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, 13 Apr 91 01:53:23 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 13 Apr 91 01:53:17 -0400 (EDT) Subject: SPACE Digest V13 #401 SPACE Digest Volume 13 : Issue 401 Today's Topics: Re: Launch Technology Re: Magellan Aerobraking Re: comsat cancellations and lawsuits Voyager CD-ROM 4 replaced with Magellan MIDR CD-ROM Re: Upper Stage Re: Launch Technology Re: I want to go to orbit... Re: Space technology Amiga satalight tracker data file Re: Teflon (Was Re: Space technology) Re: NEP to Mars!?!? - a thesis topic 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: 12 Apr 91 15:56:38 GMT From: usc!rpi!news-server.csri.toronto.edu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Launch Technology In article <3109@ksr.com> clj@ksr.com (Chris Jones) writes: >don't know whether this is really plain old kerosene or their RP-1 equivalent, >but the difference probably isn't that great. Probably zero. RP-1 *is* high-grade kerosene, and "kerosene" can be used as a generic term for it and similar fuels. -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 11 Apr 91 00:13:38 GMT From: hub.ucsb.edu!ucsbuxa!3001crad@ucsd.edu (Charles Frank Radley) Subject: Re: Magellan Aerobraking Magellan 's original orbital u insertion was by means of a Thiokol Star-48 solid motor, which weighed more than the rest of the spacecraft. It has no heat shield. I have heard of a plan to do some sdm low energy aerobrking to modify its orbit. This will presumably cause the spacecraft to become significantly heated, and I have hear Magellan is already encountering themral problems.. ------------------------------ Date: 12 Apr 91 16:31:04 GMT From: agate!bionet!uwm.edu!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!news-server.csri.toronto.edu!utzoo!henry@ucbvax.Berkeley.EDU (Henry Spencer) Subject: Re: comsat cancellations and lawsuits In article <10447@hub.ucsb.edu> 3001crad@ucsbuxa.ucsb.edu (Charles Frank Radley) writes: > NASA never guaranteed to launch anything. >The language in the standard Launch Services Agreement >states NASA will use "their best endeavours", which >means no warranty etc. Still sounds like grounds for a lawsuit to me. *What* "best endeavours"? More like "we'll launch it if it's convenient, but at the first sign of trouble, forget it". -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 13 Apr 91 01:56:13 GMT From: usenet@ames.arc.nasa.gov (Peter E. Yee) Subject: Voyager CD-ROM 4 replaced with Magellan MIDR CD-ROM Thanks to Rob Seaman at NOAO, I have a patch for my Sun HSFS driver that allows it to read the Magellan discs. The images on the Magellan disc appear to be larger than the Voyager images and are not compressed. The images are available via anonymous ftp to ames.arc.nasa.gov, and are mounted on the /pub/SPACE/CDROM2 directory (replacing the Voyager CD-ROM 4 that I had installed yesterday). -Peter Yee yee@ames.arc.nasa.gov ames!yee ------------------------------ Date: 12 Apr 91 04:46:20 GMT From: swrinde!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!Wales.Larrison@ucsd.edu (Wales Larrison) Subject: Re: Upper Stage Nick Szabo replying to message from Paul Blase >Hold on. If a market doesn't exist, why are you building the thing >in the first place? A government is the poorest judge of markets I >can think of, bar none. > > I can think of jillions of examples of this, but right off the bat >there is one that hit close to home: upper stages. In the dozens >government studies of nuclear, electric, and other advanced upper >stages I have read, use for boosting satcoms to GEO is rarely, if >ever, mentioned, even though this is by far the largest use of >upper stages. ... Sorry, but I couldn't resist replying to this. Boy, are you wrong. What if the the government is the market? Let's see - most commonly used upper stages are: - PAM-D, developed by McDonnell Douglas to launch government payloads (GOES and other geo satellites). Exclusively used for GEO launches. Commercial development, under government license. Money loser to date. Government usage estimated at approx 40% - IUS, developed by Boeing under USAF contract. Used to launch government payloads, and TDRS (operated by commercial entity for government use, with excess capacity being sold on the open market). 2(?) uses for non-GEO missions by NASA. Remaining 20+ uses for GEO. - Centaur, developed by General Dynamics under government contract. Minor/slight upgrades paid for by commercial entities. Major upgrades paid for by government for GEO missions. - TOS, developed by OSC. Only 2-3 uses are for NASA. Money loser. Almost every government upper stage study I have seen in the last decade has had GEO as a major market. The market to GEO is split about 40/60 between Commercial satellites and government satellites (including GPS in the government market). Government studies of upper stages do focus on GEO, since the majority of high altitude government payloads go to GEO, or very close. The exceptions are specific studies which examine how to meet a unique government launch requirement - well outside of the commercial requirements. For example - launching 100,000 lbs into Low Lunar Orbit usually requires a system which has little application to 2,000 lb commercial GEO satellites. >Meanwhile, Rocket Research Company and OSC, with no help from the >government, have teamed up to finally bring electric technology to >the market where it is needed most, satcom stationkeeping and upper >stages. ... Ahem. Rocket Research is developing arc-jet thruster systems under USAF contract. Their effort is part of the ELITE ("Electric Insertion Transfer Experiment") program from the USAF Phillips Lab in New Mexico to demonstrate an electric GEO transfer upper stage. Prime contractor for the USAF is TRW. Rocket Research is providing the arcjet, power conditioning, and propellant feed unit. In all fairness, RR is also developing a de-rated system of potential application to commercial spacecraft. However, my files say the primary focus of this system is to provide stationkeeping on comsats, not act as an electric stage. I would suspect a lot of the technology development for this was done under the USAF contract. Considering also that OSC is also under USAF contract to build and fly the APEX Advanced Photovoltaic and Electrics Experiments spacecraft, it sure looks to me like the USAF is supporting the development of any future commercial applications of this by funding all of the R&D, development and design work ... I think you're flaming here, Nick. -- Wales Larrison Internet: Wales.Larrison@ofa123.fidonet.org Compuserve: >internet:Wales.Larrison@ofa123.fidonet.org -------------------------------------------------------------------------- ------------------------------ Date: 12 Apr 91 14:55:19 GMT From: eru!hagbard!sunic!mcsun!hp4nl!phigate!philtis!munk@bloom-beacon.mit.edu (Harm Munk) Subject: Re: Launch Technology In article <1991Apr11.161258.29733@zoo.toronto.edu> henry@zoo.toronto.edu (Henry Spencer) writes: >I've never seen a discussion of the exact rationale for Ariane's fuel >combination, but remember another consideration: the Ariane contractors >were military missile contractors, whose experience with liquid-fuel >rockets would have been heavily biased toward storable fuels. It would >not surprise me if the decision was made based on what people had experience >designing engines for, rather than on the merits of the fuels themselves. >Engine development is often the pacing item for launcher development. Well, I don't know about the design of Ariane 4 engines, but for the boosters for Ariane 5 they certainly did a 'go-for-the-best-you-can-get' type of research. On the other hand ... that research was performed by a research institute of the Dutch Organisation of Applied Scientific Research (TNO for insiders) which usually does military research (the institute, that is, not TNO in general). Anyway, if you want to know the rationale behind the Ariane 5 boosters, read ESA Journal 1990/3. Regards, Harm Munk. ------------------------------ Date: 10 Apr 91 00:13:18 GMT From: hub.ucsb.edu!ucsbuxa!3001crad@ucsd.edu (Charles Frank Radley) Subject: Re: I want to go to orbit... Truax is in southern California, developing a small sea launched recoverable rocket for the US Navy, on a substantial contract - a couple of $M ------------------------------ Date: 12 Apr 91 06:58:55 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!spool.mu.edu!munnari.oz.au!manuel!coombs!cjp310@tut.cis.ohio-state.edu (Chris @ SSDA ...) Subject: Re: Space technology okunewck@psuvax1.cs.psu.edu (Phil OKunewick) writes: >In article <1991Apr11.221904.16361@uokmax.ecn.uoknor.edu> rwmurphr@uokmax.ecn.uoknor.edu (Robert W Murphree) writes: > Lots of stuff about frypans etc deleted... > One space spin-off was directly related to geology (and hey, this >_is_ cross-posted to that newsgroup): 4.5 million-year-old moon rocks. >These showed that the earth and moon formed at the same time, and thus >partly settled one of the greatest disputes in geoscience. From this, >we were able to develop a better theory on how the solar system >formed. Although at first this doesn't seem nearly as useful as a >non-stick frying pan, the amount it has helped us understand the world >around us (and thus help preserve it) is incalculable. I thought that the earth-moon configuration was caused via the collision of the moon onto the earth, which caused the melting of both objects, etc... I saw a simulation done on a cray which showed this... Actually I know very little about this theory, anyone got any more info about this ??? Thanks Chris. PS. I'm not crossposting to Geology ;-) -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Chris Patterson | Ph: +61 6 2492185 Social Science Data Archives | AARNet: Chris@coombs.anu.edu.oz Australian National University | "I wonder what happens if I ..." ------------------------------ Date: 11 Apr 91 17:13:13 GMT From: eru!hagbard!sunic!mcsun!ukc!strath-cs!str-va!cabp10@bloom-beacon.mit.edu (Dan Dare) Subject: Amiga satalight tracker data file I don't normal read this conferance so if you are replying to this message could you please email me. I have a program for the amiga called ORBIT it tracks satalights round the earth and reports on their position so that they can be observed I am given to understand that the data file with them is updated every 2 weeks if this is so where would I find the file. the name of the author escapes me right now but I know he was from the east cost of america. If you know where I can find this data or know how to change it inside the program please let me know. -- / / The Light of the Dan Dare \\ New Dawn Burns Bright / Even at night. ================================================================================ AKA Sean Stratton | "I came here to chew | Live life |Amiga /// Cabp10@uk.ac.strath.vaxa| bubblegum and kick ass. and | Taste Death | \\\/// on JANET | i'm all out of bubblegum." | | \XX/ ================================================================================ All misspelling is my brains fault not mine ------------------------------ Date: 12 Apr 91 16:59:39 GMT From: media-lab!minsky@eddie.mit.edu (Marvin Minsky) Subject: Re: Teflon (Was Re: Space technology) In article <1991Apr12.162023.1543@eagle.lerc.nasa.gov> banerj@mars.lerc.nasa.gov writes: >The trick in making non-stick frying pans is to get >the pan to stick to Teflon as *nothing* sticks to Teflon!! O.K., I give up. What's the trick. ------------------------------ Date: 10 Apr 91 05:18:12 GMT From: unisoft!fai!sequent!crg5!szabo@ucbvax.Berkeley.EDU (Nick Szabo) Subject: Re: NEP to Mars!?!? - a thesis topic In article <1991Apr5.012026.3888@ducvax.auburn.edu> bbayn@ducvax.auburn.edu writes: [needs background profile for nuclear electric propulsion/radiator paper] An excellent choice of technology, but you are making a big mistake: tying such a promising technology to one narrow mission. Mars is one interesting body out of dozens, and planetary exploration is one important space endevour out of several. The biggest market for NEP is as an upper stage for the $billions of satellites that are currently launched for defense, communications, and other uses including planetary exploration. A good design will cut the amount of mass needed for an upper stage, thereby increasing the mass that can be put in the payload. For example, (to pick a number out of the blue), if you could design an upper stage to double the mass to GEO for the same launcher, you could sell your upper stage for at least 5 times the price of the competitive chemical stage for that launcher, because you are effectively saving the entire price of a launch to GEO. The market for such a technology would be at least $1 billion a year, perhaps closer to $3 to $4 billion at saturation. Until we get standard payload bays, upper stages will tend be specific to certain rockets, so you have to pick the winners. The best bets at this point are Titan IV/Shuttle at the high end (where many of the political $$ are), Ariane and/or Delta at the middle end (where most of the commercial $$ are), and perhaps Pegasus, a low-end launcher with a new, rapidly growing market and so far lacking an upper stage. It would be quite fascinating, and a true technological advance, to see a nuclear upper stage made for a Pegasus. > My Tentative Thesis Outline (4/2/91) > >I. Background > A. Inevitability of deep space missions/exploration Something, almost inevitably, as there are 4 nations (counting Europe as one) that have explored the Moon or farther, with over 50 deep space missions so far, and the technology is getting better every year. The actual targets, discoveries, instruments, and scale of mission depend on previous discoveries and (alas) politics and tradition. > B. Problems/parameters of deep space missions > 1. Mission length > a. Life Support Only for manned missions, which, with current levels of technology, are politically and economically untenable beyond LEO. >.... > c. Fuel availability or lack thereof It is possible that small comets could be captured and used as reaction or heat sink mass. H, C, O, and N in various molecules can all be readily distilled. For example water, the most abundant comet molecule, can be used for liquid droplet radiators. For sufficient demand (1,000+ tons/year) the price might be $10-$100/kg, a factor of 100 to 1,000 below the costs of hauling up from earth. Unfortunately, the mission profile is not rigorous at this point, due to lack of sufficient astronomical knowledge at this point in space exploration. We don't know how to detect most small comets, even those that pass near earth. Other suggested sources of materials (such as the Moon) contain much less diversity (eg no H, N, or C on Moon) and are much harder to extract (rock instead of ice mining). These are economically untenable for any sort of science or exploration, though asteroids might be used for large-payoff industrial projects, such as solar power satellites. In sum, I would take cometary materials into consideration in your designs, but I would not count on them in the near future. > C. Need for reduction in time and/or fuel required. Most deep space missions benefit from higher Isp, but there are specific regimes where decent thrust is also required. You might want to look carefully at the thrust requirements to get a payload to GEO in a decent amount of time. I had heard that current electric designs have too low thrust for this (comments?). I know OSC and Rocket Resarch are looking at chemical/electric hybrids for this purpose. Remember, GEO is the most frequent destination for payloads needing upper stages. > E. Mars as example > 1. Why? due to database available for comparison Because it was in Collier's. It's The Plan. Of course, nobody has stepped up to pay for anything more than Mars Observer in 1992. There are some good scientific and exploration reasons to continue to look at Mars: * search for life (though it is more probable on Europa and Enceladus) * fruitful comparisons between Martian and earth weather * geology (eg search for intersting ore-forming processes) None of this justifies spending $billions, though, not to mention the fantastic $400 billion NASA proposed pricetag. Some non-reasons for exploring Mars are: * colonization: Mars is quite inferior to near-earth free space in terms of time, energy, material availability, ability to trade products with earth, and a whole host of other factors. * prestige: 1990's economic war politics are quite different from 1960's cold war politics. In the 1960's, prestige came from seeing who could launch the largest payloads into space on ICBM derivatives. Such spectaculars win propaganda wars but lose economic wars. Economic prestige comes from displaying a quality, automated, cost-effective, and customer-driven operation. If we can learn to operate in this matter, we may be able to derive some post-Cold-War era prestige from space exploration. The bulk of our space program still thinks it's living in the 60's, alas. > 2. Any specific Mars problems/advantages over other deep space > scenarios? A rough order of difficulty, in terms of energy, for the larger bodies is Moon, Venus, Mars, Jupiter, etc. Gravity assist and aerobraking can be used, eg Voyager and Galileo VEEGA gravity assist trajectories, and Apollo aerobraking on the return trip from the Moon. VEEGA trades time for energy, though Voyager gained both time and energy. There exist a few discovered, and probably 100,000 undiscovered, asteroids closer energy-wise to LEO than the lunar surface. There probably an even greater number of comets, which can be captured via gravity assist and aerobraking, but as mentioned our astronomical resources are not currently sufficient for the task of finding and tracking these dark objects. -- 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 #401 *******************