Date: Fri, 6 Oct 1989 23:44-EDT From: space-tech-request@cs.cmu.edu To: "~/st/lists/stdigest" Subject: Space-tech Digest #38 Contents: Korac MacArthur Thruster Data Don Willits Start-up Lunar Industrial Economy Paul Dietz Re: Start-up Lunar Industrial Economy Henry Spencer Re: Start-up Lunar Industrial Economy Steven Deterling Orbital Debris Joe Beckenbach Re: Orbital Debris Tom McReynolds Re: Orbital Debris Kevin Ryan Re: Orbital Debris John Roberts Re: Orbital Debris Jon Slenk Re: Orbital Debris Henry Spencer Re: Orbital Debris Henry Spencer Re: Orbital Debris Henry Spencer Re: Orbital Debris John Lukas Re: Orbital Debris Korac MacArthur Re: Orbital Debris ------------------------------------------------------------ Date: Thu, 5 Oct 89 16:13 EDT From: K_MACART%UNHH.BITNET@VMA.CC.CMU.EDU Subject: Thruster data To: space-tech@CS.CMU.EDU I am currently doing a computational physics project on an orbit to orbit transfer program. I am simulating a space tug type of craft, but don't have any idea on parameters like total mass and thrust of engines (assumed constant at 100% capacity). Does anyone know how much thrust the shuttle Orbital Maneuvering System engines puts out? I could use a cluster of four and work from there. Thanks. Korac MacArthur (k_macart@unhh.bitnet) ------------------------------ To: space-tech@CS.CMU.EDU Subject: Start-up Lunar Industrial Economy Date: Wed, 04 Oct 89 16:43:43 PDT From: willitd@uther.CS.ORST.EDU How's this for a proposed start-up industrial economy on the moon? 1 Refuelable OTV (range LEO to Low Lunar Orbit) 1 Refuelable Lunar Lander (Lunar Surface to Low Lunar Orbit) 6 "Skitters" (see below) 1 Regolith Processor Lots Empty fuel tanks (see below) The OTV would be pretty much the standard type disccussed in NASA literature (although I'm open to suggestions. The Lander hasn't had nearly as much work on it, but I would like to constrain both the Lander and the OTV by saying they should use Oxygen and powdered silicon or aluminum for oxidizer. (not as efficient as reacting with, say, hydrogen, but still workable). The Skitter is a three legged robot developed by some students at Georgia Tech. The prototype utilizes an HP calculator. This is by the far the best design I have personally seen for a lunar surface robot. It could operate either independently or through teleoperation. It can right itself if it falls over. It seems to be an ideal platform for either scientific exploration or industrial purposes. In this case, I propose to use them to gather regolith. We could probably ship up a couple of extra's for geologic and scientific research. The Regolith Processor would have two parts. A furnace for heating regolith up to 100 degrees Celsius (at which point, I'm told, the 40% oxygen composing your typical regolith sample will liberate itself and into a convienently waiting empty fuel tank). The furnace then could take the slag and refine it just enough to get either aluminum or silicon, powderize it, and empty it into another waiting fuel tank. With this proposal (presuming it would work) we now have a industrial economy to support orbital operations (i.e. fuel from the moon, which in the long run would hopefully be cheaper than lifting it from Earth). If it was successful, it would demonstrate the feasibility of other, more ambitious, projects. ________________________________________________________________________ What I would like from the "space-techies" is comments on the soundness of this idea. This was a very general description. What are some of the technical aspects which would have to be resolved? Does it sound feasible? If not, what would need to be done to take the basic idea (fuel production, or any basic economy, for that matter) and get it started? Better yet, how could this economy be expanded to produce other useful products? This is (I hope) a relatively simple infrastructure (barring the OTV and Lunar Lander, most of it could be built relatively inexpensively). What other simple "economies" might there be to get industrial manufacturing on the moon (or asteriods) going? -Don ________________________________________________________________________ Don Willits - Head Consultant * Internet: willitd@mist.cs.orst.edu Computer Science Lab * UUCP: tektronix!orstcs!willitd Oregon State University * hplabs!hp-pcd!orstcs!willitd Corvallis, OR 97331 * Voice: (503) 737 - 3273 ------------------------------ Date: Thu, 5 Oct 89 09:08:53 EDT From: dietz@cs.rochester.edu To: willitd@uther.CS.ORST.EDU Cc: space-tech@CS.CMU.EDU Subject: Start-up Lunar Industrial Economy > The Regolith Processor would have two parts. A furnace for heating > regolith up to 100 degrees Celsius (at which point, I'm told, the 40% > oxygen composing your typical regolith sample will liberate itself and > into a convienently waiting empty fuel tank). Surely not 100 degrees C. Ilmenite reacted with hydrogen at 1000 C will make water, then you recover the hydrogen by electrolysis. Paul F. Dietz dietz@cs.rochester.edu ------------------------------ From: henry@utzoo.uucp To: cs.cmu.edu!space-tech@cs.toronto.edu Subject: Re: Start-up Lunar Industrial Economy Date: Fri, 6 Oct 89 14:53:44 EDT > 1 Refuelable OTV (range LEO to Low Lunar Orbit) > 1 Refuelable Lunar Lander (Lunar Surface to Low Lunar Orbit) Better make that two of each, especially the lander. Unless, like NASA, you really believe in 1-in-100000 failure rates. > The Lander hasn't had nearly as much work on it, but I would like to > constrain both the Lander and the OTV by saying they should use > Oxygen and powdered silicon or aluminum for oxidizer... You're assuming that there are no frozen volatiles (i.e. hydrogen sources) at the lunar poles. Any attempt to set up a lunar economy really needs to verify this first. > The Skitter is a three legged robot developed by some students at Georgia > Tech. The prototype utilizes an HP calculator... Has anything on this been published? Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Thu, 5 Oct 89 12:34 CDT From: SPD7924%TAMVENUS.BITNET@VMA.CC.CMU.EDU Subject: Orbital Debris To: space-tech@CS.CMU.EDU Marc Ringuette writes: > My first idea is to have a very-large-surface-area setup where you try to > vaporize small bits of debris. For instance, a mylar sheet or some sort of > ultra-light foam. > > ... > > Actually, I have a better idea than a single film: two or three mylar films > spaced far enough apart that when debris strikes one, if it breaks up at all, > the fanned-out secondary debris hits the second sheet, and again for the > third. It may allow you to destroy much larger chunks of stuff because it > forces each object to come into contact with a larger surface area of the > sheet (as opposed to just punching a tiny little hole). This is assuming > objects break up, as opposed to just lose a few molecules off the surface. > > I wonder if you take your average small object and run it into a film at a > few km/s, what happens? What's a representative sample of debris? Marc, We also are basically keen on the idea of vaporizing debris. I do not know enough about hypervelocity collisions to say whether or not a small piece of junk running into a mylar sheet will generate enough heat to be destroyed. Some issues here are: 1) you have to consider the relative velocity 2) larger pieces will just make holes in the sheet it seems 3) if a collision does generate enough heat to vaporize the particle, might it not generate enough heat to cause the whole mylar sheet to "catch fire" and burn up 4) you can really only put a sheet like that in one orbit, it would be hard to move it from orbit to orbit for each piece of debris. And there are not too many pieces of debris in the same orbit. Thus, it can only take out a few particles. We have considered some form of encapsulation for bigger pieces of junk. Not too sure about what to yet, however. The scenario we are starting to look at real closely is to have some sort of craft with an engine on the back and a high power laser of some sort attached to vaporize small particles. The front of the craft would be a collector for larger, "non-vaporizeable" particles. When the collector was full, it could be started on a trajectory toward the Sun and the rear of the craft could be separated for re-use. We are looking at possible using an ion engine for our craft. We are not too concerned with the time span, a mission of 5 years or so would not be bad. As long as we are decreasing the amount of debris in orbit, we are being beneficial. Comments on this scheme from everyone would really be helpful. About the idea of using a gun to shoot down particles: not too sure about this. Again, I don't have enough info about hypervelocity collisions to say too much. But several particles have resulted from collisions between satellites or explosions of boosters. You get the idea. You might could use the collision to push the debris into a lower orbit, from which it would decay faster and then burn up. But I am not sure. Not too comfortable about putting up any more particles (i.e. bullets). So those are my comments. What do you think? Steven Deterling SPD7924@TAMVENUS on BITNET ------------------------------ To: SPD7924%TAMVENUS.BITNET@VMA.CC.CMU.EDU Cc: space-tech@CS.CMU.EDU Subject: Re: Orbital Debris Reply-To: jerbil@csvax.caltech.edu Date: Thu, 05 Oct 89 12:06:17 -0700 From: Joe Beckenbach Steven, Good commentary on the problems of sheets for collecting debris. In general, it's not too useful, but it should still be kept as part of the 'bag of tricks' for when some craft decides to shed particles in a common orbit (ie someone decides to empty the latrines :-). The laser&collector craft you envision seems a good way to go, though I'd rather see it return to a depot in near-Earth space. Perhaps this would make an interesting GetAway Special type of mission -- especially if you can do a "sample return" and let the materials scientists study the results. [Hey you -- stop drooling on my keyboard! It's only a concept! :-] The worry I have about shooting down debris is that if you're not careful you'll plow through the target and shattering it without having a chance to change the orbit of its center of mass. I'd much rather see it vaporized, or collected for recycling or sale as sovenoirs (better make sure the marketing guys know how to spell that word correctly :-). As for encapsulation: for anything too big to vaporize but too small to grab easily, perhaps spray on some foam concrete or let it plow through layers of foam metal, something either to increase its size or to slow it down so it will either embed or decay. I think this is the basic idea that everyone's been trying to figure out how to do. > So those are my comments. What do you think? I think they're pretty good. Someone somewhere should have already put through a brainstorming session about these matters. Joe Caltech CS department --- Joe Beckenbach jerbil@csvax.caltech.edu (818) 356-6767 ------------------------------ Date: Thu, 5 Oct 89 12:16:46 PDT From: Joe Private Pilot To: SPD7924%TAMVENUS.BITNET@VMA.CC.CMU.EDU, space-tech@CS.CMU.EDU Subject: Re: Orbital Debris How about using ice (or something else that would dissipate) as a target for the junk to smack into. If the front end was a block of ice, in an orbit counter to the debris, you ought to be able to get rid of most of it either by; vaporizing it in the collision, decaying its orbit by absorbing some momemtum, or capturing it. Any fragments of ice would sublimate after some period of time. Problems: Could end up with more pieces of junk then you started Must keep the ice block frozen Does the ice really go away? How long? Is there any way to just slow the stuff down so its orbit decays? Cloud of Gas? Magnetic Fields? Light pressure? -Tom ------------------------------ Date: Thu, 5 Oct 89 15:29 EDT From: KEVIN@A.CFR.CMU.EDU Subject: Re: Orbital Debris To: space-tech@CS.CMU.EDU X-VMS-To: CMCCVB::IN%"space-tech@cs.cmu.edu",KEVIN Cleaning orbital junk, eh? Well, thought I should mention a little idea that produces the _nastiest_ gleam in Pentagon gnomes... Most orbital junk is in reasonably low orbits - pieces of boosters, bolts, screws, paint flakes, old LEO satellites that are long since dead. Eventually the remenants of the atmosphere at LEO will slow these objects enough so that they reenter. They burn up, little bits of booster dust mix with vaporized meteors which fall unnoticed, and everyone's happy. But it takes soooooo long for these darn things to decay. If only the atmosphere did a better job of slowing them down, at least for a little while... Enter the little men in white shirts and wire-frames, with little plastic pocket protectors. They smile at the brass hats. "We have a solution to the orbital debris problem. Detonate a large, clean (relatively clean, of course - all things are relative) thermonuclear device in the upper atmosphere. It will cause a large and temporary 'hump' in the atmosphere, thus greatly slowing the orbital junk, which will soon reenter. After the 'hump' subsides, relaunch the satellites of your choice. This cleans out debris in _all_ orbits which intersect this rather large 'hump.' If you don't get them all, use a larger device, or do it repeatedly." Slowly, the brass hats start to smile. This would mean getting to use some of their BIG toys... I wish I was spinning this out of imaginary cloth. I have seen serious (!) suggestions for creating such an atmospheric 'hump' to slow/divert/destroy ICBM's - and if it works for high suborbital missiles, it should work for LEO debris, which should be at the very least less aerodynamic. Before I'm flamed, let me emphasize - "Not on MY planet, monkey boy!" Just thought I'd chuck it in for amusement... kwr kr0u+@andrew.cmu.edu ------------------------------ Date: Thu, 5 Oct 89 17:18:56 EDT From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. To: space-tech@CS.CMU.EDU Subject: Re: orbital debris I'm not sure, but it might not be necessary to remove all of the debris to greatly reduce the chance of a harmful collision. Presumably, most modern launches are made west to east, and end up in a roughly circular orbit. If absorbers moving in such orbits could eventually trap most of the debris not moving in such a manner, then it seems to me that the highest-velocity collisions would be greatly reduced. It would still be a major undertaking, and I'm not sure what damage the lower-speed collisions would be capable of causing. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: Thu, 5 Oct 89 19:45:27 -0400 (EDT) From: "Jon C. Slenk" To: space-tech@CS.CMU.EDU Subject: Re: Orbiting Junk Hmm... Space junk, huh? Like left over satellites, debris of all sorts of metals... This sounds like useful material for someone who wants to start up a space station. I have heard it said that one of the most important and most difficult things to do is to get mass up into orbit. Well, if you get your station going, you really don't have to worry: just claim all the `junk,' sort it, and use what is worth using! I would like to know what sort of `junk' is up there. Is it the remains of Shuttle toilet functions, or is it mostly satellites that have died and noone cares to get / fix / destroy? If it is the latter, we may have some nice salvage on our hands. -Jon Slenk / js9b+@andrew.cmu.edu ------------------------------ From: henry@utzoo.uucp To: cs.cmu.edu!space-tech@cs.toronto.edu Subject: Re: Orbiting Junk Date: Fri, 6 Oct 89 11:49:38 EDT The main problem with doing anything useful with the space junk is that it's all in different orbits, so you have to retrieve it before you can use it. Unless you've got a propulsion system rather better than chemical rockets, it's probably a net mass loss to try. > I would like to know what sort of `junk' is up there. Is it the remains of > Shuttle toilet functions, or is it mostly satellites that have died and noone > cares to get / fix / destroy? If it is the latter, we may have some nice > salvage on our hands. The shuttle toilet retains solids, with only urine etc. ejected, and that evaporates into space quickly. There are a lot of dead satellites, as well as dead boosters and bits of booster hardware. Numerically the biggest contributors to the junk problem are explosions, both deliberate (old antisatellite tests) and accidental (spent stages building up pressure in their tanks and blowing up). Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ From: henry@utzoo.uucp To: cs.cmu.edu!space-tech@cs.toronto.edu Subject: Re: Orbital Debris Date: Fri, 6 Oct 89 11:54:57 EDT > ... Detonate a large, clean > (relatively clean, of course - all things are relative) thermonuclear > device in the upper atmosphere. It will cause a large and temporary > 'hump' in the atmosphere, thus greatly slowing the orbital junk... Fortunately, this plan is not only ill-advised but illegal. (It would violate the test-ban treaty, which has been ratified by the US Senate and therefore is the law in the US.) However, the possibility of such a thing is worth bearing in mind for major emergencies, such as the all-too-plausible runaway replication of junk. Once the junk density goes past a certain point, not too many years away at current rates, collisions will drive the density rapidly upward and spaceflight is in deep trouble. There are worse things than a nuclear explosion or two. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ From: henry@utzoo.uucp To: cs.cmu.edu!space-tech@cs.toronto.edu Subject: Re: Orbital Debris Date: Fri, 6 Oct 89 13:55:12 EDT > Is there any way to just slow the stuff down so its orbit > decays? Cloud of Gas? Magnetic Fields? Light pressure? Jordin Kare has observed that the kind of 1MW laser that would be used as a feasibility-test system for a laser launcher could also be quite useful in sweeping up debris. It could vaporize very small pieces, and could de-orbit larger ones by blowing pulses of gas off their leading surfaces (a laser retrorocket). Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ From: ihlpl!lukas@att.att.com Date: Fri, 6 Oct 89 10:05 CDT >From: ihlpl!lukas (John A Lukas +1 312 510 6290) To: space-tech@CS.CMU.EDU Subject: Orbital Debris It seems to me that the best way to get rid of the junk would be to use it for reaction mass. If you had a satellite whose only job was to bounce around in EO, collecting the junk, and then throwing it (in some unspecified manner) in a direction calculated to: 1) Change the orbit of the junk in such a way that it will intersect more of the atmosphere, either by making the orbit more elliptical, or simply by slowing the junk down sufficiently that the orbit would more quickly decay. 2) Change the orbit of the satellite in such a way that it will be able to capture the next piece of junk. And so on. Of course, this would take some rather sophisticated radar and programming (not to mention accuraccy in "throwing"), but there would be no particualy hurry, especially if our "junkman" did not need to be monitored very closely. Im sure that it would need some ability for fine adjustments in its orbital characteristics (other than the thrower), but perhaps this could come from an ion engine using junk as reaction mass, or, if chemical engines, perhaps it could be refueled. Most of its delta-v would come from the thrower. And if it needed to "throw" a piece of junk more than once, so what? As I said, there is no particular hurry. Just a thought. John Lukas att!ihlpl!lukas 312-510-6290 PS. Please note new email address. ------------------------------ Date: Fri, 6 Oct 89 14:58 EDT From: K_MACART%UNHH.BITNET@VMA.CC.CMU.EDU Subject: Orbiting debris To: space-tech@CS.CMU.EDU X-Original-To: space-tech@cs.cmu.edu, K_MACARTHUR Would it be more energy efficient to use narrow beam microwave bursts with high power output? The frequencies could be tuned to resonate (i.e. heat up) different substances of different sizes (probably small sizes for this method). You would still need megawatts of power, but it would be spread more. Of course you don't want to aim at paths of live satellites, but look at the bright side, in some star system many years later a very bright radio source will be discovered (more power than our omnidirectional radio and tv broadcasts have been). Anythings got to be more reasonable that thermonukes. Anyone remember a short-lived, badly acted sci-fi sitcom called "Quark"? The guy's job was to cruise around the major travel lanes and scoop up space debris with his ship. It was amusing at the time, I think it starred Richard Benjamin. Tangentially, Korac MacArthur Disclaimer: I wish I had a job where I had to use a disclaimer. UNH isn't important enough to worry about its image. ------------------------------ End of Space-tech Digest #38 *******************