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#26 2021-10-10 17:04:53

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

I finished the determination of the square area to dig up for the water value and nailed the levels of co2 to supply to the sabatier reactor. Have posted thoughts on the soil digger processing for the water and shelter for it when idle. Time line from landing means being fueled up with excess by sol 490 out of the mars 500 sol mission duration. With energy supply being the key to success for all aspects.

This work will tie into the oldfart1939 mission topic. Thou it has 2 cargo and 1 crewed landing with no site preparation or landing pads.

oldfart1939I indicated there will be at least 2 to 4 supply vessels already landed or accompanying the first crewed lander. If we bring in a second crewed vessel in the same Hohmann transfer window, additional supplies will be needed for support.

This means at least another 2-3 cargo ships with additional food and building supplies/heavy equipment. Musk has indicated that many of these cargo vessels would be making one-way flights to Mars and could be disassembled for building materials.

Oldfarts1939 post in companion topic #100I envision there will be 4 Starships in this mission. One crewed vessel with my 17 member crew, plus 3 other freighters. The freighters will NOT return to Earth, and will later be cannibalized for building supplies and possibly as repair parts for the crew return vessel. There will be a superabundance of food and survival type supplies. I envision the possibility of a mission return problem caused by inadequate fuel production. Remember: Murphy was an optimist. The 2 freighters will create a 100% surplus, should they both land intact and not have any sort of RUD activities. I'm a believer in redundancy of essentials, of which food and shelter are most important. I earlier stated that we need to consider the possibility that there will be inadequate fuel and Oxygen production in 500 days for a mission to accomplish Earth return safely. I'm planning on the possibility of missing the first Hohmann transfer opportunity and the crew will be there for 3 years instead of 18 months. I'm planning on the Zubrin model of Mars Direct for power requirements: there will be 4 nuclear reactors taken along. One on each Starship, so power will not become an issue. Solar power will also be utilized as battery recharge power during daylight hours; if everything survives there will be lots of regolith moving capability with up to 6 Bobcat-style tracked front end loaders. With my construction Triad, 3 would be in operation at any given time while 3 are in battery recharge/maintenance mode.

Landing site not prepared hoping that they land safely for a minimum of 2 with all 4 cargo sharing common items to make it work.

LoiusAssuming a Space X mission, I don't foresee any difficulties. You'll have at least 4 cargo Starships in the vicinity. Each of those will have their own solar power and battery systems. Your human lander will be continuing to generate power from its substantial solar power arrays. If as I suggested you have robot rovers deployed at the surface (from lower storage points) if there is an issue with power, the robot rovers can deliver battery power to neighbouring Starships. I have also recommend you would arrive with perhaps 30 tons of charged batteries on board - so 9000 KwHes immediately available on arrival (exlcuding the Starship's internal battery array).  ATK solar arrays could be deployed by robot rovers before humans move off the Starship.

Hard to plan distance between landings to connect power grid as the cable is pre-planned for a distance due to mass even if it can supply all that is needed.

my oldfat1939 post of solar versus nuclear numbers

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#27 2021-10-10 17:06:18

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

tahanson43206 wrote:

Regarding your (important) work on the fuel/oxidizer manufacturing system.

Please remember Dr. Zubrin's original plan ... you want to have your fuel and oxidizer already stored ** before ** you land your first crew.  There is no reason to depart from that wise plan.

Your system of extraction of water from the regolith can certainly be performed by robotic equipment. Just adjust your vision to eliminate human operators and your plan will be ready for serious consideration.

You'll want some help preparing the document for publication, and help is (potentially) available from existing forum members.

Please add some labels to help us follow your reasoning.

In recent posts, you have shown Mega tons of product, but I see no way to tie those numbers to the Starship you are wanting to refuel.

Multiple ship loads of equipment will have to be landed to create your proposed manufacturing facility.

You can get an idea of what your plan needs by re-reading Dr. Zubrin's original plan.

No need to re-invent the system.  Just transcribe and update the numbers for the Starship as a customer.

(th)

Continued thoughts from the oldfart1939

tahanson43206I am recommending that the starship headed for Mars be fully restocked with fuel and oxidizer before it is pushed out to Mars, so it has plenty of propellant to be able to accelerate at Mars to reach orbit before it attempts a landing.  The supplies carried on the outside of the vessel can be cached in orbit.

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#28 2021-10-10 17:07:33

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

Of course Zubrin's with a much smaller rocket to provide fuel which uses seed hydrogen but its also got non of the issues that the starship has by virtue of its tremendous size in comparison as his lander was 20mt for all pieces with only the MAV leaving.

Note on second quote of a single cargo ship landing for oldfarts1939 topic would require it lands safely, has its own power system nuclear hopefully, conversion sabater and atmospheric co2 capture system as there is no way to get the equipment to the surface from the top of the starship cargo area to do soil water supply collection. Which means its got to bring it.

My thoughts are to land a smaller rocket payload to mars capable of using a nuke power source for the unit that gathers the soil and bakes the water from it its computer controlled. All it needs to do is bring the water to the processing sabatier reactor unit where the remaining work is done to make the fuel.

Those are straight from musk's starship page since its design is to get mass out of earths gravity well and nothing else since it arrives with earth landing fuel remaining on orbit and needs all of that same fuel to go any where.

As far as what we need I think that its still in design mode to down select what is sent to mars to make the refueling work.

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#29 2021-10-10 18:04:18

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

I think some place like this might be just the place to play with a set of designed gear to test it out.
In a rocky Israeli crater, scientists simulate life on MarsAAPluCf.img?h=533&w=799&m=6&q=60&o=f&l=f

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#30 2021-10-11 11:07:14

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

Have added quite a bit of oldfarts1939 topics post on clustering of starship as a pre-planned refueling system based on Zubrin's being automated to be create before any crew would go.

This allows for a tested but still cautious landing site supporting for more starships in the future as still failure could still occur.

The automation of a starship to drop the equipment and such, is still a problem as its systems have not been designed let alone the equipment even if we had what was being lowered to the ground.

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#31 2021-10-11 11:19:38

tahanson43206
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Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re #30

Landing is ** NOT ** your problem.  I'm hoping you will concentrate in the direction you've opened with this topic.

Work out what is needed to refuel the Starship using your "scrape-the-regolith" idea, and just trust that Elon and his engineering team can solve the landing problem.

It is definitely ** possible ** that your vision could be launched as a complete system in 2024.  What I would expect (if that happens) is that the vessel with your equipment on board would hang in orbit until one or more of GW Johnson's probes gives the all-clear for a landing.

Assuming the landing succeeds, and all your equipment arrives on the surface in working order, you'll have two (Earth) years (or so) to make fuel and oxidizer for the human crew in the next cycle.

Just concentrate on ** your ** part of the problem, and let others worry about their's.

(th)

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#32 2021-10-11 11:22:31

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

I finally took the time to figure out how to make the methane and oxygen from mars insitu materials.
Of course we need water and co2 with the sabatier reactor or something akin to one.
Here is the end results of setting up shop to get home for a starship

water gathered to make methane   oxygen    with co2 mT from the Atmosphere                                   
   540mT                      240mT    960mT       660 mt


GW Johnson wrote:

Now do you understand why damp regolith is no practical source of water?  You process tons of regolith to get kg of water,  at best.  You need massive ice deposits,  which must be under the surface so as not to have sublimed away. 

There is the problem of salt and perchlorate contamination,  so the water purification process needs to go beyond just filtering out particulates.  The salt might aid electrolysis,  but the perchlorate doesn't help that.  There is PLENTY to do,  without the added burden of a diffuse resource spread thinly through tons of regolith.

And then there's the CO2 from the atmosphere.  You have to compress this up to working pressures in your sabatier reactor,  and you need to separate out the 3% other gases.  You won't be doing that compression with an ordinary compressor,  because the inlet pressure is 0.6% of an atmosphere,  not near 1 atmosphere.  That kind of compression looks more like a vacuum pump,  which is large machinery and lots of drive power for a tiny trickle of throughput massflow. You don't get hundreds of tons in under 2 years at grams per day.

You need to be processing ice into oxygen and hydrogen at the rate of 500-1000 kg per day to meet a 2 year timeline.  This ain't no bench-top laboratory play toy,  this is a big,  powerful piece of machinery processing half a ton to a ton of ice per day.  Which also means you mine-out half a ton to a ton of massive ice per day.  You can do that with a couple of backhoes.  But if that's 1% moisture in regolith,  you must process at least 50 to 100 tons of regolith per day,  which is patently absurd;  the numbers clearly say so. 

The best way to capture the CO2 is likely cooling the atmosphere to the CO2 condensation point.  You recover the dry ice as a solid,  which has separated-out the 3% "other gases" as effective noncondensibles.  Then you confine the dry ice in a tight-fitting can and warm it into gas again,  which inherently compresses it from the phase change,  into a usable pressure range.  Now you have a proper CO2 feed to your sabatier reactor.

You need to do this CO2 recovery at about 900-1000+ kg per day,  though.  This ain't no laboratory bench-top device we are talking about here.  This is a big,  powerful piece of machinery that has yet to be built and tested at all.  And it likely requires an astronaut crew to pack the dry ice into the tight cans.

You simply ain't gonna do this robotically!  There will be too many unknown problems to be solved on site.  Robots as we know them cannot handle that.  Humans can.  But only if they have adequate supplies and tools available.

These considerations are driven by the scale of the refilling requirement.  You don't do this with the dinky lab playtoys that scientists typically devise.  You do this with giant engineering machines and devices. They may be based on the little science toys,  but those scientists are not competent to design giant equipment like what is really needed.  Engineers are.

GW

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#33 2021-10-11 11:28:50

tahanson43206
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Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re GW Johnson's post (you quoted)

Please note GW Johnson's excellent advice for working with CO2.

Don't worry about his advice about the limited amount of water in the regolith.

I like your vision because it does ** NOT ** depend upon finding a sunken glacier.

There may well be sunken glaciers all over Mars.

Your vision is of a solution that does ** NOT ** depend upon that possibility.

Hopefully your vision will not be needed, but I hope you will continue working out all the details so it is ready if needed.

You ** will ** (of course) require robust nuclear power to pull this off.

Don't worry either about doubts about what computers can accomplish with a little occasional guidance from Earth.

It is clear for all to see that the right equipment can perform as designed on Mars.

Once again, design of automation to accomplish what you need is ** NOT ** your problem.  There are thousands if not millions of engineers on Earth more than qualified to design and build automation for engineering tasks.

Your mission (if I understand the topic you created) is to work out exactly (or close enough)_ what is needed to refill a Starship by harvesting regolith.

(th)

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#34 2021-10-11 11:40:45

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

I am still looking at it as if we do not find sheets of ice sub surface or only limited quantities for sure as that is worst case.

So lets see if co2 capture which is as drawn from the atmosphere is already a worst case.

With that we are looking at future mars missions.

Marco polo is an insitu lander to prove out mars fuel creation.
Mars 2024/2026 Pathfinder Mission

our topic Mars Base Campcontains 2 posts with numbers from the units

then we have the topic MARCO POLO/Mars Pathfinder

post mentioning the marco polo unit and co2 freezer something I know that I did a design for in a topic


ISRU Part I: How to Make Fuel, Oxygen, and Water on Marsmac-rebisz-20170630-spacex-2560-005-2-1024x576.jpg
https://www.marssociety.ca/2020/09/02/isru-part2/
https://www.marssociety.ca/2020/09/16/isru-part3/

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#35 2021-10-11 16:07:39

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

tahanson43206 wrote:

As you work on the regolith harvest, please organize your findings so they are easy to understand.

As an example, something like;

Starship methane needed: XXX tons
Starship oxygen needed: XXX tons

Regolith to harvest: xxx tons

CO2 to collect, separate and store: xxx  tons

Water to collect, separate and store: xxx tons

Energy required:

1) methane ... show by stages
2) oxygen ... show by stages

3) cool to liquid form for methane
4) cool to liquid form for oxygen

5) keep cool for two years methane
6) keep cool for two years oxygen

7) energy to operate machinery to scrape regolith

8) Whatever I've missed

The output of all this work should be the size nuclear reactor needed to support the mission.

Other outputs would be the various machines needed ...

1) Material collection and movement

2) CO2 handling

3) CO2 separation

4) Water separation and disposal of unneeded material (? return to scrape site?)
(th)

thanks for the outline to place values into

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#36 2021-10-11 17:27:54

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

Since we know that the sabatier reactor and electrolysis work there is little reason to make the fuel and oxidizer as then we open up the boil off issues for both and starship tanks are not made for that issue as they are designed for load and go.

So from the marco polo we know we need for the water mining demonstrator mission which is a test with a MER rover sized unit and power source to match.

NASA study four-kilowatt-hour figure was used for the power estimates used by robotic water extraction/mining unit operations. Including the power needs to then load the water ore and transport this water ore feedstock adds another 25 percent to this number, for a total of five kilowatt-hours to mine 4,150 kilograms of water ore.

Area not given for how much regolith is brought in for the mass.

The 7.5-kilowatt-hour examples from the NASA study were then used for power estimates of the separation and vitalization processing to produce 33 kilograms of refined pure quality water from the mined Martian water-bearing regolith ore.

Energy required to separate water from the regolith

This gives an energy cost of extracting and processing (with an overhead factor) to produce purified water from Martian raw ore materials at an estimate of about 230 watts per kilogram.

I think the combined is low for the reality

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#37 2021-10-11 17:30:35

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

These processes can be done once we have the next ships at the site

NEL S20 electrolyzer https://www.fuelcellstore.com/hydrogen- … 10-s20-s40


Water Electrolysis

    The water electrolysis processing is highly power intensive because of the energy of the bond strength between the hydrogen and oxygen atoms. The electrolysis of water requires a minimum of 237.13 kilojoules of electrical energy input to dissociate each mole of liquid water. Each mole of water gives you 2 grams of hydrogen and 16 grams of oxygen gases. Put another way, commercially available electrolysis systems require about 50 kilowatt-hours of power to produce one kilogram of hydrogen and eight kilograms of oxygen gas from nine kilograms of liquid water.


Sabatier Reaction

    hydrogen is through the electrolysis of the water by-product that results from the Sabatier reactor. Unfortunately, for every 44 kilograms of carbon dioxide that is converted into 16 kilograms of methane in the Sabatier process, you need four kilograms of hydrogen. The Sabatier process only produces 36 kilograms of water in the balanced reaction. An optimized system of this design massing 50 kilograms “has been projected to produce 1 kg/day of O2:CH4 propellant… with a methane purity of 98+% while consuming 700 Watts of electrical power.”

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#38 2021-10-11 17:37:55

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

ISPP includes MACDOF (Mars Atmosphere Carbon DiOxide Freezer) to harvest CO2 from Mars atmosphere

https://sbir.nasa.gov/SBIR/abstracts/98 … 0890B.html

https://arc.aiaa.org/doi/10.2514/6.2018-5172
Full-Scale CO2 Freezer Project Developments for Mars Atmospheric Acquisition

indicate 70% is frozen from the incoming air

https://view.officeapps.live.com/op/vie … esting.doc

or
http://canada.marssociety.org/winnipeg/ … esting.doc


https://core.ac.uk/download/pdf/10562921.pdf
Evaluation of Mars CO2 Capture and Gas Separation Technologies

Gas           Boiling Point K    Freezing Point, K
Carbon dioxide   195 (sublimes)  195

Marco polo APM
https://sciences.ucf.edu/class/wp-conte … Center.pdf

Fluid-diagram-for-the-CO-2-Freezer-subsystem.png
Cyrocooler

Edit

sort of why I seeded that topic with numbers...

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#39 2021-10-11 18:30:40

tahanson43206
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Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re topic ...

Showers of discouragement are coming in from the peanut gallery.  Please hold fast to your project here.

The outcome should be a well organized, easy to understand summary of what it would take to refuel a Starship if all the grand dreams of oceans of water turn out to be so much pixie dust.

Let's start with step one ...

In a post that stands alone, please show the tonnage of fuel and oxidizer the Starship is going to need to return to MLO after landing.

In landing, I expect it will come close to exhausting it's reserves, so it would make sense (at least to me) to assume you have to refill ALL the needed propellants.

Please keep the post limited to just those critical numbers.

As we proceed with your study, you will develop a thick skin for brickbats that may arrive.

If all goes well, you will end up with a firm number for reactor size, as well as other useful numbers for landed deliverables.

(th)

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#40 2021-10-11 19:33:52

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

As you noted we need Mars Atmosphere 671.33mT that is CO2 95.32% for the 660 mt of co2, which means we will draw in at N2 2.7% or 18.12 mT and Ar 1.6% will yield 10.47 mT over the period that it takes to gather the amount we need to be drawn in and saved for later.

Of course the trick is to compress and chill to bring the volume required to store to something that we can send to mars.

Of course if we find that the ice signatures have large quantity of co2 in the water soil ice that's a bonus.

Of course the nitrogen and extra oxygen are perfect to make an earth atmosphere at the partial pressure long before man arrives.

http://www.marspapers.org/paper/Muscate … 3_pres.pdf
Atmospheric Processing Module for Mars Propellant Production

88 g CO2/hr at 50 psia plus 16.2 g/hr H2 to the Sabatier reactor that produces to 31.7 g CH4/hr and 71.3 g H2O/hr

Measured power to freeze CO2 at 0.22 W/kg (108% of theoretical) 680 W for 3.1 kg CO2/h (full scale ISRU module)
– Froze ≥70% of incoming CO2 @ ~100 g/h

Of course we have numerous topics with co2 gather and storage
http://newmars.com/2018/11/on-mars-air- … r-storage/

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#41 2021-10-11 20:08:46

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

This is similar to some of the areas we have seen in images from the rovers for the regolith soils and is the measure of what I am looking to gather.
For earth sand grain size

A square yard of a sandbox with a depth of 1 foot (30.48 cm) weighs about 900 pounds (410 kg) or slightly less than half a ton.
The water content of the sand is assumed to be moderate.

https://www.aqua-calc.com/calculate/vol … ank-packed

1 cubic meter of Sand, wet packed weighs 2 080 kilograms [kg]
The water content in sand, wet packed is equal to 19%.

so the measured area for wet on earth means lifting 1,040 kg with a water content of 197.6 kg, which mars does not as much water content, which we know that's only going to be 9 to 10 kg at best for some where closer to 725kg for the mass being lifted to gain the water we need.

1200 x 1200 x 0.5 is the area being gathered at 725kg for each meter square to depth.
522,000 mT of regolith being processed for the water content that we need 540mT

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#42 2021-10-12 11:21:02

tahanson43206
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Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re topic ....

We have some members who do not respect the project you have undertaken.  You've taken some potshots with good grace before this, and I expect you can handle ill considered comments without taking too much of a hit.

What I'd like to be sure of, and am asking for your confirmation, that you are intending to hold steady on a course that appears to (me at least) to lead to accumulation of practical knowledge and insight about how to harvest regolith on a significant scale on Mars.

We have some members tossing pixie dust as though it were Manna from Heaven, and I think that without ground truth all that speculation is just so much hot air.

Your proposal has a basis in known data from probes that have been poking and prodding Mars for several years.

Hopefully all the pixie dust showers will produce nirvana, but your proposal has the distinct advantage of having the near certainty of actually working.

Are you willing to keep going, despite the catcalls that may come your way?

(th)

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#43 2021-10-12 17:16:34

tahanson43206
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Re: Mars Water regolith soils 1 foot depth only

For SpaceNut ... GW Johnson has packaged the mission requirements, in the Starship is Go Topic...


From post by GW Johnson:
Here's the rates.  It's the same 1200 tons of propellant, regardless of stay time!  Water 540 tons/300 days = 1.80 tons (TONS!!!) per day.  CO2 660 tons/300 days = 2.20 tons (TONS!!!) per day.

Now add life support needs for water and oxygen to that.

From Starship is Go topic

http://newmars.com/forums/viewtopic.php … 02#p186002

***
SearchTerm:Mission requirements for refueling a Starship
SearchTerm:Starship refueling on Mars 1200 tons of propellant
***

Your plan needs to end up showing how to make that 1200 tons using automated equipment ** before ** any humans launch to Mars.

There is nothing (that I know of) in the Laws of Physics that precludes success.

This is a ** social ** problem

The next item in the checklist is:  Regolith to harvest: xxx tons

If you have already computed this number, please post it in a stand-alone post after this one.

(th)


tahanson43206 wrote:

GW Johnson and OF1939 have both pointed out how much more energy (not to mention time) would be required to wring chemically bound water out of the regolith, but I like the concept because it has plenty of potential benefits besides just coming up with fuel.

The energy needed to extract water is a major investment in separating the materials of which the regolith is composed, and once separated, they are valuable on their own.  The company that builds up a stock pile of material extracted from regolith has a tradable commodity.

(th)

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#44 2021-10-12 21:15:53

SpaceNut
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Re: Mars Water regolith soils 1 foot depth only

GW Johnson wrote:

Now,  let's make some assumptions about the mission and timing of events:

(1) Assume the Starship uses the 6-month trajectory,  not the nominal 8.5 Hohmann trajectory.
(2) Assume the usual timing of launch windows -- every 22 months
(3) Assume the crew arrives from one launch window,  stays through the second,  and goes home during the third.

That's a 44-month mission interval,  during which two 6-month trips must occur.  44-12 = 32 months = 960 days.  Just to make the return propellant (no other life support needs at all!!!) the crew must process water at 540 tons/960 days = 0.56 tons (TONS!!!) per day,  regardless of the weather or any other circumstances.  They must process carbon dioxide at the rate of 660 tons/960 days = 0.69 tons (TONS!!!) per day. 

That's a nice long stay on Mars,  not quite 3 years.  It may not be possible to stay that long,  for any of a variety of reasons,  especially during the first such missions.  So,  revise assumption 3 from every other launch opportunity to every opportunity.  The stay time on Mars is then 22 months less 12 months of 2-way travel = 10 months = 300 days.

These are the 2 options for being able to deliver the fuel in mars cycles and windows design for crew to go to mars and be able to return safely

Mission Profile

2) Long-Stay Mission (minimum energy) - usually referred to as a conjunction-class mission, this mission profile provides Mars stay times up to 500 days with a round trip total time of about 900 days. The energy requirements for this mission are the lowest of the three considered profiles; the trade-off is the resulting long transit time (around 250 days).

The minimum energy trajectory option has the advantage of low energy requirements. This trajectory provides an opportunity to send a more massive spacecraft (i.e. more cargo) at the same cost of a smaller spacecraft following one of the more energetic trajectories. By maximizing the payload of each launch vehicle, we can minimize the number of launches necessary to transport the required surface equipment.

The disadvantage of this trajectory for a crewed Mars launch vehicle is the crew's long exposure to the In-Space Environment. Risks to a crew following the minimum energy trajectory are similar to those described previously in the Short-Stay profile. Radiation and zero-g exposure are still quite high, although not as much shielding would be required since the spacecraft would never be inside of Earth's orbit.

The minimum energy trajectory is ideal for cargo transport from Earth to Mars. An unmanned cargo vehicle could carry a maximum payload to Mars at a minimum energy cost without the risks associated with a crewed vehicle.

3) Long-Stay Mission (fast transit) - similar to the minimum energy Long-Stay profile, this mission profile provides long surface stay times. With sensible increases in propulsive energy, the travel times to and from Mars can be reduced by up to 100 days each way (one-way travel times range from 120 to 180 days), resulting in an increase in surface stay times to a total of 600+ days. Total round trip time for a fast transit mission is typically under 900 days.

With current propulsion technology, a point is reached where it is no longer reasonable to increase propulsive impulse in order to decrease travel time. The fast transit mission profile minimizes crew exposure to the In-Space environment and maximizes surface stay time while keeping energy requirements within reason.

While the fast transit energy requirements are higher than those of the minimum energy trajectory, the physical and mental benefits to the crew are unquestionably worth the investment. Additionally, the surface stay time is maximized by the fast transit profile which will allow for maximum surface productivity.

It should be noted that, due to the orbital characteristics of Earth and Mars, fast transit times are only available for the Long-Stay mission profiles .

The big difference is in the amount of radiation exposure while in space.

Adding updates to chart as they are calculate and our research to completion in RED Text

tahanson43206 wrote:

As you work on the regolith harvest, please organize your findings so they are easy to understand.

As an example, something like;

Starship methane needed: 240mT
Starship oxygen needed: 860 mT

Regolith to harvest: 522,000 mT
1200 x 1200 x 0.5 is the area being gathered at 725kg for each meter square to depth.

My numbers ad GW's differ for how fast we need it...

CO2 to collect, separate and store: 660 mt
CO2 660 tons/300 days = 2.20 tons (TONS!!!) per day.

Water to collect, separate and store: 540mT
Water 540 tons/300 days = 1.80 tons (TONS!!!) per day.

of course longer time period means less burden on equipment and energy needs to gather and process for use.

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#45 2021-10-13 06:15:07

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,984

Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re #44

Thanks for blending the input from GW Johnson into your presentation!

We have differing numbers of Sols to work with.  I'm hoping you will be willing to concentrate on a specific scenario.

The scenario that I am hoping you will study is the one that starts with a launch of your equipment in 2022, along with the engineering probes of GW Johnson and Team.  Your equipment would remain in orbit until the engineering landers have found at least one promising landing site.

Your equipment would make propellant for a human crew that would (presumably) launch in 2024 (or thereabouts), so your equipment needs to have completed the task by the date of the human crew launch.  At that point, the propellant manufacturing system should be keeping the propellant cold, and topping off the tanks occasionally as shrinkage may occur despite cooling.

Recently I noted your reference to Dr. Zubrin's vision of preparing propellant for a return flight, by bringing Hydrogen along.

Your vision is much more appealing (to me at least) because your plan calls for production of everything needed for the return flight using locally sourced materials.  What your two visions share is a nuclear reactor as the source of energy to achieve the objective.  The difference in reactor size is significant, and as you go forward, we are going to see your presentation showing the exact power delivery capability needed.

In the mean time, I'd like to (try to anyway) bring your attention back to something GW Johnson said that (it appears) you might have missed.

There is a ** lot ** going on in your role in NewMars, and it is impossible for you to read everything that every member posts, let alone think about everything.  Therefore, it is not surprising that little details slip by.

In this case, GW Johnson offered you a way of dealing with CO2 that I have not yet seen reflected in your planning.

He pointed out that if CO2 is rendered as dry ice, then it is free of all the suspended atoms and molecules that are floating around in the Mars atmosphere.

In the posts I have seen recently, I ** think ** I have seen references to compressors.  That would certainly make sense.  One of the NASA experiments to make fuel (for example) uses a novel rotary compressor technology that contrasts with the piston pump mechanism that most of us might think of when we think about a compressor.

If you go back to take a look at the post by GW Johnson, you may be inspired to think of a way to take that idea and run with it to the tune of 660 mTons of CO2.

Thanks for continuing to invest your limited time and attention in this topic!

Update at 8:21 .... A distinct advantage of your progress in planning for the regolith harvest is that the equipment and power needed would be able to perform at a much more satisfying pace of all the pixie dust being tossed about has an effect, and a supply of water is discovered at a prospective landing site.  In that case, all your equipment will be far more productive than it would have been otherwise.

However, if all the pixie dust produces nothing more than a mirage, your equipment will have been designed to complete the assignment on time.

(th)

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#46 2021-10-13 07:31:24

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,984

Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re topic ....

because so many time durations have been put on the table, I'd like to suggest 1 Earth year as the time for planning to accumulate and maintain the 2400 tons of propellant for a Starship.

It will take (approximately) 8 months to reach Mars LMO from Earth LEO, and it will take a couple of months for landing and equipment deployment.

If you give yourself one Earth year to complete the mission, then the tanks should be showing full just as the human mission leaves Earth.

There ** is ** some leeway, because the human crew will have the duration of the flight to Mars to confirm the tanks are full on Mars.

Never-the-less, for equipment and power planning, I think that one Earth year is a useful benchmark.

If you adjust the estimates of production provided recently by GW Johnson, you will have a per-Sol measure of production requirements.

I'm assuming you'll be making Oxygen and Methane simultaneously, because the Oxygen will be accumulating as a byproduct of the Hydrogen production.

You'll need pressure tanks to hold gases that are to be chilled, and separate tanks to hold (and maintain) the chilled gases.

This is not a time to worry about how the equipment will get to Mars.  Others are ready and willing to tackle that chore.

Your mission (based upon the topic you've created) is to harvest the propellant in one Earth year, with some stretch room in case of unforeseen difficulty.

(th)

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#47 2021-10-13 10:42:16

tahanson43206
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Registered: 2018-04-27
Posts: 7,984

Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re Carbon Dioxide capture...

Just as GW Johnson has offered you an opportunity to consider dry ice as a way to capture CO2, now comes Void with a new discovery:

http://newmars.com/forums/viewtopic.php … 25#p186025

The solid Carbon produced by this process is not what is currently expected as input to a Methane production process.

We have ** real ** chemists in the membership ... anyone have a suggestion how the solid Carbon can be fed into a process to make methane?

Hydrogen will be coming in from a water separation process of some kind (there are several, apparently).

(th)

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#48 2021-10-13 19:00:19

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,829

Re: Mars Water regolith soils 1 foot depth only

The issue is still landing site testing that show dry ice is there in any amount.
Mars winter has been seen with frost by morning on the ground so depending on season and when you scoop up the soil you will add to the co2 needed to be gathered.
Phoenix Camera Snaps Frost on Marsfrost-on-mars.jpg

https://www.lpi.usra.edu/meetings/lpsc2013/pdf/2144.pdf
UNDERSTANDING THE ROLE OF CO2 FROST SUBLIMATION ON MARTIAN GULLIES

This some of the reason that the helicopter ingenuity has trouble with the changing pressure
http://luna1.diviner.ucla.edu/~dap/pubs/009.pdf
Modeling  the  Martian  Seasonal C02  Cycle

The further north you are the higher the co2 concentration on the ground will be.
pia20758-1041.jpg

The good news is that all gasses trapped or bound with the soils we put into the heating chamber to drive out the water will also evaporate from the soil as well. Its a matter of collecting each with proper cooling to separate them out from each other for storage for later use.

As far as the dry ice glaciers they may not be where we land or even accessible.

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#49 2021-10-13 20:54:32

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,984

Re: Mars Water regolith soils 1 foot depth only

For SpaceNut re topic...

We are 47 posts into this topic and your post #48 contains this ...

The good news is that all gasses trapped or bound with the soils we put into the heating chamber to drive out the water will also evaporate from the soil as well. Its a matter of collecting each with proper cooling to separate them out from each other for storage for later use.

There is a difference between gas that is "trapped" in the regolith, and gas that is chemically bound to other elements in the material.

I was under the impression this topic was about recovering water that is chemically bound to the material of the regolith.

Would you be willing to provide a table of what material exists in regolith, based upon actual probe studies of material?

I've been supporting your initiative despite doubts by some members of the forum because i thought you knew what material was present, and how it is stored.

Post #48 impies uncertainty about the nature of the state of the material comprising the regolith.

(th)

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#50 2021-10-14 18:56:45

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,829

Re: Mars Water regolith soils 1 foot depth only

The regolith mars soil will be dug up and placed into a chamber of which that action will add co2 to the soils as it breaks up and moves to the surface from gravity as it passes through the mars air its going to capture some co2 in the grains and since that's moist its also going to trap small amounts within the dumping action in the chamber. The chamber is slightly larger than the measurement of what was scooped up so additional co2 will be in the chamber once the doors are closed that's when the heating of the soil starts. Its that heating which will force out of the soils starting from negative degrees of temperature all the way up to 500'c or higher possibly 800'c to drive out the contents that we can make from the heating process over time. The chamber is going to become pressurized slowly and will be vented or pumped clear of its contents. The contents will then be cooled to produce water and several other gasses to save off separately for processing.

soil imaged up close
2-marssoilsamp.jpg

The mars spectral testing of samples works this same way in that it heats the sample and then looks at the refracted light to tell what it contained. The sample testing of soils have been going on since the MER's landed to current and the samples while they will have common amounts and levels will differ by location.

The instrument analyzed the dirt over the following two days using mass spectrometry, gas chromatography and laser spectrometry, SAM and the Chemistry & Mineralogy instrument, or CheMin, both sit inside Curiosity's body and are designed to analyze soil samples delivered by the rover's 7.1-foot-long (2.1 meters) robotic arm. CheMin has already studied Martian soil and received a fresh sample from the same scoop that fed SAM,

https://www.nasa.gov/mission_pages/msl/ … 21203.html

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


I hope that explains why the posts as well as it sets the stage for design of the equipment.

The last 2 images in post 22 are in the running to leverage a design from.

SP85.jpg

The unit will travel while in the process to clearing a 1200m x 1200 meter area a distance of 1,440 kilometers to accomplish the task.

8LS3-472.jpg

The lunar vehicle is able in 10 minutes to scoop 10 kg and has 22 buckets connected to the belt.

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