Return-path: X-Andrew-Authenticated-as: 0;andrew.cmu.edu;Network-Mail Received: from po3.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 ; Sun, 17 Jul 88 22:20:34 -0400 (EDT) Received: from andrew.cmu.edu via qmail ID ; Sun, 17 Jul 88 22:19:40 -0400 (EDT) Received: by andrew.cmu.edu (5.54/3.15) id for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl; Sun, 17 Jul 88 22:18:40 EDT Received: by angband.s1.gov id AA18246; Sun, 17 Jul 88 19:06:29 PDT id AA18246; Sun, 17 Jul 88 19:06:29 PDT Date: Sun, 17 Jul 88 19:06:29 PDT From: Ted Anderson Message-Id: <8807180206.AA18246@angband.s1.gov> To: Space@angband.s1.gov Reply-To: Space@angband.s1.gov Subject: SPACE Digest V8 #279 SPACE Digest Volume 8 : Issue 279 Today's Topics: Space Shuttle Differences Re: SPACE Digest V8 #255 Re: Henry's von Braun comment Re: advance space news from June 6 AW&ST -- Pegasus! Niven's _Ringworld_ Re: Long Term Effects of Weightlessness... Re: advance space news from June 6 AW&ST -- Pegasus! More on Data Compression Re: spacecraft computers Re: Pegasus Re: Cometesimals at Tunguska Re: Cometesimals at Tunguska ---------------------------------------------------------------------- Date: 23 Jun 88 05:22:20 GMT From: aplcen!jhunix!ins_ackg@mimsy.umd.edu (Choon Kiat Goh) Subject: Space Shuttle Differences Are all the operational shuttles the same, ie. in terms of lifting capability, weight, etc. ? Or are there functional differences? --- Ian --- ------------------------------ Date: 23 Jun 88 19:49:26 GMT From: nsc!nessus@decwrl.dec.com (Kchula-Rrit) Subject: Re: SPACE Digest V8 #255 In article <8806200320.AA02811@angband.s1.gov> R2CDN@AKRONVM.BITNET (Dess-DEMON-a) writes: > ... >Q: Does anyone REALLY believe that earthings will be able to survive in > space stations in various locations? Just a thought... (Do you think > we'll have an orbital station around Uranus? Who'd want to live there? > It's SO COLD!) ^^^^ Sure, I'll go! It'll be just like home! I'm from Minnesota... K-R -- Kchula-Rrit "In challenging a kzin, a sream of rage is sufficient. You scream and you leap." ------------------------------ Date: 23 Jun 88 19:53:26 GMT From: devvax!jplpro!leem@elroy.jpl.nasa.gov (Lee Mellinger) Subject: Re: Henry's von Braun comment In article <10722@ames.arc.nasa.gov> eugene@pioneer.UUCP (Eugene N. Miya) writes: | |I don't quite know what Todd meant about Voyager computer problems, |they added data compression for Uranus and beyond. There were a few |other things. Oh, I did meet Henry last evening at Usenix, briefly, |associated a net address with a face. | |--eugene Hi Gene, you might remember me from about 1978-79 in regards to a Modcomp Pascal project I was peripherally involved with in the DSN. Voyager, which one I don't remember (must be age, the first thing to go you know), had some serious control problems shortly after launch. One of the things the project did to clear the problems was a complete CCDS reload (which the project had promised they would never do). I remember this quite vividly, as the commanding, 8 plus hours of it, was done by the then brand new and buggy Mark III command system at DSS 12. We were all holding our collective breath. The Voyager computers have been completely reprogrammed more than twice since launch, on one occasion to make the attitude control fuel usage *much* more efficient, and twice to refine the image handling and compression techniques. Lee -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- |Lee F. Mellinger Jet Propulsion Laboratory - NASA| |4800 Oak Grove Drive, Pasadena, CA 91109 818/393-0516 FTS 977-0516 | |-------------------------------------------------------------------------| |UUCP: {ames!cit-vax,psivax}!elroy!jpl-devvax!jplpro!leem | |ARPA: jplpro!leem!@cit-vax.ARPA -or- leem@jplpro.JPL.NASA.GOV | -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ------------------------------ Date: 22 Jun 88 17:45:46 GMT From: hpda!hpcuhb!hpsel1!campbelr@ucbvax.berkeley.edu (Bob Campbell) Subject: Re: advance space news from June 6 AW&ST -- Pegasus! >> Man is the best computer we can put aboard a spacecraft. --Von Braun > . . . > > I'd like to see some fighter jock/astronaut do as well by flying a > launch manually. Perhaps you should limit the scope of this statement > somewhat. > > Phil ---------- Were all of the computers used onboard the spacecraft? I agree that Von Brauns statement may need some context help, but we could quickly disolve into a disscussion of what is a computer. Bob Campbell Some times I wish that I could stop you from campbelr@hpda.hp.com talking, when I hear the silly things you say. Hewlett Packard - Elvis Costello ------------------------------ Date: Fri, 24 Jun 88 04:03:15 EDT From: "Keith F. Lynch" Subject: Niven's _Ringworld_ To: C445585%UMCVMB.BITNET@cunyvm.cuny.edu Cc: KFL@ai.ai.mit.edu, space@angband.s1.gov, sf-lovers@rutgers.edu, Physics@unix.sri.com There are no major problems with the concept of a ringworld. Obviously it would be an extremely difficult engineering feat. There are several minor problems, most of which Niven addresses in his sequel _The Rignworld Engineers_. Personally, I think it would be more likely that people will colonize asteroids, and when we run out that we will demolish useless planets to make more asteroids. Ultimately, this strategy can support a much higher population than a ringworld. It's also much more immune to common-mode failures such as the superconductor eating bacterium in _Ringworld_ and the far greater danger in _The Ringworld Engineers_. ...Keith ------------------------------ Date: 23 Jun 88 22:58:53 GMT From: ihnp4!ihlpm!njd@ucbvax.berkeley.edu (DiMasi) Subject: Re: Long Term Effects of Weightlessness... Scott S. Campbell writes: > > ..... > > I'm generally (i.e., non-techinically) curious about the affects of > weightlessness on the human body over long periods of time. Now that the > Soviet Union has put several people into zero-G for extended periods of time, > has there been any mention of the ability of these cosmonauts to re-adapt to > the pull of Earth's gravity? How did the recovery time relate to the amount > of time spent in the space station? What thereapy was necessary to re-adjust? I don't recall the details, but I remember reading (about 2 years or so ago?) that cosmonauts who had flown on more than one long-duration mission re-adapted to 1G more quickly on their second (third if any) missions. It seems that the human body "learns" to re-adapt. As I remember, only re-adaptation to 1G in terms of ability to move around easily, pick up objects, etc. was discussed in the article I read. I don't recall anything about recovery of muscle mass, bone mass, etc. Nick DiMasi Uni'q Digital Technologies (Fox Valley Software subsidiary; ^ working as a contractor at AT&T Bell Labs in Naperville, IL) ( | this is an accent mark, supposed to replace the dot over the 'i') ------------------------------ Date: 24 Jun 88 01:14:36 GMT From: necntc!adelie!infinet!rhorn@ames.arc.nasa.gov (Rob Horn) Subject: Re: advance space news from June 6 AW&ST -- Pegasus! In article <3361@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >henry@utzoo.uucp (Henry Spencer) writes: >> Pegasus, a winged three-stage design that will be air-launched from a B-52. >> [...] Payload is 600lb into low polar orbit, 900 into low equatorial orbit. > >What does a typical commsat weigh, for example? Depends on the type. Geosynch tend to be heavier. 2000kg and up. One major consideration is power supply and another is fuel for station keeping. BUT, low earth orbit fit easily in this. The latest AMSAT (Up and WORKING !!!! yeah) weights 140 kg. This kind of satellite supports packet radio techniques. DARPA has funded paper studies of a ``cloud'' of these as an alternative to geosynch. > Or a typical package of >scientific instrumentation? I've gotten data from a 10kg satellite. But there is no typical. > Or (God forbid), a typical military payload >(warhead, spysat, whatever). Spysats are HUGE, partly because optics are huge and partly because they want maneuvering capability (fuel+motor) and partly for long life. But a lot of this is the result of the present difficulty in making a decision to launch on a day's notice. (Optics being the exception.) -- Rob Horn UUCP: ...harvard!adelie!infinet!rhorn ...ulowell!infinet!rhorn, ..decvax!infinet!rhorn Snail: Infinet, 40 High St., North Andover, MA ------------------------------ Date: Fri, 24 Jun 88 14:05:48 PDT From: Eugene Miya To: jaw@eos.arc.nasa.gov, space@angband.s1.gov Subject: More on Data Compression Just when you thought it was safe to go back and read Aviation Leak and Space Technocracy, the latest issue of Computing Surveys has an article on DATA COMPRESSION. It's not a bad article by two authors from Irvine, it lacks a few words (I think the section on Errors could say a bit more, but it is a Survey). %V 19 %N 3 %D Sept. 1987 I decided to give the above refer with keywords (The list is more than I want to type). %P 261-296 --eugene ------------------------------ Date: Fri, 24 Jun 88 16:24:37 EDT From: dietz@gvax.cs.cornell.edu (Paul F. Dietz) Interested parties might want to read this article: "Electromagnetic Launch: Highway to the Stars", IEEE Trans. on Magnetics, Vol. 24, No. 2, March 1988, pages 703-710. It is highly readable, if somewhat hyperbolic, and makes some interesting claims. To summarize... Use of space has been blocked by the stagnation of launch cost using chemical rockets. Historically, further progress depends on the introduction of new technology. Electromagnetic launchers promise much higher payload ratios. Recent progress in e.m. launcher and associated technology has been rapid. The article describes one particularly attractive concept, called the solenoid quench gun. The launcher is a superconducting solenoid with a field of 20-30 Tesla. The projectile coil, also superconducting, is accelerated up the solenoid, quenching solenoid segments as its goes (so the coil remains at the "end" of the solenoid). If the quenched coils are shunted through a s.c. circuit the efficiency can approach 100%. The most interesting things about the launcher are its inherent simplicity and small size. The article claims that a 3 ton projectile (1 ton of which is payload destined for geosynchronous orbit) could be launched by a gun with a mass in the *tens* of tons. E.m. launchers would seem to be well suited to materials processing, since only a modest kick motor is needed to raise the projectile into a long elliptical orbit (and, similarly, to deorbit it). Paul F. Dietz dietz@gvax.cs.cornell.edu ------------------------------ Date: 24 Jun 88 20:31:32 GMT From: pioneer!eugene@ames.arc.nasa.gov (Eugene N. Miya) Subject: Re: spacecraft computers In addition to the well cited CACM articles, I recall the IEEE has advertised some books on spacecraft computer systems. I seem to recall them because I think they were advertised with some books on communication systems by Pierce and Posner. Serious readers can determine this (costs were in excess of $75, I'll check Posner next time I swing past my old Branch's library). Computers onboard tend to be small, small scale things. I think Lee would agree with this. 8-) I think most of the companies who would seriously buy these books will not be on the net (like Hughes or Huge). I also note there is increasing interest in GaAs. Another gross generalization from --eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov resident cynic at the Rock of Ages Home for Retired Hackers: "Mailers?! HA!", "If my mail does not reach you, please accept my apology." {uunet,hplabs,ncar,decwrl,allegra,tektronix}!ames!aurora!eugene "Send mail, avoid follow-ups. If enough, I'll summarize." ------------------------------ Date: 22 Jun 88 15:27:35 GMT From: mnetor!utzoo!dciem!nrcaer!cognos!geovision!alastair@uunet.uu.net (Alastair Mayer) Subject: Re: Pegasus Don't have the reference handy to give the exact figures, but Pacific American's Liberty I launcher has equivalent payloads to Pegasus to orbit at around $2 to $4million. Payload weight may even be higher. Either way the per/lb cost is substantially less than Pegasus. And yes, Pacific American has a customer for Liberty I, they're currently bending metal on it. (I heard they're 'rolling out' first engine and propellant tanks this week or next). Liberty is conservative design: pressure-fed LOX/kerosene first stage, N2O4-hydrazine second stage. That's one of the keys to low cost. -- Alastair JW Mayer BIX: al UUCP: ...!utzoo!dciem!nrcaer!cognos!geovision!alastair "Anyone who is not shocked by quantum theory has not understood it." ------------------------------ Date: 24 Jun 88 15:18:49 GMT From: hplabsb!dsmith@hplabs.hp.com (David Smith) Subject: Re: Cometesimals at Tunguska In article <6719@cup.portal.com>, Paul_L_Schauble@cup.portal.com writes: > In 1908, a large explosion flatened a section of the Tunguska > region in Siberia. As far as I know, there has never been a satisfactory > explaination for this event. > > The sticking point is that the damage pattern matches that of a nuclear air > burst. Trees are broken down in a pattern radiating away from ground zero, > but with no significant crater or extra damage at ground zero itself. This > couldn't happen with a normal meteor, because anything large enough to have > caused the blast would have survived to ground impact. > > I wonder if the fluffy snowball wouldn't do it. I'm thinking that a large, > low density, fast moving object could couple all of its kinetic energy to > the atmosphere. This would leave a shock wave traveling on the same path as > the object, which might leave the right damage pattern. Around six years ago, Science News ran an article on explosions of meteors, largely based on photographic patrols in Czechoslovakia. The conclusion was that fast-moving stony meteors, undergoing great stress in the atmosphere, can suddenly shatter into many small pieces. The greatly increased surface area causes extremely rapid "burn-up" of the fragments in an explosion. The researchers believed this to be the best explanation of the Tunguska event. -- David Smith HP Labs dsmith@hplabs.hp.com ------------------------------ Date: 25 Jun 88 21:18:25 GMT From: puff!astrix@speedy.cs.wisc.edu (Lou Goodman) Subject: Re: Cometesimals at Tunguska when speaking of "old" sources for Tunguska, I seem to remember one of the films in the ACClarke "mysterious somthing-or-other" in which he examined it. One of the experiments made was to do an air blast over simulated trees. The zone of "ground zero" under the simulated blast was relatively unaffected by the blast while outside of that zone the "trees" were flattened. He also pointed out that it was not until the 20's that anyone even got to the site and that it is a morass of fens and bogs, very people unfriendly. I've always enjoyed the "spaceship (read ufo) gone critical". By now most evidence (if any does or did indeed exist) may be gone/incorporated into the current matrix. astrix (Lou R. Goodman), UW Madison ------------------------------------------------------------------- || He who knows, who really knows, and knows that he knows...... || || knows just how much he doesn't know...... || ------------------------------------------------------------------- || "Sticks and stones can break my bones, but flames... oy weh!" || ------------------------------------------------------------------- ------------------------------ End of SPACE Digest V8 #279 *******************