the eutectic point at sub-zero temperatures in the narrow window between freezing and solidifying.

You didn't mention evaporation.  Is that not a concern now, given the slow sublimation rate of ice?

And yes, -40 C is getting down there, even for CaCl2 brine, but that was just an illustration of brine's utility in extreme winter, not a suggestion for a daily operating target.  Naturally you'd want brine pools in bedrock that's warmer, somewhere around the heat lens' 0 C perimeter.  If none are quite warm enough, a very shallow borehole into the underlying lens could act as a simple heat exchanger to increase the liquid temperature.

To pick a range, maybe 15 C to -15 C?  With such a rock temperature, when brine freezes at the surface, the precipitate goes back into solution further down the water column, passively managed.

Over 25% salinity by weight? In other words, around a fifth of the volume of the crater as one specific salt.

Much less in the warmer reservoirs.  And it wouldn't be just one cation; presumably the mix would be opportunistic.  As the stockpile grows, the size and number of brine reservoirs can grow with it; molarity too, if colder reservoirs are unavoidable.  But even in deep winter you wouldn't be actively adding salt for the entire water mass; surface freezing many meters deep injects more salt into the brine beneath, increasing molarity passively.

if you have a "moon pool", you certainly can't claim that the rim is somehow also sealed.

?  I think you've mixed in someone else's idea there.  Moon pools don't need a seal; they're open to the air, by definition. 

Offline LMT

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Re: Lake Matthew - 2036
« Reply #190 on: 09/29/2017 03:00 AM »
[
Correction:  With changing solvent mass the molarity change is more accurately ~ 1 M.  So you're claiming 3x less change in freezing point.
Thank you for admitting this mistake. I had previously calculated as well that it is about 1 M to get from -20 to -40 C (post was lost in the thread reorganization)

Quote from: Paul451
For -40C, you need more than 25% CaCl₂. That is not going to apply to a large body of water, so why mention it as if applying to any significant water reservoir?
Those numbers are in rough agreement with my note on brine freezing, yes?
Or are you now trying to take back the admission of your mistake? 0.6M and 1M are not in "rough agreement"

I was asking for his numbers, for cross-check.  If his delta was also about 1 M, there's no longer disagreement in thread on this.

Now that we established that your claims related to freezing point concentrations were inaccurate, maybe you can address some of the other issues you have been ignoring.
« Last Edit: 09/29/2017 04:24 AM by Lar »

Offline Lar

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Re: Lake Matthew - 2036
« Reply #191 on: 09/29/2017 03:03 AM »
When you lead off with junk-psych like, "I hope you don't think that your last post had wowed everyone into acceptance," you're asking to be ignored.  So it's a tone to drop, cold, moving forward. 

(mod) Knock off the tone policing. That's not a request.
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Offline LMT

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Re: Lake Matthew - 2036
« Reply #192 on: 09/29/2017 03:43 AM »
Sounds like you would in fact have to heat the water first. By the way have you tried making an energy balance to figure out how much faster the crater will run out of heat with all of the ways you are using up energy?

Heat exchangers could be deployed on hotspots, in boreholes, or on the lakebed.  They would heat water, yes, and with useful efficiency, as they require electricity only for the pump, and not for the heating itself. 

The giant habs would probably be the prime sites of heat loss.  For dome heating, freshwater would be pumped through an exchanger and into the dome.  A calc for a 300-m dome calls for a pump rated at ~ 7 kW, lifting 12 liters/s.  Dome heat loss rate is roughly 2.3 MW, perhaps 18 hrs per sol.

For a set of hab, greenhouse and industrial domes, daily heat loss would total 450 billion J.  If the heat lens were devoted to heating just those giant domes, and had no other heat outlet, the bedrock would approach 0 C in about 6000 Earth years.

Heat is lost slowly elsewhere of course, and 10^18 J is a conservative estimate of sensible heat in the heat lens, but that's the rough scale.

Is that a surprising result, or about what you expected?

Offline meberbs

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Re: Lake Matthew - 2036
« Reply #193 on: 09/29/2017 05:59 AM »
Sounds like you would in fact have to heat the water first. By the way have you tried making an energy balance to figure out how much faster the crater will run out of heat with all of the ways you are using up energy?

Heat exchangers could be deployed on hotspots, in boreholes, or on the lakebed.  They would heat water, yes, and with useful efficiency, as they require electricity only for the pump, and not for the heating itself. 

The giant habs would probably be the prime sites of heat loss.  For dome heating, freshwater would be pumped through an exchanger and into the dome.  A calc for a 300-m dome calls for a pump rated at ~ 7 kW, lifting 12 liters/s.  Dome heat loss rate is roughly 2.3 MW, perhaps 18 hrs per sol.

For a set of hab, greenhouse and industrial domes, daily heat loss would total 450 billion J.  If the heat lens were devoted to heating just those giant domes, and had no other heat outlet, the bedrock would approach 0 C in about 6000 Earth years.

Heat is lost slowly elsewhere of course, and 10^18 J is a conservative estimate of sensible heat in the heat lens, but that's the rough scale.

Is that a surprising result, or about what you expected?
This is about what I expected in that it indicates that you have not done a full analysis of your plan. Right here you mentioned a couple specific uses of energy, but did not include multiple other ways energy is consumed that you have mentioned previously, or include how much is just lost to natural conduction etc.

What I am asking for seems like a lot, but given that you are proposing this and have gone as far as to get legal advice, people would expect you to have already done at least that much. Here you wouldn't have to provide the entire detailed analysis if it would reveal some truly innovative technology you have, but a summary that shows crater remaining heat and temperature vs. time, a breakdown of the different mechanisms of heat loss, and consumption. (ground conduction, atmospheric and evaporation, energy generation, base heating, melting and warming additional water, etc.) Efficiency, rates and such would change with time, since they would depend on the current crater temperature.

Are you really claiming you don't know the difference between a genuine invention and an existing known physical phenomenon?

Or do you deny that you initially refused to acknowledge that your plan used an asteroid impactor because it was proprietary? Do you still claim that the idea of using a redirected asteroid to create a crater is somehow proprietary knowledge?

Well, you've shifted from the insinuation of "hiding" to a "Do you deny / Do you still claim [some strawman]" phrasing.  Direct quote of the actual statement helps setup a question. 

Of course, if one has curiosity on NDA topics one can just ask for an NDA conversation. 
You seem to be missing the point of the mentions of NDA.
First the quotes you asked for:
In the Lake Matthew design, one quintillion Joules of sensible heat is liberated by proprietary means into bedrock at the site.
That's still the equivalent of a 240 megatons of TNT. Or about five Tsar Bomba nuclear weapons. If you're just going to handwave that away with "proprietary process", no one is going to take you seriously.

Nuclear explosives are not used.  The legal team knows the specifics, and has recommended the NDA on this point.  But many other things can be discussed in open forum.
Go back and read the first page of this thread to see just how quickly it was deduced that asteroid impact was the method you were using. From that point on, there was literally nothing gained by you not acknowledging the method you are using. You can't put the cat back in the bag. Your legal team is apparently not sufficiently familiar with the aerospace industry to understand how easy your solution is to predict. Eventually, you acknowledged that that in fact is what you are doing, but there are multiple other pieces of information you are now claiming as NDA, but are completely obvious with no point in pretending otherwise.

Offline Paul451

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Re: Lake Matthew - 2036
« Reply #194 on: 10/02/2017 09:32 AM »
Are you really claiming you don't know the difference between a genuine invention and an existing known physical phenomenon?
Or do you deny that you initially refused to acknowledge that your plan used an asteroid impactor because it was proprietary? Do you still claim that the idea of using a redirected asteroid to create a crater is somehow proprietary knowledge?
Well, you've shifted from the insinuation of "hiding"

I didn't insinuate "hiding", I stated it plainly. I used the word. And I didn't shift, I'm saying you have a pattern of hiding behind false claims of trade secrets ("under NDA", "NDA material", "proprietary method"), I then used that first page asteroid thing as an example. Then I asked if you now deny that it happened.

to a "Do you deny / Do you still claim [some strawman]" phrasing.

"Strawman" means a false argument claimed in another's name, set up to be knocked down in place of their actual argument. You are therefore "insinuating" that you didn't initially refuse to mention asteroid impacts as the source of heat, under the guise of trade secrets (for eg, the text that Meberbs quoted), and that I'm making up such a claim. That's what "strawman" means, that I invented a fake statement in your name. Is that what you are saying? That you didn't make the comment, and I made it up? If so, don't insinuate that I'm lying, state it plainly.

if you have a "moon pool", you certainly can't claim that the rim is somehow also sealed.
?  I think you've mixed in someone else's idea there.  Moon pools don't need a seal; they're open to the air, by definition.

If there's a moon-pool, the dome is connected to the outside lake that's around and above the dome. The dome will therefore experience buoyancy equal to its displacement of water. That's how buoyancy works. (By mentioning a sealed rim, I was eliminating the only possible way of avoiding buoyancy, a partial vacuum under the dome with a water-tight seal around the dome. I could have also pointed out that with broken bedrock of an impact crater, that also means you can't have a water-tight seal.)

Offline LMT

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Re: Lake Matthew - 2036
« Reply #195 on: 10/04/2017 02:25 AM »
[I want] a summary that shows crater remaining heat and temperature vs. time, a breakdown of the different mechanisms of heat loss, and consumption. (ground conduction, atmospheric and evaporation, energy generation, base heating, melting and warming additional water, etc.) Efficiency, rates and such would change with time, since they would depend on the current crater temperature.

That's quite the grab-bag of wants.  But no, the mentioned references give what's needed at this time.  Omaha Crater, at ~9 km, would have properties in the scope of the following modeled craters, from the list of useful papers previous:

7 km crater of Rathbun and Squyres 2002 (hydrothermal flow)
14 km crater of Schwenzer et al. 2012 (dry cryosphere above confined aquifer)
30 km crater with lake in Abramov and Kring 2005 (full crater lake)

The region of the preferred target site is known to have abundant near-surface ice, so the "dry cryosphere" condition is not applicable; but the 14-km scale of that example is illustrative. 

Another caveat:  Craters at the smaller end of that scale likely have some hot spot temperatures exceeding model expectation, judging from the mineral evidence of terrestrial Lonar Crater, in Hagerty and Newsom 2003.

A proper field study, with drilling etc., would be required to quantify everything for detailed modeling of the future crater.  Meanwhile there's no reason to think that Omaha Crater would have properties outside the scope of the example models.  That is, no reason to expect anything other than a crater with heat and water for millennia.  10^18 Joules of bedrock heat isn't quickly spent, nor several cubic km of meltwater.  Plus of course there's impact vapor condensation to add to the total, and also upland near-surface ice that's available for supplemental harvest.

But focusing on the crater itself, if you want to see how the various geophysical parameters alter a crater profile over time, you can consider the example models. 

Quote from: LMT
Thawing or fracturing of the cryosphere base would admit a hypothetical closed aquifer into the crater bedrock and potentially the surface water bodies.  The existence of a closed aquifer is unknown, but given the widespread regional evidence of ice, a closed aquifer should be considered.
Here are more examples of you listing various ways things could go well if you get lucky. A serious analysis would consider whether or not the plan is viable if none of these bonus things happen. Bringing them up before all of the ways things can go wrong are addressed is a waste of time.

No, that reading doesn't make sense.  Meltwater throughout the heat lens is the expected, unavoidable first water source, and a valid reason for confidence.  Aquifer beneath the cryosphere is neither assumed nor needed for viability; it's just a further possibility.  You should have acknowledged the unavoidable first water source.


Offline LMT

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Re: Lake Matthew - 2036
« Reply #196 on: 10/04/2017 03:16 AM »
If there's a moon-pool, the dome is connected to the outside lake that's around and above the dome. The dome will therefore experience buoyancy equal to its displacement of water. That's how buoyancy works. (By mentioning a sealed rim, I was eliminating the only possible way of avoiding buoyancy, a partial vacuum under the dome with a water-tight seal around the dome. I could have also pointed out that with broken bedrock of an impact crater, that also means you can't have a water-tight seal.)

Instead of re-arguing buoyancy, and re-ignoring the physical meaning of F(bot), consider applying your understanding to a simplified dome case.  Your sketch and force calculations should make the mistake evident.

you have a pattern of hiding behind false claims of trade secrets

No. 

Now I'll ask one last time, because you still haven't finished your statement:  did you also get a 1 M delta on that CaCl2 brine?

Offline meberbs

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Re: Lake Matthew - 2036
« Reply #197 on: 10/04/2017 07:14 AM »
[I want] a summary that shows crater remaining heat and temperature vs. time, a breakdown of the different mechanisms of heat loss, and consumption. (ground conduction, atmospheric and evaporation, energy generation, base heating, melting and warming additional water, etc.) Efficiency, rates and such would change with time, since they would depend on the current crater temperature.

That's quite the grab-bag of wants.  But no, the mentioned references give what's needed at this time.  Omaha Crater, at ~9 km, would have properties in the scope of the following modeled craters, from the list of useful papers previous:

What you are saying here is that you haven't even done a basic analysis yourself of the idea you are proposing. The papers you reference are obviously not going to include energy removed from the crater in all the various ways you plan to actively do so. None of the rest of your post even begins to address this, though you again mention bringing in more ice to melt with no apparent consideration of how that would reduce the available energy.

And "I want" is a complete misquote of me. I was providing a partial list of things you should already have analyzed if you had actually done any work to make sure your idea is viable. Specifically I said "people would expect you to have already done at least that much." The list was an example of what you could cover at a high level summary to make it sound like you have actually done the detailed analysis.

Quote from: LMT
Thawing or fracturing of the cryosphere base would admit a hypothetical closed aquifer into the crater bedrock and potentially the surface water bodies.  The existence of a closed aquifer is unknown, but given the widespread regional evidence of ice, a closed aquifer should be considered.
Here are more examples of you listing various ways things could go well if you get lucky. A serious analysis would consider whether or not the plan is viable if none of these bonus things happen. Bringing them up before all of the ways things can go wrong are addressed is a waste of time.

No, that reading doesn't make sense.  Meltwater throughout the heat lens is the expected, unavoidable first water source, and a valid reason for confidence.  Aquifer beneath the cryosphere is neither assumed nor needed for viability; it's just a further possibility.  You should have acknowledged the unavoidable first water source.
Try reading my post again, you seem to have missed the point. The point was that you shouldn't bother discussing the "further possibilities" until you have shown that everything balances without them. Until you do so, mentioning them is a distraction.

you have a pattern of hiding behind false claims of trade secrets

No.
I literally quoted you doing so.

Now I'll ask one last time, because you still haven't finished your statement:  did you also get a 1 M delta on that CaCl2 brine?
I did and posted it before you did (post was part of a group that got removed.)

We have established that your original statements were wrong. Why are you asking for further confirmation?

Offline Paul451

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Re: Lake Matthew - 2036
« Reply #198 on: 10/04/2017 01:36 PM »
If there's a moon-pool, the dome is connected to the outside lake that's around and above the dome. The dome will therefore experience buoyancy equal to its displacement of water. That's how buoyancy works. (By mentioning a sealed rim, I was eliminating the only possible way of avoiding buoyancy, a partial vacuum under the dome with a water-tight seal around the dome. I could have also pointed out that with broken bedrock of an impact crater, that also means you can't have a water-tight seal.)
Instead of re-arguing buoyancy, and re-ignoring the physical meaning of F(bot)

I'm not ignoring it. I'm waving it around like a frickin' banner. It's the whole frickin' point of what I'm saying.

You are pretending there is no F(bot) component because your dome is on the ground. And that is specifically the case I was eliminating by mentioning the connection between the interior and exterior. P(bot) on the ground is equal to P(bot) if the dome was one inch above the ground is equal to P(bot) if the dome was at the same depth in a theoretically ideal bottomless water column. Hence in all three cases F(bot) is the same, hence F(top)-F(bot) is the same, hence buoyancy is the same.

You can demonstrate this in practice with a simple inverted bowl in a tub or pool. Only when you reduce the pressure inside the bowl compared to the surrounding water, and have sufficient ground-seal to prevent water ingress restoring the pressure, can you remove enough of P(bot) (hence F(bot)) to overcome buoyancy. If there's a water connection between the inside and outside, you can't maintain reduced internal pressure, therefore there's no possible way to avoid buoyancy.

(Aside: You can also try with a tub of saturated sand at the bottom of the pool with an inverted bowl "dome" smaller than the diameter of the tub (or try it at the beach under a few feet of water, or ten.) Push the rim of the air-filled submerged "dome" into the sand, without touching the bottom of the tub. Reduce the air-pressure inside the "dome" via your preferred method. Then measure the buoyancy compared to when you can adequately seal the rim of the "dome".)

I will say that domes are an interesting case for buoyancy. Usually we ignore the implied internal pressure of the buoyant object and just treat pressure on the walls of the object as not requiring/implying balancing forces. But the air inside the dome requires us (well, not you apparently) to restore that component and consider how changing the internal pressure alters the pressure balance and therefore forces on the dome as a whole. Nerdy fun stuff.

[My favourite example: Take two bowls, one inverted (as a "dome") on top of one normally upright, cupped together at the rims. Submerge them together. Surface tension is enough to keep water from entering the bowls and filling the lower bowl, even if the join around the rims is pretty uneven. You can easily convince yourself by demonstration (through separating the bowls carefully until water flows in) that the bottom bowl initially has no water in it. Therefore the mass of water above the top bowl is unbalanced by any water below. Now hold the bottom bowl firmly (removing F(bot) from the water under the bottom bowl) and let go of the top bowl. It will immediately rise exactly the same as it would if the bottom bowl wasn't there. The air-pressure inside the bowls is equivalent to the water pressure around the bowls. Therefore P(bot)...  therefore F(bot)... therefore buoyancy... Woo! Science!]

Your sketch and force calculations should make the mistake evident.

Right back at you.

And I have previously (going back to the Scaling Agriculture on Mars and Envisioning Amazing Martian Habitats threads) asked you to sketch your lake/dome concept.

[or at least someone did:
You should consider making a complete diagram of your installation. Right now we can piece it together by reading the hints you spread in your posts, but that's tedious and few people will do it. And I imagine if you didn't want people to have an idea of the whole thing, you would not be talking about it.

Offline Paul451

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Re: Lake Matthew - 2036
« Reply #199 on: 10/04/2017 01:47 PM »
you have a pattern of hiding behind false claims of trade secrets
No.

Do you deny saying this:

In the Lake Matthew design, one quintillion Joules of sensible heat is liberated by proprietary means into bedrock at the site.
[...]
We dont mean to tease, but there are trade secrets at work here.  Everyone is free to speculate, and we can talk about things that arent secret [...] but some things can only be discussed under NDA.

or this

wrt the notional "Lake Matthew":  It's our unobvious, proprietary methods that liberate 1018 Joules of sensible heat in bedrock, whereby Lake Matthew becomes possible.

The "means" of liberating heat was an asteroid impact (or series of impacts). Which is not proprietary, is not a trade secret. So why did you pretend it was? Why did you refuse to confirm even that simple obvious fact for the many pages into the thread (and those other threads) even though it was the obvious first guess? [Funny enough, the thing that actually confused everyone was your submerged dome. You were waffling away talking about heat exchange fountains, yet you hadn't (and still haven't) posted so much as a napkin sketch of the overall concept.]

Speaking of...

Speaking both for myself and for the whole Lake Matthew Team...

I think most of us are pretty sure the "Lake Matthew Team" is just you.

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