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 ; Fri, 5 Apr 91 02:40:02 -0500 (EST) Message-ID: <4bz2b9a00WBw83wk4J@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 5 Apr 91 02:39:54 -0500 (EST) Subject: SPACE Digest V13 #364 SPACE Digest Volume 13 : Issue 364 Today's Topics: Re: SPACE Digest V13 #344 Re: NY Times Article: Nuclear rocket Re: "Face" on Mars Re: Nova: The Dark Side of the Moon Re: How 'bout them Titans? ESA's space science dept participates in GRO Re: Chemical rocket complexities 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: 4 Apr 91 17:02:38 GMT From: orca!bambam!bpendlet@uunet.uu.net (Bob Pendleton) Subject: Re: SPACE Digest V13 #344 In article , 18084TM@MSU.EDU (Tom McWilliams) writes: > Re; Railguns, EM launchers > > 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. > The fact that I can think of this, yet find no reference of the combination of > similar technologies to yeild better launch efficiencies elsewhere, is my proof > that the chemical rocket is not streched to it's limits, or fully explored. > BTW: That's a ditto for EM, Rail, Hotol, Reusability, etc. 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. 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. A little editorializing: One of my favorite Heinlein quotations says that if it isn't mathematics it's opinion. What is missed by what he said is that it is so easy to use pretty fancy looking pseudo mathematics to justify almost any opinion. > P.S> I think chemical rockets will never, ever, have a market outside of 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. :-) > Tommy Mac I sure hope I get to see if I'm right! > 18084tm@msu > Acknowledge-To: <18084TM@MSU> -- Bob Pendleton, speaking only for myself. bpendlet@dsd.es.com or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet Tools, not rules. ------------------------------ Date: 4 Apr 91 17:49:52 GMT From: orca!bambam!bpendlet@uunet.uu.net (Bob Pendleton) Subject: Re: NY Times Article: Nuclear rocket In article <2257@cluster.cs.su.oz.au>, ray@cluster.cs.su.oz.au (Raymond Lister) writes: > > >Article xxx of clari.tw.space: [cross refed to several clari news groups] > >From: clarinews@clarinet.com (ELIOT BRENNER) > >Subject: Nuclear rocket being developed > >Date: 3 Apr 91 15:31:24 GMT > > WASHINGTON (UPI) -- The Pentagon is trying to build a nuclear-powered > rocket to boost huge payloads, satellites or weapons into space, > scientists and government sources said Wednesday. > Rather than using conventional chemical rocket fuels to generate a > blast of hot gases to propel a rocket into space, the project involves > vaporizing liquid hyrdogen into a far stronger exhaust stream by passing > it over a bed of nuclear fuel pellets generating heat as high as 3,000 > degrees. Well, if they are going to try this kind of foolishness at least the pellet bed reactor is the right one to use. In a pellet bed reactor the fuel is sealed up inside lots of small ceramic marbles. If one pellet fails you get a very small amount of very nasty stuff coming out the nozzle. In something like the NERVA reactor if you have a fuel element failure you could get the whole reactor core coming out the tail. If one pellet fails you don't lose the structural integrity of the whole core. Aside from the bucket, a bucket of marbles doesn't have any structural integrity. In a crash you, hopefully, get lots of solid pellets scattered arround. Easy to find pellets that can be collected. A graphite core NERVA style reactor could burn and spread death all over the place. 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. -- Bob Pendleton, speaking only for myself. bpendlet@dsd.es.com or decwrl!esunix!bpendlet or utah-cs!esunix!bpendlet Tools, not rules. ------------------------------ Date: 4 Apr 91 18:33:54 GMT From: infonode!hychejw@uunet.uu.net (Jeff W. Hyche) Subject: Re: "Face" on Mars rivero@dev8.mdcbbs.com writes: > If you want to look for non-terrestrial life, current thought holds that the >most likely place to find it will be floating high in the atmosphere of >Jupiter. Wonder what is going on in SETI right now? -- // Jeff Hyche There can be only one! \\ // Usenet: hychejw@infonode.ingr.com \X/ Freenet: ap255@po.CWRU.Edu ------------------------------ Date: 3 Apr 91 12:21:43 GMT From: dev8.mdcbbs.com!rivero@uunet.uu.net Subject: Re: Nova: The Dark Side of the Moon In article <28296@rouge.usl.edu>, dlbres10@pc.usl.edu (Fraering Philip) writes: > I was just wondering if anyone here wanted to discuss > the recent Nova episodes on the Soviet space program. > > I have only seen the second: "The Dark Side of the Moon," > and I will see the third one, "The Mission," this Saturday. > > Anyone want to start? > > If noone does, I have a technical question about the Soyuz. > From what I saw on the program, the Soyuz doesn't use the > same attitude control system the Apollo CSMs did (the 4 > thrusters per point, 4 point or whatever it is called). > What sort of system does it use? Is it efficient? I always > thought the one on the CSM looked like an optimum configuration, > but I haven't given it any serious thought. > > I suppose a related question would be, where is the location > of the center of gravity on a Soyuz? > > Another good question would be: how hard would it have been to > have moved their original two-man lunar mission to the Proton > rocket, using multiple launches? How many Protons would it have > taken? > > Is the Soyuz as good a spacecraft as it was made out to be > on the program? > > Phil Fraering > dlbres10@pc.usl.edu > Disclaimer: whatever a disclaimer is, I guess it applies ;-) As I recal, the reason for the development of the 4 point system was that it best served the geometry requirements for the LEM itself, and was adapted for the CSM in order to reduce duplication of effort. The Soyuz uses a more complex system similar to the one in the Shuttle ( and in the seperated Command Module). As to how good the Soyuz is? Hard to tell, even with the show. There has been one major accident with it that killed three Cosmonauts on re-entry, but like any design that has been kept and refined over the years, has most of the bugs and problems worked out. By the time the Apollo CSM was retired ( after Skylab, etc. it had proven itself a good piece of hardware.) Mike ------------------------------ Date: 4 Apr 91 22:14:40 GMT From: att!cbnewsm!cbnewsl!sw@ucbvax.Berkeley.EDU (Stuart Warmink) Subject: Re: How 'bout them Titans? In article <740@newave.UUCP>, john@newave.UUCP (John A. Weeks III) writes: > Saw it on CNN--it was spectacular! I liked how the explosion looked > like an expanding cylinder rather than the typical expanding hemishpere. > The sparklers caused by flying debris was a nice touch. But didn't you just love the exclamations on the soundtrack? Almost like the "ooooohhhh.....ahhhh!" of a good piece of fireworks! -- ------------------------------------------------------------------------------ Stuart Warmink, Whippany, NJ, USA | sw@cbnewsl.ATT.COM | Hi! ------------------------------------------------------------------------------ ------------------------------ Date: 4 Apr 91 04:40:59 GMT From: agate!bionet!uwm.edu!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!pitt!nss!freed@ucbvax.Berkeley.EDU (Bev Freed) Subject: ESA's space science dept participates in GRO European Space Agency 8-10 Rue Mario Nikis 75738 Paris Cedex 15 Telephone: (3314) 273 7155 Telex: ESA 202 746 FAX: (3314) 273-7560 FOR RELEASE: MARCH 29, 1991 #8 ESA'S SPACE SCIENCE DEPARTMENT PARTICIPATES IN THE GAMMA RAY OBSERVATORY The Astrophysics Division at the European Space Agency's ESTEC (European Space and Technology Centre) at Noordwijk in the Netherlands built part of the Imaging Compton Telescope (Comptel), one of the four instruments carried by NASA's Gamma-Ray Observatory (GRO). The Observatory, to be launched on 5 April from Cape Canaveral, will be the heaviest science payload ever deployed by the Space Shuttle in low Earth orbit -- it weighs over 17 tons and fills half the Shuttle bay. The Imaging Compton Telescope was built jointly by the Astrophysics Division at ESTEC, the Max Planck Institute, Garching (Germany), the Space Research Laboratory at Leiden (The Netherlands), and the University of New Hampshire (USA). Comptel detects gamma rays in the 1-30 MeV energy range, using the Compton scatter principle (the rays scatter in a detector bank, and are absorbed by a second detector bank 1.5 meters away). Comptel's operational modes and data-handling are controlled by the Digital Electronics Assembly developed by scientists and engineers of the Space Science Department (SSD) under the management of Dr. Kevin Bennett. On-orbit operations of Comptel will be controlled by computers located in the United States, all the software and hardware for which has been developed by SSD. Finally, SSD provided two detectors that will monitor radio-active sources in order to provide continuous on-board energy calibration of Comptel. The Gamma-Ray Observatory is a 3-axis stabilised spacecraft. Its gamma-ray detectors can be kept pointed in a fixed direction for observation periods of 14 days each. GRO's instruments are much larger, more massive, and far more sensitive than any gamma-ray instruments flown in Space up to now. Size is crucial for gamma-ray astronomy: large instruments are needed to detect a significant number of photons in a reasonable amount of time, because the number of gamma rays from celestial sources is small. A massive detector is required because gamma-rays are highly penetrating and can be detected only when they interact with matter. The Goddard Space Flight Center in the US is responsible for the development of the Gamma Ray Observatory. The Observatory's operations will be conducted from Goddard's Payload Operations Control Center with a remote link to Comptel operations computer in New Hampshire. Gamma-ray astronomy is the study of celestial objects from their gamma-ray emissions of photons that have an energy over a million times that of visible light but whose flux is extremely small. Gamma-rays are the most energetic of all the forms of electro-magnetic radiation but Gamma-ray astronomy can only be performed from Space. Because gamma rays are so penetrating, powerful detectors allow us to "see" through all the interstellar gas and dust, and out to distant galaxies. They help us understand the structure and life-cycle of galaxies, and give us a unique glimpse of mysterious pulsars and distant quasars. In 1975 ESA's COS-B satellite used a spark chamber to confirm that pulsars, and a score of other sources including quasar 3C 273, produce gamma rays at somewhat higher energies. "Comptel will make the great break-through in this uncharted lower energy range just as COS-B did 15 years ago" says Dr. Bennett. "Detection of gamma rays from Supernovae such as SN 1987-A is a prime goal, but we are hoping to detect other supernova gamma-ray emissions as well during the 2- 4-year mission." For further information, please contact: Beatrice Lacoste Heidi Graf ESA/Paris ESTEC Noordwijk (NL) Tel: (33.1) 42.73.71.55 Tel.: (331) 1719.8.3006 Ria Weiland Evelyn Leoffler-Stegen ESOC Darmstadt (FRG) ESRIN Frascati (I) TEL: (49) 6151.90.02.66 Tel.: (39 694.18.02.60 For further information contact the above address or ESA Washington Office L'Enfant Plaza, S.W., Suite 7800 Washington, D.C. 20024 Tel: (202) 488-4158 FAX: (202) 488-4930 --- Opus-CBCS 1.14 * Origin: NSS BBS - Ad Astra! (412)366-5208 *HST* (1:129/104.0) -- Bev Freed - via FidoNet node 1:129/104 UUCP: ...!pitt!nss!freed INTERNET: freed@nss.FIDONET.ORG ------------------------------ Date: 3 Apr 91 02:12:32 GMT From: unisoft!fai!sequent!crg5!szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Re: Chemical rocket complexities In article <9104020131.AA22835@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >An additional comment: while chemical rockets *are* complex, there is no >reason to believe that exotic launchers would be significantly less >complex. The total operation of a laser launcher, for instance, would >probably be more complex than anything that has been attempted with chemical >rockets. Several things wrong with this: * The term "exotic". These technologies are only "exotic" to the extent we don't understand them. It is about time we started understanding them. * Laser launchers use water, not explosive or corossive or cryogenic fuel, as reaction mass. They also have a much higher payload/reaction mass ratio, due to laser heating being higher efficiency than chemical reactions. This means more payload, less bulk to heft, and thus smaller, simpler launch pads. All in all, quite a bit simpler. * EML and gas gun vehicles have neither fuel nor reaction mass on board (except for the small upper stage), thus are far simpler still. * See more comments below. >The exotic launchers thus far envisioned would also have very >high initial costs, and may very well have considerable recurring costs. An analysis was just posted of EML costs. Using reasonable, and sometimes even pessimistic assumptions, up-front costs are less than a quarter that of chemical rocket projects, and recurring costs are between 100 and 10,000 times smaller, depending on whether we use today's technology or technology projected for 20 years from today. The fundamental difference in how energy is stored in the advanced launch schemes means that the immensity and complexity surrounding the energy source is focused on the "launch pad", which can be reused hundreds to millions of times per year, instead of the launcher, which Shuttle has demonstrated cannot be reused at a reasonable frequency. >...(Of course there should be funding for continuing research.) Here we are agreed, but I emphasize that they should be well-funded, on the level chemical rockets research has been funded during the last 20 years. Chemical rocket improvments should become the province of private enterprise, which has produced the major chemical rocket innovations of the last 10 years, Pegasus and the Aquila engine, despite having less than 1% of the R&D funds. >I'm also concerned that there may be some tendency to equate complexity >with cost. This is similar to equating any other variable, such as energy, with costs: it can be a good rule of thumb, but we better have the whole picture in our minds, to ensure we are not discounting other variables that could be more important. This also goes for deciding what "cost" itself means: entry level costs, cost/lb., cost/response time, cost/reliability, etc. -- 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 #364 *******************