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.
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.
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.
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.
Interesting related article from Bloomberg:https://www.bloomberg.com/news/articles/2017-04-23/space-the-final-frontier-seen-for-earth-s-crude-oil-giantsQuotewater 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_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.
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.
As for lithobraking, why would a desert be preferable to say, an ocean, or lake, or maybe even a big glacier?
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.
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.
Evacuated spheres light enough to float in air will always buckle under atmospheric pressure on Earth, for any known material.
Quote from: envy887 on 04/24/2017 01:34 pmEvacuated 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?