Date: Tue, 13 Apr 93 05:19:40 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #454 To: Space Digest Readers Precedence: bulk Space Digest Tue, 13 Apr 93 Volume 16 : Issue 454 Today's Topics: ASAT wasn't orbital (was Re: Question- Why is SSTO Single Stage) Astronomy Program Civilian use of Russian missiles Clementine Science Team Selected Did any DC-X gifs show up? The world of null-a Two-Line Orbital Element Set: Space Shuttle What if the USSR had reached the Moon first? What is the significance of the name "Clementine? Why is SDIO doing "Clementine"? Why is SDIO doing "Clementine"? (part #2 of 6) 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: 12 Apr 93 17:51:44 -0600 From: Bill Higgins-- Beam Jockey Subject: ASAT wasn't orbital (was Re: Question- Why is SSTO Single Stage) Newsgroups: sci.space In article <1993Apr9.150945.7884@ke4zv.uucp>, gary@ke4zv.uucp (Gary Coffman) writes: > It would seem that a first stage built like an airplane, and > operated like an airplane, that carried an orbital stage, built like > an airplane and operated like an airplane, with an easy mate design would > make orbital flight cheaper and more effective than a SSTO requiring > ultralight structures and finicky maneovers just to get to orbit and > back. MX has been launched from a C5, and neither system was designed > for that. Really? I'd pay to see that! > A F16 has carried an orbital ASAT rocket. Whoops, factual error. The U.S. experimental ASAT was an air-launched rocket that went to the *altitude* of low-orbit satellites. It got nowhere near the *speed* required to go into orbit-- if it failed to hit its target, it would have fallen right back to the ground. Nitpicking, it was carried on an F-15, not an F-16. (If I'm wrong, I'll hear about it!) O~~* /_) ' / / /_/ ' , , ' ,_ _ \|/ - ~ -~~~~~~~~~~~/_) / / / / / / (_) (_) / / / _\~~~~~~~~~~~zap! / \ (_) (_) / | \ | | Bill Higgins Fermi National Accelerator Laboratory \ / Bitnet: HIGGINS@FNAL.BITNET - - Internet: HIGGINS@FNAL.FNAL.GOV ~ SPAN/Hepnet: 43011::HIGGINS ------------------------------ Date: 9 Apr 93 04:27:18 GMT From: kevin marcus Subject: Astronomy Program Newsgroups: sci.space Are there any public domain or shareware astronomy programs which will map out the sky at any given time, and allow you to locate planets, nebulae, and so forth? If so, is there any ftp site where I can get one? Please reply by email to tck@bend.ucsd.edu thanks. -- -=+> Kevin Marcus, Virus Researcher. Author: TSCAN, RE-xxx, MICHEX, STONEXT datadec@ucrengr.ucr.edu (619)/457-1836, 3-2400 baud, 24 hours. Comp. Sci. Major, University of California, Riverside. ------------------------------ Date: Mon, 12 Apr 1993 23:47:22 GMT From: Michael Moroney Subject: Civilian use of Russian missiles Newsgroups: sci.space In article <734459421.F00001@permanet.org> Mark.Prado@f349.n109.z1.permanet.org (Mark Prado) writes: >>The idea is that instead of destroying many of these missiles, as >>we are currently planning to do, we could instead launch things >>into orbit... I think the Russians are actually doing some of that. I read something about a launch of a satellite by Russia on a converted ICBM, and in addition they launched an ICBM at Washington State (actually the offshore ocean). Instead of a nuke it carried some sort of items to celebrate US-Russia peace and I think it was intended as an advertisement "we have these rockets, we now can do more than launch nukes, let us launch your satellites" ------------------------------ Date: Mon, 12 Apr 1993 20:35:25 GMT From: Dave Tholen Subject: Clementine Science Team Selected Newsgroups: sci.space,sci.astro Doug S. Caprette writes: >> Clementine > Why is a civilian project being spoinsored by a military agency? It isn't a civilian project. ------------------------------ Date: Tue, 13 Apr 1993 01:58:30 GMT From: Douglas R Fils Subject: Did any DC-X gifs show up? Newsgroups: sci.space sci.space, Did any GIFS show up from the roll out of the DC-X? I recall someone mentioning that they might be able to get some and I have been away from the net for a few days and thought I might have missed any notice. Thanks much for the time... and thanks to anyone who has made up and posted gifs of this important event! take care Doug -- ------------------------------ Date: Mon, 12 Apr 1993 23:09:30 GMT From: nathan wallace Subject: The world of null-a Newsgroups: sci.space In article 1@cs.cmu.edu, 18084TM@msu.edu (Tom) writes: >>>Does anyone have any info on the apparent sightings of Vulcan? > >>From memory Vulcan was an attempt to account for the precession >>of the axes of the orbit of Mercury in the late 19th century. The >>effect has now been full explained thanks to the Theory of >>Relativity. In fact Mercury's orbit was one of the first >>confermation of relativity. Vulcan was supposed to have been >>observed by a somewhat dubious 'gentleman' astronomer who kept >>his notes on a plank of wood, and used plane as an eraser. > >Another legend with the name Vulcan was the planet, much like Earth, >in the same orbit, but on the other side of the Sun. I don't know >the origin or age of this legend, though. Maybe someone else can fill >in the people and time this legend comes from. > >-Tommy Mac >------------------------------------------------------------------------- >Tom McWilliams 517-355-2178 wk \\ As the radius of vision increases, >18084tm@ibm.cl.msu.edu 336-9591 hm \\ the circumference of mystery grows. >------------------------------------------------------------------------- I believe this showed up in an ancient (relatively :)) sf book called "the world of null-a". it was about a planet orbitting exactly opposite earth, but in the same orbit, and thus always invisible to astronomers on the other side of the sun. John Norman's GOR series is set on such a world. If anyone remembers my lagrange question from a couple of weeks ago, it was to settle this exact point, namely whether a world *could* exist for any length of time in an "antipodal" position to another planet. (apologies if that term is not exactly correct.) according to the people i've asked, it couldn`t. Too bad. If there was an older legend these books were based on, I'd love to hear about it too! --- C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/ C/ Nathan F. Wallace C/C/ "Reality Is" C/ C/ e-mail: wallacen@cs.colostate.edu C/C/ ancient Alphaean proverb C/ C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/C/ ------------------------------ Date: Tue, 13 Apr 1993 04:31:55 GMT From: TS Kelso Subject: Two-Line Orbital Element Set: Space Shuttle Newsgroups: sci.space The most current orbital elements from the NORAD two-line element sets are carried on the Celestial BBS, (513) 427-0674, and are updated daily (when possible). Documentation and tracking software are also available on this system. As a service to the satellite user community, the most current elements for the current shuttle mission are provided below. The Celestial BBS may be accessed 24 hours/day at 300, 1200, 2400, 4800, or 9600 bps using 8 data bits, 1 stop bit, no parity. Element sets (also updated daily), shuttle elements, and some documentation and software are also available via anonymous ftp from archive.afit.af.mil (129.92.1.66) in the directory pub/space. STS 56 1 22621U 93 23 A 93100.58333332 .00060906 00000-0 17653-3 0 103 2 22621 57.0037 168.0276 0004614 270.7909 289.6873 15.92482227 371 -- Dr TS Kelso Assistant Professor of Space Operations tkelso@afit.af.mil Air Force Institute of Technology ------------------------------ Date: 12 Apr 93 21:17:42 GMT From: ChaOs Subject: What if the USSR had reached the Moon first? Newsgroups: alt.history.what-if,sci.space In article , dxb105@virgo.anu.edu.au (David Bofinger) writes: > jeffj@yang.earlham.edu (ChaOs) writes about the military application > of a lunar base: > >> Well, ever read (for example) Robert Heinlein's _The Moon is a Harsh >> Mistress_? A lunar colony was able to do a frightening amount of >> damage just by throwing rocks at earth. > > This made sense in the book because it was an improvised weapon -- the > rebel colonists didn't own any nukes (though they did own the human > race's best computer, for no obvious reason). Just to get off the subject a bit, having _one_ computer that controlled just about everything on the Moon from life support to transportation to calculating flight paths means that the computer would _have_ to be tremendously complex. That's why Mike woke up in the first place. Now back to the topic: > But everything they did > could far more easily have been acheived by nuclear-tipped ICBMs > launched from Earth. It's not that lunar bases can't attack the Earth, > but in a world where exterminating most of the human race can be done > fairly cheaply its hard to see what capabilities it adds. The purpose of the military is not to exterminate the entire human race - or at least it shouldn't be. Going with the rocks example: 1) No radiation. Destroyed places are not sealed off forever, there are no adverse effects on surrounding populations, etc. Also, it's more humane, because it won't cause cancer, birth defects, etc. 2) No fallout. This is generally regarded as good, because it means your own side won't get offed by your weapons. 3) Harder to affect in flight. Antimissiles can knock out nukes, but a rock? It might push it off course, but it'd still hit somewhere. Also, a lunar base could be used to supplement spy satellites, etc. Why? 1) As someone else pointed out, it's harder to destroy. 2) No problems with decaying orbits. I'm sure there are others. Not being an expert in optics, I don't know if we have the technology to make this viable, but if we're postulating a moon-base anyway... -- JeffJ@yang.earlham.edu - Official generic .sig. Under 4 lines, under 80 columns, no Amiga checks, no witty quotes, no maps of Australia, no asterisks, no ASCII art, no disclaimers or anti-flame requests, and one spelling errer. ------------------------------ Date: Mon, 12 Apr 1993 22:38:27 GMT From: James Thomas Green Subject: What is the significance of the name "Clementine? Newsgroups: sci.space What is the significance of the name "Clementine? (oh my darling :-) Is it the name of some goddess related to the moon? The wife of the cheif scientist? No meaning at all? /~~~(-: James T. Green :-)~~~~(-: jgreen@oboe.calpoly.edu :-)~~~\ | | | Support Mental Health, oR i'LL kILL yOu!?!?! | ------------------------------ Date: Tue, 13 Apr 1993 00:28:00 -0500 From: Mark Prado Subject: Why is SDIO doing "Clementine"? Newsgroups: sci.space OK, here goes. I worked for years in direct support of SDIO (which was a short walk from my office). I helped manage the Delta 180 and Delta 181 missions, and did long range planning. I'm a physicist, and my main specialization at the time was evaluating sensors, though I found myself in lots of things. I resigned in 1987 to do other, unclassified and less stifling things (though I now find myself consulting primarily to the State Dept ...) The following is a Small Business Innovative Research (SBIR) proposal which my company submitted in 1988, and which I've edited a bit so that you or your associates could use it. (Since I'm the President and CEO of the primary, I'm not in deep yogurt over doing this, though I hope none of my associates are the kind to object to this ...) Any response/growls should go to mark.prado@permanet.org and NOT to the address in the header of this message. (In deed, let's ping to see who gets it.) -------------------------------------------------------------- [ PERMANENT Program to Employ Resources of the Moon and Asteroids Near Earth in the Near Term ] Abstract of proposal Much of the BMD mass needed for delivery TO ORBIT is unsophisticated (e.g., shielding, fuel propellant, structural materials) and thus could feasibly be produced from the material of certain Near-Earth Asteroids and/or lunar materials. Recent studies conclude that this material, ALREADY in space, could be delivered to Earth orbit in quantities dwarfing what could feasibly be launched from Earth, at dramatically reduced costs per pound. (After all, the European settlers of America didn't bring everything with them -- they used indigenous resources.) Delivery of Near-Earth asteroidal material would require a simple, small low thrust vehicle (an orbit-to-orbit "tug"). The delta-v required is as small as 0.1 km/sec for known near-Earth asteroids such as 1982DB (versus 8.0 km/sec for Earth launch and a large, complex vehicle fighting Earth's threatening gravity). One 100-ton spacecraft with in-situ propellant production capability could retrieve 10,000 tons of asteroidal material. The Phase I effort would define potential products and logistical needs, but focus upon the costs and equipment required to make certain products such as shielding and fuel propellants. Phase II work could develop or verify particular processes in the laboratory. Table of Contents 1. Cover Sheet and Abstract 2. Identification and Significance of the Opportunity Products from Near-Earth Asteroidal and Lunar Materials Costs -- Economic and Technological Comparison, Nonterrestrial vs. Earth-Launched Sources of Material Compositions and Processing of Nonterrestrial Materials 3. Technical Objectives and Work Plan 4. Key Personnel, Facility Resources, and Consultants 5. Cost Proposal Figure 1: The following products could be commercial spinoff products from a program to utilize nonterrestrial materials for defense uses -- for popular support o Fuel propellant for transporting satellites from low orbit to geostationary orbit (currently requires two tons of fuel launched from Earth per ton of satellite to low orbit) o Multi-satellite platforms o Shielding for space stations o Construction materials for walls, beams, and other structural members for orbit based facilities o Silicon solar cells and silicon semiconductors o Large communications antennas o Space-based radar to track aircraft o Cobalt and platinum group metals from asteroidal materials (one product worth returning to Earth) o Settlements for corporate communities (with 24 hour sunlight, and healthy artificial gravity by rotating huge habitat for centrifugal force) o Solar power satellites for beaming energy to Earth (longterm) o Giant (revolutionary) telescopes for scientific study - radio telescopes - optical telescopes _____________________________________________________________ Figure 2: The following massive but simple products could be made from space resources and used to defend any space-based operation: o Shielding using layers of steel, concrete, ceramics, and sand - SDI systems - non-SDI assets o Propellant - orbit-to-orbit transfers of systems and supplies - stationkeeping propellants - maneuverability for: survivability better reconnaissance better battlefield support quickly deploying spare satellites adaptive constellations intercept o Portions of electric power systems - fuel to generate burst power (turbogenerator, MHD) - radiation shields around nuclear fuel sources - structural arrays for solar cells, survivable o Energy storage systems - Nickel-Hydrogen batteries - Steel Flywheels - Fuel Cells o Cryogenic liquids for cooling of systems - optics and sensors - weapons systems - power generators (cryogenic fuel) - IR signature control (e.g., cooling front side) o Electronic countermeasure antennas and power sources o Space based radar (for global monitoring of aircraft, tanks) o Particles for interactive discrimination (RV's vs. decoys) o Space stations, garages, and other facilities o Decoys o Inertial platforms for rapid retargeting and precision pointing with minimum structural vibration 2. Identification and Significance of the Opportunity Technology advances may allow the Free World to consider creating new kinds of space based defense systems which would have the capability to change the nature of warfare, both strategic and tactical, in such a way as to enhance the security of defense- oriented nations. Utilization of material already in space -- from Near-Earth Asteroids and/or from the lunar surface -- may be pivotal to making such concepts economically feasible, survivable, robust, defense-dominant, and politically realistic. The Strategic Defense Initiative (SDI) would require a mass of material in Earth orbit much greater than any other official program, past or currently planned. It is debatable whether the necessary material for a survivable and robust system could realistically be delivered into Earth orbit at an attractive cost using current and projected Earth launch vehicles, especially given budgetary constraints and other defense spending priorities, not even considering the ever present technical difficulties associated with large Earth launch vehicles. Much of the mass needed in orbit for a completely operational SDI system would be relatively unsophisticated (e.g., shielding, fuel propellant, burst power fuel) and thus could feasibly be produced from the material of certain Near-Earth Asteroids and/or from lunar materials. As stated in the abstract, recent studies conclude that Near- Earth Asteroidal material and possibly lunar material could be delivered to Earth orbit in quantities dwarfing what could feasibly be launched from Earth, at dramatically reduced costs per pound (in bulk). Delivery would require a simple, small low thrust vehicle (an "interorbital tug"), and the delta-v required to bring material back is as small as 0.1 km/sec for known Near- Earth Asteroids (versus 8.0 km/sec for Earth launch and a large, complex vehicle fighting Earth's threatening gravity). Conservative studies estimate that a 100-ton asteroid-recovery vehicle (including fuel propellant) launched from low Earth orbit would be able to retrieve 10,000 tons of a near-Earth asteroid such as 1982-DB, for a mass payback ratio of approximately 100, assuming in-situ propellant production capability. After the first return of cargo, the spacecraft would be reusable. In 1983, the Defense Technologies Study Team (DTST), headed by Dr. James C. Fletcher, met with the National Academy of Sciences and the National Science Foundation to review new ideas in BMD technology. They reported on "[t]wo new ideas that warrant serious attention and fiscal support in the years 1984-1989 ... The first of these was the possible use of extraterrestrial resources to provide large amounts of mass in Earth orbit ...", primarily to satisfy survivability needs. The DTST later sponsored a workshop to further explore the issue. "The group concluded that extraterrestrial materials may provide the required mass at costs competitive with or significantly cheaper than options requiring launch from Earth's surface ... Material from the lunar surface or from nearby asteroids can be brought to the vicinity of Earth for a much lower energy budget than launching from Earth's surface - 1 to 3 orders of magnitude less." However, the funding suggested was not officially allocated. The Soviet Phobos lander currently under construction for launch in the early 1990's will effectively be landing on an asteroid to sample its minerological and elemental composition and its physical consistency. (Phobos is an asteroid moonlet of Mars, with practically no surface gravity.) The Soviets are cooperating with 14 nations on this project, most of these nations being western technological powers. Also, consistent with President Reagan's stated consideration of sharing SDI technology with the Soviets, it may be conceivable to negotiate with the Soviets a sharing of technology used in retrieving Near-Earth Asteroidal and lunar material, and to engage in a cooperative effort. As stated in a 1986 report of the NASA Advisory Council, which devoted 30 pages to the topic: "As other advisory groups have pointed out, large-scale human activities in space will, in time, become an integral part of Earth's economy. The use of near- Earth resources, obtained from the Moon and nearby asteroids, will be essential. The ability of the U.S. to be prepared to act, when the time comes, depends on our preparedness, including having in hand a scientific survey of the resources that are potentially available in space." However, the strong recommendations of the NASA Advisory Group have failed to produce significant additional support from within NASA due to competing interests in an era of declining spending. As of this day, January 6, 1988, there has yet been an official committment to this project, though there are numerous groups doing work in this area with funding from sources largely unknown to us. Further, there is apparently no central databank of information available to new researchers interested in this field, nor is there an available report establishing a clear foundation for future development. This proposal is to justify support for a Phase I evaluation of: 1. potential products from near-Earth asteroidal material and lunar material that would help create survivable and robust space based defense systems and civilian products; 2. key materials processing issues for making the above products; 3. other logistical, equipment and technology needs; and 4. economic factors in retrieving and processing materials for manufacturing valuable defense system components. [continued in next message] * Origin: PerManNet Communications, Washington D.C., U.S.A. (1:109/349.2) ------------------------------ Date: Tue, 13 Apr 1993 00:29:01 -0500 From: Mark Prado Subject: Why is SDIO doing "Clementine"? (part #2 of 6) Newsgroups: sci.space Product #1: Shielding It would be difficult to acquire a capacity to attack and destroy BMD or other defense satellites protected by several feet of armor consisting of layers of steel, "lunarcrete", ceramic, fiberglass, and sand. This would lead to a stable strategic situation, instead of a space based arms race, by making the defense dominant. The great expense of attacking well protected BMD satellites makes it extremely unlikely that a potential adversary could acquire the ability to "punch a hole" in an SDI system by destroying most or all of the BMD satellites in a position to prevent ballistic missile attack, in a short enough time to make such an attack practical. Several layers of thick, laminated steel and fiberglass could greatly enhance the survivability of satellites contained within them. While not impermiable, these shields would be immune to most current threats -- multimegawatt directed energy weapons, nuclear detonations more than a mile away, impact of co-orbiting explosive projectiles up to several hundred pounds, and impact of counterorbiting projectiles up to tens of pounds. Survivability has a long military history. There are four primary methods of acheiving it: - concealment (including decoys) - hardening (e.g., shielding) - escape (e.g., using propellant) - shoot-back (e.g., using propellant and shrapnel) Nonterrestrial materials (NTM) could provide shielding, decoy shields, propellant for maneuverability, and possibly shrapnel and energy stores for shootback systems. (Regarding concealment, low Earth orbit is an impossible environment to conceal a size- able object from view. Proliferating decoys would be necessary to conceal valuable satellites.) Electronic countermeasures is an additional possibility, given enough power. (Power is discussed later in this proposal.) It can be argued that we can employ reactive protection tech- niques to thwart a specified threat, but the enemy can usually develop and deploy a different type of threat which defeats the reactive protection technique before significant advantage can be gained, especially if the enemy is committed. The best recourse is a combination of shielding, decoys, maneuver, and shootback. The only protection technique with a history of success against a wide variety of threats - some not anticipated at the time of its production - is to put thick pieces of strong material between the threat and the target. While any protection technique can be defeated, thick armor is relatively difficult to penetrate and thus requires the enemy to use expensive and large weapons which he cannot afford in great quantities. These heavy weapons are much easier to find, attack ("shootback") or avoid than are numerous lighter weapons. Product #2: Fuel Propellant Large amounts of oxygen would be useful for rocket fuel. Oxygen is ubiquitous in nonterrestrial materials, averaging 42% of the lunar crust and around 30% of many near-Earth asteroids, bound as mineral oxides. Because water is 86% oxygen by weight, 6-8 times as much oxygen as hydrogen would be consumed in a hydrogen-oxygen rocket engine. In other words, 86% of regular rocket fuel is oxygen and is abundant in asteroidal and lunar material. Hydrogen is almost certainly abundant in near-Earth asteroids, as is carbon. Therefore, 100% of rocket fuel could be derived from nonterrestrial materials. These elements are extractable simply by heating the material, using a small nuclear or solar oven. Inexpensive propellant could enhance survivability by allowing BMD satellites to perform significant orbit changes when under attack. These orbit changes could also be used to enhance systems performance by allowing satellites to adjust their orbits for maximum defensive effect, or to cover gaps left by overwhelmed or destroyed satellites. Orbital maintenance also requires fuel propellants. A typical satellite in low Earth orbit requires about 25% of its weight to be stationkeeping fuel over a 5-year operational lifetime. Pointing and tracking systems may require additional propellant. Product #3: Power Generation In addition to use as fuel propellants, oxygen and hydrogen are useful for electric power generation. Large amounts of inexpensive oxygen and hydrogen or hydrocarbons would provide an excellent fuel source for turbogenerators or MHD/turbogenerator hybrid systems. This would be very useful for directed energy or electromagnetic launcher weapons systems, space based radar, and electronic countermeasures. Turbogenerators and MHD (magnetohydrodynamic) systems have the advantages of being able to provide burst power on a moment's notice, minimal housekeeping requirements, and simplicity in design and operation. Turbogenerators can be extremely compact and simple power supply devices when fueled by combustible liquids. The availability of inexpensive oxygen could provide abundant energy stores and reduce the operating costs of currently envisioned systems. (20 to 50 times as much oxygen as hydrogen could be consumed in an oxy-hydrogen gas turbine.) The cryogenic oxygen and hydrogen can also be used to cool systems by circulating the fluid thru pipes enroute to the combustor. A robust defense is one which has the capability to react to unanticipated threats, to react to more extensive threats than were expected, and to be on alert whenever there is some possibility of trouble. All of these capabilities require large amounts of propellants for maneuvering and power generation. If fuel is cheap, evasive maneuvers can be taken, systems warmed up, or warning shots fired without the need to worry about running out of propellant or power or running over budget. Without low cost fuel, there will be the temptation to sit tight in tense situations - which could lead to being badly out of position, unprepared and vulnerable when an attack is launched. Other Products: A prerequisite to considering a product to be made from nonterrestrial materials is that the product must satisfy all of the following criteria: - consist of elements known to be abundant in NTM - be simple to produce, requiring minimal machining - be in massive demand Figure 1 lists the components of a space defense system which might be feasible to produce from nonterrestrial materials. Figure 2 lists potential civilian products, many of which are important to national security. Many of these products are basic structural items. In addition to making space based defense systems feasible and effective, space resources can also be used for products of economic and cultural benefit, as well as for spreading free societies beyond Earth's biosphere. A significant public motiv- ation for supporting SDI research is that there will inevitably be commercial spinoffs of great value to our nation and mankind from SDI technology and infrastructure. Research into using Near-Earth Asteroidal and lunar material would enhance this public interest. The projected rewards of creating a space based economy, in terms of benefits from space based products, the trade deficit and multi-billion dollar space exports, enhanced security for the Free World, and the spread of free societies, are immense compared with the cost and risk of the preliminary R&D necessary to determine the feasibility of doing so. Costs Low Earth orbit (LEO) is much more energetically accessible from "Near-Earth Asteroids" than either the lunar surface or Earth's surface. Table 1 compares transportation requirements from the three candidate sources of material. Figure 3 illustrates the difference in propulsive requirements to leave the Earth or the Moon with roughly equivalent payloads (two men in a gemini capsule vs. two men in the lunar module). _______________________________________________________________ Table 1: Comparison of accessibility Material source Earth Moon Near Earth Asteroid (e.g., 1982DB) Energy 2000 180 1 Delta-V, km/s 8 2.4 0.1 Mass of planet[oid] 81 1 10^-18 _______________________________________________________________ The economics of delivering space resource derived manufactures to Earth orbit have been discussed in a variety of contexts, as has the possible utility of space resources for SDI. However, these analyses have not been performed in adequate detail to confidently apply their positive results to calculating approximate costs for providing shielding and propellants for SDI like missions, nor have they been done in the depth required to believably generalize their results and have some confidence that the answers are meaningful. The attendant issues could be substantiated further by the proposed Phase I SBIR effort. DoD-sponsored workshops have looked into utilizing nonterrestrial materials (NTM) for SDI, and there are numerous recent NASA studies into the issue. Conservatively assuming production of primarily fuel propellants, shielding, and structural materials, the conclusions of these workshops and studies were that these commodities might feasibly be produced from space resources for much less than the cost of launching equivalent materials from Earth, in a scenario of major demand such as a deployed SDI system. Despite positive reports, these concepts have not received the requested follow-on funding and thus have not been pursued much further. It should be emphasized that nonterrestrial materials become more economical than Earth sources only in scenarios where large quantities of material are needed in a relatively few years. A large front-end investment is needed to initiate nonterrestrial materials utilization. After that one-time investment, nonterrestrial materials will thereafter be available at lower cost than Earth-derived materials. The crossover point has yet to be defined. However, general statistics on the quantity of SDI shielding mass and propellants needed may provide one single legitimate application to justify evaluating the relative merits of nonterrestrial materials utilization and estimating an economic crossover point. [continued in next message] * Origin: PerManNet FTSC <=> Internet gateway (1:109/349.2) ------------------------------ From: Bill Higgins-- Beam Jockey Newsgroups: sci.space Subject: Perishable food (was Re: Quick reaction shuttle) Followup-To: sci.space.shuttle Date: 12 Apr 93 17:02:01 -0600 Organization: Fermi National Accelerator Laboratory Lines: 26 Message-Id: <1993Apr12.170201.1@fnalf.fnal.gov> References: <1q5381$1k6@access.digex.net> <1q7vki$q7@access.digex.net> <1qage2$4hr@access.digex.net> Nntp-Posting-Host: fnalf.fnal.gov Summary: A possible solution to the food problem? Sender: news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU In article , jbh55289@uxa.cso.uiuc.edu (Josh Hopkins) writes: > prb@access.digex.com (Pat) writes: > > How difficult can it be to keep a >>shuttle stacked, and waiting for the occasional light weight >>mission? > > Try impossible. Or at least, not practical for the amount of money we're > willing to spend. For one thing, you'd be tying up a launch pad or VAB spot. > For another, the shuttle doesn't have an infinite shelf life. You can't keep > the fuel in it forever (or the food for that matter). Roger on the hydrazine and N2O4, Josh, but as for the food, surely they could install vending machines in the Shuttle? In a national emergency, I'm confident astronauts could subsist for a week on peanut-butter cheese crackers. After all, hackers do it all the time. (Although in times of real stress, I tend to fall back on microwave popcorn.) Bill Higgins, Beam Jockey | "Enough marshmallows Fermi National Accelerator Laboratory | will kill you Bitnet: HIGGINS@FNAL.BITNET | if properly placed." Internet: HIGGINS@FNAL.FNAL.GOV | --John Alexander, leader of SPAN/Hepnet: 43011::HIGGINS | "disabling technologies" [*Aviation Week*, 7 Dec 1992, p. 50] | research, Los Alamos ------------------------------ End of Space Digest Volume 16 : Issue 454 ------------------------------