How to pick pocket the riches of space

Great Debates
21

Well, generally, I’m assuming we want some of this energy on Earth, and some of it to be used to boost other rockets, and to generally move things around the solar system with. Now, I’ll even say that I’ll believe you that beaming microwave energy to earth is impossible. (I say nothing about solving parts of the problem by lifting the reception station high in the atmosphere. This is a technical problem, technical problems have solutions.) But generally, if the mining facility is to be on the moon, we’d want most of the energy to go there, too. If you want individually target satellites, fine, that works too. But generally, these satellites will be out of the plane of the elliptic (you don’t want them blocking energy to planets, so you’re going to need to bounce them off something to send the energy to the destination, so I figure, since there’s going to be, at least at start, a single redirection point, there might as well be a single reception point.

I’m aware of the issues of lunar dust. Perhaps a lagrange point will be better. I’m not fixed on a static refinery. I’m just giving the simplest possible solution I can think of to the issues. One of the points I have is that we’re going to want this stuff in the vicinity of earth, one of the points is that we’re going to want all of these various metals together, and one of them is that we’ll need a load of energy to deal with it. Further, we’re going to have to deal with control lag the further we go out, and the less gravity there is, the worse it’ll be for the poor bugger who will have to be on site, and there will need to be at least three.

My main point about keeping things on or near the moon is that having the works there, will keep it useful to us here on earth, as well as making it easier to build in the first place. Your movable refinery is a superior product, but I’m talking about a first-gen solution.

22

Probably not. The sun’s is a deep gravity well, and the asteroids are nowhere near the top. You almost certainly won’t be propelling them with enough oomph to leave the solar system. In fact, to conserve power you probably give them enough of a push to get close to earth orbit, eventually, and depend upon attached steering mechanisms or catcher folks to ease it into the moon or your factory ship or whatever.

Of course, putting it that close to the Earth is going to make lots of folks nervous, including me. Any uncertainties in your firing direction and/or velocity are going to add to your uncertainty in position as it nears the moon. I’d sure as heck want a dedicated team with really good asteroid-diverting capabilities to avert any possible Tunguskas.

Another good argument for processing on-site at the asteroids.

23

I don’t have a cite per se, but if you look at any reference about atmospheric water vapor absorption, you’ll find that frequencies above 10 GHz are readily absorbed by water vapor (0.1-0.5 absorption). The atmospheric heating will result in cloud formulation and local atmospheric turbulence effects that will further degrade the signal, and will also scatter the signal which will interfere with the K- and X-bands used for communication and radar. Going to lower frequencies (longer wavelengths) there is much less absorption but the efficiency drops dramatically, requiring a very large area transmitter (on the order of thousands of square kilometers) and even larger receiver surface area. Using a large cross-section beam helps alleviate the absorption problems but then requires an even larger receiver area; in effect, once you add up the efficiencies of the various components of the system, it is barely (no more than an order of magnitude) more efficient that just collecting solar power directly at the surface. If the intent is to transmit power to the surface, it is probably more efficient, at least in terms of transmission efficiency through a non-obscured atmosphere, to transmit via a laser in a visible light frequency to a compact, high altitude receiver. However, given the inherent inefficiencies of producing high throughput power transmission, it seems unlikely that this would be a feasible justification for orbiting solar power collectors.

Stranger

24

If it’s that unworkable, they why are so many groups currently trying to build such systems? If the theory predicts a ludicrously low efficiency, they’d be throwing money away.

25

Small detail re: refining: Why not simply seek out the type-M asteroids that are nearly pure iron and nickel and sling only them towards an earth-vicinity refinery? Heck, those things are what our ancestors used for making iron implements in the first place. Little initial refining needed.

26

Many asteroids, and presumably those that would be the first targets for exploitation, are at least periodically closer and require less energy to reach than the Moon. It would actually take more energy to get materials too the Moon for processing than processing in situ and sending them to Low Earth Orbit or Earth’s surface. The idea that it is easier to operate upon the Moon’s surface just because it is a surface belies a lack of understanding of the difficulty of dealing with the particular challenges of that environment.

Which groups, exactly, are trying to build large scale demonstration or practical projects utilizing orbit-to-ground microwave power transmission? From the Wikipedia page you cited, I see PowerSat, which has a “desktop wireless power transmission demonstrator”, Space energy, Inc, which has some fairly vague assertions about the benefits of space based solar power, SolarEn, which has contracted with PG&E to provide the utility with 200 MW of solar power starting in 2016 (about which PG&E spokesman Jonathan Marshall stated that “We’ve been very careful not to bear risk in this,”), and some research and experimental plans by various government agencies to support small scale prototype experiments. I don’t see any concerted, practical efforts to develop a full scale system. Note that I didn’t say it is impossible; if you spread the beam out wide enough, you can minimize the interaction with the atmosphere. You’ll just require a massive array of transmitters and millions of hectares of receivers in a relatively cloudless environment. It is doubtful that this will be more efficient in total than a terrestrial array of PV solar panels or thermal salt solar collectors. Beamed power may be useful for providing power to satellites in orbit (allowing the payload to be lighter and more compact, and carry less batteries or fuel cells for operations and station-keeping).

Just because a concept is unworkable or grossly beyond a reasonable extrapolation of extant technology doesn’t keep people, and especially government agencies, from investing in research and development, often for decades. Look at all of the money poured into directed energy weapon research despite major fundamental problems with atmospheric opaqueness, basic energy throughput issues, and power source limitations; or HTL single stage spaceplanes.

Stranger

27

The only thing I can imagine is the availability of research money for magic beans. At least for the final product they are talking about. But this may be a shot in the arm for the sub-technologies that are employed. The Apollo program didn’t result in moon tourism, but contrary to popular belief, it gave us a lot more than Velcro and Tang. Just providing money for space shots is important in moving in the direction of a goal that we can’t predict in its final form yet. And many of the efforts to find alternative energy sources will need the same forms of distribution and energy storage that a space based system will require.

Do you think a laser induced plasma could be used transmit electricity through the atmosphere? Once induced by a laser, possibly the plasma could be made self sustaining through the constriction around a magnetic field.

28

Haven’t read through all the replies, but some thoughts on the OP (sorry if all this has been covered…posting from my phone so hard to read through everyone’s posts):

First off, self replicating machines are a fantasy atm…nano-tech isn’t even close to being able to do this. Secondly, if we could do this, why wouldn’t we do it HERE…most everything we need is already here, after all, and would be easier for self replicating machines to get to and, more importantly, get the refined product back to us here than out there. Which brings me to the next point…if you have millions of self replicating machines refining materials and tossing them back to earth, all it would take is one fuck up and you have a large, dense object smacking into the earth at high speed. Not a really good idea. Then you have the problem of devaluation…if you go out and bring back a lot of, say, gold, that is going to devalue all the gold here on earth. Now, you might think that’s a good thing in your proposed brave new world, but it’s going to cause a lot of economic disruption.

Most of the valuable stuff in space would be valuable to explorers, not necessarily to folks back on earth. Stuff like water ice would be worth it’s weight in gold, for instance, out in space…but not so much here.

As an aside, was watching an episode of Sci-Fi Science on the Science channel the other day, and the subject was transforming another planet. Basically, the idea proposed was the smash a boat load of asteroids (especially ones with water ice on them) into the poles of Mars in order to create an atmosphere (by heating up the planet and releasing CO2, which would act as a GhG and thicken the atmosphere and also heat up the planet, continuing the heating cycle). Assuming we could/would do this, you could send ‘self replicating machines’ in the form of engineered organisms that could take that CO2 and create oxygen (and also improve the soil), to create, someday, a usable planet (even if you couldn’t breath without a respirator or whatever, it would take less protective gear to move around or live on the planet…not sure how this solves the radiation problem, but he didn’t go into that little detail).

Anyway, I see that as a possible way to use ‘self replicating “machines”’ to do something similar to what the OP is describing…to build something humanity could use that is beyond earth. Gods knows what it would cost or how long it would take, but thought it sounded pretty cool anyway.

-XT

29

As I’ve said in countless other space colonization threads, if you can build a self-sustaining human habitat in space or on the moon or on Mars, for a fraction of the cost you could build the exact same thing and put it on Baffin Island instead. If you can mine the moon or asteroids with autonomous self-replicating robots, for a fraction of the cost you can do the same thing in the Sahara Desert. If you can build closed-ecology hydroponic farms in space, for a fraction of the cost you can build the same farms in the Tibetan Plateau.

I can easily imagine a future where people regularly travel to Mars and live there. But that is a future where everyone on Earth is so wealthy that Mars colonists are doing it for fun, like the guys today who climb Mount Everest for fun.

But people aren’t going to do this to gather raw materials, or to escape from an impoverished Earth. If Earth is too poor for people to live comfortably on Baffin Island, we’ll be much too poor for people to live comfortably on the Moon. The fantasies of the 30s and 40s and 50s, where interplanetary rockets are cheap and safe and don’t need fuel, are simply not possible. Yeah, invent antigravity and we’re talking. Except, while we might someday invent antigravity or space wormholes or warp drives or whatever, we have no reason to suspect that anything like that will ever be invented. And rockets powerful enough to send people to the moon are going to cost billions of dollars. If in 100 years the gross world product is so large that lots of people think nothing of spending the equivalent of a billion dollars on a once-in-a-lifetime vacation trip, then sure. But nobody is going to be building a rocketship in their back yard that is going to take them to the moon.

And so any operations on space have to face the budgetary constraints that you have to spend incredible amounts of money just to get people to LEO, and even more to get them to the moon. So anything they do up there has to be worth more–lots more–I mean a lot more–than what they can do back here on Earth.

30

No offense, but this seems to be a pointless objection Nobody ever builds a large-scale project of unproven technology. Of course they’re building trial stations. What else would one start with?

The point is, they clearly don’t believe that it’s economically infeasible to put up such a power satellite and receiver setup. Even R&D with a small-scale setup will be expensive.

31

As I mentioned, couldn’t the commercial interest differ from the stated purpose?

32

Many asteroids are periodically closer than the moon. They’re close, but… that close?

I understand two passed inside the orbit of the moon recently, but I don’t think they’re really all that common or that useful. Still, yes, we’d be starting with the NEO units. And I’m really not seeing how it would assuredly take more energy. I never said you had to move the asteroids quickly. The point is that once they start hitting the impact point (slowed by gentle retrorockets), there will be a constant flow of supply. It may take a few years for them to start hitting. If you send the station hither and yon, you’re either ejecting the formed metal somewhere, or dragging it around with you. The first just puts the ‘point of target’ a step further up the line, the second is reaction-mass intensive.

33

Except that advocates are, in fact, claiming this to be proven technology. SolarEn, for instance, has made an agreement with PG&E to provide 200MW by 2016. Of course, the company has yet to negotiate with a launch vehicle provider like Boeing, Lockheed, or Arianespace to build and support four vehicles capable of delivering their satellites to MEO; given the lead time on heavy lift launch vehicles averages about five to six years, that seems a little surprising. Or perhaps not; this interview with SolarEn’s "Director of Energy Services provides some rather vague answers to questions about the technology, and this SFGate article casts very reasonable doubts on the technical and fiscal maturity of such plans. It may very well be that SolarEn is simply relying on optimistic evaluations of the feasibility of this technology rather than intentionally scamming investors, but the fact remains that there are significant fundamental hurdles that remain unproven to be overcome. Until orbit-to-ground microwave transmission of energy at flux densities comparable to those required for practical energy transmission are demonstrated, claims that the technology will justify the expense of solar power satellites and receiving stations remain highly suspect.

Stranger