Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Sat, 29 Jun 91 02:02:14 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 29 Jun 91 02:02:07 -0400 (EDT) Subject: SPACE Digest V13 #739 SPACE Digest Volume 13 : Issue 739 Today's Topics: Regular postings of Sky + Telescope Re: SPACE Digest V13 #617 Re: Fred Vote Thursday Solar Flares Re: NASA Budget Re: Earth Gravity Assist and Aerobraking Safety SPACE Digest V13 #623 Re: Fred Vote Thursday Re: Risks of technology Re: Lost satellites Re: Microgravity? Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: Wed, 12 Jun 91 18:41:47 EDT From: Tom McWilliams <18084TM@msu.edu> Subject: Regular postings of Sky + Telescope Re: Sky and telescope postings This thought just occured to me. Would anybody be interested in regular factoids from Sky + Telescope magazine, similar to what Henry does with AW&ST? BTW, does any one know the legal situation of such an idea? (assuming anyone's interested, of course). Tom Acknowledge-To: <18084TM@MSU> ------------------------------ Date: 13 Jun 91 02:20:35 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!ub!galileo.cc.rochester.edu!rochester!dietz@ucbvax.Berkeley.EDU (Paul Dietz) Subject: Re: SPACE Digest V13 #617 In article <9106122349.AA25412@ucbvax.Berkeley.EDU> space+%ANDREW.CMU.EDU@msu.edu writes: >Re : Future of energy and materials (was asteroid mining) >>There are multiple possibilities in the wings for new energy sources >>when the oil runs out (various forms of nuclear and solar power >>have nearly unlimited potential; obstacles of cost can be >>confidently predicted to be overcome if a strong incentive is there). >Quite idyllic, if untrue. Bullshit, as I will argue... >SOLAR ENERGY, besides being inefficient (on Earth, but then, who's going >to build solar-energy collectors in space witout asteroids?) are dependent >on clouds, lack of space, and night. Very good for passive use, but then, >solar will never power cars, trucks, planes, heat (and cool) large builidngs, >toast bread, run refridgerators, refine metal, etc, on Earth. Nonsense. Drop the cost of PV cells by a factor of ten -- and no law of physics prevents us from doing this -- and PV electricity becomes competitive with just about all existing sources, (except in Rochester :-)). Now, yes, the storage problem does have to be overcome, but there are ways to do this at lesser or greater cost. Note that PV cells have dropped in cost by much more than a factor of ten since their invention. >NUCLEAR (fission) depends on Uranium, which, like oil, will become more and >more difficult to find and refine. (reserves are about equal to oil right now Wrong. Reserves of uranium are fairly small IF WE DON'T BREED. If we do breed, either in fast breeders, in thermal breeders using the thorium-U233 cycle, or in other schemes (electronuclear, fusion hybrid, etc.) the available fuel becomes enormously larger, because (1) the energy produced from a given quantity of uranium ore that are used increases by a factor of 60 or so, (2) it becomes economical to mine much leaner ores, which contain, in aggregate, far more uranium, and (3) thorium can be used. Thorium breeding is possible in some of today's reactors (CANDUs and HTGRs). Thorium is about 4 times as abundant in the earth's crust as uranium. >FUSION is still a pipe-dream. Since your post was presenting evidence that >supported the pipe-dream-ness of Asteroid mining, I will assume that Being A >Pipe Dream is sufficient to exlude an energy option. Wait -- I wasn't saying that asteroid mining is a pipe dream. I was arguing that it wasn't *necessary*. Plenty of unnecessary things are feasible and profitable. Also, your point is technically false. Mankind has been constructing devices which achieve thermonuclear ignition since the 1950's. It is feasible to explode H-bombs in steam-filled underground cavities for the purpose of power generation or breeding. This isn't done now for obvious political reasons, but it could be done if necessary without great technical advances. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 13 Jun 91 05:04:49 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!news@ucbvax.Berkeley.EDU (Steinn Sigurdsson) Subject: Re: Fred Vote Thursday In article <12053@hub.ucsb.edu>, 3001crad@ucsbuxa (Charles Frank Radley) writes: > > >Design by successive approximation is attractive to reduce >risk, but it is VERY expensive. The cost so far is not in the "expensive" category? > These days as systems get more complex there is greater >reliance on communal computer databases, everybody inputs their >status and the other player view it to see what is going on. > And simulations, cheaper than flight testing. Simulations are cheaper then testing, but testing tells you if it will work! The best way of learning is by doing. - even if it means making mistakes along the way (maybe that should read _especially_ if...) ------------------------------ Date: 13 Jun 91 17:59:37 GMT From: mcsun!ukc!edcastle!hwcs!sfleming@uunet.uu.net (Stewart Fleming) Subject: Solar Flares A front page article in the British "Independent" newspaper today warns of the dangers of severe magnetic storms (as pointed out by the regular solar flare postings on this newsgroup). The British Geological Survey in Edinburgh reported the detection of the shock wave produced by an extra large solar flare. Any reports of actual disturbance from anywhere else on the ground ? [We have one (possibly true) story of a Computer Scientist being transformed into a Psychologist due to a bit flipping in an admin computer.] The article also mentions that international computer networks could be affected since they rely on satellites to route me%^#.)*{|{@ STF -- sfleming@cs.hw.ac.uk ...ukc!cs.hw.ac.uk!sfleming +44-31-225-6465 x553 "I saw Sean Connery eating mushroom soup and watching the Repulican march." ------------------------------ Date: 11 Jun 91 16:56:20 GMT From: snorkelwacker.mit.edu!usc!wuarchive!emory!wa4mei!ke4zv!gary@bloom-beacon.mit.edu (Gary Coffman) Subject: Re: NASA Budget In article <1991Jun7.210944.22123@sequent.com> szabo@sequent.com writes: >In article <18194@venera.isi.edu> cew@venera.isi.edu (Craig E. Ward) writes: > >>>The American Geophysical Union recognizes that passage of this >>>amendment would do serious damage to future space science programs >> >>With all due respect, the AGU is wrong and is playing the role of a patsy for >>non-space special interests. > >With all due respect, you don't know what the hell you are talking >about. The AGU was one of the main forces behind the 1957 IGY, which >led to Sputnik and Explorer and started the whole civilian space >program off in the first place. Much of the subject matter and >experimentation in the field of geophysics takes place in space. >Calling the AGU "non-space" is like calling Boeing "non-airplane" >or Toyota "non-automobile". Pretty silly. With all due respect, Sputnik and Explorer were spawned by Cold War ballistic missile posturing. That a few instruments managed to hitch a ride is peripheral. Nor did Craig say the AGU was "non-space". He said they were, perhaps unwittingly, playing into the hands of non-space interests like HUD. Gary ------------------------------ Date: 12 Jun 91 21:30:44 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!ox.com!fmsrl7!wreck@ucbvax.Berkeley.EDU (Ron Carter) Subject: Re: Earth Gravity Assist and Aerobraking Safety In article <1991Jun10.073924.9596@latcs1.lat.oz.au> burns@latcs1.lat.oz.au (Jonathan Burns) writes: >Is there any percentage in magnetic braking, in which a conducting >body passes transverse to the geomagnetic field, and experiences >drag as the field does work generating eddy currents? Not as you lay it out; the magnetic field varies only slowly over space and time as seen by a passing asteroid, so the possible coupling (and energy dissipation) is very small. It is necessary to couple to the ambient plasma medium to achieve much braking. >A possibly useful complication would appear if the body could be strung >out along a cable like beads, and connected by conducting wire, so as >to intercept more flux. You would need to either put substantial masses at either end of a conductor to hold it taut, or spin the conductor ditto. A long conductor is required to get more voltage induced; power dissipated is equal to I*E, and E = integral((B x V).dl). Current will be limited by the plasma density. The idea of a pinwheel conductor, with the downward-pointing half conducting current and the upward-pointing half not carrying current, is possibly useful. It would tend to spin itself up, rolling like a wheel. To keep it from overspeeding, chunks of the asteroid carrying the pinwheel tether could be released from the ends. If the asteroid was in a very eccentric orbit, the releases could put the chunks into near-circular orbits; a high circle at the top, and a low one at the bottom. In this way, the entire asteroid could be returned to LEO in small, innocuous pieces, with the main body held high enough that it presents no danger of inadvertent re-entry. Excellent idea, Jon! It has many possibilities to build on. ------------------------------ ReSent-Message-ID: Resent-Date: Wed, 12 Jun 91 18:13:31 EDT Resent-From: Tom McWilliams <18084TM@msu.edu> Resent-To: space+@andrew.cmu.edu Date: Sat, 8 Jun 91 05:00:10 EDT Reply-To: space+%ANDREW.CMU.EDU@msu.edu From: space-request+%ANDREW.CMU.EDU%CARNEGIE.BITNET@msu.edu Subject: SPACE Digest V13 #623 Comments: To: space+@ANDREW.CMU.EDU To: david polito <15432DJP@MSU.BITNET>, Tom McWilliams <18084TM@MSU.BITNET> Subject: Re: Asteroid mining >If I were >company, I would not invest in asteroid mining unless I had good reason to >believe I could meet current market prices with my products and current >technology does not seem to be able to do this wrt nickel production in >space. > Decrease transport and production costs in space, and maybe ths will >change. What reason wqould a mining company to have to expect this in the >short run? My question has been: "What reason would a company have to get into the space transportation business, thus increasing efficiency and decreasing costs, as NASA seems to find impossible?" How about a big, salable asteroid? Tom Acknowledge-To: <18084TM@MSU> ------------------------------ Date: 12 Jun 91 21:01:53 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!news@ucbvax.Berkeley.EDU (Steinn Sigurdsson) Subject: Re: Fred Vote Thursday In article <1991Jun12.104303.2364@nntp-server.caltech.edu>, carl@juliet (Lydick, Carl) writes: >In article <12031@hub.ucsb.edu>, 3001crad@ucsbuxa.ucsb.edu (Charles Frank Radley) writes... >>>>Maybe this near-death will scare the Freedom people into getting some >>>>hardware built... > >OK, I'm about to play devil's advocate here (I'd personally like to see a space >station built and manned in the near future). ditto > >>The schedules we have been working to do not require delivery of >>hardware until 1993. >> We have been on schedule all along. Why do people >>keep complaining the hardware has not been built, we have to design >>it first.....and we have not even had a PDR yet. > >There are lots of ways to design and build just about anything. Some >techniques tend to work better than others. The technique that I've found >works best over a wide area of technology is what I like to call "design by >successive approximations". I think Carl has hit the essence of the problem here, it sounds as if NASA has produced $5G of CAD drawings in the last 8 years, when one would think that building test assemblies and flying small pieces of the station should be taking a large fraction of the budget. My current impression is that the money spent so far has only produced blueprints, and no pieces of hardware to see how they fit together, or operate in orbit - I would love it if someone would prove me wrong on this and tell us of $2G worth of components has been built and tested? ------------------------------ Date: 13 Jun 91 02:58:31 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!wuarchive!rex!rouge!dlbres10@ucbvax.Berkeley.EDU (Fraering Philip) Subject: Re: Risks of technology I think there is a risks group possibly as appropriate to discuss this stuff. Maybe people posting on that subject should crosspost. And my 2 cents: Well, the material will probably be broken up and shipped in small 10 ton pieces anyway... And there seems to be the possibility of Tungusta style events in the future. If someone is worried about risks, now is the time to develop the technology to move the stuff... Phil F. dlbres10@pc.usl.edu ------------------------------ Date: 13 Jun 91 12:33:17 GMT From: agate!spool.mu.edu!sdd.hp.com!think.com!rpi!news-server.csri.toronto.edu!utgpu!cunews!semifs3!testeng1!stanfiel@ucbvax.Berkeley.EDU (Chris Stanfield) Subject: Re: Lost satellites In article <1991Jun12.202202.19204@sequent.com> szabo@sequent.com writes: >In article <1991Jun11.235056.45799@frodo.cc.flinders.edu.au> mowl@pippin.cc.flinders.edu.au (Wolfgang Lieff) writes: Deleted discussion about broken GEO satellites >>- If this sum is a considerable amount, what would be a competitive >> price the Soviets could charge for stationing a technician and a >> Soyuz modified as an 'Inter-orbit-toolshed' (maybe without re-entry >> capabilities) onboard their space station ? > >Olympus, like most satcoms, is in GEO. Mir is limited to an >inclined low earth orbit, far away from GEO. > Still a little quick to flame aren't we Nick? I think the original poster was suggesting using a modified Soyuz as a "space tug" for either going to the satellite and repairing it, or bringing the satellite down to an orbit where it could be recovered for return to earth. Like the original poster, I don't know if that is possible - that is why the question was asked - but I think we are both aware of the relative orbits of MIR and GEO satellites. Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel (613) 592 2122 Ext.4960 We do not inherit the world from our parents - we borrow it from our children. ------------------------------ Date: 10 Jun 91 18:17:00 GMT From: cix.compulink.co.uk!dingbat@ucbvax.Berkeley.EDU (Codesmiths) Subject: Re: Microgravity? In-Reply-To: joefish@disk.uucp (joefish) Good grief ! Real facts ! As you've seen this thing, could you answer a couple of points: What diameter is the shaft ? What sort of experiment mass can this thing handle ? The catapult trick is neat, that simply hadn't occurred to me |-( <-- stupid smiley _ / ) ' ,_ , / _ ) _/_ dingbat@cix.compulink.co.uk /_ / / / / (_) /_) (_) /_ +44 091 232 9827 (_) ------------------------------ End of SPACE Digest V13 #739 *******************