Date: Mon, 24 Aug 92 04:59:57 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #138 To: Space Digest Readers Precedence: bulk Space Digest Mon, 24 Aug 92 Volume 15 : Issue 138 Today's Topics: Balloon Launches Economics of light gas guns Energya and Freedom and Soyuz ACRV and... Home made rockets (2 msgs) Inflatable Space Stations - Why Not ? Opinions on NLS Private space ventures (2 msgs) Satellite of the Month Saturn class (Was: SPS feasibility and other space Size,Mass,and velocity.... Space Economics Space probe information SPS fouling astronomy WANTED: Quicksat.zip satellite tracking program What happened to Viking? With telepresence, who needs people in Earth orbit? (4 msgs) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Sun, 23 Aug 1992 22:41:28 GMT From: Henry Spencer Subject: Balloon Launches Newsgroups: sci.space In article ruca@pinkie.saber-si.pt (Rui Sousa) writes: >I don't think dirigibles are fast enough to be really useful to give a >first kick to a Pegasus launcher, for example. That's why they use B-52's. Indeed, the speed of the B-52 is relatively unimportant. The main benefit Pegasus gets from air launch, apart from bypassing a lot of bureaucracy associated with fixed launch sites, is thinner air. (The speed is useful, just not very important.) -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 23 Aug 92 21:06:06 GMT From: Douglas R Fils Subject: Economics of light gas guns Newsgroups: sci.space sci space, The recent issue of _Aviation Week and Space Technology_ has a report on the light gas gun and its possible use for sending payload to LEO and to the Moon (with added boosters). My question concerns the economic aspects of a light gas gun capable of placing 2000 Kg (Shuttle ~ 30,000 Kg to 185 Km) to LEO. I wonder what use such a project has and its reception by the space market. The main point of discussion in a light gas gun would seem to be the high acceleration the payload would have to undergo when being launched to orbit. -Would a significant amount of support payload for a manned orbital facility be able (or made able) to take the high acceleration? (Water, food, mail, clothes...) -Small satellites are becoming popular. Not addressing if this enthusiasm will continue, can small satellites that can be launched by light gas guns be manufactured with current or foreseen technology? -Are the friction problems while traveling through the atmosphere solved or solvable and are there limits to the diameter of -shell- that light gas can launch? I seem to recall the report saying that larger shells are easier to launch than small ones from a friction standpoint. What is the current understanding of dimension (of shell) to feasibility with light gas guns? -What is $/Kg comparison to the projected DC-X? -- ------------------------------ Date: 23 Aug 92 23:59:57 GMT From: Henry Spencer Subject: Energya and Freedom and Soyuz ACRV and... Newsgroups: sci.space In article <1992Aug20.115651.6968@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>>after PMC will only occupy 1/4th the Shuttle fleet at any given time. >>The Shuttle flies eight times a year and four of those are needed for >>Fred resuply. Thus Fred uses 50% of Shuttle... >The Shuttle has flown 8 times a year without Endeavor and with Columbia >down for update mods. NASA is taking about 2 months at it's current >leisurely pace, one shift, no overtime, to stack and launch a Shuttle... Children, children, simmer down. :-) :-) Having been involved in such debates before (although the subject then was the Saturn V, not the shuttle), I would observe that it's easy to argue past each other endlessly. The fact is, we *don't know* what the readily sustainable shuttle launch rate is, because we don't have enough experience with it yet. Too much of the experience to date is spoiled by various problems that one can easily argue are non-recurring. Station resupply is also a rather different flavor of mission from the ones done so far; we don't have much relevant experience to judge things like preparation times for such missions. (Sure, it *ought* to be less... but NASA has made hash of that kind of seemingly-reasonable prediction before.) I'd say there is reasonable evidence that, with the post-Challenger improvements in infrastructure, NASA can do 8/year easily... if there are no more major one-time problems lurking in the wings. Big increases in that rate do not seem to be in the cards. (You really don't want to rely on overtime work on a sustained basis, for example -- that was one of the pre-Challenger problems.) Or at least, big increases are not in the cards without a massive organizational shakeup, which won't happen. I suspect it could be done -- merely firing half the inspectors and hiring workers instead would boost output a lot and would probably *improve* quality in the long run -- but it won't be. However, even a small increase, say to 10/year, would make a big difference in what you have left after deducting 4/year for Fred. There is some hope that small increases might be had. On the other hand, it's far too early to confidently say that they *can* be had without major changes. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 22 Aug 92 18:50:25 GMT From: "Steve J. Quest" Subject: Home made rockets Newsgroups: sci.space Frederick.A.Ringwald@dartmouth.edu (Frederick A. Ringwald) writes: > I really doubt it. First, that he even brings up the topic of a > KNO3/sugar mixture, melted and spooned into a rocket casing - just that > he can bring up this particular specification at all - shows he has no > idea just how dangerous it is, that there are much safer and more > effective ways of making rockets, and most seriously, that since he > didn't know this, he didn't do his homework FIRST before beginning work > with obviously hazardous materials. (It's a rocket, for crying out > loud!) > > P.S. I have extreme difficulty believing your claim of building a > rocket with 40 kg of propellant for a few hundred dollars as a > teenager. ThatUs a veritable anti-aircraft weapon! Furthermore, I think > your assertion that it's not science unless you break the safety rules > is unconscionably irresponsible: look what happened when some real > rocket scientists broke the safety rules with Challenger. Fred, As a scientific professional (NOW I am an adult, and merely reflect on the exploits of my past), I can say that in MY opinion, this guy had and could successfully fly homebrew rockets without mishap. I would NOT impede his quest for knowledge. Chemically, the temperature sugar melts at (only the fuel will melt, not the oxidizer) is FAR below the combustion temperature for that fuel. It *IS* safe to melt and cast sugar/saltpeter fuels. Rate of combustion is very slow with that fuel too- so chances of an explosion are low, and if pressures DO build, you can only get a minor explosion. Estes rocket fuel is black powder- classified as a high explosive by the DOT for transport. Estes engines can explode if the pressures are confined, and the explosion is quite dangerous! This statement is based strictly on the chemical compositions we are discussing- it contains NO opinion. His sugar fuel is safer than black powder. Trinitrification of toluene resulted in a waxey solid. I experimented with this waxey solid as a younger man. I melted and cast it into "shells". I was dumb, but not stupid. I also never had a mishap. If I hadn't gone through my "basement bomber" stage, I would not be a professional scientist today. The fun I had then was the driving force that kept me interested in science, all the way to where I am today. I work in science research and education. If everything goes the way I have planned, I will move more into education- so I can take people like him, and make them into people like me. If this guy were to experiment with aluminum/ammonium perchlorate fuels, I would HOPE he were very safe, as black powder is a mere combustible solid. Under the right pressures, aluminum/oxidizer mixtures can be quite powerful explosives, with velocities of shock wave measured in thousands of feet per second. I would call them potential explosives- but that risk is there if you want your rocket to reach altitudes of greater than 12,000 feet (with guidance and payload). Science is a risk. I do somewhat risky things every day. Common sense has kept me alive to be able to comment on my work. Let's hope common sense is working for this guy too..................sq ------------------------------ Date: 22 Aug 92 19:17:32 GMT From: "Steve J. Quest" Subject: Home made rockets Newsgroups: sci.space george.gassaway@matrix.sbs.com (George Gassaway) writes: > If "Estes" rocekts are not enough for you folk, try some of the > commercially made larger rocket motors. Notably, Aerotech, who makes > engines for consumers in the that go to E and F power. FAR more snesible > than making your own. I've been into this hobby for 22 years and know > better than to try to make up my own. Eventually, somebody gets injured > of killed making up their own stuff. Just not worth it!!! > George, Every day I commute to work. I see at least one accident on the way every day. I know that there is a good chance that someday I could be one of those killed in a serious auto accident. I probably could say "it is just not worth it" and go on welfare, but I keep driving my inherently dangerous automobile, each and every day. I hope I have made my point...............sq (is it more dangerous to mix fuel and stuff it into an engine, or is it more dangerous to store the finished product in your home- be it homemade engines or commercially available engines. As soon as oxidizer meets fuel, you have a combustable solid- and is dangerous from that point, until the rocket is launched and the fuel consumed. I just don't see what everyone is so uptight about. Homemade engines CAN be safe, and if you don't feel you are engineer enough to design your own nozzles or tubes, simply COPY the commercial engine design! A special level of pride goes with the knowledge that you made the WHOLE rocket, engine included. How can you have any pride in your work knowing someone ELSE made the primary propulsion device? Say, there are people like you and me at Estes making thousands of engines every day. If they were to go home and make engines in their basement, would THEY be considered dangerous? Hmmm?) ------------------------------ Date: Sun, 23 Aug 1992 23:02:08 GMT From: Henry Spencer Subject: Inflatable Space Stations - Why Not ? Newsgroups: sci.space In article <1992Aug21.135325.18668@ornl.gov> geg@ornl.gov (GILES JR G E) writes: >The LEO environment contains lots of trash. Thin skins might not >survive in this environment. This is a problem whether the thin skins are inflatable or not. It does seem to be a manageable problem, however, for either form. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 23 Aug 92 23:38:21 GMT From: Henry Spencer Subject: Opinions on NLS Newsgroups: sci.space In article jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes: >I've been noticing a distinct lack of discussion on the New (or is it National?) >Launch System in this group, which kind of surprises me given the number of >other topics that are discussed. NLS gets mention occasionally. You won't see very much about it as long as it remains a paper program. All the public-relations posturing about it has been heard before, repeatedly. There is no indication that more will come out of it this time than all the previous times. >... They discussed the lower costs, high reliability, and the Keep It >Simple Stupid aprroach ... NLS, and its predecessor ALS, has always been All Things To All Customers. Sure, they talk big about reliability and simplicity... but when one of the ALS competitors proposed an approach focussing heavily on improving manufacturing processes to reduce variability and improve reliability, they were dropped from the next stage of competition, on the grounds that they were supposed to *know* how to build ALS before starting. ALS/NLS has made a few decisions right -- notably, they aren't using the staged- combustion cycle of the SSMEs, despite its performance advantages, because it's such a bag of snakes in practice -- but I've seen no signs of truly fundamental change. If it ever flies, expect it to be expensive, complex, and not particularly reliable. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 23 Aug 92 09:09:46 GMT From: Nick Szabo Subject: Private space ventures Newsgroups: sci.space In article jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes: > >>[Another poster asks why Bill Gates et. al. have not invested in space] > > Actually, according to the internal IBM equivalent of netnews, Gates has >started investing in movies in the last few months. In fact, Gates and Microsoft co-founder Paul Allen have invested in Skypix, the direct broadcast satellite company. Since they'll be beaming movies, it's interesting to see that Gates is also investing in the movies themselves. -- szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81) ------------------------------ Date: Sun, 23 Aug 1992 23:14:37 GMT From: Henry Spencer Subject: Private space ventures Newsgroups: sci.space In article <8780.2339210127@kcbbs.gen.nz> Simon_Demler@kcbbs.gen.nz (Simon Demler) writes: >> [It bugs me that there are people like H Ross Perot, who >> themselves have enough cash to finance their own space >> programs, but that none, so far, has underwritten one.] > >Does it also bother you that these people could be spending some money >on the drought problems in Africa rather than on some space program... >Come on get real...there are MUCH larger problems that need solving >on this planet before trying to get peoples private wealth for space ... How much of *your* private wealth have you spent on those problems lately? Organizations like Oxfam will happily tell you just how much even a small donation will buy; it's a lot more than you think. Surely people dying in Africa is more important than you having a beer when your throat is dry. Have you done *anything* for the poor and unfortunate of the world lately? If not, why are you criticizing people like Perot? (They may have lots of money by our standards, but even a typical third-world government has much more; it's not as if HRP could single-handedly wipe out hunger and suffering.) "He who gives no thought to what is distant will find sorrow close at hand." Concern for the problems of today should not preclude spending modest amounts on longer-term projects. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 22 Aug 92 19:53:16 GMT From: Bruce Watson Subject: Satellite of the Month Newsgroups: sci.space,sci.astro Earth Satellite Cosmos 1220 (NORAD #12054, COSPAR 1980-089A) was launched from the (then) USSR from Tyuratam (Baikonur) on 1980 Nov 4 with a SL-11 (F-1-m) launch vehicle. This satellite is in an orbit inclined to the earth's equator by 65.0 degrees. It makes one revolution every 97.8 minutes and comes to within 552 km of the earth's surface and is most distant at 751 km. It's brightness is similar to a sphere of 6.0m diameter. Cosmos 1220 is thought to be an military electronic intelligence ocean surveillance satellite. It is one of three similiar satellites. The others are Cosmos 2096 and Cosmos 2122. In June of 1982 Cosmos 1220 exploded into 80 pieces. The elements below are for the largest fragment. It is beginning a sequence of evening passes for North American observers. I have observed Cosmos 1220 from Denver once the last three summers at magnitude +2, but it has been observed by others to flash to zero magnitude. Cosmos 1220 6.0 0.0 0.0 4.5 1 12054U 80089 A 92217.72121940 .00000921 00000-0 12141-3 0 1192 2 12054 64.9963 343.0911 0141730 59.8679 301.6396 14.73087339547258 -- Bruce Watson (wats@scicom) Tumbra, Zorkovick; Sparkula zoom krackadomando. ------------------------------ Date: 23 Aug 92 23:00:32 GMT From: Henry Spencer Subject: Saturn class (Was: SPS feasibility and other space Newsgroups: sci.space In article <19AUG199220200286@judy.uh.edu> wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov writes: >>> There >>> is a demonstrated need for larger lift capability. >> >>Sure, I believe you. I'm curious to know: what is the demonstrated >>need? How is it demonstrated? > >... Look at the growth in size of geosync communications satellites. >Ariannispace has and that is the basline for the growth into the Arianne 5... Ariane's numbers on the subject are somewhat controversial, since some of the organizations involved might be considered to have ulterior motives (making A5 big enough for Hermes). Even setting that aside, though, we're talking about slow incremental growth of existing boosters, the sort of thing that is accomplished most cost-effectively by tank stretches and more/bigger strap-ons. This is especially so when you bear in mind that the comsat suppliers and customers are far more concerned about reliability than cost -- as well they should be when the birds cost much more than the launches -- and they see upgrades to an existing system as less risky. At the moment, there is *one* firm customer that appears to really need larger lift capability than is now available: NASA's space-station office. Possibly I exaggerate when I call them a "firm" customer, mind you, although their political backing appears more solid now than it used to be. In any case, they are very heavily hemmed in by politics, and also don't want very many launches. They aren't a very promising "launch customer" for a new vehicle. Apart from them, there is *no* actually-rolling project, anywhere, that has a firm need for more than incremental improvements to existing boosters. If there were, there would be commercial interest. There have been several commercial heavylift projects that needed only some committed customers to justify proceeding with privately-funded development. None have appeared. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sat, 22 Aug 1992 16:00:52 GMT From: Livy Subject: Size,Mass,and velocity.... Newsgroups: sci.space Hi. Can anybody please email me the Mass(in kg),the Size (r in meters),and the x and y velocity (m/s) of all the planets in the Solar System? Thank you very much, Livy ------------------------------ Date: 22 Aug 92 19:02 PDT From: Mark Goodman Subject: Space Economics Newsgroups: sci.space To: sci.space From: Mark Goodman (mwgoodman@igc.org) Re: space economics Date: 21 aug 1992 I want to raise a subject that I have not yet seen in sci.space. It has to do with the economic value of space activities. I use commercial viability as the sign of economic value, though I recognize that this fails to account for "public goods" values like weather forecasting or the long-term (and unpredictable) value of R&D. Much of the discussion here has dealt with human spaceflight and solar power satellites, neither of which is close to to being commercially viable. Satellites (a.k.a. automated spacecraft) and related services are where it's at, which leads me to the questions: What is the future of small satellites? They go by many names (lightsats, microsats, Little LEOs, Brilliant Eyes and Pebbles). Is there a potential market niche for these systems, say in mobile communication or remote sensing? Will they create a viable market niche for small launchers like Pegasus? +-----------------------------+-----------------------------+ | Mark W. Goodman | What a terrible thing it is | | mwgoodman@igc.org -- econet | to lose your mind. | | goodman@ksgbbs.harvard.edu | | +-----------------------------+-----------------------------+ ------------------------------ Date: 23 Aug 92 22:47:36 GMT From: Henry Spencer Subject: Space probe information Newsgroups: sci.space,sci.astro In article <1264@niktow.canisius.edu> geiger@niktow.canisius.edu (Tucson Al) writes: >Does anyone out there know of a simple routine to compute the launch angle >and speed for a space probe, once the routine is given the current positions >of the launch and destination planets? ... Whole books can be (and have been) written about such subjects. You won't find a single canned routine that will do the job. There are too many possible variations. For example, you haven't even specified whether you want a flyby or a rendezvous. (For a rendezvous it is important to minimize relative velocity at encounter, which doesn't matter much for a flyby.) The Frequently-Asked-Questions posting has reference to several books on astrodynamics that will introduce you to the complexities of the subject. Bates, Mueller, and White's [beware possible typos in names] "Introduction To Astrodynamics" (Dover) is the most common starting point, but there are others. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 23 Aug 92 13:36:38 GMT From: "Frederick A. Ringwald" Subject: SPS fouling astronomy Newsgroups: sci.space In article mwallis@clubzen.fidonet.org (Michael Wallis) writes: > I have NO idea where you got your info in SPS systems, but it seems there > is little in what you say that relates to actual SPS designs or proposals. > The SPS systems transmit power in the microwave frequencies not in visible > light. Get some facts, please!! The power transmission has nothing to do with this. An SPS sits in sunlight, reflects it just like the Moon or any other satellite: the metal/silicon/ceramic structure certainly isn't invisible! This goes whether the beam is visible or invisible, or even on or off. See the calculation above, done by me and corrected by Steve Willis. ------------------------------ Date: 23 Aug 92 23:05:14 GMT From: Keith Vanavery Subject: WANTED: Quicksat.zip satellite tracking program Newsgroups: sci.astro,sci.space Would some kind soul out there in Usenetland e-mail me quicksat.zip? I checked archie; it isn't available via ftp. I don't have a modem to download it from TS Kelso's Celestial BBS. Thanks in advance. Keith ------------------------------------------------------------------------------- >ERROR: no .sig file found ------------------------------ Date: 23 Aug 92 23:26:49 GMT From: Henry Spencer Subject: What happened to Viking? Newsgroups: sci.space In article <1992Aug21.222739.19157@nas.nasa.gov> eugene@wilbur.nas.nasa.gov (Eugene N. Miya) writes: >>What happened the Viking spacecraft? > >Both lands and orbiters were shut down for lack of funds and the need to use >the antenna resources for other projects (Galileo, Magellan, power >distribution experiments, SETI, etc.) > >>I heard through the grapevine that someone sent a bogus signal to it which >>turned the antenna away from Earth, resulting in LOS. > >That was Voyager II (briefly). Eugene, are you getting enough sleep? :-) This does *not* correspond to the history of Viking as I'm aware of it. Although antenna coverage was reduced as the Viking primary mission was completed, it wasn't eliminated. And although there was *talk* of shutting down the program for funding reasons, it never quite happened. Both the Viking orbiters were shut down when, as expected, they ran out of attitude-control fuel after lengthy and successful missions. The second lander had some sort of electrical problem that cut its life short; I don't remember the details. The first one lasted several more years, in a low- activity mission that did weather reporting and an occasional image, using modest funding and very little antenna time. It was during this phase that there was some threat of shutting it off due to funding shortages, but politicking (including the Viking Fund's fundraising activity, which had far more significance as a political message than as an actual source of money) averted that. What finally happened was that a routine contact to pick up recent weather data couldn't get an answer from the lander, all attempts to reach it failed, and it was eventually declared dead. I believe it *was* eventually established that this was due to a command error that fouled up antenna pointing, although this was not obvious at the time. -- There is nothing wrong with making | Henry Spencer @ U of Toronto Zoology mistakes, but... make *new* ones. -D.Sim| henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 23 Aug 92 09:30:03 GMT From: Nick Szabo Subject: With telepresence, who needs people in Earth orbit? Newsgroups: sci.space In article <174ns5INNqom@agate.berkeley.edu> gwh@soda.berkeley.edu (George William Herbert) writes: >cecil@physics.unc.edu (Gerald Cecil) writes: >We can't get away (now) with just using robots in space. Funny. All commercial space projects, the vast majority of military space projects, and all exploration projects that have gone farther than Moon, have gotten away with using fully automated spacecraft. -- szabo@techbook.COM Public Access User --- Not affiliated with TECHbooks Public Access UNIX and Internet at (503) 644-8135 (1200/2400, N81) ------------------------------ Date: Sun, 23 Aug 92 22:46:25 GMT From: Dave Cole Subject: With telepresence, who needs people in Earth orbit? Newsgroups: sci.space Many of the robot probes have died because the antenna won't open too. Gee... If only someone could just shake the antenna a bit. Oh well, there goes another million bucks... ------------------------------ Date: 23 Aug 92 23:45:11 GMT From: Matthew DeLuca Subject: With telepresence, who needs people in Earth orbit? Newsgroups: sci.space In article <1992Aug23.093003.5591@techbook.com> szabo@techbook.com (Nick Szabo) writes: >In article <174ns5INNqom@agate.berkeley.edu> gwh@soda.berkeley.edu (George William Herbert) writes: >>We can't get away (now) with just using robots in space. >Funny. All commercial space projects, the vast majority of military >space projects, and all exploration projects that have gone farther than >Moon, have gotten away with using fully automated spacecraft. And, if we want to remain at our current level of space capability, we can keep on using what we've got. If we actually want to go places and do things, though, we're going to have to open things up for *real* robots (despite what you have claimed in the past, things like Voyager are *not* robots) and real manned space travel. -- Matthew DeLuca "I'd hire the Dorsai, if I knew their Georgia Institute of Technology P.O. box." Office of Information Technology - Zebediah Carter, Internet: ccoprmd@prism.gatech.edu _The Number of the Beast_ ------------------------------ Date: 24 Aug 92 02:26:25 GMT From: George William Herbert Subject: With telepresence, who needs people in Earth orbit? Newsgroups: sci.space szabo@techbook.com (Nick Szabo) writes: >gwh@soda.berkeley.edu (George William Herbert) writes: >>We can't get away (now) with just using robots in space. > >Funny. All commercial space projects, the vast majority of military >space projects, and all exploration projects that have gone farther than >Moon, have gotten away with using fully automated spacecraft. Ahem, Nick. Bad boy; you deleted the sections describing the things in particular that need some attention (most biology, some materials science, permanent presence (stations etc) maintenance) and tood my conclusion out of context. You know better 8-) About (18 months ago?) I proposed and Nick championed the concept of a "LabRatSat", an unmanned, robotically tended bioresearch satellite. Having talked to some space robotics people now, I have a bad feeling that it might be more difficult that I thought to deal with the lab animals on board; I'm not sure it's feasible. (It is worth looking in to. I'd hate to have to justify the experiments in acceptable delay on telehandling lab animals though 8-( ugh). There's only so much you can do with fixed and irrepairable systems. If you want to do something else, you have to either put a robot able to move things, operate things, and fix things up there with it, or put a person there, or both. Both are preferable if you can afford them, from the capability standpoint. I am by no means suggesting putting people on every exploration vehicle or communications satellite. Some things need little maintenance and have no mobile/dexterity operations needs (they don't need robots either). Unless you want to put an Energizer Battery Bunny on the next Jupiter mission, for good luck... -george william herbert gwh@soda.berkeley.edu gwh@lurnix.com ------------------------------ End of Space Digest Volume 15 : Issue 138 ------------------------------