On Thu, Jun 14, 2007 at 11:05:23PM -0300, Lúcio de Souza Coelho wrote: > >Check your energetics. Asteroid mining is promising for space-based > >construction. Otherwise you'd better at least have controllable fusion > >rockets.
It is quite useful to utilize space recources where they are, because the hardware is there, and all you need is a high-bandwidth link, or dropping a matter packet with data. > (...) > > Not really. > > Elements that are incredibly rare on Earth - such as platinum group Reasonably advanced nanotechnology (biological life) doesn't use large quantities or rare elements. A lot of elements people consider rare have actually quite nice crust abundancies, but lack ores. If you have good enough enrichemnet, then everything is ore. > metals - could be mined in asteroids and simply dropped into Earth in > round-of-the-mill reentry capsules - and those would't even need > rocketry tech beyond the current level. Take in consideration that > even a few tonnes of platinum - well below the weight of the space > shuttle - would be of immeasurable value. Sure, and don't forget to add some hand mirrors, and glass pearls. > As for "bulk" elements like iron, copper, nickel, etc, there are small > asteroids - a few tens of meters in length - that could potentially > have thousands of tons of those metals. My suggestion for that would Why asteroids? The Moon is close enough, both in distance, and in terms of delta v. > be a controlled crash - simply boost the asteroid (using a mass driver > or whatever) to a trajectory where it will be aerobraked by Earth's > upper atmosphere (preferably over the ocean to avoid hazardous > hypersonic booms over populated areas) and then, stripped of most of > its kinetic energy, crash in an uninhabited area. Probably the crash > will still look like a small nuke, but then we devastate similarly > larger areas for comparable gains (as in the case of hydroelectric > plants or extensive surface mining). By the way, talking about mining > on Earth, some of the ore deposits currently explored are in fact > ancient asteroid crashes... Good luck finding an insurer for that. > Finally, in the long term space elevators may well be possible, and > then the limitation of bringing raw materials from space to Earth will > be similar to the limitation of moving materials between continents > using ships. Look into linear motors on Luna, topped off with rocket burn. ----- This list is sponsored by AGIRI: http://www.agiri.org/email To unsubscribe or change your options, please go to: http://v2.listbox.com/member/?member_id=4007604&user_secret=7d7fb4d8
