Against all odds, an asteroid mining company appears to be making headway
arstechnica.com
arstechnica.com
It seems to me that when people make the kind of argument that you're making they're forgetting to price the negative externalities that Earth based mining cost our society via environmental damage.
If the environmental damage and species decline that we're experiencing from our planet-side economic endeavours were properly priced in space based manufacturing and asteroid mining would look a lot more attractive.
NEO is too resource starved for it to ever be independent enough to be cheaper than just managing resources better on the surface of Earth.
Design the robots out of materials that can be found in space. Then make them capable of reproduction. Then you can just scrap damaged robots as long as you can replace them fast enough. This also has the benefit that you just need to send up a tiny bootstrap population, but with time you will have quite the formidable workforce.
Also how are the robots going to know what and how to maintain things? Otherwise they must be remote controlled. Yet their sensors break down over time.
Do reproducing robots even exist on Earth? How robust, nimble, and capable are they? Are their inputs found in space?
All that said, I do love the idea of a robot space colony producing useful things, even if all we gain are space probes and knowledge.
It's """simply""" a matter of separating taking all those steps and separating them from the whole, packaging them into a bunch of boxes and sending them to space.
So in other words it's incredibly complicated... but possible.
And isn't it already a thing that we're progressing to with increased industrial output and reduced labour requirements?
This is where we're going, we just need an driver to push us to do it. Space exploration and resource extraction from the asteroid belt/moon to prevent the complete destruction of our environment seems to be as good a driver as any.
Do you have any sources for that? Because from a quick search online I’m seeing that SE requires a tensile strength of 60-80 GPa and the theoretical max strength of carbon nanotubes can reach 150-200 GPa (with a 63 GPa being demonstrated back in 2000)
We can imagine a molecular machine that would grow carbon nanotubes like a silkworm grows silk filaments, but we are many decades away from this kind of things.
Moreover, the tensile strength is not all. It must resist to some intentional or accidental collisions, to earthquake waves and so on.
http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf
It does not contain any experimental results supporting this hope, because only a strength similar to steel has been obtained.
Perhaps it will become possible to obtain a higher tensile strength than with other materials by this method, but it is likely that this will require longer nanotubes and perhaps some other kind of polymeric resin instead of epoxy. It is very difficult to find anything that has high enough adhesion to carbon.
A key part of the design is for the glue to have a low enough melting point, so if the cable breaks, it melts on reentry and you don't get lots of little fluttery bits instead of a big super-strong cable wrapping around the planet.
http://images.spaceref.com/docs/spaceelevator/521Edwards.pdf
The study also addresses lots of other engineering issues. This work sparked a lot of subsequent R&D that is still ongoing. We're not yet able to actually make the ribbon described in the study, but we're getting there.
Then again, if you're willing to rely on dynamic support, a minimal orbital ring could be built with materials we have today:
> The material required for construction of the cable is a carbon nanotube composite: currently under development and will be available in 2 years.
Its actually crazy that the report thinks that we would have the necessary material in 2005 and is still used as evidence of a practical space elevator. The graph on page 10 shows the absolutely massive extrapolation from data at the time. It seems disingenuous to even talk final price and time to construct a space elevator (as is done in the one-page brief) without any data confirming the possibility of manufacturing the goal material.
In geology, we do something incredibly similar called the Bowens Reaction Series. Take a bunch of stuff, melt it and cool it, watch what precipitates and crystallizes from the melt in order to determine the overall composition.
Can't you just throw it in the shade and wait? Space is an excellent insulator, but radiation cooling still happens. Just let it sit there for a few weeks/months and you're all set, right?
But maybe you can do something better with carbonaceous asteroids, or simply with regolith, to produce a cheap ablative shield. I suppose the problem would be with the changes to aerodynamic profile during reentry - but perhaps regolith tiles could be manufactured to ablate in a consistent-enough pattern?
Scott Manley did a good video about it.
https://youtu.be/5kl2mm96Jkk?si=Uf9ntP6R39SJrVBm
Skip to 3:45 for your exact "well meaning suggestion from people who aren't rocket scientists".
The existence proof here is the shuttle, which did indeed manage to glide from orbit.
The challenge is that you need some strategy to dissipate the kinetic energy on reentry. The approach that both the shuttle and these hypothetical gliders use is ablative heat shielding.
A glider manufactured in space and autonomously piloted would have a lot more design space to explore, since you don’t have the constraint that it has to be launchable on a rocket, and you can potentially spend years on successive aerobrake approaches if that is optimal.
It's a good and important point that the term "glider" needs to be qualified. But you failed to make this point.
It does not work for asteroid mining.
There you have just pieces of iron with a low content of alloying elements.
Among the alloying elements, nickel is the most abundant (17.3 times less than iron), then cobalt (20.9 times less than nickel), then germanium (20.4 times less than cobalt).
The precious metals that would justify the mining operation are present as a few grams each for a ton of iron.
Melting the alloy will never separate the metals by itself.
However perhaps some kind of floating zone melting could enrich the proportion of precious metals in a part of the iron, but it is very unlikely that a high enough enrichment could be achieved by a reasonable number of zone melting passes.
On earth the cheaper metals could be dissolved by an acid solution, but on metallic asteroids you have neither water nor acids.
The SciFi solution would be to vaporize and ionize the metal alloy and separate the metal ions by their specific charge, like in mass spectrometry.
This would need a lot of energy, but at least it does not need reactants and it is the only method that achieves almost perfect separation.
However for now, the throughput of such a ionic separator is extremely small, too small for industrial production. Perhaps it will become possible to scale such ionic separators to acceptable productivities.
There are no materials from which you could make a centrifuge for gaseous osmium and iridium.
Vaporizing the input metal with an electron beam and ionizing the vapors allows after that contactless interaction with the ions, using electric fields and magnetic fields, guiding them into separate condensation chambers (which need strong cooling).
The ionic current of such separators must be increased several orders of magnitude over those currently existing, for this to become a viable separation technology.
Of all metals that could be extracted, osmium and iridium are those for which there is the greatest difference in abundance between the surface of the Earth and the metallic asteroids.
If the temperature is not high enough to vaporize the platinum-group metals, they will remain as solid grains, which are likely to damage any centrifuge.
Making a centrifuge from a ceramic material like hafnium carbide is unlikely to work, due to its fragility and low tensile strength, especially at very high temperatures. A ceramic coating of the parts in contact with the hot gas might work, but even if there is a lot of experience in making such things nobody has made parts working at temperatures so high as needed for this application.
The problems for making such a gaseous centrifuge are similar to those for making a high temperature gas turbine.
During the last century, tremendous resources have been dedicated for increasing the maximum temperature of gas turbines. The working temperatures have been slowly increased, but more and more slowly in recent years and there is very little hope that it is possible to increase the working temperatures much beyond what has been already achieved.
A metal separation centrifuge would require working temperatures not higher by 10% or by 50%, but temperatures at least 3 to 6 times higher than for the existing gas turbines.
Based on the existing experience in improving gas turbines, I believe that this separation method can be safely dismissed.
While a centrifuge is not feasible, there are chances to use a part of your proposal.
Heating the metal alloy at a temperature high enough so that iron will sublimate quickly (together with nickel, cobalt, gold etc.) while platinum-group metals will sublimate very slowly could produce an alloy highly enriched in platinum-group metals with a mass many times lower than the starting mass.
This method cannot separate any individual metals and it would lose the gold and other possibly useful components, like germanium, gallium or cobalt, but it could reduce the mass enough so it may make sense to take the concentrated alloy with platinum-group metals away from the asteroid, to a place where it could be processed with more selective methods.
While such a method has some small chances of being profitable, it is very wasteful. Real asteroid mining must separate the metal alloy in all its components, because all can be very valuable, less for being brought back on Earth, but for building any kind of structures in space or on other planets/asteroids.
Another idea, taking advantage of the vastness of space and relative masses in another way. Rather than containing the gaseous material could you not vaporize a large amount of material and linearly accelerate it at the same time by a fixed amount. Maybe even a high powered laser could accomplish both at once without physical contact, or a laser combined with a magnetic field. The mass of the heavier metals will mean their ultimate velocity will be significantly less than the lighter ones. Over some distance they would condense back to liquid then solid but would have striated and continue to separate in distance as the relative velocities continues to pull them apart in distance. You could even do this by producing a pulsed beam of material moving towards earth from the mined asteroid. Closer to earth you would collect material in order of arrival and separating them into bins by expected relative arrival time by elemental mass. Would this not lead to a pretty refined mixture and require no physical contact?
To your point about the sublimation points being different slowly heating the material while applying force to the vapor would also increase the separation in space, and leaving some highly concentrated high vapor point platinum group residual alloy to be refined on earth - maybe this would be considerably less wasteful as you would capture everything at the collection point relatively separated with no exotic materials or centrifuges?
I suspect that near term they might make some decent money just returning small samples for labs to analyze. If they can figure out how to do that economically they can likely survive off of grant money from various government entities. Contracting their asteroid lander for various science missions is also a good opportunity.
That said, we're a long long way from being able to build a skyhook. I'm only objecting to the "never, ever" part of your post.
Sure, let me qualify "never, ever" as having a time horizon of "so long that anyone claiming that you, the eager investor, will see an economic return on this endeavor in your lifetime is secretly banking on breakthroughs in life extension technologies to make that statement technically correct".
We may never ever mitigate our climate concerns, which obfuscates that it is a choice we'll have made, not an inevitability.
If you read the comment sympathetically, it is definitely possible to infer that was their original intent. In fact, i think its the most reasonable interpretation.
If we had these materials in absurd excess, we could literally build hospitals from silver and the electric grid from gold, and it would be great for our civilization.
You sure about that? Here's just one asteroid made of mostly gold, nickel, and / or iron that's supposedly worth many times more than the entire global economy. Pretty sure that anything we have here on Earth also exists "out there" in much greater abundance than we could ever possibly imagine here on our finite little speck of a planet (except maybe "life", which we only have absolute proof of here on Earth).
However the Earth is made of layers with different chemical compositions and many elements are concentrated in layers that are too far from the surface to hope that we will ever reach them. So in the accessible part of the Earth, close to the surface, those elements are seriously depleted.
Some asteroids, unlike the Earth, have never been melted. In that case their composition is homogeneous, similar to the averages of the Solar System. Other asteroids are broken parts from the cores of bigger planets, so they have a composition like in the Earth at very high depths.
However, in the latter kind of asteroids the useful metals are dissolved as tiny percentages in an iron-nickel-cobalt-germanium alloy. This will make their extraction incredibly energy-consuming. On Earth such metals have been separated during millions of years from their surrounding minerals and they have been accumulated as native nuggets or metallic sulfides that are very easy to process for their final separation and purification.
With the alloy that exists in planet cores and asteroids nobody has demonstrated an efficient separation method yet. The laboratory methods used for such separations use huge amounts of water and acids and they will be impossible to implement on an asteroid. Carrying raw metal from asteroids, which is almost completely iron, would also increase the costs tremendously.
So it is absurd to even consider asteroid mining before demonstrating a method that can extract the metals from iron at the mining sites and with a minimum consumption of energy and of non-recyclable reactants.
You hear these statements sometimes about asteroid mining, and they betray a misunderstanding of the way economies work. The reason gold/etc. is expensive is because it is scarce. If we suddenly have an abundance of these materials, then they will be cheap. The intrinsic value of these metals is not worth multiples of the global economy.
Even with/if there's a 'flood the market' eventuality, you'd have approx multiple generations for the market to grow and mature, improving the associated technologies along the way, and wealth generated orders beyond the Carnegies Rockefellers and Vanderbilts combined.
Also, not sure why the prior comment was gettin' down-voted. I'm just tryin' to be encouraging here. If this guy has an idea and wants to write, I'm just sayin' "go ahead and do it then". Why not? Even if nobody ever reads it, if you enjoy writing it, then something was gained.
They are extremely numerous, but most of them are extremely small. Changing the spaceship orbit to catch one of them, which might have a few tons only in rare cases, will provide only a few grams at most of useful elements, far too little for the energy spent to achieve this.
Mining a big asteroid that is a fragment of the core of a former bigger planet has much more chances to be worthwhile, but even for that nobody has gives any suggestion yet for how to separate the mined metals from iron and nickel at the extraction place, otherwise the transportation of the raw alloy would also need too much energy.
Nevertheless, in the crust that covers the surface of the Earth, the abundances of gold and silver and of platinum-group metals are many orders of magnitude lower than their average abundances in the Solar System.
For instance most of the silver has remained in deep parts of the mantle when the crust has formed, so silver is 11 times less abundant at the surface of the Earth than in the Solar System.
Gold and the platinum-group metals have gone to even higher depths, in the iron kernel. So at the surface gold is almost 300 times less abundant than in the Solar System, rhenium almost 600 times and nickel more than 900 times less abundant than in the Solar System, palladium around 3000 times, platinum and ruthenium around 5500 times and osmium and iridium around 50000 times less abundant than in the Solar System.
Similar numbers apply to all of the 8 planets that are big or medium-sized and also for some of the small planets and big satellites, because all these have been melted at some point in their history, when all the metals with high affinity to iron or sulfur have gone to inaccessible depths below the surface of those planets.
In the outer parts of the Solar System, the bodies are covered by thick layers of ice, but for the 4 inner planets the silicate crust that we see covering their surface is similar to the slag that forms at the surface of the iron smelted in an iron furnace and it is similarly depleted in the metals with low electropositivity.
16 Psyche might, or might not, be such an object. If so its surface is still covered by a "rubble pile" layer of rocky material.
https://www.space.com/james-webb-space-telescope-psyche-plan...
While the depletion has reduced the amount of platinum-group metals by many thousands of times, the enrichment only increases their concentration a few times over the average concentration.
The reason is that the planet cores still include iron, one of the main 10 elements of the universe, the least abundant of which is many times more abundant than all the other elements combined.
The enrichment consists only in the removal of the magnesium, silicon and oxygen from the planet core, while the iron stays there.
Even with all the platinum-group elements in the core, their abundance cannot increase beyond the limit imposed by the ratios between their average abundances and that of iron (actually their abundances become a little larger than those ratios, because a bigger fraction of iron remains oxidized in the mantle than the corresponding fraction of platinum-group metals, but the difference above the average ratios remains very small).
https://pv-magazine-usa.com/2023/11/20/reconductor-existing-...
https://haas.berkeley.edu/wp-content/uploads/WP343.pdf#page=...
https://www.entsoe.eu/Technopedia/techsheets/high-temperatur...
That would enter the atmosphere orders of magnitude slower than meteors do. Would that be enough for it to largely survive the fall to the surface either stay largely intact on impact or break up but the pieces would all be in the same general area?
Edit: based on a quick chat with Claude Sonnet, reentry velocity would be about a fourth as high, but getting to that initial orbit in the first place makes the whole project significantly harder. But maybe if ablation from reentries became an environmental problem, and deep-space propulsion got really good, it'd be worthwhile.
I wouldn't expect asteroid mining to be viable until we have Starship or something like it at scale, doing thousands of launches per year. If most of those flights return empty, then that's a lot of cargo space already available.
Starship uses $1 million in fuel to launch 100 tons to LEO, so half that much should be plenty to take 50 tons back down. But Starship's propellant mass for launch is 2600 tons[1] so that'd be up to thirteen launches to put the landing fuel in orbit. Actually it'd be less, since a lot of the orbital velocity is burned off by atmospheric breaking, not sure how much.
Ideally though, get the fuel from the same asteroids you're mining already. Starship uses methane, so you're just looking for water ice and carbon, both abundant in asteroids.
At current prices, 5000 tons of gold is worth about $400 billion, so it's not obvious that this wouldn't be economical. The world mines about 3000 tons of gold annually and the price of gold has still been going up, so if our asteroid miner returns a couple thousand tons per year it might not crash the price too badly.
[0] https://space.skyrocket.de/doc_lau/super-heavy-starship.htm
And of course gold has all sorts of really useful properties, so long term, it'd be worthwhile to make it abundant and cheap.
that isn't the way price elasticity on the demand curve works. that isn't the way any of this works
i mean i'm not an expert in the area, but i think this is a well-understood set of problems. passive reentry vehicles have been used for decades for spy satellite film canisters, v-2 ballistic missiles, scud ballistic missiles, icbms, mirvs, and space capsules like those used in the vostok, apollo, and mercury programs. it gets easier in this case because you don't care if it breaks when it hits the ground, so you don't need parachutes or retrorockets; you just don't want it to vaporize
specifically, a hunk of mass at rest at the von kármán line of 100 km has 981 kilojoules per kilogram of gravitational potential energy with respect to the ground. one degree of temperature is roughly one kilojoule per kilogram, so that's roughly 981 degrees of heating if it falls to the ground from that height with no further air resistance—not enough to melt steel, nickel, gold, platinum, or even mafic rocks. and it's still 981 kilojules per kilogram whether it's a kilogram of platinum or a thousand tons of platinum. but it gets better! that heating is shared between the reentry vehicle and a somewhat larger mass of whatever it hits, roughly in inverse proportion to their stiffness. and of course there is atmospheric resistance, even without a parachute—quite a significant amount of it at the comparatively low sectional densities you need to lose most of your escape velocity from hitting the atmosphere. so, typically, when meteorites land, they aren't even hot. the arguments above explain why in most cases they can't be hot unless they hit so hard as to blow open a crater
980 kilojoules per kilogram is 1400 meters per second, about mach 4, so you really don't want it to hit you. but it won't even melt, and newton's penetration depth approximation assures you it won't penetrate very far into the ground, like, less than a meter
so basically you're worried about a nonproblem
It’s true that the relative value of these materials will be higher in space (since your alternative is lifting it out of the gravity well) but there may be so much supply that you can saturate the space market and justify the extra transport cost to sell it on earth too.
Suddenly you only need to get to orbit, as everything else is cheap, because you can refuel and get water. You can go where you want to go, you can grow food, you can stay in low earth orbit for cheap.
Getting all the other elemental material we need without screwing that up will be a win for our descendants.
Thankfully, forests are self-renewing, and we no longer use charcoal as a carbon source.
Mines are also generally pretty small compared to forests.
Charcoal is very much in use around the world, forests are now small enough that entire forests are marked to make way for mines, and forests are not-self renewing on time nor does a mine convert back into a forest.
Charcoal is no longer used as a primary heating source in the way it was in antiquity, given the global trade in oil, gas, and coal.
Furthermore, mines in civilized parts of the world generally do have reforestation requirements as part of their decommissioning.
We can certainly gripe about the legacy of toxic tailing ponds et al., but tree cover is usually handled decently.
Someone talked about 3D printing mostly hollow golf balls in outer space and dropping them onto a desert where they could be picked up .
The first obvious assumption is would have to be launched from space and return to space because the cost of getting a payload from Earth to LEO is a huge extra expense.
Then you have to consider the delta-V of getting to the asteroid, doing a rendezvous and getting back. If that's so significant that the Earth launch cost is trivial then the delta-V budget is so huge, it must make the endeavour even more uneconomical.
I believe humanity's future is in a Dyson Swarm. There are simply too many advantages. This is a deep topic. The question is how do you bootstrap that? Where do you get raw materials?
I don't think it's from asteroids. I very much suspect it's from a larger body and my money is on Mercury. Why? On pretty much any body in the Solar System you're living underground so Mercury is at no disadvantage here. It has no atmosphere. That's an advantage. Mars's super thin atmosphere is the worst of both worlds. Additionally, Mercury is metal rich and due to its proximity to the Sun, energy is abundant (ie solar power). Interestingly, it has a higher orbital speed than Earth (47km/s vs 30km/s). That's really interesting because it's free velocity to leave the Solar System.
Resources on EArth are so ridiculously cheap. You can mine iron ore for a few dollars a ton at scale. You can convert it into steel really cheaply too (again, at scale). Doing anything in space requires having truly stupendous amounts of cheap energy available.
Highly doubt such chunks are floating around our solar system but it's an amusing thought that one day hundreds of years from now we could nudge a (much) smaller chunk into orbit or park it in a Lagrange point and shave off pieces to return to earth.
Aren't neutron stars 12 miles in diameter on avg?
A neutron star 12-16 miles in diameter contains the mass over HALF-MILLION earths, it is very hard to fathom but yet they exist!
So popping out an earth-sized chunk of gold after collision with say another neutron star (kilonova) and ejecting matter to "normal" density is plausible.
Considering just the initial mining and construction, bodies with low gravity and proximity to the earth feel like an efficient starting point, right? I always thought the moon would be a good place to bootstrap the first few thousand space habitats.
Your point about energy will probably be the biggest deal. Wondering how complicated it would be to ship a bunch of nuclear reactors to the moon. There seems to be quite a few companies working on small, "mass produced" reactors currently.
Or so that you can do other things, like drink it...
We can't even just laugh.
That "isn't competitive" is quite an understatement. But yeah, technically it doesn't break any law of Physics.
And the sun is a gravity well. Mercuries higher orbital speed will not help you leave the solar system. In fact, it is the other way around.
Oh, and solar cells are already crazy good. With all the space you have out there, higher energy density on mercury will be very marginally important.
You've also got to slow it down when it gets to where your smelters are. For that I'd propose we just let it smash into the moon and then mine it on the surface. We can alternate which sides we smash into in order to prevent the moon's orbit from changing significantly.
Of course you still need to provide the initial nudge, which ain't nothing, but it's a far cry from towing an asteroid or towing a smelter.
Based on my calculations, with optimistic assumptions (including the asteroid being made solely of the desired material), you need 5 Falcon 9 launches and in-space assembly to bring back one ton of material, which would require selling the material for 350k$/kg for parity. But gold is only 80k$/kg, platinum is 30$/kg, etc.
Doesn't look feasible with current technology.
If you don't pay the demanded price before it arrives in orbit, it will be delivered a full speed on your lawn. Your entire city will be destroyed.
Nothing about actually mining resources and returning those materials to Earth. So they've gotten funding from investors? In the past, even dumber endeavours have gotten even more funding than this, it really doesn't mean anything.
While that sounds simple, it does make it sound like the mining part just became much more difficult.
Thinking about some of the sci-fi regarding asteroid mining, I've always liked the idea of bringing the asteroid to park into an orbit around earth to make it easier/cheaper for multiple deliveries, but I've always wonder what kind of ownership claims that would imply. If I took the time and effort to park an asteroid in orbit, would I have sole ownership of it or would you be able to mine from it as well?
The biggest amount of delta-v is necessary to leave Earth's gravity well. Once you're there, going from and to asteroid is time-consuming but doesn't need that much delta-v, moving ore from the asteroid to Earth would cost some fuel, proportional to the mass.
So moving it into orbit would save time but require us to pay for the fuel all at once.
So why should someone do this, unless you need a permanent human presence on the asteroid?
Activity is only economically valuable if it is valued - i.e. by people.
Unless there's a population of people living in space, the ore or products derived from ore need to eventually make their way to Earth in order to be worth while.
Nobody cares in sci-fi about whether something should/could be done. That's not the purview of the plot. It's also not the purview of the original comment.
I think you're dramatically underestimating the difficulty of doing this.
If you look at rockets, they're 90-95% propellant. Even relatively svelt upper stages like Centaur III (the upper stage from Atlas v) are more than 50% propellant. And that's for just taking payloads to LEO - for higher energy missions, the usable payload gets smaller, which means the percent of the upper stage that's propellant increases.
How difficult would it be to get an amount of propellant, say, 5 times the mass of the asteroid to the asteroid? You'd also have to get the engines and other structures to let you use the propellant in a productive way.
It's way easier to extract valuable parts from an astroid and move a lot less mass there and back.
As for moving the asteroid you could use extremely high specific impulse ion thrusters, in situ propellant from the asteroid itself, or a solar sail. But you are right that simply firing the valuable stuff back to Earth is probably easier.
Mass drivers and linear rails are also viable ways of bringing raw material into Earth's orbit from asteroids of a certain size.
So what you’d want is a LEO starting point/station. You launch a barge from there to snag an asteroid. You could use a mass driver using solar or nuclear and mass from a previously spent asteroid to get to the asteroid belt, then snag an asteroid and use its mass to get back. You strip the important parts of it, construct a capsule for what you mined, and nudge it so it falls someplace in say a shallow part of the ocean. Then recover from there.
Or hell why mine it up there? Simply nudge an asteroid on a collision course towards Earth to make sure it falls someplace “safe”. Sure most of it will burn up but not all. It’s free material after all.
Meteors fall onto Earth all the time. It is a matter of composition, trajectory, and mass, no?
We're talking very specifically about an asteroid made up of iron. Logic would follow that it would be on the more massive end of the scale. No? That's like the worst possible composition and the very type that worries the doomsday types.
But that aside, we have plenty of iron right here on earth. There is zero reason to mine iron in space unless you need it in space. An asteroid of pure gold on the other hand…
But setting all that aside, you get to choose the size! And the trajectory! And the arrival point! Like if you toss a 100kg asteroid and get 1kg of gold out of it, no you won’t kill the planet. You get to choose all the variables.
Ideally you’d put an asteroid in LEO, slow it below orbital velocity, and have it come down at a shallow angle so aero breaking removes most of the remaining velocity.
I guess one risk would be introducing unknown biological or chemical nastiness. Another would be how precise we could be to target open ocean/desert/etc.
As all these options are cheaper and easier than asteroid mining, and as none of these bright-eyed ‘entrepreneurs’ are undertaking these tasks, I can only assume the things being ‘mined’ are gullible investors. (Not that I’m blaming them… what’s easier? Finding an asteroid with a precious metal, mining it and getting it back to earth at less the cost of mining it here? Or, finding a gullible venture capitalist who will cover your salary for a few years? Probable the latter…)
Water, volatiles and carbonaceous materials anywhere else in the solar system: priceless
(1) Build a solar sail factory on a CC asteroid and you can deliver sunshades to Earth-Sun L1 without wasting volatiles as reaction mass
(2) If you read this paper and really thought about it
https://arxiv.org/pdf/2011.07487
You’d realize that it strictly dominates all other space colonization schemes that have been proposed because it doesn’t waste volatiles for transportation. Certainly O’Neill’s ideas look infeasible in comparison (where do you get the nitrogen to fill those big airspaces? My plan for a baby Bernal sphere intended to be a luxury hotel in LEO still takes 15 starship loads of LN2 for the atmosphere)
Even Musk’s plan to colonize Mars is something that only makes sense to people who were born on a planet. If “grabby” aliens capable of interstellar travel and building such things here they might find the Earth a curiosity at best.
Using ion thrusters it is already the case that we have access to power-generation-limited domain of specific impulse; Nobody thinks a mission at 30,000isp instead of 3,000isp is superior for interplanetary because of the sheer amount of waiting time and the extreme mass fraction of the solar panels. Solar sails, even moreso.
And one more dream to kill - large open volumes are probably never going to happen. This is implied by the mathematical engineering reality of the thin-walled pressure vessel, whose minimum mass scales directly with (volume * pressure) / tensile strength. Contrary to my naive expectations, there is no square cube ratio to the structure of a pressure vessel, so every cubic meter costs mass.
Solar sails with any significant mass attached to them would either need to be impossibly large, and/or operate on timescales that make ion propulsion seem like a warp drive. And that's not counting the issue of stopping when you get to your destination, which will either require some insane laser/power source already at your destination, or propellant- in which case you're back to just using that in the first place.
https://en.wikipedia.org/wiki/Long_Duration_Exposure_Facilit...
Better these two as a role model than Theranos though.
Obviously the lack of any squishy humans that need to be part of the process makes it less of an issue when nothing comes of it.