Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.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, 3 May 90 02:09:40 -0400 (EDT) Message-ID: <8aDwg6i00VcJI27k5r@andrew.cmu.edu> Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 3 May 90 02:09:11 -0400 (EDT) Subject: SPACE Digest V11 #348 SPACE Digest Volume 11 : Issue 348 Today's Topics: Update to "Listening to the Stars". Re: PegBlimp (was Re: Pegasus launch from Valkyrie (or ...) Re: (How to get rid of) space garbage Apollo 11-17 Re: (How to get rid of) space garbage Re: Niven's inertialess drive (was Re: Dyson spheres, heat flow) Re: Giant crawler transporter to pass 1000 miles on STS-35 rollout (Forwarded) Re: * SpaceNews 30-Apr-90 * Phhotos from Space (was: Hubble Telescope) Re: (How to get rid of) space garbage ---------------------------------------------------------------------- Date: 3 May 90 03:50:03 GMT From: usc!samsung!munnari.oz.au!gwydir!gara!pnettlet@ucsd.edu (Philip Nettleton) Subject: Update to "Listening to the Stars". 0. The Debate. From the debate I appear to have started concerning methods of long distance communications, it is evident that a few people have got slightly off the track. Let us tackle the most frequently mentioned types of telecommunication separately and see what we get. The first question is what uses do we put telecommunications to in our (modern) society (not forgetting that we may well be rank amateurs in this branch of technology). (a) Communications. (b) Navigational aids. 1. Communications. One hundred years ago we had a number of methods of communications but how many are still used today? Not many and none to speak of that produced electromagnetic (EM) transmissions of any note. Why is this? Well, basically, because we discovered better and more cost effective ways of sending information. We don't use the telegraph any more because it is obsolete. The principles are still there in telephone but even that is changing with the use of fibre optics and telephones themselves have greatly changed over time. Satellite communications are used extensively in this era, but in a hundred years time? If a method could be developed whereby we could transmit signals unimpeded through the body of the Earth, satellites would no longer be cost effective and such a method would be unlikely to use EM transmissions. What about communicating to other worlds? Inside the solar system we could still use EM transmissions to send messages in a reasonable time (by today's standards), a few minutes or hours at most. In a hundred years time we will not be satisfied with such excessive delays, businesses and governments will demand faster responses and technology will have to supply it. Beyond our solar system the issue is even more critical. No one is going to wait around a few years to receive news from a remote settlement. So what would an advanced technological species need to serve its basic interstellar communications needs? Well, a faster than light communications system that could traverse through normal matter without noticeable distortion. A tall order you say, but what if we don't develop such a method? I guess we'd better learn to make do with this little planet of ours that we are so rapidly destroying. The point I was making before was that we cannot even guess at what would be required for such a method of communication but technology may well supply it in the near future, and then what would we need EM transmissions for? 2. Navigational Aids. Radar and navigational satellite systems may well be around for quite some time because both of them negate principles outlined above. In both these cases we need the Earth to act as an obstacle reflecting or blocking our EM transmissions. However, for interstellar space flight, it could be that entirely new methods are developed which could be applied back on Earth. These, again, would be unlikely to use EM transmissioned because they are so slow. 3. Electronical and Electronic Emissions. One of the most interesting aspects of the debate was over unintentional EM transmissions from electrical and electronic devices. Most devices produce EM transmissions when in operation, even though they have shielding to minimise the volume of EM leakage. The problem with detecting leakage of EM transmissions from another world is that it would show up as so much static, indistinguishable from natural EM sources. 4. In Summation. So I reinterate, there would perhaps be a window of 200 (terran) years in the history of a sentient species where they MAY knowingly or unwittingly transmit EM signals between themselves, maybe much shorter if they don't survive the invention of mass destructive weaponry and the ravages of ecological irresponsibility. (They could even simply be smarter than us, which I realise to some would be totally unthinkable). Philip Nettleton, Tutor in Computer Science, University of New England, Armidale, New South Wales, Australia. ------------------------------ Date: 2 May 90 06:29:07 GMT From: hplabsb!dsmith@hplabs.hp.com (David Smith) Subject: Re: PegBlimp (was Re: Pegasus launch from Valkyrie (or ...) In article <1990May1.153359.13569@eplrx7.uucp> leipold@eplrx7.UUCP (Walt Leipold) writes: >"As long as you've lit one candle, Walt Leipold >you're allowed to curse the darkness." (leipolw%esvax@dupont.com) Curse the candle, let's have the night sky! -- David R. Smith, HP Labs dsmith@hplabs.hp.com (415) 857-7898 ------------------------------ Date: 2 May 90 16:27:40 GMT From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: (How to get rid of) space garbage In article <13846@thorin.cs.unc.edu> leech@homer.cs.unc.edu (Jonathan Leech) writes: >...ways to get rid of orbital debris. First off the wall >suggestion: use high-powered lasers to accelerate decay from the >Poynting-Robinson effect... No need to invoke something as slow as the P-R effect. Use the lasers more directly: vaporize small fragments, de-orbit larger ones by laser rocketry (blowing bursts of gas off their leading faces). If I recall correctly, Jordin Kare said that even the first-phase proof-of-principle laser for a laser-launcher system could do a dandy job on this. -- If OSI is the answer, what is | Henry Spencer at U of Toronto Zoology the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 3 May 90 02:05:14 GMT From: dino.qci.bioch.bcm.tmc.edu!skywalker@tmc.edu (Timothy B. Reynolds) Subject: Apollo 11-17 Ok here's a trip back in history. In the late 60's or early 70's I remember watching TV when the astronauts were walking on the moon, one of the major networks was doing the "moon-walk" simulations with puppets of the astronauts. The looked very real ! Anyway I have spent 15 years calling the networks trying to find out where these puppets came from or who made them. On the broadcast they even interviewed the man that was operating them ! No one I have talked with remembers this (at the nets) if I remember correctly it was WALTER CRONKITE that did this, this means means CBS. If anyone has any info on this or remembers it please e-mail me with the details. I WONT GIVE UP... Thanx...T ============================================================================== Timothy B. Reynolds | VAX Systems Manager Howard Hughes Medical Institute | Structural Biology Laboratory Baylor College of Medicine | Houston, Texas ============================================================================== Disclaimer: My opinions are my own, not HHMI's or Baylor College of Medicine ============================================================================== ------------------------------ Date: 2 May 90 17:02:19 GMT From: sdd.hp.com!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!aristotle!pjs@ucsd.edu (Peter Scott) Subject: Re: (How to get rid of) space garbage In article <13846@thorin.cs.unc.edu>, leech@homer.cs.unc.edu (Jonathan Leech) writes: > > In light of the current 'life of HST' discussion, maybe we could > talk about ways to get rid of orbital debris. First off the wall > suggestion: use high-powered lasers to accelerate decay from the > Poynting-Robinson effect. If this thread takes off, I'll run some > numbers on this suggestion. Since I saw a similar suggestion in the space-tech group, I've been impressed with this idea. The suggestion was to use a mirror to reflect sunlight onto trash to deorbit it gradually. I think this is an even neater suggestion, since it doesn't require any onboard power and could be launched right now. I don't understand why this isn't being pursued vigorously, since it would have the greatest effect on the small trash and very little on larger items such as satellites. Of course, one would hope that it wasn't in the wrong position when Hubble came around one orbit, or whoops... Maybe you could run some numbers for the mirror; what diameter Mylar film to deorbit 50% of LEO junk < .5cm within 6 months, say? This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@aristotle.jpl.nasa.gov) ------------------------------ Date: 2 May 90 23:49:21 GMT From: sdd.hp.com!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!mephisto!prism!ccastbs@ucsd.edu (Shannon Bell) Subject: Re: Niven's inertialess drive (was Re: Dyson spheres, heat flow) In article <1990May2.063218.32404@uokmax.uucp> spcoltri@uokmax.uucp (Steven P Coltrin) writes: :In article clive@ixi.co.uk (Clive D.W. Feather) writes: :>But in "Flatlander" an Outsider ship accelerates Beowulf and Elephant to 0.9c :>in a matter of minutes. This can't be a simple reaction drive; it has to act :>on the occupants as well as the ship, or they'd be squashed. :> :The Outsiders likely just have unghodly gravity generators and are able to :compensate. I'm not nearly sure, but I think one of the Louis Wu stories :mentions grav. generators needed to compensate for thruster acceleration. Or maybe they used the anticoncussion field from _The_Soft_Weapon_. While Niven didn't give any particulars about the operation of the field, I don't thing gravity generators could do that (basically an anti-motion field) and still not generate a healthy change in perceived weight. Perhaps something like an inductor, but acting on kinetic energy in a volume, rather than electricity in the wire? Shannon Bell Internet: ccastbs%prism@gatech.edu uucp: ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!ccastbs PO Box 36266 Georgia Institute of Technology, Atlanta Georgia, 30332 Any opinions herein are probably not held by Ga. Tech, even if I say they are. ------------------------------ Date: 2 May 90 16:22:13 GMT From: convex!ewright@uunet.uu.net (Edward V. Wright) Subject: Re: Giant crawler transporter to pass 1000 miles on STS-35 rollout (Forwarded) henry@utzoo.uucp (Henry Spencer) writes: >power. They burn Diesel oil; mileage is something like 30 ft per gallon. Don't you mean footage? -:) ------------------------------ Date: 2 May 90 21:56:15 GMT From: uokmax!michaelt@apple.com (Michael Dean Thompson) Subject: Re: * SpaceNews 30-Apr-90 * In article <283@ka2qhd.UUCP> kd2bd@ka2qhd.UUCP (John Magliacane) writes: > > >* STS-31 NEWS * >=============== >Mike (WD8KPZ) of Phoenix, Arizona reported hearing space shuttle astronaut >communications on a frequency of 279.000 MHz AM during their EVA during the >deployment of the Hubble Space Telescope. > >Mike used an Icom R-7000 receiver and a quarter-wave ground plane antenna at >an altitude of 15 feet to receive the astronauts. When I watched the deployment of the Hubble, I never remember Bruce or Kathy being let out of the airlock. So when was this EVA? (I'm sure Bruce would like to know :-) ) -- michaelt@uokmax.ecn.uoknor.edu "I don't know...I can imagine quite a bit..." H. Solo ------------------------------ Date: 2 May 90 14:55:08 GMT From: philmtl!philabs!ttidca!jackson@uunet.uu.net (Dick Jackson) Subject: Phhotos from Space (was: Hubble Telescope) In article <299.263BF427@ofa123.FIDONET.ORG> Russ.Tillman@ofa123.FIDONET.ORG (Russ Tillman) writes: >something they understand. I remember back in the 70's, that while enroute to >Jupiter, Pioneer took a picture of both the earth and the moon in the same >frame. A picture like that get's people thinking! Is there not a plan to have Voyager turn around to get a family snap of the solar system? Has this been approved? Dick Jackson ------------------------------ Date: 3 May 90 05:03:45 GMT From: deimos.cis.ksu.edu!maverick.ksu.ksu.edu!uafhp!bmccormi@rutgers.edu (Brian L. McCormick) Subject: Re: (How to get rid of) space garbage In article <1990May2.204013.29461@helios.physics.utoronto.ca>, neufeld@physics.utoronto.ca (Christopher Neufeld) writes: [stuff deleted] > ... My proposal was to have a 300km diameter mirror out > around 80000km from the Earth, balanced off the solar radiation pressure > and the Earth's gravitational pull. Essentially, it is a solar sail which > can't quite get away from the Earth's pull when it's 80000km out. The > existing solar sail technology seems to indicate it should work. [more stuff chopped] > Because of the way it is positioned, it has a 100% duty cycle. It does not > orbit the Earth, but floats ahead of it in orbit around the Sun. [remainder zapped] I am not particularly inclined towards the mathematics of this sort of calculation, but it seems to me that this proposal ignores the gravitational effect of the moon on an object "floating" in the vicinity of the Earth. I have heard that the moon has enough of an impact to shorten the orbital life of satellites considerably and it seems as though this effect would be much more significant for an object that is not actually orbiting the Earth. Any thoughts on whether or not such an orbit is actually possible? -------------------------------------------------------------------- (|||) Brian McCormick a.k.a. bmccormi@uafhp.uark.edu (|||) ||| - I deny being in any way affiliated with engineering - ||| (|||) Any disclaimer you can think of probably applies. (|||) -------------------------------------------------------------------- ------------------------------ End of SPACE Digest V11 #348 *******************