Talk:Asteroid mining

From Wikipedia, the free encyclopedia

	Space Portal This article is within the scope of WikiProject Space.
Start	This article has been rated as Start-Class on the assessment scale.
Related projects:
	WikiProject Space exploration	Importance to Space exploration: Mid
Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.

This article is still in need of a section about processing ore in outer space, although this could be covered along with Lunar mining. — RJH 17:35, 21 Apr 2005 (UTC)

Negative. Lunar mining is a very different process than asteroid mining, because of the different compositions. Heating carbonaecous chondrite to get out water is much different than breaking apart oxides. Michaelbusch 21:34, 5 October 2006 (UTC)

Contents 1 Density and Composition 2 Proposed Merger with Space Mining 3 Proposed History paragraph 4 History

[edit] Density and Composition

The only major problem I can see with placing rockets on asteroids to slow the revolution, even ones of high density, is that the gravity is still too tenuous to act on the body as a whole. In fact, the weak gravity would require that we come up with different method of mining all together, because shaft mining would weaken the integrity of the asteroid and as stated strip mining would create a ring or cloud of debris around the asteroid. -nick

This is largely a question of composition. In the case of bodies made of solid material, rather than gravitationally bound conglomerations of loose material, this is not an issue. Higher density bodies are much more likely to be solid, and given that higher density objects are more likely candidates for mining, this is unlikely to pose the problem you suggest. There is, of course, a lot of variety between individual asteroids, and certainly some would exhibit the problems you talk about, but asteroid selection is just that much more important.Azriphael 19:29, 5 October 2006 (UTC)

Higher density doesn't necessarily imply cohesion. A metallic rubble pile will have a much higher density than a solid silicate rock. More importantly, our current understanding of asteroids is that most of them are rubble piles (that is, they are held together largely by gravity rather than their own cohesive strength). This means that shaft mining is not necessarily a bad idea, because the asteroid is weak anyway. With regards to slowing the rotation with rockets: all that is required is that the rockets be anchored well enough to the surface that they don't pull themselves loose. That can be achieved by driving stakes into the surface. There are a few asteroids known that rotate so fast that they must be solid, but most of these are very small (<100 m) and they are definitely in the minority. Michaelbusch 21:34, 5 October 2006 (UTC)

I agree that solidity and density are only correlated, not linked. However, even if the vast majority of asteroids were rubble piles, there are an awful lot of 'em in the belt. If the techinique you are using requires a solid asteroid to be effective, you can find one. It is also my understanding (though I lack an authoritative source to link you to) that solid iron asteroids are actually more likely than silicate ones. Assuming roughly equivalent spectroscopy, density is a good indicator of solidity. Azriphael 18:07, 6 October 2006 (UTC)

I have learned from experience that spectroscopy is not a reliable indicator of composition (see M-type asteroid). More importantly, we have zero information on the densities of most objects (although they generally have to be more than 1 g/cm^3 to hold together, and aren't solid lead). Iron asteroids are much rarer than silicate asteroids, by about a factor of a hundred. This is based on radar observations, which give bulk densities of the near-surface material. Among asteroids known to be metallic (from radar observations), four of six have bulk densities such that they have to have high porosity. The remaining two don't have good bulk density constraints as yet (just >3.5 g/cm^3). Our information on this will get better: Mike Shepard of Bloomsburg University will be releasing some of his results next week. But there is still a shortage of solid objects. Modeling of the asteroid belt indicates that only very small (less than order 100 m) objects have high probability of remaining monolithic chunks. This is supported by the morphologies of objects in the km size range. Of course, once an object is big enough, it doesn't matter if it is a rubble-pile or not. The Earth isn't held together by cohesion and neither is Ceres or 216 Kleopatra. Michaelbusch 18:21, 6 October 2006 (UTC)

Is the basis of the modeling argument that larger monolithic bodies would not have formed, or that they would have been pulverized by now? Or is there some other perfectly reasonable argument here that isn't immediately apparent to me? Azriphael 20:23, 6 October 2006 (UTC)

Both. Objects of km size fragment during accretion (there have been many good papers on this. The work of Erik Asphaug of UC Santa Cruz comes to mind first), so the only way to produce solid shards is by annealing in the interiors of large objects (in the extreme case, melting to get out nickel-iron). Then, over the age of the solar system, objects up to tens of km in size are collisionally disrupted, which is what maintains the number of small objects. During collisional disruption, shards tend to be cohesive only on sub-km size scales (the is based both on the observed morphologies of small objects and the works of Holsapple, Morbidelli, and Canup, among others). Michaelbusch 21:25, 6 October 2006 (UTC)

Very well, then. I haven't reviewed the literature you suggest, but based on your explanation, that seems sensible. Azriphael 22:04, 19 October 2006 (UTC)

Given the above, is the debris resulting from surface (strip) mining really an issue? To the extent that the process kicked up a lot of small particulate debris, I could see it posing a threat to the mining vehicle as it attempted to leave the asteroid to return its cargo to Earth. However, in the case of waste material generated by the extraction process, even if it can't be safely placed back into the asteroid (unlikely, perhaps), simply ejecting it away from the craft's intended departure vector should render it harmless. Then again, I suppose that in large part the danger of disrupted clouds of debris is a function of their individual particles' mass and relative velocity vs. the fragility of the vehicle. Can someone cite a source for the specific techniques proposed and their respective advantages and drawbacks? Azriphael 22:04, 19 October 2006 (UTC)

Debris is a problem, because you don't want to be throwing lots of dust into space around the object. Unless you throw it away very quickly, it will stay near the asteroid for a long time. There aren't many very good references on the advantages and disadvantages of various techniques. Probably the best is Lewis & Lewis, 1987 "Space Resources". It is unfortunately somewhat dated. Michaelbusch 22:10, 19 October 2006 (UTC)

[edit] Proposed Merger with Space Mining

Keep separate - I think that this has been discussed before, though I'm in a bit of a hurry right now and don't want to go digging through the history of the talk page. I don't think that this is a particularly good plan. You might take a look at Michaelbusch's comments above about the differences in processing ore. The evidence presented here seems to me to suggest that the processes of mining on an asteroid are radically different from those needed to mine a extra-Terran planet. Given this distinction, I think it would be more sensible to include a small note about the major differences in these processes in the space mining article and to leave this information in its own space, with similar articles for extra-Terran planetary mining and any other major category that makes sense. At present, the only real argument I can see to merge the two is that the space mining article is nearly empty, while this article is considerably more extensive. However, I view that as being an issue of a shortcoming of the space mining article, not a mis-categorization of this one. Azriphael 22:04, 19 October 2006 (UTC)

Agreed. — RJH (talk) 14:44, 20 October 2006 (UTC)

[edit] Proposed History paragraph

I added the following paragraph yesterday. User Michaelbusch promptly deleted it.

[edit] History

The idea of moving mining to space dates back at least to Russian space visionary Konstantin Tsiolkovski (1903). Robert Goddard's pioneering rocketry experiments in the 1920's were paid for by the Guggenheim foundation, with money from mining. Goddard himself envisioned the migration of industry and people to space (1918). (Source: ref. 2)

From the Asteroid mining history page: 04:54, 5 December 2006 Michaelbusch (rv. additions. History is not a bad idea, but this paragraph is not well written and is inaccurate. Citations!)

Reply: All of these statements are drawn from Ref. 2, John S. Lewis, "Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets". Do you want them individually footnoted? What did you think was inaccurate?

As for the writing quality, editing would seem better than deletion.

Comments from others? Pete Tillman 18:24, 5 December 2006 (UTC)

MB:The implication of the second sentence is that Guggenheim somehow thought that they would mine space, which I very much doubt. I would simply remove that sentence and edit the rest of the paragraph.

PT: My intent was just to show that a mining-based foundation was supporting space exploration in the 1920's. The Guggenheims were a remarkable family. For all either of us knows, someone at the family/foundation had read Tsiolkovski....

MB: I don't have Lewis' book in front of me, but I would prefer citations to the original statements by Tsiolkovski and Goddard if someone can find them (note also that asteroid mining as discussed here and the industry invisioned in the early 20th century are somewhat different). John is very good, but he is on occasion over-enthusiastic. Michaelbusch 18:43, 5 December 2006 (UTC)

I'll try to remember to look at the book at the library -- though I can't think of any reason Lewis would fabricate this. In any case, secondary sources are fine for WP, so long as they're cited properly. Pete Tillman 18:40, 7 December 2006 (UTC)

I wasn't suggesting that John fabricated, merely that he was making a sales pitch. Michaelbusch 18:52, 7 December 2006 (UTC)