Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!cs.uoregon.edu!ogicse!sequent!muncher.sequent.com!szabo From: szabo@sequent.com Newsgroups: sci.space Subject: Re: Mining El Dorado Message-ID: <1991Jun17.052228.8112@sequent.com> Date: 17 Jun 91 05:22:28 GMT References: <1991Jun16.195153.9959@stb.info.com> Sender: news@sequent.com (News on Muncher) Organization: Sequent Computer Systems, Inc. Lines: 74 In article <1991Jun16.195153.9959@stb.info.com> charles@stb.info.com (Charles (from bbs)) writes: >We do not want lots of fragments flying everywhere, all we need >is to create a powerful shock wave to disrupt the asteroid structure. >The shock should be small enough that gravity will continue to hold >the pieces together. We could literally surround the asteroid with a >safety net to ensure most of it is retained. Any significant shock wave is going to be greater than the escape velocity (a few m/s). The net, perhaps nylon, is a better idea. Also, if possible set up the explosive(s) so that they fracture the insdide of the asteroid while leaving a surface shell intact. (Charles suggests this also later in his post). The combination of the net and the shell may be sufficient. Cold metal is brittle, but I am not sure whether it would fracture in the way we like, rather than just melting and recondensing. Data from underground nuclear explosions would help here. It would be best if we could produce powerful ultrasound with little heat. >pieces can be individually transported or processed by a robot >smelter. Pumping a very thin atmosphere, and/or magnets may suffice to move the gravel through tubes in microgravity. >In the immediate term it would be interesting to send a probe to >El Dorado, to see if it is differentiated or homogoneous. It is mostly likely homogoneous, I am afraid. The metal asteroids that have struck earth (iron meteorites) are homogenous. Another interesting thing we need to know is how much metal regolith exists on the surface. This saves us the blasting and grinding steps. In general, exploration is cheaper than mining, and we should search widely to discover the most easily extracted resource before committing $billions to mining projects. >thermonuclear shaped charge could be inserted into the interior of El >Dorado, and the drill hole widened. The blast would then be mostly >directed out through the vent hole, creating a more substantial thrust >reaction, which could maybe manouver El Dorado within a few million >miles of Earth. Some issues here: * We can't use Earth gravity assist or aerobraking for such a large asteroid and unpredictable propulsion scheme. Therefore, the delta-v is likely to be quite large (several km/s). * The energy required to achieve that delta-v would likely disrupt or vaporize the asteroid. For example, to achieve 4,000 m/s the power output is (1e10 kg)(4,000 m/s)^2/(.01 s) = 1.6e19 watts assuming a propogation time of .01 second. Of course, we could do multiple explosions, but hundreds to thousands of small nuclear warheads starts to get expensive. * The Christic Institute et. al. don't like things called "nuclear". There is also a treaty that ban putting nuclear explosives in space which would have to be changed (this is a good idea anyway -- it would be much better to allow nuclear explosives in space and ban them on Earth!) Interesting brainstorm. -- Nick Szabo szabo@sequent.com Embrace Change... Keep the Values... Hold Dear the Laughter... These views are my own, and do not represent any organization.