wjb@burl.UUCP (Bill Buie) (05/02/84)
-- With regards to the current debate about a safe way to get rid of nuclear wastes: Has anybody givin serious thought to launching it into space and tossing it at the sun? Are there practical considerations that would prohibit this? -- --Bill Buie
ntt@dciem.UUCP (Mark Brader) (05/03/84)
Bill Buie asks why it is impractical to send nuclear waste into the sun. One reason is that in a few decades or centuries we might have more efficient techniques for using the remaining energy, and we might want it back. A more immediate reason is that rockets are not all that reliable a form of transportation. Constructing a worst-case scenario of what happens when it crashes (or is blown up in mid-air because of the even worse effects of where it was going to crash) is left as an exercise for the reader. Another case is that it might go into orbit around the Earth or Sun; presumably Bill feels that such "space pollution" is likewise undesirable or he would have proposed that easier feat in the first place. I agree. Finally, a direct trip from Earth to Sun with a payload of any size is infeasible. It requires a speed of about 70,000 mph*, as against only 18,000 to put a satellite into orbit around Earth or 25,000 to escape Earth, because you have to cancel the Earth's speed around the sun. However, I've read** that there is a way around this; by cleverly aiming the vehicle to pass near Jupiter, it can be made to fall into the sun from there. But the trip takes two years each way, and a failure on the way out would likely make the accurate aiming needed near Jupiter difficult. *Earth's speed in its orbit is 66,000 mph and escaping Earth needs 25,000. Square each, add, take the square root. At least, I think that's right. **Arthur C. Clarke, "The Promise of Space", citing a NASA study. They were talking about scientific probes, not garbage disposal. Mark Brader
amigo@iwlc6.UUCP (John Hobson) (05/04/84)
A couple of comments on Mark Brader's response to Bill Buie: >> Bill Buie asks why it is impractical to send nuclear waste >> into the sun. >> >> Finally, a direct trip from Earth to Sun with a payload of >> any size is infeasible. It requires a speed of about >> 70,000 mph*, as against only 18,000 to put a satellite into >> orbit around Earth or 25,000 to escape Earth, because you >> have to cancel the Earth's speed around the sun. However, I've >> read** that there is a way around this; by cleverly aiming >> the vehicle to pass near Jupiter, it can be made to fall >> into the sun from there. But the trip takes two years each >> way, and a failure on the way out would likely make the >> accurate aiming needed near Jupiter difficult. >> >> *Earth's speed in its orbit is 66,000 mph and escaping >> Earth needs 25,000. Square each, add, take the square >> root. At least, I think that's right. >> **Arthur C. Clarke, "The Promise of Space", citing a NASA study. >> They were talking about scientific probes, not garbage disposal. First of all, will someone please explain to me why the earth's orbital speed needs to be cancelled out. Sending it on some sort of parabolic or hyperbolic orbit into the sun should be do-able, without having it go outside the earth's orbit. One thing, however, that Mark did not mention, is the cost. Rockets capable of lifting appreciable masses to earth escape velocity are most decidedly NOT cheap. John Hobson AT&T Bell Labs--Naperville, IL ihnp4!iwlc6!amigo
barry@ames-lm.UUCP (05/04/84)
[] > With regards to the current debate about a safe way to get rid of > nuclear wastes: > > Has anybody givin serious thought to launching it into space and > tossing it at the sun? Are there practical considerations that > would prohibit this? > > --Bill Buie Throwing nuclear wastes into the sun has been suggested before. Unfortunately, there is a practical difficulty: the delta-v (read "energy") needed to get something to the sun from earth orbit is large (either 20 km/sec or 20 miles/sec, I forget). It would probably be cheaper to shoot the stuff clean out of the solar system, then to throw it into the sun. Fortunately, there is another solution which is much more economical: sell the stuff to any country (like France) that uses breeder reactors. Breeder reactors can use spent fuel from light-water reactors like the US's as 'breeding' fuel. If breeders become popular, I would bet that our nuclear 'wastes' might be worth quite a bit of $$$. Kenn Barry NASA-Ames Research Center Moffett Field, CA ------------------------------------------------------------------------------- Electric Avenue: {dual,hao,menlo70,hplabs}!ames-lm!barry
rcd@opus.UUCP (05/05/84)
<> >With regards to the current debate about a safe way to get rid of >nuclear wastes: > >Has anybody givin serious thought to launching it into space and >tossing it at the sun? Are there practical considerations that >would prohibit this? Yes, it's been considered seriously - and just as seriously rejected. One factor is that uranium, plutonium, etc. are obnoxiously heavy - almost twice the density of lead. It's expensive to launch heavy payloads, especially all the way to escape velocity. But the much more serious objection is this: What if the rocket fails? You just can't afford to let the thing blow up on the launch pad or after it's only gone a few dozen miles. -- ...Relax...don't worry...have a homebrew. Dick Dunn {hao,ucbvax,allegra}!nbires!rcd (303) 444-5710 x3086
bitmap@ucbtopaz.CC.Berkeley.ARPA (05/06/84)
<...> >...will someone please explain to me why the earth's orbital speed >needs to be cancelled out. The earth (and everything on it) has a large angular momentum with respect to the sun. If you could kick the earth towards the sun, it would still stay pretty much in a circular orbit, because of this angular momentum. This is analogous to having a large object, say a horse, go galloping (sp?) by towards the south, and as he goes by, you give him a push to the west. He might go a little bit to the west, but will still go mostly south. For the sun, you don't need to cancel all of the earth's orbital speed (angular momentum), but you'd need to cancel a lot of it. Sam Hall decvax!ucbvax!ucbtopaz!bitmap