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#1 2019-08-31 20:20:19

SpaceNut
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Artificial Valley Atmospher Pressure

I think this would be sort of what is wanted:

tahanson43206 wrote:

For SpaceNut .... here is a possible new topic.  I searched for "drill and down" and found 13 pages of interesting posts about looking for water and other substances, but nothing showed up along the lines of what I'm offering here.  Please move this to the right topic, as I'm sure there must be a better one than the chat.

Given that atmospheric pressure at the surface of Mars varies depending upon elevation, with the greatest pressure found in valleys, is there a point at which the pressure would equal Earth sea level pressure, if someone were to drill far enough down?

Anticipating possible replies from forum members, I'm not sure there would be a particular advantage to having a location below ground where Earth sea level pressure can be maintained without mechanical support, but perhaps there might be a reason this would be a good idea.

(th)

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#2 2019-08-31 20:25:57

SpaceNut
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Re: Artificial Valley Atmospher Pressure

Sort of like an open pit mining where the removal of materials is a spiral down leaving a cone shape for the pressure to increase.

3-s2.0-B9780128023198000103-f10-01-9780128023198.jpg?_


1-s2.0-S0074614299800369-gr3.gif?_

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#3 2019-08-31 21:22:01

SpaceNut
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Re: Artificial Valley Atmospher Pressure

Starting with what we know

Standard sea-level air pressure on Earth is 1,013 millibars.

https://en.wikipedia.org/wiki/Atmosphere_of_Mars

The surface pressure is only about 610 pascals (0.088 psi) which is less than 1% of the Earth's value

Goggling topic:

https://astronomy.stackexchange.com/que … t-on-earth

This one indicates a depth of 55km

https://marsed.asu.edu/mep/atmosphere

lowest place on Mars lies in the Hellas impact basin, 7.2 km (4.4 mi) below "sea level."

The pressure there averages about 14 millibars.

But on top of Olympus Mons, 22 km (14 mi) high, the pressure is only 0.7 millibar.

https://www.quora.com/Mars-At-what-alti … sure-1-bar

Of course so far we are using just co2 where we will want it to be breathable so we will want at depth oxygen, nitrogen but we would also need ozone plus other gas mixes to make it healthy for man.

https://www.reddit.com/r/askscience/com … derground/

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#4 2019-09-01 05:48:51

tahanson43206
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Re: Artificial Valley Atmospher Pressure

for SpaceNut re Topic!

First, thanks for creating this new topic, and for finding all the supporting pictures and links!

The Reddit reply seems (to me at least) particularly helpful.   It arrives at a figure of 11.1 kilometers of depth, which is (from my point of view) much less than I had feared, and it has the potential of being achieved.  the Reddit author points out (as I recall the article) that on Earth such depths have not been achieved on land, but the gravity is much greater.  My hope would be that on Mars the mechanical factors that would inhibit drilling to such a depth would be less than on Earth, but the initial attempt to pound a rod into Mars did not go well.  My (limited) understanding is that the rod could not be hammered because the soil jiggled with the hammer blows, instead of receding and gripping, as (apparently) was expected.

However, the Reddit article presents a challenge that (I believe) cannot be answered right now, and that is the amount of heating that would be experienced by an instrument placed at the bottom of an 11.1 km shaft on Mars.  My understanding is that the failed probe was intended to attempt to measure temperature inside Mars.  If there is still a warm core in Mars, then it could (presumably) be tapped for energy.  However, it would heat the instrument at the bottom of the bore hole, although (at this point) there is no way to know by how much.

If on the other hand, the core of the planet has cooled significantly, then it would (potentially) not have much of an impact upon the instrument at the bottom of the bore hole.

The Reddit article seems (as I read it) to imply that heating of the atmosphere would occur naturally as pressure increases .  I'd appreciate some help from more knowledgeable forum members on that point.  The atmosphere would NOT be compressed by a piston (for example).  It would be compressed by gravity.  Is there a natural heating of a gas as it is compressed by gravity?  I would think that because a gas is free to distribute heat evenly, it would do so, and therefore the gas compressed by gravity would be the same temperature throughout the column.

(th)

Last edited by tahanson43206 (2019-09-01 05:51:15)

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#5 2019-09-01 17:45:44

SpaceNut
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Re: Artificial Valley Atmospher Pressure

Compression from a heat source can only happen when there is containment that will amount to anything. See compressing co2 from heat.

The open atmosphere does shrink and rise with the cycle of mars rotation in that the sunward side with have a greater altitude but as a result its pressure is also lower with that altitude with only slight pressure gain at the surface.

The cold side of mars has a lower altitude of atmosphere but the pressure is going to be higher as a result of the denser atospher as its cold.

The lesser value of a hole depth looks better and better as the inside of the hole can be used to create a burm at the surface to create a greater level of possible means to concentrate the air of mars.

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#6 2019-09-01 19:34:06

SpaceNut
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#7 2019-09-01 19:41:26

louis
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Re: Artificial Valley Atmospher Pressure

This thread has just made me think...

Could you have an artificial atmosphere in a gorge based on the following:

1. Intake fans built into the ground to suck the air in and recirculate via pipes to the top of the gorge.

2. So all along the gorge there would be a circular flow of air from top to bottom.

3. The  top of the gorge would be covered in multiple - maybe thousands - of gossamer-like coverings, to attenuate the vaccuum effect (the differential pressure between the gorge and the outer Mars atmospheric pressure which is v. low).

How much energy per sq. metre would such a system require?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#8 2019-09-01 20:11:01

tahanson43206
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Re: Artificial Valley Atmospher Pressure

For SpaceNut re topic in general...

Google came up with the following discussion when I asked it about pressure at depth on Mars.

https://astronomy.stackexchange.com/que … t-on-earth

Unlike the Reddit discussion cited (by SpaceNut) earlier, which came up with -11 km depth, this one offers -55 km as the needed depth.

In addition, the stackexchange offering reports -24 km as the Armstrong limit.

That is quite a difference.  The discrepancy between the two offerings may be sufficient to inspire a mathematician (or equivalent) to compare them.  I would be grateful for an explanation of the reason(s) for the difference.  There may be an error of computation, or inputs used for the estimates may have been different and perhaps obsoleted by subsequent rover or satellite information.

(th)

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#9 2019-09-01 20:15:14

SpaceNut
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Re: Artificial Valley Atmospher Pressure

Solar heat concentrating, solar chimney or evn the heat of an rtg or nuclear source could be used to help in the moving of air to the gorge.

http://newmars.com/forums/viewtopic.php?id=243
http://newmars.com/forums/viewtopic.php?id=261

Air curtain is what you are thinking of to a degree and of an air ram to force air into the gorge as well.

http://www.gasho.org/wp-content/uploads … Basics.pdf

BLOWER AND MOTOR CALCULATIONS
http://docshare01.docshare.tips/files/1 … 657364.pdf

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#10 2019-09-01 20:21:44

kbd512
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Re: Artificial Valley Atmospher Pressure

tahanson43206,

The primary problem you're going to have with drilling deep enough for a column of CO2 to provide Earth sea level or even Himalayan mountain type atmospheric pressure has nothing to do with containing the atmosphere and everything to do with holding back the immense pressure of the ground in the vertical tube / shaft / tunnel from collapsing in.

I've seen this idea before.  To achieve an atmospheric pressure equal to that at the summit of the tallest mountains in the Himalayas, you'd need to drill about 20km deep.  The Kola bore hole was 9 inches in diameter and just 12.2km in depth.  That took Russia about 20 years.  However, Maersk Oil achieved the same feat in less than 2 months.  Exxon completed a similar well with abut 12km of vertical drilling and another 12km of horizontal drilling in just under 2 months.  I'd like to point out that the temperature at the bottom of the Kola bore hole was 356F.  You've merely traded one pressure and temperature problem for even more extreme problems of the same type.

Louis,

Why not just stay inside a pressurized habitat?

What is the end goal here?

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#11 2019-09-01 20:41:52

SpaceNut
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Re: Artificial Valley Atmospher Pressure

I got thinking about air flow and the laptop cooler panel came to mind for creating a down pressure for the gorge.

http://www.sunon.com/uFiles/file/03_pro … gy/004.pdf

http://www.componentsengineering.com/wp … ations.pdf

th?id=OIP.j_3rKA5-0Q9DpgzARn_tlwHaFd&w=291&h=196&c=7&o=5&pid=1.7

th?id=OIP.aYF2VkAOdHgJWRHTbKOVFAHaEL&w=300&h=169&c=7&o=5&pid=1.7

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#12 2019-09-01 22:33:25

kbd512
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Re: Artificial Valley Atmospher Pressure

It's possible to pressurize a shaft with a turbine by restricting the flow of the gas escaping a shaft.  We wouldn't have to dig down so far and the temperature increase from pressurizing the CO2 could be regulated with intercooling to provide a livable temperature.  You'd still need an oxygen mask, but wouldn't have to wear any kind of pressure suit or cold weather garments.  That would certainly making manual labor during construction easier.  In the end, a surface or subsurface habitat module in a shallow bore hole with just enough regolith over the top to attenuate the radiation is still the best human habitation concept that we've come up with.

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#13 2019-09-02 08:20:38

tahanson43206
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Re: Artificial Valley Atmospher Pressure

For kbd512 ....

Thank you for taking up this question!

Aside from the side pressure issue, which I concede, your reply was helpful in adding weight to the Stackexchange prediction, as compared to the Reddit one. By extrapolation, I'm deducing that the 20 km depth you've cited is within the margin of error for the Armstrong limit. 

Combining the ideas presented in this topic, as you have done here, seems like a useful compromise.

Where I was headed was to try to find a depth at which Earth normal (sea level) pressure could be maintained without mechanical assistance.  Your alternative (as I understand it) is to compromise by keeping some mechanical assistance but reducing it by taking advantage of the increased pressure with depth.

In practice, I would expect humans to seek an optimum solution somewhere between the extremes of trying to live on the surface, and living comfortably without mechanical assistance at depth.

For someone with more current math skills than I am able to muster at this point, I'd appreciate clarification of the computations which led the Stackexchange author to the 22 km Armstrong prediction, or the 45 km sea level equivalent.

For anyone .... to the best of my knowledge, no one (on Earth for sure) has any idea what temperatures may be found when measurements are taken at Mars.

There are speculations in great number, and some may even rise to the level of "educated guesses", but that's all they are until measurements are taken.

I would presume that the researchers who failed with their first attempt to pound a stake into the regolith are hard at work trying to design an improved instrument able to overcome whatever unexpected properties are (by now) known to exist there.

(th)

kbd512 wrote:

tahanson43206,

The primary problem you're going to have with drilling deep enough for a column of CO2 to provide Earth sea level or even Himalayan mountain type atmospheric pressure has nothing to do with containing the atmosphere and everything to do with holding back the immense pressure of the ground in the vertical tube / shaft / tunnel from collapsing in.

I've seen this idea before.  To achieve an atmospheric pressure equal to that at the summit of the tallest mountains in the Himalayas, you'd need to drill about 20km deep.  The Kola bore hole was 9 inches in diameter and just 12.2km in depth.  That took Russia about 20 years.  However, Maersk Oil achieved the same feat in less than 2 months.  Exxon completed a similar well with abut 12km of vertical drilling and another 12km of horizontal drilling in just under 2 months.  I'd like to point out that the temperature at the bottom of the Kola bore hole was 356F.  You've merely traded one pressure and temperature problem for even more extreme problems of the same type.

Louis,

Why not just stay inside a pressurized habitat?

What is the end goal here?

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#14 2019-09-02 09:08:04

SpaceNut
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Re: Artificial Valley Atmospher Pressure

As one makes the mining shaped cone or valley gorge you could create a cone of glass from the materials above the mined operation to cause the counter pressure of escape to be reduced as it rises above the place we would pressurize.

open-pit-mining-pros-and-cons-1-1000x667.jpg

One mght also leave a center cone while channeling the gorge valley around it.

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#15 2019-09-02 12:43:40

kbd512
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Re: Artificial Valley Atmospher Pressure

tahanson43206,

Nobody knows with any degree of certainty what temperatures will be encountered if we drill that deep into the crust, but odds are pretty good that they'll be above the range that humans would find comfortable.  We could insulate the shaft, but we'd probably still require active cooling of some kind.  I honestly think a shallow subsurface base with a CO2 compressor of some kind would provide the best compromise to increase temperature and pressure to a level that humans find tolerable without wearing space suits.  If we drilled a geothermal well, we could use the geothermal power to drive the compressor and provide electrical power for other uses.  That sure as heck would be substantially easier than living and working 20km+ deep in the crust of the planet.

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#16 2019-09-02 15:16:58

SpaceNut
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Re: Artificial Valley Atmospher Pressure

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#17 2019-09-02 18:30:38

tahanson43206
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Re: Artificial Valley Atmospher Pressure

For kbd512 re #15 ....

Thanks for your thoughtful reply. 

SpaceNut (in post #14 just above) has given us an image which could be extrapolated to the Mars environment.

Louis earlier opened this topic with a visualization of a deep canyon on Mars, at the bottom of which atmospheric pressure would be greater than at the average surface level of the planet.

The open pit mine SpaceNut showed us might be possible on Mars, given sufficient time for slow excavation of material for projects here and there, but mostly there.

My concern is that (unless something changes) humans on Mars are going to be dependent upon a constant flow of external energy to maintain their habitats.

On Earth, there are locations where a constant flow of energy is required to sustain human life, so it's not a new concept.  On Earth, however, there exists the possibility of leaving an inhospitable location to return to a more benign one.   On Mars (as I understand the situation) that will never be the case.  It was for that reason I inquired about digging down to find a place where natural forces are in balance with human needs.

Upon reflection, I realize that for most of us living in first tier cultures, a constant flow of money is required to sustain the comfort we enjoy.

Perhaps that state of affairs will seem "natural" to Mars residents.  It will certainly hold for life on the Moon, or in most other Solar system locations I can think of. 

The only exception that comes to (my) mind right now, is an O'Neill habitat, where natural forces can be balanced so that a constant worry about energy input is not necessary.  Of course, a constant source of solar energy ** is ** required for an O'Neill habitat, but my impression is that the habitat engineering team will be able to go for long periods of time without having to tweak the power flows.

In contrast, a habitat engineering team for Mars will be in a constant state of worry about any power source other than nuclear fission. 

(th)

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#18 2019-09-02 18:46:09

kbd512
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Re: Artificial Valley Atmospher Pressure

tahanson43206,

I agree with your sentiment that a pre-requisite for establishing a colony on another planet is a functionally inexhaustible power source and a source of water.  Molten salt solar thermal plants, fission reactors, and geothermal wells fit that description.  All other power resources are intermittent and/or unreliable in nature.  At this juncture in our technological development, heat engines are the only power source that humanity has really mastered to any significant degree.

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#19 2019-09-02 18:50:41

SpaceNut
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Re: Artificial Valley Atmospher Pressure

The natural forces of mars start out with a solar energy deficit (-600W), a gravity that man is not ready for (.38%) and an atmosphere thats not breathable (92% co2 at .007 Mbar) without the sources of energy to create in a contained environment its not happening.

Robotics with sounders and other positioning devices can excavate the mine quite fast if the vehicles have the power to move them. The Nasa kilowatt units would seem to fit the early and later use for man and vehicles.

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#20 2019-09-02 20:22:59

tahanson43206
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Re: Artificial Valley Atmospher Pressure

For kbd512 and SpaceNut re conical valley dimensions

Assuming the open pit mine shown by SpaceNut has a slope angle of 45 degrees, and assuming that angle would work for Mars, and assuming the Stackexchange estimate of 45 km depth to fine Earth sea level pressure is accurate, then

Given: https://www.calculatorsoup.com/calculat … s/cone.php

Then:

The radius will equal the height.

The cross section of radius, height and slant is an equilateral triangle.

Thus, entering 45 radius and 45 height, we get:

Note that the computation was performed in meters!

r = 45 m
h = 45 m
s = 63.6396 m
V = 95425.9 m3
L = 8996.84 m2
B = 6361.73 m2
A = 15358.6 m2

Where:


r = radius
h = height
s = slant height
V = volume
L = lateral surface area
B = base surface area 
A = total surface area
π = pi = 3.14159
√ = square root

Assuming the Stackexchange prediction of a depth of 45 kilometers, then ...

An excavated cone which delivers Earth sea level atmospheric pressure would be 90 km across and 45 km deep, with a slant angle of 45 degrees.

Edit(1): The desirability of real estate on the slopes would be reversed from Earth "normal"

On Earth, height (elevation) of domicile is often a perquisite of wealth.

On Mars, the inverse might be observed, if increased air pressure is regarded as a desirable feature of a site.

Edit(2): I note that the 90 km diameter cone is nearly the size of Sagan City (2018).

(th)

Last edited by tahanson43206 (2019-09-02 20:40:46)

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#21 2019-09-02 20:56:58

kbd512
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Re: Artificial Valley Atmospher Pressure

tahanson43206,

Can you name off a single open pit mine that's 20km deep?

I'm not aware of a single example.

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#22 2019-09-03 07:17:31

tahanson43206
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Posts: 2,550

Re: Artificial Valley Atmospher Pressure

For kbd512 re #21 ...

Your inquiry helps to move this discussion from theory to practice, which is good.  A quick check with Google delivered some modest valleys on Earth, of only 2 km depth or so.  The winner in the natural valley competition appears to be Valles Marineris on Mars.

It comes in at 7 km deep. 

However, the bottom of that natural canyon would certainly appear to be the best place to begin digging if the goal is to find a location where atmospheric pressure appoximates Earth sea level.   

https://en.wikipedia.org/wiki/Valles_Marineris

This page is being actively maintained.  The last edit was dated 1 September 2019.

I searched again and found this discussion from 2013, in www.marsroverblog.com

Jack Finche
Posts: xxx
Reply: 2
Posted: January 14, 2013 12:04 PM    
If atmospheric pressure is substantially higher at the bottom of Valles Marinaris than on the Martian surface (e.g. the planitia)it would make sense that this would be one of the best places for an initial colonization attempt. First, fluids are not going to boil away instantly and liquid water may exist in a liquid state for some period; Second, the colony will have enhanced protection (reduced exposure) from daily low-angle cosmic radiation, Third, weather conditions will be somewhat more stable as the canyon's base would not necessarily be prey to the dust storms sweeping across the surface; Fourth, if liquid water can exist at the base of the canyon, it probably has existed there for some time, and this would be an excellent place to look for residual Martian lifeforms.

The quote above by Jack Finche came after a post by marsman...

That's a good question. The triple point for water is listed at 0.0886 psi. At the bottom of Hellas Planitia (similar to Valles Marineris?), the atmospheric pressure is listed as being 0.168 psi, so there would be an interval during the day in which water would be in a liquid state.

http://en.wikipedia.org/wiki/Atmosphere_of_Mars

Summer temps can go up to 70 degrees Fahrenheit.

(th)

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