Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from corsica.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID ; Thu, 31 Aug 89 05:18:10 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 31 Aug 89 05:18:01 -0400 (EDT) Subject: SPACE Digest V10 #8 SPACE Digest Volume 10 : Issue 8 Today's Topics: Anyone else see the Neptunian Vaxen? (Forwarded from Info-Vax) Re: How is Voyager powered? Voyager, etc. info sources re message on Mars Space Digest Re: Thanks to NASA and JPL Re: Analysis of Martian "Face" Announced Re: Pluto fly-by Rings Re: Pluto fly-by Test message. Re: How is Voyager powered? ---------------------------------------------------------------------- Date: Fri, 25 Aug 89 10:17:59 PST From: Peter Scott Subject: Anyone else see the Neptunian Vaxen? (Forwarded from Info-Vax) X-Vms-Mail-To: EXOS%"space@andrew.cmu.edu" In INFO-VAX (comp.os.vms), mailrus!sharkey!atanasoff!atanasoff.cs.iastate.edu!hascall@tut.cis.ohio-state.edu (John Hascall) writes: > I was watching the NASA/JPL feed last night (wow!). During one > "Voyager Update" they had a little counter showing the seconds > to closest approach: > 00:00:05 > 00:00:04 > 00:00:03 > 00:00:02 > 00:00:01 > 17-NOV-1858 [= 0 in VAX system time units] > > Oh well! :-) >John Hascall >ISU Comp Center >"Have your people call my people and we'll do lunch by the pool." ;-) Probably not programmed by the same folk that got the Triton Earth/Sun occultation aiming on target. (The parameters for the burn to achieve that weren't uploaded until hours before target; the calculated time of arrival had been jumping around all week.) Peter Scott (pjs@grouch.jpl.nasa.gov) ------------------------------ Date: 25 Aug 89 17:00:58 GMT From: rochester!dietz@louie.udel.edu (Paul Dietz) Subject: Re: How is Voyager powered? In article <1910@crdgw1.crd.ge.com> oconnordm@CRD.GE.COM (Dennis M. O'Connor) writes: >I believe Voyager uses one or more RTGs. RTGs contain a sub-critical >mass of a fissionable material ( plutonium, I think ? ). The >fission occuring causes the fuel to be hot. No, the RTGs use Pu-238, which undergoes alpha decay, not fission. >There is another kind of "no-moving-part" radioisotope generator. >Don't know the name. It uses isotopes that emit charged particles >( usually beta particles, I think. i.e. high-energy electrons ). You may be thinking of the thermionic generator, where high temperatures cause electrons to boil off certain metal surfaces. The electrons are certainly not high energy. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 25 Aug 89 15:47:46 GMT From: att!mtuxo!erw@ucbvax.Berkeley.EDU (XT154-E.WENDLER) Subject: Voyager, etc. info sources . . . Hi: I'm interested in sources for technical information (navigational techniques, etc.) about and photos from the Voyager missions as well as Pioneer. Is JPL the best place to go, and if so, is there an address/person to write? Or NASA, or a third party? Please EMail responses--I'll summarize and post if I receive responses. Thanks. E.R. Wendler ------------------------------ Date: 25 Aug 89 19:04:00 GMT From: apollo!nelson_p@eddie.mit.edu (Peter Nelson) Subject: re message on Mars > The "Message of Cydonia": > First Communication from an Extraterrestrial Civilization? > > By Richard C. Hoagland* > > [Copyright (C) 1989 > All Rights Reserved] > > Abstract Abstract from WHAT? What is the paper that this is abstracted from? IS there an actual paper? > The "face" and its surrounding "enigmatic landforms" appear > to be a carefully layed out, highly-sophisticated, redundantly What 'enigmatic landforms?'? > latitudes." When examined by the authors, using published > geodedic planetary maps from NASA and U.S Geological Survey > sources, these latitudes are observed to be associated with a > hitherto unknown planetary and stellar energy phenomenon -- > blatantly emerging at these specific latitudes And just what 'planetary and stellar' energy phenomenon might that be? Radio waves? Light? X-rays? Rock'n'roll music? Orgasmotronic emissions? I dunno. Sounds like ca-ca to me. ---Peter ------------------------------ Date: 24 Aug 89 19:40:53 GMT From: mcsun!ukc!icdoc!syma!nickw@uunet.uu.net (Nick Watkins) Subject: Space Digest Could some kind soul tell me how to subscribe to Space Digest. My feed is from Imperial College London, and I am reading UseNet with rn if these are relevant. Nick -- Nick Watkins, Space & Plasma Physics Group, School of Mathematical & Physical Sciences, Univ. of Sussex, Brighton, E.Sussex, BN1 9QH, ENGLAND JANET: nickw@syma.sussex.ac.uk BITNET: nickw%syma.sussex.ac.uk@uk.ac Voice: +44 273 678072 ------------------------------ Date: 26 Aug 89 02:35:03 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Thanks to NASA and JPL [ Followups directed to sci.space as this is not a shuttle issue. ] Sentimental as John Bridge's proposal sounds, I think he is 100% right. The Voyager team deserve medals at the White House, including posthumous ones for the two deceased PI's. Should we call the WH feedback number and tell them this? If so what is it? :-) -- "We walked on the moon -- (( Tom Neff you be polite" )) tneff@bfmny0.UU.NET ------------------------------ Date: 25 Aug 89 02:30:48 GMT From: jtsv16!geac!censor!jeff@uunet.uu.net (Jeff Hunter) Subject: Re: Analysis of Martian "Face" Announced harry@moncam.co.uk (Jangling Neck Nipper) writes: > In article <6103@ingr.com> tdj@ingr.com (Ted Johnson) writes: > > 2. The authors pulled in facts from all over to justify, amplify and > expand the significance they see. Any theorist knows that, given enough > parameters, any observation can be explained. > Could you perhaps point out the bits of the said article that are > wrong, and could you say why they are wrong? Are the `facts from all > over' incorrect ones? Is there anything inherently wrong with doing > such a thing? I read an article Hoagland wrote for Analog several years ago. He started with the picture of the face. It's pretty crude and doesn't contain enough detail to draw many conclusions. So he started in on nearby objects. There's a hill (to the north?) that is roughly like a five-sided pyramid. The faces are all about the same length, and fairly flat. Hoagland pointed out the resemblance in proportion to Da Vinci's famous sketch of man in a circle. He concluded that the hill was a reinforcement of the face directing a message to mankind. I think it looks more like a giant Pontiac commercial. He then started in on a nearby ridge saying it was "obviously artificial". There's a notch in the ridge, and if you line it up with the eye of the "face" (or the main street of the "city", I forget) you get a completely useless direction. But wait! If you calculate back in time as Mars' poles precess the notch will eventually line up with some star or other on the vernal equinox, or the summer solstice. Hoagland picks one of these matches and thereby "proves" that the whole complex was created at some ancient date. This goes on, but the pattern is the same. At the time I was vividly reminded of the fact that you can reach *any* conclusion from any data as long as you are allowed to use completely 'ad hoc' rules. It's too bad, because until then I had thought Hoagland was an informed, if unconventional, commentator. After reading that article I concluded that the Pauling effect had set in. -- -- my opinions -- jeff@censor.uucp Keep track of the current path, and use it naturally. Glenn Reid (Postscript Language Program Design) ------------------------------ Date: 26 Aug 89 02:58:32 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Pluto fly-by In article <1989Aug25.183710.3054@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >>Would going via a third planet, perhaps prior to Jupiter, make the trip >>any shorter? >An intermediate stop before Jupiter will probably make it longer, although >it may reduce fuel requirements a bit. This is true for all MAJOR planets. However one intermediate "stop" you can make without undue penalty is to fly by a minor planet. Galileo itself will do this on the way to Jupiter, at great scientific benefit. The interesting question is whether it's worth more to fly by the lone remaining unseen planet, or to concentrate on orbiters for the seen ones. -- "We walked on the moon -- (( Tom Neff you be polite" )) tneff@bfmny0.UU.NET ------------------------------ Date: Fri, 25 Aug 89 09:27 CDT From: Samitha Amarasiri Subject: Rings To: With the discovery of a ring on Neptune, it really looks like rings on the outer planets on the solar system is becoming the rule and not the exception. The two major differences between the 'outer' and inner planets are the temperature on them, and gravitational pull by the sun. Could it be that either of these cause planets to have rings on them? Could the asteriod belt be a ring that never quite formed? Does this mean that Pluto will have a ring on it too? Please excuse the barrage of questions, I was watching 'Neptune up all night' and feel delerious with excitement. -- Samitha Amarasiri. ______________________________________________________________________________ | BITNET : samitha@ksuvm | (913) 532-6311 (office) | | INTERNET : samitha@ksuvm.ksu.edu | (913) 537-1978 (home) | | sxa@phobos.cis.ksu.edu | 931 Bertrand, Manhattan KS 66502 | | | | Administration is a gross waste of human resources. | | Standard disclaimer implied with every letter. | ------------------------------------------------------------------------------ ------------------------------ Date: 25 Aug 89 18:37:10 GMT From: mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Pluto fly-by In article <8908241857.AA02943@fermat.Mayo.edu> hess@FERMAT.MAYO.EDU (d. scott hess) writes: >From: KROVETZ@cs.umass.EDU >}I assume a fly-by of Jupiter would shorten the [Pluto] trip (with >}respect to a direct flight), but by how much? Infinite -- we cannot reach Pluto with current technology without a Jupiter flyby. I'd guess a Jupiter-Pluto mission at perhaps 7-8 years, but I don't have real numbers handy. Remember, also, that Jupiter will be in the right place only about once every 8 years (its orbital period). >}Would going >}via a third planet, perhaps prior to Jupiter, make the trip >}any shorter? An intermediate stop before Jupiter will probably make it longer, although it may reduce fuel requirements a bit. Galileo will pay a considerable price in transit time for its inner-planets gravity assists, since it means doing several more orbits around the Sun to pass said planets. Multi-planet gravity assists shorten trips only when the planets are in *exactly* the right places, and particularly in the outer solar system that isn't common; the Voyager 2 Jupiter-Saturn-Uranus-Neptune window won't be open again for a couple of centuries. >... I've spent time trying to figure out >exactly how gravity-assist works, and thus far, its beyond me... I'll explain it briefly here, because it's relevant below. (This one is common enough that it probably ought to go in the frequently-asked- questions list.) Doing a pass by Jupiter will not change your speed with respect to Jupiter, but it will change the direction of your motion. This matters because Jupiter itself is moving. Call Jupiter's orbital velocity J (don't have the number handy). If you approach Jupiter "from the front" at 5 km/s relative to Jupiter, and do a tight hyperbola around it so that the direction of motion with respect to Jupiter gets pretty much reversed, then with respect to Jupiter you went in at 5 km/s and came out at 5 km/s, but with respect to the *Sun* you went in at J-5 km/s and came out at J+5 km/s. Jupiter got slowed down infinitesimally in the process. >A little input I _can_ give is that Pluto is a helluva long ways out >there... Actually, right now it's at about the same distance as Neptune. It's near perihelion in its orbit, which is elliptical enough that an average distance isn't too meaningful. >... I think Pluto's [year] is >somewhere over 230 years. That's why we;d have to plan quite far ahead. No, not really. Something that moves that slowly can be treated as motionless for rough planning purposes. >... I suspect that the fastest way to get to pluto, albeit >fairly weird, would be to do a gravity (un)assist around Jupiter, and >the a gravity assist around the SUN... Unfortunately this doesn't work, because the whole basis of gravity assist is that the gravity-assist planet is moving with respect to your target. You can't do it with the Sun. (Although there are some related tricks.) -- V7 /bin/mail source: 554 lines.| Henry Spencer at U of Toronto Zoology 1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 25 Aug 89 22:24:38 GMT From: wrksys.dec.com!klaes@decwrl.dec.com (CUP/ASG, MLO5-2/G1 6A, 223-3283 25-Aug-1989 1321) Subject: Test message. test message. ------------------------------ Date: 26 Aug 89 04:54:57 GMT From: gem.mps.ohio-state.edu!csd4.csd.uwm.edu!mailrus!jarvis.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: How is Voyager powered? In article <1910@crdgw1.crd.ge.com> oconnordm@CRD.GE.COM (Dennis M. O'Connor) writes: >There is another kind of "no-moving-part" radioisotope generator. >Don't know the name. It uses isotopes that emit charged particles >( usually beta particles, I think. i.e. high-energy electrons ). The >beta-emitter is in the middle of an exacuated sphere. The >electrons are emmited by the beta-emitter and travel to the >sphere wall. The sphere wall becomes negatively charged, >and the central mass of beta-emitting material becomes >positive. Connect wires to each and you have a battery. Nuclear batteries have been built with this system, but the power output is very low. A related scheme with much better power output is to use heat from an isotope or a reactor to "boil" electrons off a suitable cathode. This scheme, thermionic conversion, is used in the Topaz high-power space reactor that the Soviets have flown experimentally (and are now offering for sale). >I've heard that high-power radarsats use actual reactors >( with control rods, coolant, et cetera ), but have no idea >how the heat is made into electricity. The Soviet radarsats do indeed use reactors, mostly because they want to operate at the lowest possible altitude (radar effectiveness requires the shortest possible range) and with fairly high power output, and the necessary solar arrays would produce too much air drag. I think their operational reactor uses thermocouples, just like the Voyager RTGs. Topaz may be intended as a replacement. -- V7 /bin/mail source: 554 lines.| Henry Spencer at U of Toronto Zoology 1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ End of SPACE Digest V10 #8 *******************