Date: Mon, 4 Jan 93 05:00:04 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #628 To: Space Digest Readers Precedence: bulk Space Digest Mon, 4 Jan 93 Volume 15 : Issue 628 Today's Topics: Aluminum as Rocket Fuel? Biosphere 2 Agriculture Galileo's high-gain antenna still stuck (3 msgs) GOVERNMENT-RUN PROGRAMS Justification for the Space Program (3 msgs) Let's be more specific (was: Stupid Shut Cost arguement lunar military position Media and space Poker Flat russian solar sail?+ (2 msgs) SSTO vs 2 stage (2 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, 3 Jan 93 20:20 GMT From: Karl Dishaw <0004244402@mcimail.com> Subject: Aluminum as Rocket Fuel? >george william herbert writes: >aluminum is the wrong fuel to use if it's an earth based application. Most discussion has centered on an Al rocket being used for exporting Lunar material, probably as a second stage to a mass driver or laser launcher. A mass driver would need a rocket on its payload anyway for orbit circularization and course corrections. Aluminum is the most energetic of the common lunar materials (runner-ups Si, Ti, Fe, Mg, Ca). >Bruce Dunn writes: >When the >aluminum is melted in the tank, the fuel line, valve, and injector will all >be heated to above the melting point of aluminum. I'd hate to see the performance hit from carrying a heater that powerful. Wouldn't it make more sense to pump the aluminum onto the rocket as a liquid and only have a heater powerful enough to offset cooling? Karl sold my soul to Uncle Sam . . . now marked down for resale. ------------------------------ Date: Sun, 03 Jan 93 15:24:00 PST From: Taber@bio2.com Subject: Biosphere 2 Agriculture My name is Jane Poynter, the Biospherian in charge of the Field Agricutlure Systems inside Biosphere 2. Taber MacCallum has given progress reports on Biosphere 2 and given general outlines. I thought I would give a brief outline of the Agriculture Biome of Biosphere 2. What I write here are my own opinions and not to be taken as opinions held by Space Biospheres Ventures. The Biosphere 2 Agriculture covers an area of approximately 0.5 acres, which includes the field agriculture, orchard and domestic animal barns. It was designed to produce enough food for the 8 biospherians and domestic animals (goats and chickens), to be non polluting and totally recycling. Our main staples are beans (mostly a tropical variety called hyacinth bean, or lab lab), rice, wheat, sorghum, sweet potatoes, taro, bananas (green as a starch and ripe as a fruit), papayas (also green as a vegetable and ripe as a fruit), peanuts (which give us a large percentage of our daily fat intake), and of course all sorts of vegetables such as carrots, squash, eggplant, tomatoes, chilis, bell peppers, beets and lots of greens. >From the animals we get mainly milk and eggs. Meat is quite a luxury, eaten once a week and for feasts. We currently have 4 African Pigmy does, one buck and 2 kids, 10 hens, 2 cocks and 3 pullets. There are also tilapia fish in the rice paddies which live off the azolla (a small water fern which grows on the surface of the water) and the small crustacea and insect larvae in the water and mud. At the outset of the experiment we had included a breeding pair of Ossabaw Ferrel Swine, which are a medium sized pig, somewhat larger than the Vietnamese Potbellied Pig, but much smaller than a farm pig. The boar weighed 110 lbs. However, it became increasingly clear that this pig, and probably any pig, is not suitable for this agriculture system at its current level of production. There was no starch available for the pigs, as had been thought there would be when the decision was made to include the pigs. I am sure that this agriculture system will go through many phases of evolution as we discover what works and what does not, and how to improve on existing systems. We use no polluting pesticides to control pest outbreaks. We use soap and other such sprays where necessary, and use many of the commonly used methods of integrated pest programmes. We also do not use chemical fertilisers, but recycle waste products. Animal wastes and crop residues not fed to the domestic animals are composted, human waste, the wash down from animal barns and the waste water from the human habitat is cycled through a marsh waste recycling system. Our nutrient recycling in the agriculture is therefore essentially a closed loop. There are some nutrients that may be tied up in forms unretrievable by plants in the long run, and this is a possible problem that we may have to face in the future. As in all new ventures there have been problems which we are currently attempting to solve, and doubtless there will be many more challenges along the way to reaching the afore mentioned goals. Some of our main problems have been in pest management which has led to problems with crop diversity. Light levels are also of concern as the plants receive approximately 45% ambient light. This is because of the shading of the structure and glass. The pest problems have arisen because, despite efforts to introduce a wide variety of predators and parasites on several occasions, before closure and once during closure, the food web is by no means complex enough to handle the fluxes in pest populations. We have also seen the development of damaging population levels of broad mites which we did not see before closure at all. This tiny mite has devastated white potatoes, and is now attacking our sweet potatoes, despite efforts to control it by spraying vegetable oil (which we have found to be the most effective non-toxic spray to date) and to lower levels of relative humidity as far as possible as this seems to be the most effective method of population control. Because of this and other pest and disease problems our species diversity has been diminished in the agriculture which of course does not help in itself. We begin to rely on fewer and fewer crops for our main staples, which is not a healthy situation to be in, especially when one's lively hood relies upon the crops' success. Species diversity is an important factor to consider in any agriculure system as it is necessary to have several crops that perform the same funtion in the diet (such as white potato and sweet potato). Unpredictable growing conditions may arise and one crop may do well where the other may fail. Diversity is also important to maintain an interesting diet, one aspect of keeping high morale among the crew of any long expedition. Both the pest problems and the species diversity are problems that we are currently trying to solve, but will also be a large part of the work being done during the transition phase betwen this 2 year experiment and the next one year experiment. Then there is the problem of light: the plants will indeed grow and produce under the existing light levels, but it makes the plants somewhat etiolated and much more susceptible to disease and prone to pest infestations. People have often asked what the Biosphere 2 Agriculture system has to do with space exploration, habitation. There are several answers to that question, but the general answer is in long term colinization of planets, and eventually even the totally man made space colonies as in Gerard O'Neill's vision of the High Frontier. There are indeed many methods of growing plants. NASA is doing great work in the realms of hydroponics for maximum efficiency and reliability in the production of food and have succeeded in obtaining extraordinary yields, making the production of food a viable option during spaceflight. However, this kind of system is as yet non-recylable. The nutrient solution itself can be recycled, but no way has been found to date to recycle the nutrients that have been taken up by the plants themselves. Hydroponics will most probably be the way to go for space flights needing to get materials up out of a deep gravity well, like that of Planet Earth's, but in situations where there are materials at hand with which to make the main bulk of the growing medium, like on Mars, or possibly larger asteroids, then the soil based totally recycling, non-toxic, intensive agriculture approach may well be more viable in the long run. I will say, however, that I think domestic animals will be a long time in arriving in space and are not an essential part of our system, either for nutrient recycling, or for food production. They are currently essential for a good portion of the fat in our diet, but this can be remedied by the inclusion of other oil crops. Another aspect of the food production systems used in space, is the diversity that can be produced for the human diet. Living inside Biosphere 2 for 15 months has shown that food, and the cuisine aspects of the daily meals, is an extremely important aspect of group morale. If someone cooks a poor meal, or if there is a period of time when the number of species which end up on our plates is low, or very monotonous for a period of time, people become grumpy and somewhat dispondent. However, feasts have become very important, where we all make great efforts to produce favorite dishes like cheesecake and sweet potato pies, stuffed chickens, ice creams, rice and peanuts, chutneys and crepes. Whilst humans can, for the most part, tolerate poor living conditions for periods of time, they do nothing to contribute to group morale, and high morale on any long space expedition will be extremely important to ensure success. In any food production system in space there must be room for unpredictablility and failure. Plants will be plants. They will grow very differently with only very small changes in evironmental parameters, and problems will arise that were not seen before, or planned for, as we have seen with the Bisophere 2 agriculture system. Although many crop and variety production trials were run under conditions as close to those in Biosphere 2 as possible many plants have acted quite differently under actual Biopshere 2 conditions. Bananas have become an extremely high producer for us in here, which we did not experience in our test beds. Pests are of great importance to consider. Even in NASA's environmentally controlled chambers where they take great precautions against the inclusion of pests they have seen problems with pests. Learning how to exclude pests completely from a system is very important but there needs to be a back up system of pest management if unexpected pest populations do arise. This non-toxic integrated pest management approach, with complex food webs, is an important aspect of the resarch being done in Biosphere 2. Energy is a big concern in space, both the acquisition of the energy for artifial lighting etc. but also the dealing with the heat load created by electric motors, lights etc. Using the sun's photons as far as possible seems the obvious way to go, but some artificial lighting may be needed for periods of time or for general supplementation. Finding the optimum light levels for food production, which may not necessarily be the ideal levels for maximum production/unit area, is another important area of research which needs to be carried out. There are many questions to be answered about food production systems and many yet to be asked that have not been thought of, but you might say that the Biosphere 2 Agriculture system is a step towards the total system's approach to space agriculture. This approach and the as yet non-recyclable systems of hydro and airoponics have very different applications, just as the different rocket propulsion systems have their pros, cons and very different applications. I would welcome food production as a new thread on the net. Jane Poynter Biospherian in charge of Field Agriculture Systems in Biosphere 2 ------------------------------ Date: 3 Jan 93 16:19:18 GMT From: Peter Monta Subject: Galileo's high-gain antenna still stuck Newsgroups: sci.space henry@zoo.toronto.edu (Henry Spencer) writes: > The on-board computers don't have the horsepower to do serious compression > at 100-odd kbps. Perhaps the DSN improvements currently in the pipeline would increase the HGA raw data rate, so that the processors would just have to send the data faster. Speaking of which, as I understand it, the claim is that the link capacity can be increased 10-fold. For HGA, that would give some 1+ Mb/s (assuming the better code could be run at that rate). That is remarkable. Where does it come from? The Gaspra briefing notes say that the system noise temperature will drop to 12K, 4K better than current; that's a couple dB. This means that maybe 8 dB has to come from more aperture, better coding, or out of the link margin: is there that much reserve in the DSN? Such a state-of-the-art system would be hard to improve more than incrementally, I would have thought. How will the arraying be done? Is it real-time or recorded, combined offline? What coding is used? Leech's notes mention a "50% higher data rate", plus "several magnitudes better" error rate; this might be another 2 dB. That's a large jump, and the natural question is why the new code wasn't used in the first place. A previous poster suggested chirping the motor: does the spare HGA on the ground show any such useful mechanical resonances? I think many of us here in non-JPL-land are watching all of this with intense interest and excitement. Best of luck. Peter Monta monta@image.mit.edu MIT Advanced Television Research Program ------------------------------ Date: 3 Jan 93 18:28:12 GMT From: "Peter J. Scott" Subject: Galileo's high-gain antenna still stuck Newsgroups: sci.space In article <1993Jan2.234235.16100@ee.ubc.ca>, davem@ee.ubc.ca (Dave Michelson) writes: > In article <2JAN199323293310@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: > >The hammering sessions will continue all the way through the entire month > >of January, if necessary. Even though the first hammering attempt didn't > >open up the antenna all the way, it did have a postive effect. > > !! It did? I sure don't remember seeing reference to that in the last > report but I'm glad to hear it. > > What was the "positive effect"? How was it determined or measured? The GLL nav team chief told me the other day that although nothing had unfurled, the degree of bowing had increased. This was determined from sun sensor data. On the premise that any movement is better than none, this is a positive effect. They're quite prepared to break the HGA if necessary, assuming they can. -- This is news. This is your | Peter Scott, NASA/JPL/Caltech brain on news. Any questions? | (pjs@euclid.jpl.nasa.gov) ------------------------------ Date: 3 Jan 93 19:13:00 GMT From: Ron Baalke Subject: Galileo's high-gain antenna still stuck Newsgroups: sci.space In article <1993Jan3.182812.13825@elroy.jpl.nasa.gov>, pjs@euclid.jpl.nasa.gov writes... >In article <1993Jan2.234235.16100@ee.ubc.ca>, davem@ee.ubc.ca (Dave Michelson) writes: >> In article <2JAN199323293310@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: >> >The hammering sessions will continue all the way through the entire month >> >of January, if necessary. Even though the first hammering attempt didn't >> >open up the antenna all the way, it did have a postive effect. >> >> !! It did? I sure don't remember seeing reference to that in the last >> report but I'm glad to hear it. >> >> What was the "positive effect"? How was it determined or measured? > >The GLL nav team chief told me the other day that although nothing >had unfurled, the degree of bowing had increased. This was determined >from sun sensor data. On the premise that any movement is better than >none, this is a positive effect. They're quite prepared to break the >HGA if necessary, assuming they can. The sun sensor data has indicated that the hammering has affected the antenna in some way. Either the tension on the antenna has been increased or a rib has sprung loose, it cannot be determined which way at this point. Some clarification on "breaking the HGA". The two motors may apply enough force to be able to break the stuck ribs, but having an open High Gain antenna with a couple of broken ribs is a much better situation than having to use the Low Gain antenna by itself. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Choose a job you love, and /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | you'll never have to work |_____|/ |_|/ |_____|/ | a day in your life. ------------------------------ Date: 3 Jan 93 13:43:00 GMT From: Dave O Subject: GOVERNMENT-RUN PROGRAMS Newsgroups: sci.space >But here's somethin to think about: did people lose interest and the media reduced it's coverage in response, or did the media cut back >coverage and convince people that they weren't interested in it? > I'd have to agree with you that media coverage can increase interest in a particular topic - for instance, consider the plight of Somalia. I do believe that NASA has not done a good job in promoting its own interest in mass media lately. Our space endeavours could certainly spur the imagination of voters today if the media was used as a tool of inspiration, as it was in the '60's. Dave O'Leyar Energon Computing, Rochester, NY USA ------------------------------ Date: 3 Jan 93 15:12:55 GMT From: Matthew Kaiser <52kaiser@sol.cs.wmich.edu> Subject: Justification for the Space Program Newsgroups: sci.space seems a kinda silly thing to think about to me.. it's like asking if i should leave my dorm room, or state for any particular reason.. so much out there.. so many new things my $0.02 matthew 52kaiser@sol.cs.wmich.edu ------------------------------ Date: Sun, 3 Jan 1993 14:40:37 EST From: Graydon Subject: Justification for the Space Program Newsgroups: sci.space The Lunar advantage is mass, Henry. If you want a 'hard' satellite, you can do three things - stealth it (which is pretty ridiculous for a comsat, but not neccesarily for a weapons platform), give it defenses (a hard problem), or armor it - design the components to be rad hard, put it in a Faraday cage, and wrap it in a lot of inert mass. The Moon has a real advantage when it comes to shipping inert mass to an Earth orbit, in terms of energy. This doesn't do them any good unless they have a full industrial economy there, though. Taking out a radiation hard satellite with a nuclear weapon, particularly one that is behind several meters of lunar regolith, isn't all that easy - no blast effect means either a *big* bang is required (which will annoy the people whose territory over which is was detonated, never mind the commercial comsats), or a very close hit. The very close hit is basic orbital mechanics, but assumes no counter measures on the launcher, launch site, etc. This is all handwaving anyway, since a good analysis involves knowing the launch costs from earth and the moon *after* that functioning lunar economy gets put in place. I'd *love* to have reliable instances of such figures, truly I would. Graydon ------------------------------ Date: 3 Jan 93 20:14:53 GMT From: "James Borynec; AGT Researcher" Subject: Justification for the Space Program Newsgroups: sci.space henry@zoo.toronto.edu (Henry Spencer) writes: >How? Earth-based antisatellite weapons are simple and cheap; anything >in Earth orbit can easily be destroyed from Earth. Unless you assume Ok, I'll take that bet, blow up the moon. It's certainly in Earth orbit. By your argument it should be "easily destroyed". I'll even let you break a small sweat in your efforts. I do not grant that current ASAT weapons would be effective against "hardened" satelites. We have never gotten into that kind of arms race in any serious fashion. I do know that transportation from the moon to LEO is about 25 times easier than transportation from Earth to LEO. The military tends to follow ther merchants. A powerful moon colony would have MUCH more at stake in the orbital sweepstakes than the mother planet (with all of her unruly children). j.b. ------------------------------ Date: Sun, 3 Jan 93 15:48:20 PST From: Brian Stuart Thorn Subject: Let's be more specific (was: Stupid Shut Cost arguement Newsgroups: sci.space >NASA is chartered as a research organization, not an operational agency. >Shuttle is operations, not research. Shuttle is the only manned system we have, so it is in large part still a research article. I agree, however, that operations is the major part of the Shuttle system. >>Pegasus as a current example of the effect of optimistic development >>scheduling. That causes financial problems for a commercial venture >>that government agencies can shrug off. > >However, DCX is on budget and has slipped very little (30 days in a three >year contract). It looks like these guys know more than you about how >do schedule launcher development. As Gary and I pointed out, Pegasus really started slipping after maiden flight... about eighteen months between flights 2 and 3, to be precise. That DC-X has slipped little prior to maiden flight is a good sign, but hardly justifies such smugness. -Brian ------------------------------------------------------------------------- Brian S. Thorn "If ignorance is bliss, BrianT@cup.portal.com this must be heaven." -Diane Chambers, "Cheers" ------------------------------------------------------------------------- ------------------------------ Date: 3 Jan 93 23:15:29 GMT From: Henry Spencer Subject: lunar military position Newsgroups: sci.space In article <93003.144037SAUNDRSG@QUCDN.QueensU.CA> Graydon writes: >If you want a 'hard' satellite, you can do three things - stealth it... >... give it defenses (a hard problem), or armor it ... >... The Moon has a real advantage when >it comes to shipping inert mass to an Earth orbit, in terms of energy. I'm sure the Moon colony would be the main supplier of armor for armored military satellites. That doesn't mean they'd own them, or that they would have a monopoly on them. Sure, it's more expensive to launch the mass needed for armor from Earth, but it *can be done* -- the cost is not prohibitive under the assumptions necessary for a lunar colony to exist at all. And the lunar colony is not going to be able to afford Earth-sized military budgets for a very long time. Their advantage, while noticeable, is nowhere near enough to put them in a commanding position over a much bigger and richer neighbor. >Taking out a radiation hard satellite with a nuclear weapon, particularly >one that is behind several meters of lunar regolith, isn't all that >easy... Direct hits are already-demonstrated technology. You don't really need nuclear weapons for this kind of thing; a direct hit from a ton of sand will punch through that regolith layer pretty easily. Knocking out satellites is *easy* -- they can't maneuver very much (especially if they're hauling many tons of armor around), reaching orbital altitude is much easier than reaching orbital velocity (a Scud with suitable guidance and course-correction systems would be a workable antisatellite weapon), and their own orbital velocity makes warheads almost superfluous. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 3 Jan 93 15:49:05 GMT From: Herman Rubin Subject: Media and space Newsgroups: sci.space,talk.politics.space In article <1993Jan2.045416.15301@ringer.cs.utsa.edu> sbooth@lonestar.utsa.edu (Simon E. Booth) writes: >Concerning public opinion about the space program, IHMO those opinions can >and are greatly influenced by the media's depiction of space exploration. >Next time watch news coverage of a shuttle flight. Invariably some reference >is made to the cost of that particular mission, plus any important technical >information is either watered down or omitted. >I've had people tell me that the media doesn't cover the space program very >much because people aren't interested. >But here's somethin to think about: did people lose interest and the media >reduced it's coverage in response, or did the media cut back coverage and then >convince people that they weren't interested in it? How much interest SHOULD there be in any particular shuttle launch? If we had an adequate space program, there should be not much more interest than in a trip of an ocean liner. As the saying goes, "When man bites dog, that's news." Nor should anyone expect every observation made by a space probe to be spectacular. Any research program will have experiments or observations made which are valueless; if we knew what we would find, it would not be necessary to look for it, unless we can directly exploit it. The first landing on the moon was quite properly a big media event, but it is not at all surprising that the later ones were less so. -- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399 Phone: (317)494-6054 hrubin@snap.stat.purdue.edu (Internet, bitnet) {purdue,pur-ee}!snap.stat!hrubin(UUCP) ------------------------------ Date: Sun, 3 Jan 93 14:02:24 -0500 From: cohn@zephyr.meteo.McGill.CA Subject: Poker Flat > Does anyone know anything about "Poker Flats" in Alaska.. > Up near Fairbanks, AK.. If I remember right it is run by the > University of Alaska Fairbanks.. Mostly does atmospheric (northern lights, et > > Michael Adams > Alias: Morgoth/Ghost Wheel > nsmca@acad3.alaska.edu This is rather dated information but...10 years ago the University of Alaska's Geophysical Institute operated the Poker Flat MST Radar. It was used to study tropospheric and stratospheric (below about 30 km) atmospheric turbulence, winds, and waves, as well as mesospheric (around 85 km) echoes. Nearby related facilities (the Poker Flat research range?) were used to launch rockets for mesospheric research, and track balloons to 30km for wind profiles. More recently they have been involved in 'active' experiments using rockets to release chemicals perturbing (temporarily and locally!) electron and ion concentrations in the ionosphere. Also, I think I recall GI getting money from congress to build a high latitude radar for ionospheric research. Anyway, I'm sure GI would be happy to send you a glossy brochure if you write to them (Geophysical Institute, Univ. of Alaska, Fairbanks, AK 99701) and I think they also have a quasi-periodic newsletter. Steve ------------------------------ Date: Sat, 02 Jan 93 20:48:12 CST From: Victor Laking Subject: russian solar sail?+ Newsgroups: sci.space > > New one on me, but I have heard of the supposed race to the moon with solar > sails, to celebrate the 500 anniversary of Columbus, not sure if it > actually came about.. Maybe the olymbics will have a solar sale race or > some other organization will have a solar sail race.. > > == > == > Michael Adams alias Ghost Wheel/Morgoth NSMCA@acad3.alaska.edu I know that there were some plans for an international "race" to Mars with Canada, the US, Russia, and some other countries that I don't remember. The plan was to have each country make their own. This way, the benefits of each design could be looked at. Unfortunately, the project was canceled from what I have been told. (I was talking to one of the NASA guys from sci.space.news about it.) I seem to recall that the limiting factor that was mentioned was money. Actually, using a solar sail to just go to the moon would be pointless as they are only practical over a distance. Remember, they use the solar winds to carry them. This means that they are going to take a long time to build up a decent velocity. However, over a longer distance, they can be quite good. Personally, I would like to see the use of solar sails catch on as a method of travel. If nothing else, it would be another case of sci-fi become fact. victor@inqmind.bison.mb.ca The Inquiring Mind BBS, Winnipeg, Manitoba 204 488-1607 ------------------------------ Date: Sun, 3 Jan 1993 22:43:44 GMT From: Henry Spencer Subject: russian solar sail?+ Newsgroups: sci.space In article , ida@atomic (David Goldschmidt) writes: > I saw something a few months ago about a Russian plan to test a small solar > sail from the Mir space station on Dec 10. of this year. I haven't heard > anything about it since - does anybody know if it happened? Now scheduled for February, timing set by the timing of other activities aboard Mir. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Sun, 3 Jan 1993 10:40:49 GMT From: "Simon E. Booth" Subject: SSTO vs 2 stage Newsgroups: sci.space The idea of a 2 stage DC configuration seems technically sound, but how would it be compatible with the launch facilities designed around the intended DC-vehicle (single stage)? Could the service gantries and launch pads be designed to accomodate different spacecraft configurations? I know that the launch pads in use today are built around the rockets launched from them (i.e. Pads 39 A and B can only be used for the shuttle). One possible use for a two-stage DC configuration might be a lunar flight without having to re-fuel in LEO. Unless I'm way of the mark again on this one. Simon ------------------------------ Date: Sun, 3 Jan 1993 22:45:41 GMT From: Henry Spencer Subject: SSTO vs 2 stage Newsgroups: sci.space In article <1993Jan3.104049.2581@ringer.cs.utsa.edu> sbooth@lonestar.utsa.edu (Simon E. Booth) writes: >The idea of a 2 stage DC configuration seems technically sound, but how >would it be compatible with the launch facilities designed around the >intended DC-vehicle (single stage)? It wouldn't be, basically. It would be a special configuration for special needs, and would require special launch facilities. >Could the service gantries and launch pads be designed to accomodate >different spacecraft configurations? It can be done, but it runs up the price, so it isn't done unnecessarily. -- "God willing... we shall return." | Henry Spencer @ U of Toronto Zoology -Gene Cernan, the Moon, Dec 1972 | henry@zoo.toronto.edu utzoo!henry ------------------------------ End of Space Digest Volume 15 : Issue 628 ------------------------------