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Hypothetically...
You've captured your stony-iron asteroid and parked it at the Earth-moon L4 point. You've got mines and smelters producing tens of megatons of refined metal annually, enough to meet a noticeable fraction of Earth's demand for metals. The endless bounty of the space is within humanity's grasp. So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and let them drop into the ocean or an artificial receiver lake? Mike Miller, Materials Engineer |
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"Mike Miller" wrote in message
om... You've got mines and smelters producing tens of megatons of refined metal annually, enough to meet a noticeable fraction of Earth's demand for metals. Wouldn't it make more sense economically to use the material where it is -- in space? After all, if you have a substantial enough infrastructure in space to capture an asteroid, would that not imply that rather than giving up all that kinetic energy (in fact, dumping a whole lot more into it to drop it down the Earth's gravity well), it would be better to retain it and use it a lot closer (in energy terms) to where it is to expand that infrastructure and add to its capability?\ Jim McCauley Mountain View CA |
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Mike Miller wrote:
Hypothetically... You've captured your stony-iron asteroid and parked it at the Earth-moon L4 point. You've got mines and smelters producing tens of megatons of refined metal annually, enough to meet a noticeable fraction of Earth's demand for metals. The endless bounty of the space is within humanity's grasp. So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and let them drop into the ocean or an artificial receiver lake? Would simple steel spheres of around 2cm work? Quite a lot of them of course. |
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Mike Miller wrote:
So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and let them drop into the ocean or an artificial receiver lake? Nothing really stopping you from forming the ingots as disk shaped blunt reentry vehicles. Sure you have some mass disappearing during reentry, but a cheap and reliable tug for the deorbit burn that can be refurbished and sent back up completes the package. Ocean landing is the least hazardous, but does contaminate the surfaces. Do a scheduled drop of a series of very large reentry masses on a single day, then spend the rest of the month retrieving them either the ocean surface or the ocean floor depending on how bad of an impact. This allows you to do a not heavily disruptive warning to mariners. Fresh water lakes would be nice, but you're effectively dealing with an unguided reentry which requires a big landing ellipse, and you may need the lake to be somewhat deep in case of a bad impact, which increase hazards and costs. Junkboy |
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Mike Miller wrote:
Hypothetically... You've captured your stony-iron asteroid and parked it at the Earth-moon L4 point. You've got mines and smelters producing tens of megatons of refined metal annually, enough to meet a noticeable fraction of Earth's demand for metals. The endless bounty of the space is within humanity's grasp. This has always fascinated me - why do people think there is a shortage of metals here on earth that requires asteroid mining? The metal - leaving the cost of asteroid capture aside for the moment - is not going to be free, and increased availability will decrease prices. So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and let them drop into the ocean or an artificial receiver lake? Preferably, you would have found a way to get people to pay for these materials without these leaving earth orbit, or even more, go to a not much different orbit. So you sort of have to have lots of orbital infrastructure first before it makes sense. Mike Miller, Materials Engineer -- Sander +++ Out of cheese error +++ |
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(Mike Miller) wrote in message . com...
So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Why would you not resort to space tethers? If you are lowering things with a rotating tether you can use the energy to bring stuff up. So lowering metal to Earth would help you be able to bring things off of Earth. You can make rotating tethers out of Spectra-2000, which is used for fishing line. You could really make a reusable suborbital rocket to match speed with the end of the tether. So why put tethers with "beanstalks" or "anti-gravity"? A rotating tether is just a rotating rope using existing rope materials. Why do you want to avoid them? I am really puzzled that people don't take space tethers much more seriously than anti-gravity. Please explain... -- Vince ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~ Vincent Cate Space Tether Enthusiast http://spacetethers.com/ Anguilla, East Caribbean http://offshore.ai/vince ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~ You have to take life as it happens, but you should try to make it happen the way you want to take it. - German Proverb |
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In article ,
Mike Miller wrote: So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and let them drop into the ocean or an artificial receiver lake? In principle, you can just form it into suitable reentry shapes -- hollow spheres might be good, you want something light enough that it decelerates aerodynamically to near-zero terminal velocity -- and hard-land them in some convenient location. It's probably better to just lease a big chunk of desert rather than fooling around with water; you don't much care whether they break on impact. In practice, you may have a problem with nitrogen-oxide formation during reentry, and possible adverse effects thereof on the ozone layer. This is not a big deal for modest numbers of manned spacecraft, but aerodynamic braking of megaton quantities of materials would be a real concern. Time to warm up the rotating tethers. -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
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Mike Miller opined
Hypothetically... You've captured your stony-iron asteroid and parked it at the Earth-moon L4 point. You've got mines and smelters producing tens of megatons of refined metal annually, enough to meet a noticeable fraction of Earth's demand for metals. The endless bounty of the space is within humanity's grasp. So...How do you land megatons of metal annually without resorting to beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and let them drop into the ocean or an artificial receiver lake? Form it into a big hollow sphere, with vacuum in the center. Make it big enough so that the specific gravity is less than sea level air. Drop it into Earth's atmosphere, wait for it to sink to ~300m and tow to where ever. -ash Cthulhu for President! Why vote for a lesser evil? From an old Analog story. |
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