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, 6 Apr 91 01:41:24 -0500 (EST) Message-ID: <0bzKqCO00WBw49D05s@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 6 Apr 91 01:41:18 -0500 (EST) Subject: SPACE Digest V13 #366 SPACE Digest Volume 13 : Issue 366 Today's Topics: New Improved Rail-Gun, now with Hotol for Added Pep and Verve... Re: How 'bout them Titans? Re: NY Times Article: Nuclear rocket Re: Space Junk Re: Space technology Re: Advancing Launch Technology Laser launchers Re: Railguns, EM launchers Re: space news from Feb 18 AW&ST SPACE Digest V13 #364 Re: comsat cancellations and lawsuits Re: News from Spaceflight 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: Thu, 4 APR 91 10:24:13 GMT From: F026%CPC865.EAST-ANGLIA.AC.UK@BITNET.CC.CMU.EDU Subject: New Improved Rail-Gun, now with Hotol for Added Pep and Verve... > Use a short rail, with moderate acceleration to put a fully-loaded, already- > been-tested-and-budget-approved chemical rocket moving up at around, say, > 300mph, then fire the rockets. [...] > Now, combine that with the HOTOL concept, saving all the weight of the O2, the > heaviest part of the fuel anyway, for a payload savings around, say, 90%. [...] > Tommy Mac 18084tm@msu Ignoring, for a moment, the difficulties of building and using a rail-gun capable of lobbing something as massive as a Hotol, why would this save the weight of the O2? Surely it would only reduce the amount of H2 used, as Hotol breathes air while it can? That doesn't necessarily mean you couldn't achieve savings, as the H2 tanking must weigh a lot. I don't know how much it uses to get to 300mph, but at a guess not as much as a conventional rocket because it doesn't have to support its entire weight on a plume (wings!) Out of interest, what size of craft (shell/bullet/blob) are rail-guns being designed for firing? What's the chance of being able to track them accurately enough to combine rail & laser/ice propulsion? _________________________________________________________________ Mike Salmon, Climatic Research Unit | "Spin, spin, spin the Univ. of East Anglia, Norwich, England | Wheel of Justice..." F026@CPC865.UEA.AC.UK +44-603-592875 | ------------------------------ Date: 4 Apr 91 16:23:23 GMT From: skipper!shafer@ames.arc.nasa.gov (Mary Shafer) Subject: Re: How 'bout them Titans? In article <10902@ncar.ucar.edu> murphy@hao.hao.ucar.edu (Graham Murphy) writes: I'd be interested in knowing where the sound track for CNN's footage of the explosion came from---presumably not the control room. Shortly after the Titan was destroyed, one hears a voice in the background say, "Is it supposed to do that?" followed by another voice giving a very emphatic "No!" From the media. CNN et al. were out at the press site to cover the burn and they picked up what the other crews around them said. I actually think they were just inside the PIRA (precision impact range area--bombing range to real people) on the west range. I was out there in the PIRA a few months ago and that's what it looked like to me. (I've got a project that we're putting in the East Range, as soon as the EIS and archeology people get done.) It's not uncommon for the press to be invited to these events. We have them at Dryden for such unspectacular things as first flights and they come out in hordes for anything that would provide a nice film clip. Pegasus, Titan burns, etc. A little more background--when I first moved to Lancaster in 61 they were doing a lot of rocket burns at the Rocket Site (now the Astronautics Lab), in support of Apollo, etc. They'd fire them at night and you could see them in Lancaster. A long silent burn and then, just before the burn ended, the sound would finally make it into town. Beautiful, just beautiful. I don't remember anything blowing up then, but I'm not sure I'd have noticed unless I saw it. -- Mary Shafer shafer@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA "A MiG at your six is better than no MiG at all"--Unknown US fighter pilot ------------------------------ Date: 4 Apr 91 20:13:35 GMT From: rochester!sol!yamauchi@louie.udel.edu (Brian Yamauchi) Subject: Re: NY Times Article: Nuclear rocket In article <1991Apr4.174952.12458@dsd.es.com> bpendlet@bambam.dsd.es.com (Bob Pendleton) writes: >Personally I'm glad to hear that they are developing the pellet bed >reactor for propulsion applications. BUT, I'm very distressed to hear >that they were looking at using it inside the atmosphere. According to the UPI article, Timberwind will use a conventional first stage -- the nuclear stage will not fire until AFTER the rocket leaves the atmosphere. -- _______________________________________________________________________________ Brian Yamauchi University of Rochester yamauchi@cs.rochester.edu Department of Computer Science _______________________________________________________________________________ ------------------------------ Date: 1 Apr 91 22:53:35 GMT From: agate!bionet!uwm.edu!rpi!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!Paul.Blase@ucbvax.Berkeley.EDU (Paul Blase) Subject: Re: Space Junk to: SOCKIELY%vax1.ucg.ie@BITNET.CC.CMU.EDU S> I am interested in obtain information on a project based at the S> University of Arizona named the 'Space Janitor' (a spacecraft S> designed to trash unwanted satellites in LEO). S> S> Any references to space junk in general would also be S> appreciated (particularly references to any discussions that S> took place on this list in the past). Check out the Analog article quoted in my other posting on the subject. It has a rather complete biblography and some suggestions for a 'space janitor' --- via Silver Xpress V2.26 [NR] -- Paul Blase - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!Paul.Blase INTERNET: Paul.Blase@nss.FIDONET.ORG ------------------------------ Date: 5 Apr 91 05:09:30 GMT From: unmvax!uokmax!rwmurphr@ucbvax.Berkeley.EDU (Robert W Murphree) Subject: Re: Space technology Actually, I like to think of the word "spinoff" as one of the great PR triumphs of the 60's-basically its a publicity hoax invented to quiet disturbed tax payers like your father. Carl Sagan is fond of saying that in matters of applied research, if the object is a no-stick frying pan, you're almost always better off backing research into no- stick frying pans rather than laser-guided tennis balls. The major technologies of importance from space are (in order of importance) ICBM's, military reconnaisance satellites, weather, and communication satellites, astronomy and planetary science probes. ------------------------------ Date: 5 Apr 91 06:24:24 GMT From: sdd.hp.com!cs.utexas.edu!sun-barr!newstop!exodus!norge.Eng.Sun.COM!jmck@ucsd.edu (John McKernan) Subject: Re: Advancing Launch Technology szabo@crg5.UUCP (Nick Szabo) writes: >In article <1991Apr1.172946.11907@eplrx7.uucp> leipold@eplrx7.uucp (Walt Leipold) writes: >>For >>the sake of discussion, let's assume a modest 500g acceleration in a purely >>horizontal launcher.... >We can actually get much more than this right now in the lab, but >perhaps this is a good number for a system with low materials >costs. I don't think a 500g or greater acceleration EM launching device would replace chemically powered launchers. It might be useful for launching bulk materials, but it can't launch large complex systems like space stations, the Earth observation system, Gallileo, human beings, etc. So even if we had an EM launcher, we would still need chemically powered launchers. It does seem possible to replace chemical launchers with a laser powered launch system, but not for at least 15 or 20 years. The technology to generate and maintain a beam of sufficient energy for the required length of time, and then focus and aim it simply doesn't exist. There has been a lot of research on lasers, but there is still a LONG way to go before we get to the level of technology we need. Since we're stuck with chemically powered launchers for at least the next 15 or 20 years, it makes a lot of sense to try and reduce their cost by an order of magnitude or so. And Nick, you can repeat yourself until you're blue in the face, but it's just a fact that with such a small number of complete chemical launcher design iterations, we just DON'T KNOW what the lowest possible cost of that technology is. John L. McKernan. jmck@sun.com Disclaimer: These are my opinions but, shockingly enough, not necessarily Sun's ------------------------------------------------------------------------------- "It's kind of a macho thing, programmers are always trying to be weirder than their machines." ------------------------------ Date: 4 Apr 91 11:03:42 GMT From: eru!hagbard!sunic!mcsun!ukc!slxsys!ibmpcug!demon!news@bloom-beacon.mit.edu (Ian Stirling) Subject: Laser launchers >Chem rockets cannot provide even a one order of magnitude drop, but >tethers combined with suborbital airplane or laser launch, combined ^^^^^ what is a laser launcher? I have heard some references to it,Is it using a ground based laser to heat fuel on-board a vehicle so that the fuel boils violently,propelling the vehicle.Is this a current technology or does it still need massive advances in laser technology? ------------------------------ Date: 4 Apr 91 16:09:39 GMT From: udecc.engr.udayton.edu!blackbird.afit.af.mil!lonex.radc.af.mil!andrewsh@tut.cis.ohio-state.edu (Harold G. Andrews II) Subject: Re: Railguns, EM launchers Tom McWilliams writes: > >Use a short rail, with moderate acceleration to put a fully-loaded, already- >been-tested-and-budget-approved chemical rocket moving up at around, say, >300mph, then fire the rockets. To which Henry Spencer responds: > >Unfortunately, those chemical rockets aren't designed for a horizontal >takeoff. You could get useful gains by catapulting them at such speeds >*vertically*, and in fact there was a recent Japanese proposal to do >just that. To which I now ask: What kinds of problems are the Japanese running into, and what kinds of set-ups are they looking at? Are the EM launchers under-ground? Could you point me to some articles discussing the Japanese efforts? Just curious. Thanks. -Andy ******************************************************************************* * Harold G. "Andy" Andrews II * "Many the man whose punctuality * * andrewsh@lonex.radc.af.mil * serves only to warm his chair." * * Rome Laboratory/IRRE * * * Griffiss AFB, NY 13441-5700 * - M. Kabrisky * * (315) 330-7788 (AVN Prfx 587) * (Not an official USAF viewpoint) * ******************************************************************************* ------------------------------ Date: 5 Apr 91 18:05:41 GMT From: swrinde!elroy.jpl.nasa.gov!sdd.hp.com!spool.mu.edu!snorkelwacker.mit.edu!primerd!primerd!os@ucsd.edu Subject: Re: space news from Feb 18 AW&ST From Henry's notes of Feb 18 AW&ST: >[March issue of Spaceflight mentions that astronaut William F. Fisher has >left NASA to return to medical practice. No big surprise, on thinking >about it: he was co-chair of the group that reported the bad news about >EVA requirements for Fred, which probably killed his chances of future >flight assignments.] Personal comment: This is really sad. The recent book on Apollo (I forget whose) lamented the passing of the age within NASA et al where one could mention something to one's boss. One could tell the boss something, just like a colleague, without asking for or receiving a decision. This period of "camalot" is now gone. If the note about Dr. Fisher is true, things are now much worse. Things are becomming so political that one can destroy one's career by succeeding at one's assigned tasks just because it is politcally unpopular. Shoot the messenger, perhaps. Sigh. Jim Cook ------------------------------ ReSent-Message-ID: Resent-Date: Fri, 05 Apr 91 14:51:18 EST Resent-From: 18084TM@msu.edu Resent-To: space+@andrew.cmu.edu Date: Fri, 5 Apr 91 02:50:59 EST Reply-To: space+%ANDREW.CMU.EDU@msu.edu From: space-request+%ANDREW.CMU.EDU%CARNEGIE.BITNET@msu.edu Subject: SPACE Digest V13 #364 Comments: To: space+@ANDREW.CMU.EDU To: david polito <15432DJP@MSU.BITNET>, Tom McWilliams <18084TM@MSU.BITNET> >> Use a short rail, with moderate acceleration to put a fully-loaded, already- >> been-tested-and-budget-approved chemical rocket moving up at around, say, >> 300mph, then fire the rockets. >Good Idea. (Tom says that since he can think of it, but no-one doing actual launches has chemical rockets must not be 'stretched to their technical limits') >You must not have read the same science fiction I did. Bob Heinlein >used this idea alot in his stories. I think "Space Cadet" was the >first place I remember reading about it. >The "short" rail ran up the west side of Pike's Peak. The rocket >planes sounded like scaled up X-1s with swept wings. The Great Plains >served as a great place to ditch if the engines didn't fire. And, of >course, being an early Heinlein juvy (don't ever lie to kids!) you can >bet that there was a solid engineering and mathematical basis for >believing that it would work. I'm a fan of his too. Agreeing with his politics helps. :-) >one of the reasons I don't think chemical rockets have topped out is >that ideas like this one have been around, and practical, since the >1930s and know one has even tried them. You said it! >> P.S> I don't think chemical rockets will ever have a market outside LEO >> My personal favorites are the ion rocket and solar sail. >I agree that chemical rockets haven't much future beyond LEO. But I'm >rather fond of fission torch rockets myself. I want to get there NOW, >not next year. :-) But where can you go? You certainly won't be using fission in MY back lagrange point (oops, I mean yard) |-) Actually, with Ion systems, since the ISP is so high, you can accelerate for the entire trip. Toward your destination at first, and slowing down after the half-way point. You'll start out at only a few meters/minute, since the amount of mass is so low. But after a day you'll be moving 76400 times faster. after a week, 534800 times, and after a year, 2.7e+7 times. (.90c) This is all ignoring relativity, of course. As an example, at .9c, a trip to Alpha Cent. would appear (th those on earth) to take 4.4 years. But you would feel like it only took about 2.5 years. That's 2 times the speed of light! Either way, I hope it happens soon enough for me to see it. Tommy Mac 18084tm@msu Acknowledge-To: <18084TM@MSU> ------------------------------ Date: 5 Apr 91 20:06:57 GMT From: swrinde!zaphod.mps.ohio-state.edu!wuarchive!rex!rouge!dlbres10@ucsd.edu (Fraering Philip) Subject: Re: comsat cancellations and lawsuits In article <1991Apr5.112818.12256@pbs.org> pstinson@pbs.org writes: >Considering passed performances and some questionable over charging, I'm >not sure that Hughes or any other aerospace firm has a "right" to be ticked >off. Call it poetic justice. This law suit, no matter who wins, is going to >cost the U.S. taxpayer. Since Henry is Canadian he doesn't have to worry, >though. :-) This is really twisted, when you think about it: "Based on past wrongs by 'aerospace companies' which may or may not include Hughes but which the government refused to sue them for breach of contract (nicely avoiding the question of whether or not the company itself is guilty; maybe it's guilty just for being a member of the group of 'aerospace companies') gives the government the right to abbrogate contracts without penalties." Come on, if the government thinks something wrong has occured, then they should fight for their rights, not lie in wait for some company which may or may not be guilty to trust them and then breach the contract... Phil Fraering dlbres10@pc.usl.edu ------------------------------ Date: 5 Apr 91 20:18:02 GMT From: deccrl!news.crl.dec.com!shlump.nac.dec.com!ryn.mro4.dec.com!troa09.enet.dec.com!sklein@decwrl.dec.com (Susan Klein) Subject: Re: News from Spaceflight In article , shafer@skipper.dfrf.nasa.gov (Mary Shafer) writes... >In article <1991Apr5.080709.6477@zoo.toronto.edu> >henry@zoo.toronto.edu (Henry Spencer) writes: > > March issue of Spaceflight mentions that astronaut William F. Fisher has > left NASA to return to medical practice. No big surprise, on thinking > about it: he was co-chair of the group that reported the bad news about > EVA requirements for Fred, which probably killed his chances of future > flight assignments. > Anna Fisher was chosen in August 1978 Group 8 astronaut group. Bill Fisher was chosen in May 1980 Group 9. Interesting that both have made only 1 flight so far and the Anna, still an active astronaut, has not made a flight since STS 51A in November 1984. Bill's flight was STS 51I August 1985. Susan Klein sklein@troa09.dec.com --or-- ...!decwrl!troa09.dec.com!sklein --or-- sklein%troa09.dec@decwrl.dec.com ------------------------------ End of SPACE Digest V13 #366 *******************