I don't know if it's from the Goldman Sachs paper or just written for the Business Insider article, but that comparison of $2.6B (IMO optimistic) cost estimate for a 500-ton asteroid capture and $1B set-up cost of a new mine on Earth isn't exactly apples-to-apples.

I agree that once you are out there going for volatiles it's perhaps marginally less to go for metals as well, and vice-versa. I do not agree that it's ever trivial to bring back large amounts of very heavy, dense material to Earth.

Not trivial, it just has to be profitable. Do that, and the process should ratchet, each step justifying investment in infrastructure and capacity that lowers the price of the next step.

Re: ISS. The material being bought back is prepared scientific samples. It needs to be protected, in some cases even refrigerated. It necessitates a re-entry capsule.

If there is large scale mining of high-value items, such as PGMs -- if that business case ever closes -- then subsequent efforts to lower costs may be to shape the metal into a direct re-entry capable shape and coat it with slag from the mining as a heat-shield. (The PGMs "lithobrake", but at a reasonable terminal velocity to allow simple recovery of the metal.) Once that capacity exists, then the same method may also work on larger amounts of lower value metal like nickel.

Not having a parachute or other gentle recovery doesn't mean "asteroid impact", it's not binary. Recovery systems on capsules only cover the final few hundred km/h, the bulk of braking comes from the re-entry shape. A bubble of metal covered with an ablative heat-shield can reduce that terminal velocity to any arbitrary level. Trades will come from impact speed (risks plus recovery costs) vs processing costs to produce and coat the bubble.

And when people on this thread are talking about doing that for hundreds of thousands of tons of metal, that is not at all trivial.

Iron is cheap. So obviously it will be a long time before metallic iron from space is cheaper than mining and processing iron ore on Earth.

IMO, decades before it would ever compete with prices on Earth, there'll be earlier steps where it's cheaper to use asteroidal iron (and aluminium, etc) in "export replacement" for in-space uses. The point where it is cheaper than Earth-mining will spin-off from the existing in-situ use. (Ie, at some point, someone might be able to argue, "Cost of expanding production to meet projections of next 30yrs in-space use is $X billion, giving a unit price of $n/tonne. However, the cost of tripling the production rate is much less than $3X billion, giving a unit price much less than $n/tonne, that not only undercuts our rivals for in-space markets, increasing both revenues and profit margin per unit, but it even brings us within range of Earth prices...")

Finally - I'm not sure how your argument refutes my point that resource extraction is not a compelling rationale for exploration of space, at least given the current economics surrounding PGMs. It's certainly an enabling technology for exploration, and there may come a day when, if we're out there anyway for a different reason or set of reasons, it starts to make sense to bring stuff back.

It's the self-reinforcing aspect.

We clearly want to explore space. We spend a small fortune on it each year. Yet the cost of access and operations puts hard limits on what we can do. Demonstrated by the fact that multi-billion dollar space-rated (hence dumb, slow, limited) robotic systems are cheaper than sending an underpaid grad student with a trowel. Anything that significantly lowers the cost of accessing space will increase the number of people who can do the things they want. Anything that significantly lowers the cost of operating humans in space will increase the number of people who can do things they want personally, on site.

And once you get to that level, it's obvious that people will do foolish and wasteful things, like tourism or even colonies, expanding the demand for volatiles (fuel, air, water), shielding, habitats, even food. That creates potential business cases for new industries, creating yet more activity...

Flipping it around. If lowering the price of access to space brings the cost of PGMs within range of Earth prices, at production rates that don't crash the price too hard, then the infrastructure that is created to do so can be used for other things. (By "infrastructure", I'm including transport systems to/from the asteroid & Earth.) And the mining operation itself becomes a market for other materials (such as fuel), which may help close the business case for volatile mining. Creating routine reusable transport to/from Earth means that you lower the price for many other activities in space (even if mostly unmanned). And lowering the price of fuel (hence the price of delta-v), lowers the cost of even manned activities in space. Which increases the market for other materials and products in space, which....

It doesn't matter what the entry point is, once we're in, we're in.

My personal opinion is that the case for PGMs doesn't close yet, even if New-Space lowers the launch prices. Cheap in-situ fuel must come first. The neat thing about that is that I strongly believe the ices trapped at the lunar poles will be extremely scientifically valuable. So confirming the existence and studying the nature of that polar ice is of existing scientific value, without any regard for future commercial markets. You don't need to commercially justify a survey of lunar polar ice, it's just a scientific mission. (Likewise studying remnant comets in the inner solar system, to see if they are "dry" or just an insulating layer of carbon-materials over mixed ices. Any answer is scientifically valuable, and one specific answer might be commercially valuable in the future.)

But if someone actually can make money from mining PGMs, it simply makes volatile mining more viable, giving the volatile-miner a guaranteed anchor client. So I'm hardly going to be disappointed if PGM-advocates are right.

[Aside: Some people argue that if you lower the price of launch, you undermine the market for in-space fuel. However, IMO, by lowering the price of launch significantly, you expand the range of activities in space enough to increase the overall demand for in-situ fuel (and air/water). Look at SpaceX's Mars plans. Even ITS doesn't work if they had to bring their return fuel with them. A fully fuelled ITS-BFS in LEO is just capable of landing on the Moon and returning to Earth on a single tank; but it's vastly more capable if it lands on the Moon, refuels, then returns to Earth. It's even more capable if an ITS-tanker operating on the Moon is ferrying fuel to L1.]

water accumulated in space would become valuable as it could be used for rocket fuel for interstellar voyages. The substance is too heavy and costly to transport from Earth.

Re: lithobraking, I think Jon Goff once proposed constructing hollow platinum spheres that might be able to survive reentry. Actually, since the sphere would be made in a pure vacuum, if it was thin enough, and big enough, it would have neutral buoyancy in air. The diameter d of such a sphere with a thickness t can be given by:

d = 6 * t * Pt_density/Air_density

Thus, if I did it right, 195 mT in one sphere, if it was 0.64 mm thick walls, would have a diameter of 67.24 meters and have neutral bouyancy, assuming the atmospheric pressure didn't crush it.

« Last Edit: 04/24/2017 01:29 PM by Warren Platts »

Logged

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

water accumulated in space would become valuable as it could be used for rocket fuel for interstellar voyages. The substance is too heavy and costly to transport from Earth.

Re: lithobraking, I think Jon Goff once proposed constructing hollow platinum spheres that might be able to survive reentry. Actually, since the sphere would be made in a pure vacuum, if it was thin enough, and big enough, it would have neutral buoyancy in air. The diameter d of such a sphere with a thickness t can be given by:

d = 6 * t * Pt_density/Air_density

Thus, if I did it right, 195 mT in one sphere, if it was 0.64 mm thick walls, would have a diameter of 67.24 meters and have neutral bouyancy, assuming the atmospheric pressure didn't crush it.

Evacuated spheres light enough to float in air will always buckle under atmospheric pressure on Earth, for any known material.

However, extremely thin sheets or foils might both survive reentry and land mostly intact at a very low terminal velocity due to an extremely high ratio of surface area per unit mass.

d = 6 * t * Pt_density/Air_densityThus, if I did it right, 195 mT in one sphere, if it was 0.64 mm thick walls, would have a diameter of 67.24 meters and have neutral bouyancy, assuming the atmospheric pressure didn't crush it.

You used sea-level air density, which exerts 10 tonnes/m³ of pressure. 0.64mm of any substance won't sustain 10t/m³ without crushing.

However, re: lithobraking. You don't need to have any kind of gentle descent. As long as it is subsonic by the time it hits the chosen landing zone, the metal will be easily recoverable. You'll be aiming for a desert, of course, but recovery is simple.

I found a pressure vessel calculator. 0.64 mm would work for a vacuum chamber about 4 feet in diameter, but as you increase the diameter, the thickness of the wall must also increase. To get the average density to equal air, the diameter must also increase, so there's never a point where a metal ball can float in air, I am convinced.

As discussed previously, a 500 meter iron asteroid would have a trillion dollars worth of Ni at current prices. (100 million tonnes at $10/kg). Current mining production is about 2 million tonnes per year, so one asteroid would be a 50 year supply. (There are about 130 million tonnes of nickel in known, unmined reserves.) So if we could figure out a cheap way to get such masses down to Earth's surface, there is definitely some money to be made.

As for lithobraking, why would a desert be preferable to say, an ocean, or lake, or maybe even a big glacier?

Logged

"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

For high value metals like gold and platinum, they could be returned to earth in reusable 2nd stage. Assuming moon or asteriod water extraction is already in place, the metals can be delivered to LEO on water/fuel tanker as secondary payload. A 1t gold would take up very little space in 2nd stage but could add a few $M to mission profit for normally unprofitable return leg.

Even if water isn't being return to LEO a OTV still needs to return so a extra few $M on this leg from 1t gold would help profit margin.

Wasn't Planetary Resources looking into foaming metals for return? The idea being that by drastically decreasing areal density, you could just aim the material at some open land and then pick up the (flattened) pieces.

What kind of temperature would a chunk of metal reach if allowed to reenter on its own? PGMs don't burn I think. They could boil away, but would have to get pretty hot to do so.

It wouldn't melt, but some portion of it would ablate away. Best to have it shaped into a sphere-cone shape and coated in a heatshield material to minimize any losses.

Logged

"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk"There are lies, damned lies, and launch schedules." - Larry J

Why not making a "dumb" container with some parachutes activated by pressure?The container does not have to be pressurized, so it could be made in modules, launched folded and assembled in space, to save volume. Parachutes would be just a box attached to one of the panels/struts.

A UKIP candidate has pledged to invest more than £1 billion in the asteroid mining industry if he wins a seat, as he believes that Brexit provides a major opportunity for Britain to lead the world in sending nanoprobes to outer space to mine platinum.

Aidan Powlesland, who is standing for parliament in the rural seat of South Suffolk, told BuzzFeed News he wants to set aside £100 million for "an interstellar colony ship design" and £30 million for an "interstellar nano-probe fleet design" designed to attract the attention of Russian investor Yuri Milner, and will provide a £1 billion prize to any private company that can mine the asteroid belt by 2026.

Doesn't the idea that extra Platinum will crash the market assume that there won't be new uses for Platinum once the price drops?

I've heard Aluminium used as a analogy for something that was once expensive and rare.

Platinum, Palladium, Iridium are all metals that would be really useful in wider applications if they were less expensive and less rare.

The top of the Washington Monument is aluminum because at the time it was the most expensive metal on earth. Now it's so cheap people don't bother to recycle it. Yet plenty of profit is still made.The rare metals have so many amazing engineering uses, but the engineers don't get to entertain any of them because of the cost. Go ahead and crash the market, so us engineers can innovate and develop thousands of new uses.

Keeping platinum expensive and rare makes as much sense as keeping aluminum expensive and rare, and only using it for trinkets.In an alternate reality, there are no airplanes, no rockets, and everyone wears aluminum wedding rings.

Note: The Washington monument was completed in 1888 and at that time, barely a single modern use of aluminum was known to man.

Returning metals from 16 Psyche needn't be quite as elaborate as many seem to think.

After mining, assuming a healthy mix of silicates and non-volatile gasses, one simply does a preliminary bit of refining, separating much of the silicates from the metals, as well as separating and storing the various gasses.

After separating the gasses, using the non-volatile gases from the more volatile ones; use those gases in a low gravity melt pot with the silicates to foam the silicates and coat the ingots of semi-refined metals with the foamed silicates, formed into a rudimentary lifting body.

Using a portion of the volatile gasses from the initial refining, as well as some disposable guidance units including rocket motors 3d printed from local, available materials, and using a linear accelerator, again, 3d printed from local materials, send the ingots, roughly about 10 tonnes each, towards Earth.

The guidance packages would then fly the ingots into an aerobraking set of orbits around the Earth to slow the ingots down enough for a controlled reentry. Once in the atmosphere, the guidance package would use the on board rocket motors to guide the ingots to a desert area, where they could make a controlled slideout or air stalled crash. (How the final landing is accomplished isn't that important as the delivered payload isn't really crash sensitive)

As 3/4 of the silicate foam would likely have ablated during the aerobraking and reentry, recovery and removal of the ingots should be fairly simple.

The above assumes of course, that more traditional smelting and refinery techniques would be used on Earth. The task becomes much more simplified assuming that the ingots are simply aerobraked into orbit for zero g recovery and refining. (I'm more a fan of a Lunar L-5 smelting site, rather than in LEO).

Overall; this set up assumes minimal onsite Human interaction with the systems, if any at all. In theory, the entire operation could be automated. It would, however, be a good idea to have someone on site for repairs and modifications as needed. Likely a team of between 4 to 6 people, with overlapping skill sets. Accidents can and likely will happen, and unfortunately, most likely, they'd usually be quite fatal.

Even assuming single 10 tonne ingots could be launched at a rate of one an hour, it would take many months, if not years, before the prices of metals, both common and rare earth, would be significantly affected. This again, assumes that the metals are transported Earth side, rather than simply used in space.

If the latter happened, the effects it would have on the markets on Earth would be minimal, if any.

Evacuated spheres light enough to float in air will always buckle under atmospheric pressure on Earth, for any known material.

Is there a middle ground though? If you are advanced enough to make a hollow sphere in space, then you can probably make other shapes as well like wings, and can probably find some gaseous internal pressurant too, like oxygen. Give it enough internal pressure not to crumple.

I'm thinking something like JP Aerospace airship to orbit, only in reverse. Humongous slightly negative byuoyancy flying wing made out of platinum, coming from orbit. Would that work, physics wise?

Evacuated spheres light enough to float in air will always buckle under atmospheric pressure on Earth, for any known material.

Is there a middle ground though? If you are advanced enough to make a hollow sphere in space, then you can probably make other shapes as well like wings, and can probably find some gaseous internal pressurant too, like oxygen. Give it enough internal pressure not to crumple.

I'm thinking something like JP Aerospace airship to orbit, only in reverse. Humongous slightly negative byuoyancy flying wing made out of platinum, coming from orbit. Would that work, physics wise?

If you want something that works physics-wise, don't use JP Aerospace as your inspiration.

Evacuated spheres light enough to float in air will always buckle under atmospheric pressure on Earth, for any known material.

Is there a middle ground though? If you are advanced enough to make a hollow sphere in space, then you can probably make other shapes as well like wings, and can probably find some gaseous internal pressurant too, like oxygen. Give it enough internal pressure not to crumple.

I'm thinking something like JP Aerospace airship to orbit, only in reverse. Humongous slightly negative byuoyancy flying wing made out of platinum, coming from orbit. Would that work, physics wise?

The important thing to remember is that when you're in orbit, you have a huge amount of kinetic energy relative to the surface. To land your blob of platinum, that energy has to go somewhere. Where is it going to go?

There's a reason that most meteors that enter the Earth's atmosphere explode before reaching the surface.