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The merits of Lunar resource mining versus mining on Earth


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The idea of launching materials from the lunar surface is intriguing.  The lack of atmosphere and shallow gravity well make it ...well maybe not practical, but perhaps less-unfeasible?  I mean, you can use the Flats on Minmus to get to orbital velocities with no gravity losses, right?

Let's see, it's about 1700 m/s dV to get from the Lunar surface to LLO.  If you built a long, very straight track, and accelerated craft at 50m/s (5G), it would take about 34 seconds, and require a track (0.5 * 50m/s^2 * (34s * 34s) )= 29km long.  That'd be a pretty substantial civil engineering project.  But using such a system would eliminate most of the need for fuel, along with the nasty issue of kicking up the regolith on launch.

If you wanted to go whole hog and get the payload on an escape trajectory back to earth, you'd need 2400m/s, and a 58km rail...

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19 hours ago, Gargamel said:

Oy!

Topic!

 

:D

 

Has SpaceX (or Musk) ever even mentioned mining anywhere (other than Mars for fuel)?  If you are planning a colony, you'd think you'd want some sort of idea of what could justify such a thing.

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Posted (edited)
15 hours ago, sevenperforce said:

What’s more energy-expensive: sending ore from Earth to LEO or sending ore from the lunar surface to LEO?

It is mostly downhill from lunar orbit to LEO (aside from escape burn), so it would mostly be a comparison of launching from the Moon or from Earth, right?  Given lunar gravity is 16.6% of Earth's I think the net would definitely favor sourcing ore from the Moon as lunar escape wouldn't be that much relatively speaking.  And as noted earlier in thread, magnetic rail-gun-ish launchers on the Moon would be the way to go

Edited by darthgently
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All this talk of "downhill" makes me wonder if some people ever accepted a KSP contract to get a suborbital flight on the sun. You need just as much delta-v to leave orbit as you do to get into orbit, except if you can use aerobraking.

Of course, you don't have to worry about "gravity losses" on the way down -- if you don't care how fast you hit the ground. But those are also the same as going up if you want to get to a soft landing.

Edited by mikegarrison
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Posted (edited)
13 minutes ago, mikegarrison said:

All this talk of "downhill" makes me wonder if some people ever accepted a KSP contract to get a suborbital flight on the sun. You need just as much delta-v to leave orbit as you do to get into orbit, except if you can use aerobraking.

Of course, you don't have to worry about "gravity losses" on the way down -- if you don't care how fast you hit the ground. But those are also the same as going up if you want to get to a soft landing.

DV req'd to escape the Moon targeting a periapsis in Earth atmo for aerobraking is much less than raising apoapsis from LEO to encounter the Moon.  Not sure what you mean.   If you aren't aerobraking and circularizing in LEO instead then sure, I agree

13 minutes ago, mikegarrison said:

Of course, you don't have to worry about "gravity losses" on the way down -- if you don't care how fast you hit the ground. But those are also the same as going up if you want to get to a soft landing.

The topic was launching ore from Moon to aerobrake and land in ocean on Earth and recovered there, so maybe a soft-ish landing, but soft-soft not required

Edited by darthgently
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20 minutes ago, mikegarrison said:

Of course, you don't have to worry about "gravity losses" on the way down -- if you don't care how fast you hit the ground. But those are also the same as going up if you want to get to a soft landing.

Yeah. While this can be done passively on Earth—scrub off velocity with the atmosphere, then presumably a parachute, I don't see mining as being super useful as extraction will still be cheaper on Earth. Bezos has the goal of heavy industry up there, so maybe the cost/kg for products returned makes more sense if they are actually products. Dunno, a capsule of 1000 tons of smart phones or something ;)

I don't want that delivered directly to my house, however.

Space resources is very much a chicken and egg thing. Useful mostly in space by people who live in space who need resources to be able to build where they live, so that they exist to need the resources. My head hurts.

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The carrot to "asteroid mining" is that there are a lot of heavy elements that have mostly sunk to the center of the earth precisely because they are heavy. Asteroids may not be as big as a planet, but any heavy elements they have should be a lot more accessible.

 

Anyway, thread topic creep again.

Edited by mikegarrison
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8 minutes ago, mikegarrison said:

The carrot to "asteroid mining" is that there are a lot of heavy elements that have mostly sunk to the center of the earth precisely because they are heavy. Asteroids may not be as big as a planet, but any heavy elements they have should be a lot more accessible.

Yeah, that seems like the golden ticket. Find things that are value dense, so the cost/kg of return is worth the investment.

I was coming at it from the lunar stuff (oxygen, Al, Ti, etc) which is more commonplace on Earth.

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2 minutes ago, tater said:

Yeah, that seems like the golden ticket. Find things that are value dense, so the cost/kg of return is worth the investment.

I was coming at it from the lunar stuff (oxygen, Al, Ti, etc) which is more commonplace on Earth.

Yes, but water on the moon, even just oxygen from rocks would make an moon base cheaper to operate. 
Non precious metals would not be viable to return but its quite we could make some materials in zero g who would be valuable enough. 

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18 minutes ago, magnemoe said:

Yes, but water on the moon, even just oxygen from rocks would make an moon base cheaper to operate. 
Non precious metals would not be viable to return but its quite we could make some materials in zero g who would be valuable enough. 

I watched presentations on lunar ISRU years ago, and yeah, it helps. At the time they were not exclusively talking about polar regions, so it was largely scraping regolith at lower latitudes, and so the result was offsetting landing dv more than breaking even or coming out ahead. Math probably somewhat better on areas with ice, but we don't have a great idea yet on the quantity of ice available for easy extraction.

 

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7 hours ago, darthgently said:

It is mostly downhill from lunar orbit to LEO (aside from escape burn), so it would mostly be a comparison of launching from the Moon or from Earth, right?  Given lunar gravity is 16.6% of Earth's I think the net would definitely favor sourcing ore from the Moon as lunar escape wouldn't be that much relatively speaking. 

So one of the critical questions is whether we are only comparing dV costs from the surface to LEO, or if we are also considering the cost of getting the necessary propellant to the lunar surface.

To bring the discussion back to the thread topic: consider a bog-standard Starship (85 tonnes dry mass, 1200 tonnes propellant, 150 tonnes to LEO, 380 s). Suppose your goal is to get 150 tonnes of raw materials into LEO. Is it easier to get it from a mine on Earth or a mine on the Moon?

Well, obviously, you can get that 150 tonnes into LEO in just one Starship launch if you're bringing it from Earth.

On the other hand, if you're starting on the lunar surface and aerobraking at LEO, then you'll need 2.74 km/s. Starship will need to burn 265 tonnes of propellant to transport itself and the materials to LEO. And since that 265 tonnes has to get to the moon, you're obviously going to need to lift more than 265 tonnes of propellant into LEO in the first place, so you might as well just lift the 150 tonnes of raw materials into LEO in the first place.

What about 450 tonnes of raw materials? Well, if you're starting from Earth, that will require three Starship launches to LEO, quite obviously. On the other hand, if you're starting from the moon, it will cost you 583 tonnes of propellant. Now, that's a better trade-off; 583 is a lot closer to 450 than 265 is to 150. But you're still losing, overall.

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4 minutes ago, sevenperforce said:

So one of the critical questions is whether we are only comparing dV costs from the surface to LEO, or if we are also considering the cost of getting the necessary propellant to the lunar surface.

To bring the discussion back to the thread topic: consider a bog-standard Starship (85 tonnes dry mass, 1200 tonnes propellant, 150 tonnes to LEO, 380 s). Suppose your goal is to get 150 tonnes of raw materials into LEO. Is it easier to get it from a mine on Earth or a mine on the Moon?

Well, obviously, you can get that 150 tonnes into LEO in just one Starship launch if you're bringing it from Earth.

On the other hand, if you're starting on the lunar surface and aerobraking at LEO, then you'll need 2.74 km/s. Starship will need to burn 265 tonnes of propellant to transport itself and the materials to LEO. And since that 265 tonnes has to get to the moon, you're obviously going to need to lift more than 265 tonnes of propellant into LEO in the first place, so you might as well just lift the 150 tonnes of raw materials into LEO in the first place.

What about 450 tonnes of raw materials? Well, if you're starting from Earth, that will require three Starship launches to LEO, quite obviously. On the other hand, if you're starting from the moon, it will cost you 583 tonnes of propellant. Now, that's a better trade-off; 583 is a lot closer to 450 than 265 is to 150. But you're still losing, overall.

Assumptions (some already mentioned in thread):

  • Magnetic rail-gun launchers on the Moon for launching ore from the Moon.
  • Aerobraking directly to landing (with maybe a skip entry, or aerobraking an orbit or 3 to reduce velocity)
  • Cargo is can take a fairly rough splashdown, maybe with parachutes if required
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1 hour ago, darthgently said:

Assumptions (some already mentioned in thread):

  • Magnetic rail-gun launchers on the Moon for launching ore from the Moon.
  • Aerobraking directly to landing (with maybe a skip entry, or aerobraking an orbit or 3 to reduce velocity)
  • Cargo is can take a fairly rough splashdown, maybe with parachutes if required

Things going to crazy anyway, so it seems to me that somehow it would make more sense to build a space elevator on the moon than to shoot something up into the orbit with rail-gun:lol:

But perhaps it could also be a limitation of our current perception, like the 'computers' and 'mobile phones' of science fiction films from 20 or 30 years ago. Perhaps by that time people will look at this again and wonder: why you guys thinking of doing that? [Insert better ways for that era here] wouldn't it be better and easier to do it that way?

Edited by steve9728
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This thread has been split off from the SpaceX thread.  So if things look a little confusing, that's why.  We can split threads apart by post, but we can't put posts themselves through the mitosis machine.

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4 hours ago, steve9728 said:

Things going to crazy anyway, so it seems to me that somehow it would make more sense to build a space elevator on the moon than to shoot something up into the orbit with rail-gun:lol:

That seems so easy and obvious, doesn't it? Until you start to dig into the details, that is. The problematic detail is that you want the space end of your elevator to be on the stationary orbit to facilitate docking and undocking. Because the Moon rotates so slowly, it does not have a stationary orbit. You would have to build the elevator taller than the Moon's Hill sphere is, or in other words, higher up than where things stop orbiting the Moon and start orbiting the Earth. Literally the Earth would rip the top of the elevator away.

Well, maybe build the elevator just to the edge of the Hill sphere and gently push the cargo towards Earth from there? That should work, but in essence you have then just built a very long and slow railgun. Far cheaper to build it smaller but stronger.

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On 4/18/2022 at 5:40 PM, JoeSchmuckatelli said:

gold nuggets literally laying about the surface of the desert in AZ and NV

Azerbaijan has oil, not gold.
And what is owned by New Venus i even dk.

On 4/18/2022 at 5:40 PM, JoeSchmuckatelli said:

Should Musk

Moonbase Newca Chica.
They will build an extremely high Twitter Tower and turn it into a bridge to the Earth with boring ore trains, shuttling there and back again.

On 4/18/2022 at 5:45 PM, darthgently said:

Look! 

Somebody has already drilled a lot of holes there to steal the titanium!

We'd better hurry.

Spoiler

95NiMencc6tRzo23R2y8xR-970-80.jpg.webp

 

Quote

Mare Serenitatis and Mare Tranquilitas

Spoiler

1822e8178af30bb53d9a3739d3f2b97b.jpg

 

On 4/18/2022 at 6:20 PM, darthgently said:

A lot of iron and aluminum also.  More silica than we could ever use really

Clay is Al.
Sand is Si.
Fe is rust making them dirty.

15 hours ago, mikegarrison said:

The carrot to "asteroid mining" is that there are a lot of heavy elements that have mostly sunk to the center of the earth precisely because they are heavy. Asteroids may not be as big as a planet, but any heavy elements they have should be a lot more accessible.

Below just  200 km of rocks and ice instead of  2 000 km of rock.

That's much better!

(Even if the limit of a mountain height/pit depth is just several tens of kilometers, so you can't just dig it out).

9 hours ago, sevenperforce said:

Suppose your goal is to get 150 tonnes of raw materials into LEO

Two standard railcars of ore?

Makes sense.

Hundred starships - got a train,

***
Annual ore production is 2 billion tonnes.

Ten million Starship launches per year is a deal.

***

2 bln t  /  3.5 t/m3  ~= 600 mln m3 = a ball 1 km in diameter

Yearly the humanity mines a 1 km large asteroid of iron ore.

 

Let's send it to Earth a 11 km/s.

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Why need lunar titanium?

To build a fence and a roof.

Spoiler

Because this old-fashion thing has all your base from another side of the Moon with a single shot.

 

You need something strong but lightweight to put sand bags on top when your module is finally digged in a pit.

Micrometeorites, radiation, thermal insulation, anti-flechette sand bags.

So, you need the lunar titanium for supporting 3d structures, to put your habitats inside.

Edited by kerbiloid
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On 4/18/2022 at 11:23 PM, JoeSchmuckatelli said:

Fishnet floats are going to get lost, high tides and tsunamis are going to wash stuff out to sea, some nations are literally going to dump their floating trash in rivers and ocean as policy, and some people are going to throw empty soft drink bottles overboard.  Having focal points where a lot of this stuff concentrates and washes up actually makes it a lot easier to clean up.   It looks horrible all gathered up like that, but so does the pile of debris one gets when sweeping one's kitchen floor.  But you don't consider it some kind of defect of reality that your kitchen floor requires sweeping, right?  It just is what it is.  There are other beaches that tend to be gathering points for debris and we should be glad for this as it is like a self-sweeping floor making clean up easier.   Glass half-empty, glass half-full...

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10 hours ago, steve9728 said:

Things going to crazy anyway, so it seems to me that somehow it would make more sense to build a space elevator on the moon than to shoot something up into the orbit with rail-gun:lol:

But perhaps it could also be a limitation of our current perception, like the 'computers' and 'mobile phones' of science fiction films from 20 or 30 years ago. Perhaps by that time people will look at this again and wonder: why you guys thinking of doing that? [Insert better ways for that era here] wouldn't it be better and easier to do it that way?

Yes, it is impossible to predict far future. Almost all such predictions have failed and we do not have better ability than previous generation scifi writers. I think only reasonable reason for space mine cheap and common metals, like titanium, will be environmental. We will want polluting metal refining away from our planet and bring as far refined as possible materials back. But it is clearly closer scifi than foreseeable future. It is not much point to speculate what kind of cargo ships or other means to send stuff from one planet to another is then available. It is absolutely sure that any  current or under development rockets can not do it economically.

I do not believe that Moon will ever be important source of industrial materials, except what is needed for lunar colonies. Asteroids have precious stuff in addition to basic metals and much easier available in microgravity environment.

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On 4/18/2022 at 12:00 PM, StrandedonEarth said:

Once the infrastructure is set up, magnetic launchers will be dirt cheap, and why brake into LEO? Direct entry will be cheaper. 

Now for the controversial part: simply slam the slugs of metal into the deserts and pick up the pieces. The dust clouds raised will counter the greenhouse effect that causes global warming. But it also turns until a cheap, non-nuclear weapon of mass destruction, fired from some very high ground (although even higher ground is available outside Earth’s SOI…)

Shaping the metal into whiffle balls might a solution.  With decent backspin, a whiffle ball can generate more lift than just about anything.  On the other hand wind would take it away from precision landings.

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19 hours ago, darthgently said:

Fishnet floats are going to get lost, high tides and tsunamis are going to wash stuff out to sea, some nations are literally going to dump their floating trash in rivers and ocean as policy, and some people are going to throw empty soft drink bottles overboard.  Having focal points where a lot of this stuff concentrates and washes up actually makes it a lot easier to clean up.   It looks horrible all gathered up like that, but so does the pile of debris one gets when sweeping one's kitchen floor.  But you don't consider it some kind of defect of reality that your kitchen floor requires sweeping, right?  It just is what it is.  There are other beaches that tend to be gathering points for debris and we should be glad for this as it is like a self-sweeping floor making clean up easier.   Glass half-empty, glass half-full...

There is no excuse for dumping. Trash goes other places too- a lot of it sinks all the way to the sea floor and micro plastics are just kind of everywhere.

https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-pollution

Even if the pile of junk on the kitchen floor is convenient, I don’t let it sit there, nor do I want to have it continually accumulate.

Furthermore the kitchen pile is a poor comparison because it doesn’t threaten my food safety and raise my risk of cancer and other health issues, nor damage the ecosystem.

-to avoid veering too far off topic-

Targeting marine garbage patches would be overkill. The South Pacific satellite graveyard is already a thing, at most, a notice to sailors and a redirection of marine traffic around the area would be required but otherwise there shouldn’t be need for that level of accuracy.

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4 hours ago, SunlitZelkova said:

Even if the pile of junk on the kitchen floor is convenient, I don’t let it sit there, nor do I want to have it continually accumulate.

Furthermore the kitchen pile is a poor comparison because it doesn’t threaten my food safety and raise my risk of cancer and other health issues, nor damage the ecosystem.

 

Who said anything about not cleaning it up?  Wow.  Was just saying that having it in one place made it convenient.  I figured the cleaning up part was kind of obvious.   Amazing

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4 hours ago, SunlitZelkova said:

Even if the pile of junk on the kitchen floor is convenient, I don’t let it sit there, nor do I want to have it continually accumulate.

That's why you can't mine helium-3 right there.

6 minutes ago, darthgently said:

I figured the cleaning up part was kind of obvious.

Purists' propaganda.

Any stock of garbage is a future tech treasure.

Just heat it up and ionize, and you can separate all chemical elements it contains.

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2 minutes ago, kerbiloid said:

That's why you can't mine helium-3 right there.

Purists' propaganda.

Any stock of garbage is a future tech treasure.

Just heat it up and ionize, and you can separate all chemical elements it contains.

Exactly.  I've always felt that our landfills should be sorted by material and documented as they could very well become mines later.  But if done as you describe then sorting is not even necessary until reduced to atoms first.  Pre-sorting might simplify that though

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7 hours ago, kerbiloid said:

Just heat it up and ionize, and you can separate all chemical elements it contains.

The biggest hurdle is the energy required. When energy finally becomes too cheap to meter, then it will make sense. Until then, it costs to much compared to newly extracted resources. Or until there are no untouched resources left to extract…

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