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In a recent set of posts, this forum has learned about ongoing research by ESA and others, showing that there is a significant quantity of water on Mars, buried under hundreds of meters of regolith.
That water is accessible to those who can deploy the appropriate equipment on the surface of Mars.
The water retrieved will have high value. In other words, this is to Mars what Oil has been on Earth.
Thus, it is clear to see that a capitalist venture could fund the entire enterprise, and charge it's customers for the delivered product.
This topic is available for posts that consider various aspects of this proposal.
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This post is reserved for one by GW Johnson ...
From the GW Johnson Postings topic:
http://newmars.com/forums/viewtopic.php … 07#p218907
I stand by what I said in post 233 above. It takes a real drill rig, and you inject steam to melt the ice-dirt composite and send the water (probably muddy) back up the well. Then you have to clean up the water. Vacuum-flash distillation ought to be pretty easy in a 6 mbar atmosphere. Steam extraction is how they do tertiary recovery in oil fields. We already know it works quite well.
The salts and evaporites like the perchlorates are symptomatic of an old sea that dried up. We see the same things here. In fact, that is very likely how the dirty ice got down there: sea bottom mud covered up with wind-blown sediments. Yeah, there's a lot of water down there, but that's too deep to mine with shafts. So do it with wells and slant-well drilling. You cannot do that with some small robot rover. It takes big equipment and a well-trained crew. Just don't overdo it, or you risk cave-ins.
I'm surprised and disappointed that nobody is working on these support technology things. Until these things are ready to use, the notion of refilling "Starships" on Mars for the return home is utter BS. All the "Starship" journeys to Mars, if they ever really take place, will have to be one-way suicide missions. Until such equipment and crews are there. Am I the only one who sees this killer item?
GW
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Calcium perchlorate brine has a eutectic temperature as low as 198K.
https://www.researchgate.net/figure/Pha … _341298596
The ice could be solution mined by injecting warm perchlorate rich brines into a well at high pressure. We maintain this pressure until a sufficient quantity of ice is liquefied. At this point, we reverse the pressure gradient, allowing melt water to seep into the well, where we withdraw it. The withdrawn brine is then heated about 0°C and is filtered before being input to reverse osmosis cells. This produces two outputs: (1) Fresh water; (2) Concentrated brine, which is then reused for solution mining in a fresh well.
Last edited by Calliban (2024-02-01 17:09:35)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #3
Thanks for this promising looking/sounding contribution to the topic!
I am wondering if it would help to drop two lines into the deposit you want to mine?
One would deliver the brine you've prepared on the surface, and the other would return the melt from the deposit, plus some of the brine from the surface.
Is this a practical implementation of your idea?
It is a little bit like what I understand is being done to harvest heat from geological sources on Earth. If I understand the process correctly, two already existing oil wells are enlisted to harness energy from the depths. One pipe accepts input from the surface, and the other pipe allows for delivery of hot material from below.
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For Calliban re #3
Thanks for this promising looking/sounding contribution to the topic!
I am wondering if it would help to drop two lines into the deposit you want to mine?
One would deliver the brine you've prepared on the surface, and the other would return the melt from the deposit, plus some of the brine from the surface.
Is this a practical implementation of your idea?
It is a little bit like what I understand is being done to harvest heat from geological sources on Earth. If I understand the process correctly, two already existing oil wells are enlisted to harness energy from the depths. One pipe accepts input from the surface, and the other pipe allows for delivery of hot material from below.
(th)
I think that is a practical approach. A single injection well could be surrounded by multiple satellite wells, from which brine is extracted.
However we do this, mining water in this way does require a lot of low grade heat. Even if the brine reduces freezing point, we need enough heat to overcome the latent heat of fusion of the ice ~0.1kWh/litre. Any other material that the ice is mixed in with will absorb sensible heat. We then need to heat the brine we extract, to allow reverse osmosis without the pure water freezing out. RO needs moderately warm water as input, as diffusion rates will be effected by viscosity. For water mining, we therefore need mobile low-grade heat sources in the single digit MW range. Things that we can tow on a trailer.
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #5
Please take your version of the idea and carry it a bit further. I'm happy to offer a full scale proposal to a suitably (very large) capitalist enterprise. This is a long term major investment, with a monopoly of fresh water supply on Mars as the payoff, and very ** very ** few competitors to worry about.
Please try to formulate your design in 40 ton chunks. 40 tons is the target delivery (that I understand was) requested by NASA. I'm working with another member on a method of delivering a number of 40 ton chunks from Hohmann Transfer Orbit.
I just reported what looks like a possible breakthrough in the AI drawing competition. ChatGPT4 has held the field for several months, but BARD has surged onto the course, and my first outing with BARD shows superior capability. Please see BARD's implementation of a grasping tool in the asteroid mining topic.
I'll open a new topic for 40 ton Hohmann Transfer Payload Delivery.
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We could use Strontium-90 as a portable heat source. If we get ~400W/kg, then we need 2,500kg or SrTiO3 to generate 1MWt. SrTiO3 is about 5,120kg/m^3, so 2,500kg is ~0.5m^3. If the cylinder of radioactive material was 9in diameter and 40ft long, that's half a cubic meter. Pu238 would require a lot less volume, but it's not nearly as easy to get. Bore hole sizes for reaching the depths GW spoke of would be around 9in to 12in, or at least they would be if we were drilling for oil, so this hot lance should pass through to heat the brine below. I would think we'd still need substantial pumping power to lift the liquid brine out of the bore hole, but maybe Calliban knows of a better way. I think you need oil-based mud to drill with, but molten Sulfur might also work.
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For kbd512 re #7
Thanks for the heating method you suggested in #7
SearchTerm:Heat for Mining Water on Mars
SearchTerm:Strontium-90 as heat source for melting ice on Mars.
The distinctive characteristic of your suggestion (as I understand it) is that the heat source would be dropped to the region where ice needs to be melted.
The design problem at hand is an interesting one, and this topic provides an opportunity for various designs to receive study by members and readers.
If you have time, please develop your ideas for lubricating fluid.
This topic was set up with the intention of providing an opportunity for one or more members to lay out the design of a full scale water mining operation on Mars, with all equipment and supplies delivered from Earth. Thus, if a particular mixture of mud/lubricant is needed, then it can be specified and added to the inventory to be shipped.
I do not think we necessarily need humans on the ground. Everything is now possible using Teleoperation form LMO, so there is no need to worry about the difficulty of caring for workers on the ground.
On the other hand, and operation of the scale of the one for which this topic is set up would (probably) be able to set up human accommodation as a rounding error in the overall capital expenditure.
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If the water is an ice with not much for soil debris within it heating will work but if it's more like a mud, we will not only need to put in heat but water to thin it so as to suck the mud into a separating unit to get what water was within that sample for man's use.
With the obvious the drilling unit to get to depth.
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The pressure drop due to friction in a pipe carrying a fluid at average flow velocity, v, can be calculated using the Darcy-Weisbach equation.
https://www.engineeringtoolbox.com/darc … d_646.html
https://en.m.wikipedia.org/wiki/Darcy%E … h_equation
The Darcy friction factor depends upon the reynolds number of the flow regime.
https://en.m.wikipedia.org/wiki/Darcy_f … r_formulae
If you can calculate pressure drop, then the amount of pumping power needed can be calculated thus:
https://www.engineeringtoolbox.com/pump … d_505.html
But note - this is mechanical pumping power. Each pump has its own efficiency profile, that will be influenced by the pressure ratio across it, tip speed, motors characteristics, etc. I am no expert on pumps. But centrifugal pumps are generally the most energy efficient and are the most widely deployed throughout industry. But they need a feed pressure to avoid cavitation (which is damaging to the impeller), are limited in their achievable pressure ratio (multi-stage pumps are used where high pressure ratio is needed) and will not tolerate heavy particulates. In situations where water is contaminated with grit that could damage the impellor, you have three options.
(1) Pump clean water down an inner tube within the well and push the dirty water up the gap between the tube and well lining. This allows clean water to be pumped, which prevents damage to the pump. But the hydraulic diameter of the pipes is greatly reduced, which increases pumping power or reduces flowrate.
(2) Use a submersible pump but include a filter on the inlet to the pump. This might work, but the pump would need retrieving periodically to change the filter.
(3) Use an airlift pump. This reduces the density of water in an inner tube by bubbling air through it, allowing a denser outer water column to fliw down displacing it. This is sometimes used for pumping water that is full os suspended particulates that would otherwise be difficult to pump in other ways. It is not a particularly energy efficient option and is only suitable for low head pumping. But it has the advantage of simplicity and no moving parts in contact with dirty water being pumped out of the well.
I am inclined to favour Option 1, because we need to pump heat down the well anyway. We would have an upcomer tube within the well lining. Hot clean water would be pumped down the well lining tube, where it would cool as it transfers heat into the dirt and ice around the well. At the bottom, it would mix with melt water, which would be pushed up the inner tube by a combination of the weight and dynamic pressure of the downward flowing water.
We need a heat source that can generate hot water. The hotter the water is, the higher the temperature gradient and the rate of heat transfer into the surrounding ice and rock. So hotter is better. But there is a trade off between temperature and operating pressure. At 200°C, the saturation pressure of water that we pump down the well is 15.3 atmospheres.
https://www.engineeringtoolbox.com/wate … d_599.html
This is a relatively easy pressure to deal with. You don't need specialised alloy steels for the pipework, and the static pressure of the mud down the hole will balance the saturation pressure at a depth of 150m on Mars. But at 310°C, saturation pressure approaches 100atm.
The aqueous homogenous reactor is probably the easiest reactor to develop for small power applications, where direct heat is needed at moderate temperatures. This reactor is limited by corrosion problems to relatively low temperatures. But a temperature of 200°C should be easily achievable. Such a reactor could be mounted on a trailer. The reactor itself would be a cylindrical stainless steel tank, with an internal heat exchanger. We would pump water through the heat exchanger and down the well. The reactor tank would be surrounded by a shield tank, which would absorb neutrons and gamma rays produced by fission.
Last edited by Calliban (2024-02-07 18:12:35)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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Here is a snippet about the HH 300 oil drilling rig I found on the web site suggested by kbd512 in Sunday's Google meeting.
Drillmec manufactures the HH-300, a trailer-mounted, automatic drilling rig. The HH-300 is designed for geothermal applications and cold climates. It has a 180 m3 tank capacity, a power control room, and three 1000 hp mud-pumps. It also has a remotely controlled MCC (Motor Control Center) for the rig and mud system.
This design is looking better and better for the Mars venture.
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