Author Topic: Liquid Water found on Mars  (Read 6988 times)

Offline dsky

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Re: Liquid Water found on Mars
« Reply #20 on: 08/18/2018 09:44 pm »

they will figure out how to get to all this...on Deimos...at some point we will turn 80 meter energy subsurface radar lose on Deimos and find out amazing things

Sadly doing this is well at best 30 years away :(


MARSIS has been already used to probe Phobos interior. Deimos is just too small (and its orbit does not quite match Mars Express' one for close opportunities) for any possible detection.
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Offline dsky

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Re: Liquid Water found on Mars
« Reply #21 on: 08/18/2018 09:50 pm »
... there are easier ways to obtain water on Mars and those are all very difficult and expensive.

Indeed.

One that is never mentioned properly is the discovery of HUGE quantities of nearly pure ice ON (not UNDER) the surface of Mars. These are called Debris Covered Glaciers. They are in fact covered by an estimated 2 to 10 meters layer of debris.

The options to get that ice instead of any other fancy method of evaporating ice from soil is a game changing paradigm for Mars exploration.

The quantity of ice in the probed zones at mid-latitudes (very suitable for exploration) are staggering. This is going to have a far-reaching impact in plans for human exploration. It is time to stop thinking about drilling for samples, but to go claim the first ice mines on the Red Planet.

These results come from SHARAD, MARSIS little brother, which has less penetration but higher resolution, and it is flying on MRO.
« Last Edit: 08/18/2018 09:52 pm by dsky »
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Offline Russel

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Re: Liquid Water found on Mars
« Reply #22 on: 10/28/2018 07:59 am »
... there are easier ways to obtain water on Mars and those are all very difficult and expensive.

Indeed.

One that is never mentioned properly is the discovery of HUGE quantities of nearly pure ice ON (not UNDER) the surface of Mars. These are called Debris Covered Glaciers. They are in fact covered by an estimated 2 to 10 meters layer of debris.

The options to get that ice instead of any other fancy method of evaporating ice from soil is a game changing paradigm for Mars exploration.

The quantity of ice in the probed zones at mid-latitudes (very suitable for exploration) are staggering. This is going to have a far-reaching impact in plans for human exploration. It is time to stop thinking about drilling for samples, but to go claim the first ice mines on the Red Planet.

These results come from SHARAD, MARSIS little brother, which has less penetration but higher resolution, and it is flying on MRO.

How do you get the water from these mid latitudes to a place where its actually habitable?

Offline sanman

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Re: Liquid Water found on Mars
« Reply #23 on: 10/28/2018 12:59 pm »
How do you get the water from these mid latitudes to a place where its actually habitable?

I thought the mid latitudes are supposed to be the places that are most habitable - which places are better?

Offline RonM

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Re: Liquid Water found on Mars
« Reply #24 on: 10/28/2018 01:39 pm »
How do you get the water from these mid latitudes to a place where its actually habitable?

I thought the mid latitudes are supposed to be the places that are most habitable - which places are better?

Technically, nowhere on Mars is habitable. Base location has to be where the water is located. Question of solar power efficiency will impact latitude decision. Lower altitude with higher atmospheric pressure make EDL easier. Probably several other factors to consider.

Offline Russel

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Re: Liquid Water found on Mars
« Reply #25 on: 10/28/2018 02:01 pm »
How do you get the water from these mid latitudes to a place where its actually habitable?

I thought the mid latitudes are supposed to be the places that are most habitable - which places are better?

Technically, nowhere on Mars is habitable. Base location has to be where the water is located. Question of solar power efficiency will impact latitude decision. Lower altitude with higher atmospheric pressure make EDL easier. Probably several other factors to consider.

Yes this is true. However, from what I've seen, anything beyond about 30 degrees has a truly hostile winter. Moving away from the equator also adds to the cost of both landing and ascent.

There is sufficient atmospheric water at least in equatorial regions to resupply basic needs. There is no need to use water for ascent fuel provided a) your purpose is scientific so its a limited crew and b) your return vehicle is in orbit. Together this means a modestly sized ascent vehicle for which it is practical to import sufficient hydrogen in the form of ammonia or methane.

Also, I don't regard landing at relatively low altitudes as absolutely essential. The reason is because I firmly believe that the crew should be landed separately (to cargo) on a low g trajectory that gives them a much wider margin (subsonic at higher altitude). We can discuss what I have in mind if you want.

If someone can point me to a place on Mars where a) there is a deep deposit of reasonably pure ice close to the surface b) the climate data is acceptable and c) is of some scientific interest, then I'm happy to know about it.
« Last Edit: 10/28/2018 02:46 pm by Russel »

Online Robotbeat

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Re: Liquid Water found on Mars
« Reply #26 on: 10/28/2018 10:58 pm »
There's also a lot of water in hydrated minerals (such as gypsum) all the way to the equator. The energy required to extract this water is FAR less than the energy required to produce that water into propellant, so the more easily available solar power near the equator could easily more than compensate for the greater energy required to extract water.

There's water effectively everywhere on Mars.
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Offline guckyfan

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Re: Liquid Water found on Mars
« Reply #27 on: 10/29/2018 03:54 am »
The energy required to extract this water is FAR less than the energy required to produce that water into propellant, so the more easily available solar power near the equator could easily more than compensate for the greater energy required to extract water.

Yes, but it requires moving and processing a huge amount of regolith. Water ice is much preferable if feasible at all.

Offline Russel

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Re: Liquid Water found on Mars
« Reply #28 on: 10/29/2018 09:51 am »
There's also a lot of water in hydrated minerals (such as gypsum) all the way to the equator. The energy required to extract this water is FAR less than the energy required to produce that water into propellant, so the more easily available solar power near the equator could easily more than compensate for the greater energy required to extract water.

There's water effectively everywhere on Mars.

Even if you get 1Kg for water per 100Kg of soil I think people completely underestimate the difficulty and cost of getting the sheer tonnages of soil needed. It works out be simpler, less energy intensive and involves less actual landed mass to simply import hydrogen in the form of ammonia or methane.

Edit: I'll concede that extracting water from soil might be useful for getting the relatively small quantities of water needed for life support purposes. However even then an atmospheric extraction unit is going to be a lot simpler, more robust and less likely to break.
« Last Edit: 10/29/2018 09:53 am by Russel »

Offline Russel

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Re: Liquid Water found on Mars
« Reply #29 on: 10/29/2018 10:00 am »
The energy required to extract this water is FAR less than the energy required to produce that water into propellant, so the more easily available solar power near the equator could easily more than compensate for the greater energy required to extract water.

Yes, but it requires moving and processing a huge amount of regolith. Water ice is much preferable if feasible at all.

Agreed. The quantities involved are a real problem. But with water ice I've yet to see an actual site where there is a large quantity of water near the surface, where the climate isn't a showstopper and where there is some point in being there - in other words scientific value.

Just one site, please, with some actual climate data.

- A large quantity of ice means many metres thick, preferably tens of metres. Otherwise the method of boring a hole and using heat won't be particularly useful.

- Close to the surface means preferably less than ten metres, but could be a few tens of metres provide the ice below it is thick enough that when it gets mined it won't collapse.

- The climate is a showstopper where the typical average daytime temperature in mid winter doesn't go above -40C. Below this many things (like electronics) break and keeping the heaters on without interruption is both difficult and costly energy wise. Add to this the difficulty with solar power beyond about 30 degrees from the equator.

Offline KelvinZero

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Re: Liquid Water found on Mars
« Reply #30 on: 10/30/2018 01:23 am »
Even if you get 1Kg for water per 100Kg of soil I think people completely underestimate the difficulty and cost of getting the sheer tonnages of soil needed. It works out be simpler, less energy intensive and involves less actual landed mass to simply import hydrogen in the form of ammonia or methane.

Edit: I'll concede that extracting water from soil might be useful for getting the relatively small quantities of water needed for life support purposes. However even then an atmospheric extraction unit is going to be a lot simpler, more robust and less likely to break.
A quick google suggests gypsum holds about 20% water. I think you get similar results for portland cement.

There is a glut of possibilities of water that I suspect are far better. those 20% are worst of the worst case examples. There is no reason to discuss 1% cases. There are many scientists confident of better locations closer to the equator than that halfway between pole and equator "worst cases" where we have actually seen ice at a couple of meters down.

I think the topic of debate should be focusing on the fact that we can never be absolutely so certain that we can just land a BFS with the right equipment on a totally workable spot.. or that a short search around would not find a spot ten times better.

I would like to see a plan that got large long range prospecting rovers on the surface, and did not lock us to the location of the first landings.

I suspect scientists do have a lot of confidence though. The plan might be based around an 80% possibility that the spot your initial unmanned BFS land on is spot on, close enough to contribute to the base infrastructure, with more prospecting and a delay of a synod being a "20% possibility" plan B.

Online Robotbeat

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Re: Liquid Water found on Mars
« Reply #31 on: 10/31/2018 02:01 am »
There's also a lot of water in hydrated minerals (such as gypsum) all the way to the equator. The energy required to extract this water is FAR less than the energy required to produce that water into propellant, so the more easily available solar power near the equator could easily more than compensate for the greater energy required to extract water.

There's water effectively everywhere on Mars.

Even if you get 1Kg for water per 100Kg of soil I think people completely underestimate the difficulty and cost of getting the sheer tonnages of soil needed. It works out be simpler, less energy intensive and involves less actual landed mass to simply import hydrogen in the form of ammonia or methane. ...
"It works out" only if you actually present analysis, which you haven't done.

To extract water from Gypsum takes about 4MJ/kg of water (and digging it out is even less). To split it into hydrogen and oxygen, then make methane and liquefy it takes about 40MJ/kg, so an order of magnitude higher. If you get more sun on the equator, or ability to produce propellant even during winter, then an equatorial site with gypsum may be more productive than a mid-latitude site with liquid water coming straight out of a tap.
« Last Edit: 10/31/2018 02:08 am by Robotbeat »
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Offline Dalhousie

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Re: Liquid Water found on Mars
« Reply #32 on: 10/31/2018 06:45 am »
The energy required to extract this water is FAR less than the energy required to produce that water into propellant, so the more easily available solar power near the equator could easily more than compensate for the greater energy required to extract water.

Yes, but it requires moving and processing a huge amount of regolith. Water ice is much preferable if feasible at all.

That depends on the grade.  The Burns Formation at Meridiani is 10-20% water overall.
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Offline Russel

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Re: Liquid Water found on Mars
« Reply #33 on: 10/31/2018 05:21 pm »
Once again I feel compelled to point out that if your purpose is to land a few people on Mars for exploration and scientific purposes and to get them safely home, there is absolutely no reason to extract local hydrogen for the purpose of propellant production.

Local oxygen, yes. But that's an altogether easier thing to do.
Four fifths of the mass of methane/oxygen propellant is oxygen.

It just isn't worth the complexity and risk of establishing hydrogen extraction. In any event to do so will almost certainly mean landing more mass on Mars than simply landing hydrogen in the form of ammonia or methane.

Let us suppose that to take 4 humans from Mars surface to Mars orbit requires a vehicle with a mass of 10 tonnes (nice round number) sans fuel. The vehicle would require 30 tonnes of propellant and thus 7 tonnes of methane.

This methane can either be landed prior to the mission and it would represent a fraction of the cargo mass that would be needed to be delivered in any case.

Alternately you could land 10 tonnes of ammonia. From which it is simple to synthesis methane. The bonus being a) its relatively dense and b) you get 8 tonnes of nitrogen which is going to be needed for life support.

The real problem I have with all of these arguments about extraction of large quantities of water is that they are fundamentally about the requirements of large, permanent human bases. This isn't going to happen prior to exploratory and scientific missions and these kinds of missions don't need the complexity and risk of local hydrogen production. Indeed, all that is achieved in this is delay. We just don't need to do it because we can easily ship enough hydrogen to begin with.

I also have a problem with the entire notion of large scale permanent human presence on Mars. Whenever I see these romantic renders of Mars bases with a bunch of BFSs parked off to the side, the engineering side of me thinks hey wait a moment, where are the vast areas of shallow strip mining needed to support this? That doesn't show up in the picture. Worse, a permanent base that requires the processing of tens of thousands of tonnes of soil per BFS launch is going to end up with logistics problem because you're going to have to go further and further away to carry the soil/rock.

Not to mention how ugly this is, or how much much it reeks of environmental vandalism.

Consider also the requirements of a manned base. You don't want to be located anywhere near deep, soft soil. So pretty much by definition, if you want to mine soil, the soil is going to be pretty thin and you'll be dealing with a large mass of stones and rocks. On earth you can get away with large, powerful machinery running on air breathing liquid fuelled engines. You've got complex hydraulics and lubricants. You've got maintenance issues and wear and breakage. All very easy to do in on Earth, but very, very difficult to accomplish on Mars. Much of the speculation on automated mining seems to depend on fairly predictable conditions and very shallow strip mining. Hence my comments about logistics.

It would be far easier to have a nearby glacier, drill a hole and use heat to extract water. But like I said, try finding a site within 30 degrees of the equator and with some good scientific/exploration credentials. Otherwise you end up with remote mining and very long, slow and fussy haulage routes.

And frankly what I want to see is getting to Mars, as soon as reasonably and safely possible. Doing so in style (no not Hollywood fashion, but having decent redundancy and robustness) and engaging in sensible exploration and discovery. All the talk here about mega extraction geared towards large permanent manned settlements is for me a distraction. It may happen later. Certainly technology will get better. But its not really helping the goal of actually getting there.
« Last Edit: 10/31/2018 05:24 pm by Russel »

Online Tulse

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Re: Liquid Water found on Mars
« Reply #34 on: 10/31/2018 05:34 pm »
Quote
Once again I feel compelled to point out that if your purpose is to land a few people on Mars for exploration and scientific purposes and to get them safely home, there is absolutely no reason to extract local hydrogen for the purpose of propellant production.

If the goal is exploration and discovery, you're right.  But some folks see the goal to be settlement, in which case getting infrastructure set up for a colony is the main priority.

Offline A_M_Swallow

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Re: Liquid Water found on Mars
« Reply #35 on: 10/31/2018 06:51 pm »
If the refining process produces hydrogen it would be simpler to refrigerate the gas and burn it as fuel. For instance the Centaur upper stages have RL10 engines that burn liquid hydrogen.

Offline Russel

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Re: Liquid Water found on Mars
« Reply #36 on: 11/01/2018 09:15 am »
Quote
Once again I feel compelled to point out that if your purpose is to land a few people on Mars for exploration and scientific purposes and to get them safely home, there is absolutely no reason to extract local hydrogen for the purpose of propellant production.

If the goal is exploration and discovery, you're right.  But some folks see the goal to be settlement, in which case getting infrastructure set up for a colony is the main priority.

Well I'm glad you acknowledge that. My point is that the gap between exploration and settlement if it occurs at all, may be substantial. Hence the following presumptions on my part

1. Exploration will lead to a much better understanding of water resources. Such knowledge is probably essential.
2. There is plenty of time to develop technology for water extraction. Probably decades.
3. I'm happy to entertain discussions about extracting water for settlements as an exercise in curiosity. What I don't care much for is predicating exploration missions on having solved all these other problems. That just delays exploration.
« Last Edit: 11/01/2018 09:16 am by Russel »

Offline Russel

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Re: Liquid Water found on Mars
« Reply #37 on: 11/01/2018 10:09 am »
If the refining process produces hydrogen it would be simpler to refrigerate the gas and burn it as fuel. For instance the Centaur upper stages have RL10 engines that burn liquid hydrogen.

I've wondered about that too.
Lets suppose a Mars ascent vehicle with target mass of 10 tonnes dry mass (includes crew) and we want 5Km/s delta-V.
For the methane/oxygen version assume an O:F mass ratio of 3.5:1 and an Isp of 370.
28 tonnes propellant
6.2 tonnes methane
21.8 tonnes oxygen
For the hydrogen/oxygen version assume an O:F mass ratio of 6:1 and and Isp of 450.
20.3 tonnes propellant
2.9 tonnes hydrogen
17.4 tonnes oxygen

21.8 tonnes of oxygen is a sphere 3.4 metres in diameter.
6.2 tonnes of methane is a sphere 2.6 metres in diameter.
2.9 tonnes of hydrogen is a sphere 4.3 metres in diameter.
I'm just doing this to get a feel for the size of the tankage.

Now if you imported the hydrogen..
For the methane/oxygen vehicle you get the choice.
6.2 tonnes of methane (9.5 cubic metres)
8.8 tonnes of ammonia (12.1 cubic metres)
For the hydrogen/oxygen vehicle you wouldn't want to import the hydrogen as methane so for ammonia
16.4 tonnes of ammonia (22.5 cubic metres)

Basically the hydrogen/oxygen ascent vehicle forces you to import roughly double in terms of mass and volume.
Also the hydrogen/oxygen ascent vehicle requires a more massive tank (for hydrogen). All else being constrained it can carry less useful mass (or it has to be a more massive vehicle and that means more fuel and more import).

That in a nutshell is why I stuck to methane/oxygen.


Edit: Of course I could have looked at this from the point of view of mining water.
The methane/oxygen ascent vehicle would require 14 tonnes of water
The hydrogen/oxygen ascent vehicle would require 26 tonnes of water

So methane still wins.
« Last Edit: 11/01/2018 10:44 am by Russel »

Online Lar

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Re: Liquid Water found on Mars
« Reply #38 on: 11/01/2018 03:37 pm »
Once again I feel compelled to point out that if your purpose is to land a few people on Mars for exploration and scientific purposes and to get them safely home, there is absolutely no reason to extract local hydrogen for the purpose of propellant production.

That's not my purpose. I want us to become a spacefaring, multiplanetary, and ultimately interstellar species. Exploration for the next 20 years won't cut it.

Occupy Mars.

So that means ISRU of everything. If it makes sense initially to only do partial ISRU, viewed in the context of an ever increasing traffic level, sure. But I don't think it does.

Also, strip mines on lifeless planets don't bother me much.

YMMV.
« Last Edit: 11/01/2018 03:39 pm by Lar »
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Offline sghill

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Re: Liquid Water found on Mars
« Reply #39 on: 11/01/2018 04:43 pm »
Atmospheric condensation is the way to guarantee a water source for a small base. Mars' temperature swings and low pressures will provide all of the work. The colonists need only have a collection method worked out. As long as you have condensers and the means to collect frost from it, you can always have a relatively free local water supply. I can't imagine a base where some sort of emergency condensing capability is not always available.

We have lots of methods for condensing atmospheric water in Earth's deserts. Particularly at high altitudes such as the Atacama Desert. On Mars, because of the super low pressures, I'd think they'd want to capture the water as frost and not a liquid, but that might be the case anyway because the saturation point will be close to (or below) the freezing point of water.  Look at the third image below taken by a Viking Lander. I see a whole plain full of water ice frost at dawn, but no way to collect it.  A large smooth plate or screen will allow a nice layer of water to frost onto its surface overnight, and then in the morning an oversized ice scraper can sweep off the frost for collection, filtering, and storage. Heck, even martian-sourced glass would be ideal as a frost collection device. That flat surface will have a large windshield wiper or zamboni that collects several gallons of new frozen water every morning.  The problem is scalability. Once a base gets large enough, the size and mass of condensers required for atmospheric condensers may get too high to be sustainable. But remember that the colony is a sealed system. Once the water is inside there are very few losses unless you open a window. IMHO, a large moisture farm would be doable. 

Then, the second most likely, but unproven, source of water sufficient for towns is going to be digging wells. 

Dig straight down and eventually, you are going to hit a water table where the pressures and temperatures are high enough that liquid water is going to flow into the well. On Earth, a well dug deep enough always hits water. Always. It may be bound in minerals, but it comes out when pressures are reduced. Aquifers may also abound on Mars, we won't know until we dig some deep wells there. We do, however already have arial radar sounding sufficient to find a water table on Mars, and shallow depth versions already at Mars have discovered subsurface lakes as we all know. http://www.geologypage.com/2011/09/finding-freshwater-aquifers-in-the-desert-with-radar-sounding.html

IMHO, the first base will spend much of its time validating assumptions on how to scale itself up. Digging wells will be a primary activity of an early base (along with activities related to shipping logistics/launch support, power generation, habitat construction, and agriculture).
« Last Edit: 11/01/2018 04:58 pm by sghill »
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