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 ; Thu, 4 Jul 91 01:27:38 -0400 (EDT) Message-ID: <4cQf6zS00WBw0Dck4v@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 4 Jul 91 01:27:28 -0400 (EDT) Subject: SPACE Digest V13 #772 SPACE Digest Volume 13 : Issue 772 Today's Topics: Re: Fred's Operatic Death Re: Mining El Dorado Re: Mining El Dorado Re: Fred's Operatic Death Magellan Images Re: == No Subject == Trying to contact oldtime SCI.SPACE people Earth-crossing water (was Re: Platinum-group..) 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 ---------------------------------------------------------------------- Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 19 Jun 91 19:33:59 GMT From: agate!spool.mu.edu!mips!swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Organization: U of Toronto Zoology Subject: Re: Fred's Operatic Death References: <1991Jun18.170059.15059@watdragon.waterloo.edu>, shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes: >Nick has informed me that "Public employees slandering [him] on the >net are cruising for a bruising." Ah yes. If you can't refute them, intimidate them. -- "We're thinking about upgrading from | Henry Spencer @ U of Toronto Zoology SunOS 4.1.1 to SunOS 3.5." | henry@zoo.toronto.edu utzoo!henry ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 20 Jun 91 01:50:07 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!news@ucbvax.Berkeley.EDU (Steinn Sigurdsson) Organization: Theoretical Astrophysics, Caltech Subject: Re: Mining El Dorado References: <1991Jun17.052228.8112@sequent.com>, <1991Jun17.144137.23456@watdragon.waterloo.edu>, <1991Jun19.144714.23618@watdragon.waterloo.edu> Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu In article <1991Jun19.144714.23618@watdragon.waterloo.edu>, jdnicoll@watyew (James Davis Nicoll) writes: >>> Why assume that you must use rockets or bombs to move asteroids, after all you have plenty of time (for mining - different problem for dinasaur killers but then the deltaV is smaller) - instead use continuously operated ion thrusters and/or solar sails. With the thrusters you can take a long time of low continuous acceleration, your reaction mass will mostly come from the asteroid, and your acceleration only depends on the power available - start with solar cells or small nuclear reactor and either build more cells in situ or ship more power units - you can in principle also build more thrusters in situ. - of course unless you have a continuous stream of these things the interest on your capital costs will wipe you out before the first one arrives, so you use the old railroad trick, capitalise a dummy company, file bankruptcy _after_ you get the think moving and have someone else pick it up in earth orbit... ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 19 Jun 91 14:47:14 GMT From: agate!spool.mu.edu!caen!zaphod.mps.ohio-state.edu!swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@ucbvax.Berkeley.EDU (James Davis Nicoll) Organization: University of Waterloo Subject: Re: Mining El Dorado References: <1991Jun16.195153.9959@stb.info.com>, <1991Jun17.052228.8112@sequent.com>, <1991Jun17.144137.23456@watdragon.waterloo.edu> Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu >> >>* 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. I'm still trying to get a handle on the cost of using nukes to move El Dorado. ED masses 10**10 kg, and we want to cause a delta-v of 4000 m/s. If the Isp of our system is the same as the pulsed-fission idea Orion would have used (50000 s), then the mass ratio would be 1.008. We'll need to throw 8.1x10**7 kg at 500,000 m/s. The Ek works out to 1.0x10**19 J, or about the 2400 megatonnes. That's, what, about one quarter the world's supply of nuclear explosives? Two questions: 1: How much would it cost to built 2400 1 MT nuclear propulsion units? 2: How much would they weigh? I have dim memories of an article in Scientific American on cruise missiles, and I *think* the 100 KT warhead was about 250 kg. *If* that's correct, then we'd be looking at about 6000 tonnes of nuclear explosives. 6000 tonnes is a lot of shuttle launches. Geez, that value for Ek looks low. James Nicoll ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 20 Jun 91 01:53:59 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!news@ucbvax.Berkeley.EDU (Steinn Sigurdsson) Organization: Theoretical Astrophysics, Caltech Subject: Re: Fred's Operatic Death References: <1991Jun18.170059.15059@watdragon.waterloo.edu>, , shafer@skipper (Mary Shafer) writes: >I wrote: > >>In article <1991Jun18.170059.15059@watdragon.waterloo.edu> jdnicoll@watyew.uwaterloo.ca (James Davis Nicoll) writes: >>>> 'Do NASA employees post self-serving propaganda (also 'should NASA...')' >>>> argument deleted. >> >>>I have the damned feeling I've seen this thread before. How did the >>>tiff that ended with Ms Shafer briefly leaving sci.space start? >> >>Wit Nick Szabo claiming that NASA employees should only post stuff that >>Nick thought was OK. That is, it was OK for the informational stuff >>to appear, but if one disagreed with Nick ..... > >Nick has informed me that "Public employees slandering [him] on the >net are cruising for a bruising." > >It was not my intent to slander Nick and if his feelings, amour propre, >or net reputation were damaged by my comment, I apologize and retract >my comment. I'm not a public employee - Nick, your posts are getting way out of line. It has become my distinct impression that in fact you _do_ wish to suppress the honest expression of people's opinion based on the fact they work for government organisations. I disagree with some of what you say, agree with some of it, but I think you are going too far - please try to lighten up! It will make everybody's life a little less stressed. ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 20 Jun 91 05:38:00 GMT From: agate!usenet.ins.cwru.edu!magnus.acs.ohio-state.edu!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!jato!kelvin.jpl.nasa.gov!baalke@ucbvax.Berkeley.EDU (Ron Baalke) Organization: Jet Propulsion Laboratory Subject: Magellan Images Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu =================== MAGELLAN IMAGES June 19, 1991 =================== I've placed 17 more Magellan images at the Ames SPACE archives, bringing the Magellan total to 36 images. These new images are in VICAR format which is the format used at the Image Processing Lab (MIPL) at JPL. The images are obtainable via anonymous ftp from ames.arc.nasa.gov (128.102.18.3), and are in the pub/SPACE/VICAR directory. All of the Magellan images I've put at the Ames site are public release images from the Magellan project, and are in the public domain and can be freely distributed. These new images are *not* on the first Magellan CDROM released earlier this year. The new Magellan files and their sizes are: alcott.img 1,049,600 bytes ammavaru.img 1,312,000 bytes arachcom.img 971,880 bytes barton.img 2,626,020 bytes flows.img 3,616,434 bytes golubnew.img 1,025,145 bytes golubold.img 1,025,145 bytes gulamons.img 914,328 bytes hestia.img 1,422,603 bytes lakshmif.img 822,584 bytes mead.img 1,312,000 bytes navka.img 2,521,800 bytes ovda.img 1,180,310 bytes pandora.img 918,528 bytes sifflows.img 621,600 bytes test25pvo.img 1,006,304 bytes test25rm.img 1,006,304 bytes All of the VICAR images have a corresponding caption files (with a .txt extension) which contains detailed descriptions of the image. Make sure you are in binary mode when transferring the image files, and in ASCII mode when transferring the txt files. The VICAR images can be viewed on an IBM PC computer with the IMDISP program stored in a zip file called imdisp56.zip, located in the pub/SPACE/SOFTWARE directory, at the same Ames site. IMDISP is the same program distributed with the Voyager and Magellan CDROMs. Since I am one of the programmers for IMDISP, I would welcome any feedback on IMDISP, including any problems encountered with its use or suggestions on improving the program. A new version of IMDISP will be released in a about a couple of weeks; I'll post an an announcement when it is ready. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 301-355 | "Imagination is more /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | important than knowledge" |_____|/ |_|/ |_____|/ | Albert Einstein ------------------------------ Date: 16 Jun 91 18:39:45 GMT From: nuchat!lobster!n5abi!gak@uunet.uu.net Subject: Re: == No Subject == > #In article <2955@ke4zv.UUCP> gary@ke4zv.UUCP (Gary Coffman) writes: > # > ##The only manmade structure that can be seen with the naked eye from > space, > ##the Great Wall of China, has been around for a fair amount of time > in > #....... > # > >BZZZT...Wrong. TONS of stuff is visible from LEO. Do you think that > >Manhattan or LA suddenly become invisible because you are 120 miles > >up? Perhaps the Great Wall is the only object visible from the Moon > or > >somesuch distance. > > > BZZZZZT,BZZZZZZT WRONG WRONG WRONG. 8^) > > The Great Wall of China is the only thing visible from space > with > "the naked eye." Should I say "Wrong again"? The real story of this myth is this: On his mercury flight Gordon Cooper claimed that over Tibet (the country) the air was so thin that he could see individual houses and the smoke from the chimneys.... "Somehow out of this came the myth that the Great Wall of China was espically visible, even though Gordo had not flown far enough north to see it, and, a few years later, this notion had grown to the point that it was suppose to be the only man-made feature on earth visible from the moon, which I can attest is certainly not the case." Quote from "Liftoff" by Michael Collins (Apollo 11 astronaut) page 59. > ----------------------------------------------------------------------- Gene Kennedy - Ham Radio Operator, N5ABI - lobster.hou.tx.us!n5abi!gak ----------------------------------------------------------------------- ------------------------------ Date: 20 Jun 91 08:47:32 GMT From: SUWATSON.STANFORD.EDU!REM@ucbvax.Berkeley.EDU Subject: Trying to contact oldtime SCI.SPACE people In 1987 somebody named Adam J. Richter posted a message about L5, and I wanted to reply. Unfortunately his return address of jade!tart14.berkeley.edu!adamj@ucbvax.berkeley.edu didn't work for me. Does anybody know how to reach that person? In 1987 somebody (name unknown) posted a message about cleaning up clutter in LEO, and I wanted to reply. Unfortunately his return address of apollo!nelson_p@eddie.mit.edu didn't work for me. Does anybody know how to reach that person? In 1987 somebody named Jorge Stolfi posted a message about using interstellar matter as fuel for reaching the stars, and I wanted to reply. Unfortunately his return address of jumbo!stolfi@decwrl.dec.com didn't work for me. Does anybody know how to reach that person? In 1988 somebody named Kevin B. Kenny [the Arch-Traitor] posted a message about writing to Congresspeople regarding space (this was on SPACE-ACTIVISTS, not SCI.SPACE, but I don't see that group in the list of UseNet newsgroups), and I wanted to reply. Unfortunately his return address of kenny@b.cs.uiuc.edu didn't work for me. Does anybody know how to reach that person? ------------------------------ Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Date: 20 Jun 91 06:55:33 GMT From: ogicse!sequent!muncher.sequent.com!szabo@decwrl.dec.com Organization: Sequent Computer Systems, Inc. Subject: Earth-crossing water (was Re: Platinum-group..) References: <43978@fmsrl7.UUCP>, <99957@lll-winken.LLNL.GOV>, <1991Jun20.021049.10770@cs.rochester.edu> Sender: space-request@andrew.cmu.edu To: space@andrew.cmu.edu In article <1991Jun20.021049.10770@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes: >Water should also be available on some class C asteroids, if >carbonaceous chondrites are any indication (some contain significant >water of hydration in their minerals). If these meteorites are >derived from earth-approaching asteroids, there would be no need to go >to the outer solar system. Water is also available on Mars. As we continue to explore we may find much better sources. Several short-period comets cross the orbit of Earth. Comets are made primarily of water ice, with significant amounts of carbon monoxide and dioxide, methane, and other volatiles. They give off dust as the volatiles are vaporized by the Sun. Comets are often associated with meteor showers, which contain mostly dust sized particles but sometimes also larger objects that produce fireballs. The Tungaska event is believed to have been caused by a 100,000 ton fragment from P/Encke. Some fireballs have been photographed even in daylight; one crossed over Wyoming on August 10, 1972 and skipped back into space. The Alpha Capricornids meteor shower features a large number of fireballs. Fireballs associated with meteor showers do not end up as meteorites; they are either volatile ice or very fragile conglomerations of dust and burn up in the atmosphere. There are also fireballs not associated with a comet orbit; these can be carbonaceous, stony, or metal and produce the meteorites. As a side note, we may see some good fireballs from the Alpha Capricornids this summer during July and August, since the parent comet (something like P/Honda-Mrkos-Pjd from my abbreviated notes :-) reaches perihilion at the end of this year. Comets tend to break up. We have observed more than twenty occurences of comet fragmentation. We can assume this is quite common. What we don't know is how fast these fragments evaporate. If they are consumed slower than they are replenished by new fragmentations, there could be a significant number of ice-bearing bodies in orbits with favorable capture trajectories. The ice itself can provide reaction mass to simple solar-thermal engines. Most of the delta-v can come from Earth and Lunar gravity assists. It is also possible that some Earth-crossing asteroids are extinct comets, and these may contain ice underneath the surface. The asteroid 3200 Phaeton is associated with the Geminid meteor shower stream, for example. Another note of interest is that the comet P/Griggs-Skjellerup, which Giotto is planned to flyby in 1992, is associated with the Pi-Puppid meteor shower. This should give a good showing next April as GS nears perihilion. Overall, we haven't done nearly enough exploration to know where the best sources of water and volatiles are to be found. references: _The Mystery of Comets_, Fred L. Whipple, 1985 _Comets_, Laurel Wilkening ed., 1982 appendix: Here are some data on Earth-crossing ice and dust gleaned from _The Cambridge Encyclopdia of Astronomy_ and similar sources: _warning_: due to informal scholarship, the perihilion figures are +/- 2 months, at best. Better figures solicited. meteor showers and their parent bodies -------------------------------------- next shower max range ZHR parent period peri ------ --- ----- --- ------ ------ ---- Quadrantids Ja4 Ja1-5 100 ? ? ? v Pi-Puppids Ap24 Ap21-26 60 Griggs-Skje 5.2 Au 92 Oc 97 d Beta Taurids Jn29 Jn23 - Jl5 20 Encke 3.3 ? f Alpha Capricornids Au1 Jl15 - Au25 10 Honda-Mrkos-Pjd 5.28 Ja 92 My97 Perseids Au12 Jl25 - Au18 70 Tuttle 2 ? ? v Draconids Oc8 Oc7-10 "high" Giac.-Zinner 6.52 Fe 91 Oc 97 Orionids Oc21 Oc6-27 35 Haley 73 2069 Taurids No1 Oc10 - De5 12 Encke 3.3 ? v Leonids No17 No14-20 1,000 Tempel-Tuttle 33.3 Oc99 Geminids De13 De8-16 60 3200 Phaeton ? ? Ursids De21 De17-25 5 Tuttle 13.6 Jn 94 ZHR = Zenith Hourly Rate v = variable, ZHR for perihilion d = daytime f = fireballs -- Nick Szabo szabo@sequent.com "If you want oil, drill lots of wells" -- J. Paul Getty The above opinions are my own and not related to those of any organization I may be affiliated with. ------------------------------ End of SPACE Digest V13 #772 *******************