Subject: Space-tech Digest #128 Contents: payload to orbit cost projections (2 msgs) Seeking contacts in CFD (1 msg) Railgun to orbit (7 msgs) Radio Frequency Allocation (1 msg) ------------------------------------------------------------ From: ssi!lfa@uunet.UU.NET (Louis F. Adornato) Subject: payload to orbit cost projections To: uunet!cs.cmu.edu!space-tech@uunet.UU.NET Date: Sun, 25 Oct 92 10:45:32 CST Dear space-tech, I have a multi-disciplinary question that I think would be ideally suited to this forum. For years, a debate has raged in sci.space regarding "realistic" payload to orbit costs in the near and far term. This represents a real problem; if there's no rigorously developed projection, it's pretty much impossible to do realistic planning for large space projects. It's also impossible to get any kind of private sector interest going as long as current costs are (excuse the term...) astronomical, and the future costs "anyone's guess". And without some idea of what will be the driving cost factor, any attempt to bring down launch costs is going to be more a matter of luck than science. I propose that a projection can be developed based on a study and extrapolation of maintenance, support, and turn around costs for existing transportation systems. While the margin of error for such a projection might be relatively large, the _size_ of the margin might at least be defined with some accuracy. What I'd like to do is let the list brainstorm this for a while. Then I'll write it up and see if I can pass it under the nose of an economics professor _somwhere_ , with the goal of getting some grad student to base a thesis on what we come up with. I realize this sounds like a cop out, but (1) I don't have the time, (2) I don't have the expertise, and (3) I certainly don't have the credentials needed to get a grant to do this myself. Now, here's what I have in mind: If the costs of land, sea, and air transportation are compared, there is a progressive increase in costs, due to amortization of the initial investment, operational, and maintenance costs. If we define a critical subsystem as one for which a failure has a high probability of resulting in loss of vehicle, we can see a correlation between the number of critical subsystems and effective costs. If we factor in the stresses on these subsystems, along with some measure of complexity, the correlation may become clearer. The goal would be to develop a formula that takes a number of factors into consideration. Ideally, this formula would yeild the same number for each mode of transportation; it's more likely that it would yeild similar numbers within a well defined error envelope. The list I've come up with so far of cost factors: Number of critical subsystems ----------------------------- These are subsystems in which an unbacked failure would directly lead to a situation with a high probability of in a high probability of loss of life and/or vehicle. For a motor carrier, this is limited to the steering system, the tires, and the brakes, for a ship it's the hull and bilge pumps, for an aircraft its the hull (including the wings), the engine, the control system, the langing gear, and the aero surfaces (about what you find in a Piper Cub). For a spacecraft, add: environmental control, electrical power generation, cooling, navigation system, attitude control system, reentry propulsion, thermal protection system, and a landing system (parachute?). Subsystem Complexity -------------------- My best guess is that this would be the number of moving parts in all of the critical subsystems. It might also factor in the amount of training needed by the support crew. Subsystem Reliability --------------------- This factor would cover the need for such things as regular P.M., inspections, and (indirectly) turnaround time. This might actually be redundant; it may be covered by the subsystem complexity, stress, and weight factors. It might also turn out to be completely artificial; the 1000 hrs to MOH requirement on light aricraft engines predates a lot of engine and lubrication technology improvements, and is therefore probably too arbitrary for what we want to do. Payload capacity --------------- Self explanatory Facilities ---------- Costs of support facilities (roads, railbeds, harbors, airports, terminals, air traffic controllers, ground crews, etc). This should include some fraction of the initial costs and the ongoing maintenance costs. It will therefore probably have to include a subfactor for flight frequency and may well be tied to payload capacity. An interesting point on this: in the early 1930's, flying boats where considered to be the wave of the future in large inter- continental aircraft. Reason? No need for long concrete runways. One of the byproducts of WWII was a liberal sprinkling of long runways throughout the world. Sometimes it doesn't pay to take the status quo for granted. Stress on critical subsystems ----------------------------- This would factor in things like hull stress or engine chamber pressure, and more or less assumes similar materials. Dry weight penalties -------------------- This covers the development, manufacturing, and maintenance costs associated with developing lightweight versions of critical subsystems. For example, it's a lot easier to manufacture or maintain a truck axle that weighs 300 lbs than one that weighs 5. Fuel costs ---------- This seems to be the driving cost behind most transportation pricing, although I suspect is that this is because it's so highly variable and highly resistant to internalization (and direct control). I'd venture a guess that fuel costs are _not_ the primary pricing factor for the Saudi airline. This factor should reflect the cost to purchase, transport, and store fuel, and possibly any environmental costs associated with the production or use of any particular fuel. Ok, that's what I have so far. Feel free to flame away, just make it constructive. Please note that what we're looking for here are primary factors that would contribute to the cost of putting a payload into orbit, and not the cost of onorbit operation of the payload. We want to limit the factors under consideration to those for which we can get hard numbers from other transportation industries, and then to extrapolate the figures into _goal_ figures for launch systems. We want to keep it general enough so that any particular design approach can be plugged in. I also think it would be a good idea to shy away from "future technology" and "technology on the horizon" rationales for eliminating or reducing cost factors. We'll let the people who make the breakthroughs rething the cost factors. Lou Adornato uunet!ssi!lfa | The secretary (and the rest of the company) Supercomputer Systems, Inc | have disavowed any knowledge of my actions. Eau Claire, WI | ** Space IS our future! ** ------------------------------ From: henry@zoo.toronto.edu Date: Fri, 30 Oct 92 14:02:10 EST Subject: Re: payload to orbit cost projections To: space-tech@cs.cmu.edu >I propose that a projection can be developed based on a study and >extrapolation of maintenance, support, and turn around costs for >existing transportation systems... I think there are two major factors that Lou missed: Reliability constraints. I think it is fair to say that the maintenance bill for Air Force One is higher than for an airline 747. Vehicles that must not fail are expensive. Testability. Confidence in a complex system is enormously higher if it can be tested extensively, at affordable cost, before production use. Note that there are two separate kinds of testing: testing the design (will the O-rings work in freezing temperatures?) and testing a specific vehicle (were the gyros wired backwards?). Most transport systems test the design extensively and do at least a basic checkout on each vehicle. Current space transport systems generally permit only minimal design testing (because test flights are too expensive to fly more than a few) and no vehicle testing at all (real testing requires flying). Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 27 Oct 1992 01:44:43 -0500 (EST) From: "GORDON D. PUSCH" Subject: Seeking contacts in CFD To: space-tech@cs.cmu.edu This is probably a bit outside SPACE-TECH's mandate, but it seems likely there'll be members of this group who'll be able to help, so here goes... I'm seriously thinking about trying to make a "horizontal career move" from Accelerator Physics to Computation Fluid Dynamics (the reason being that my current profession is over-specialized and under-demanded :-T). If any of you have contacts within the CFD community, or suggestions regarding how one might make such a move, they'd be muchly appreciated. I suggest responding via private e-mail to keep the bandwidth down; however if there's general interest, I'll be happy to summarize. Thanks in advance, Gordon D. Pusch ! BITnet: TASCC A&D, Stn. 49a ! AECL, Chalk River Laboratories ! Phone: (613) 584-3311, X-4107 (off.) Chalk River, Ont. CANADA ! (613) 584-2368 (hm.) K0J 1J0 ! ------------------------------ Reply-To: davidsen@crdos1.crd.ge.com Date: Tue, 27 Oct 92 09:45:08 EST From: davidsen@crdos1.crd.ge.com To: space-tech@cs.cmu.edu Subject: Railgun to orbit I was thinking the other night about a discussion which we had here some months ago. It was stated that you could not use a railgun to launch something into orbit without power on the projectile, because the orbit would intercept the ground. I don't think that's correct. While it would be correct for a body in empty space, the earth-luna system is a two body system, and I don't see any reason in theory why a launch wouldn't work, by using a fly-by on the other body. In particular I would expect to be able to hit either earth or lunar orbit from the moon. While theory is nice I don't believe we could do that from earth, because the atmosphere would add both drag and random deflection. Comments? I just looked at the back of the envelope, and didn't try to get more than ballpark figures, so there could be something I'm missing. Take as a given lunar orbits will be subject to all sorts of decay, the question is could this be done at all. ------------------------------ Date: Tue, 27 Oct 1992 11:30:23 MST From: "Richard Schroeppel" To: space-tech@cs.cmu.edu Subject: Railgun to orbit davidsen@crdos1.crd.ge.com (name?) writes > I was thinking the other night about a discussion which we had here some months ago. It was stated that you could not use a railgun to launch something into orbit without power on the projectile, because the orbit would intercept the ground. I don't think that's correct. While it would be correct for a body in empty space, the earth-luna system is a two body system, and I don't see any reason in theory why a launch wouldn't work, by using a fly-by on the other body. In particular I would expect to be able to hit either earth or lunar orbit from the moon. While theory is nice I don't believe we could do that from earth, because the atmosphere would add both drag and random deflection. Comments? I just looked at the back of the envelope, and didn't try to get more than ballpark figures, so there could be something I'm missing. Take as a given lunar orbits will be subject to all sorts of decay, the question is could this be done at all. Another possible source of perturbations is the sun. Other variations: If your spacecraft is very high, it needs only a small amount of delta-V to raise perihelion above the atmosphere. If you launch it real high, a space-tug might rendezvous with it before it falls back. This works if the average projectile contains enough fuel for one rendezvous, plus some payload. If the projectiles are small enough, the unfavorably located ones can be allowed to reenter. On the other hand, if there's a significant possibility of Earth escape, they may require tracking forever, and pollute the Earth's orbit. Rich Schroeppel rcs@cs.arizona.edu ------------------------------ From: henry@zoo.toronto.edu Date: Wed, 28 Oct 92 16:25:42 EST To: space-tech@cs.cmu.edu Subject: Re: Railgun to orbit >While it would be correct for a body in empty space, the earth-luna >system is a two body system, and I don't see any reason in theory why a >launch wouldn't work, by using a fly-by on the other body... Should work, for suitable values of "work" :-). Problem: the orbit always (ignoring fine points) passes through the point where it was last changed. That means, yes, we can get an Earth orbit by launching from Earth to a lunar flyby... but it's always an Earth orbit that swings out as far as the Moon. This is unfortunate, since low orbit is where we want to be for most purposes. We could raise the perigee using a lunar flyby and then do aerobraking to lower the apogee, but we'd still need a final rocket kick to get the perigee up out of the atmosphere. Also, to reach the Moon you need to boost essentially to escape velocity rather than just to orbital velocity. That's a lot harder; notably, the energy per kilogram doubles (or worse; I'm not sure how atmospheric effects will scale). >I would expect to be able to hit either earth or lunar orbit from the >moon... For Earth orbit, the problem is getting the apogee down. (Remember that although Earth-Moon is a two-body system, it's a very asymmetric one. Lunar effects are insignificant near Earth.) You could aerobrake. For lunar orbit, what I'd do is essentially launch into very high *Earth* orbit, by launching to lunar escape, and then treat it as getting into lunar orbit from there... which is feasible although tedious. Not if you want a low lunar orbit, though. More to the point, any of these approaches means serious complexity -- onboard navigation and maneuvering -- because they all need precision guidance. In particular, a lunar flyby is a good example of a mission that really has to have midcourse corrections, because even small velocity errors at injection get magnified horrendously as you coast up out of Earth's gravity well. (The Moon is 99% of the way to escape.) The whole point of using a railgun (etc) for launch is small dumb payloads. It's cheaper to just add a kick motor and accept some loss in payload. Henry Spencer at U of Toronto Zoology henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: Wed, 28 Oct 1992 15:03:39 MST From: "Richard Schroeppel" To: space-tech@cs.cmu.edu Subject: Re: Railgun to orbit Henry Spencer writes ... > Also, to reach the Moon you need to boost essentially to escape velocity rather than just to orbital velocity. That's a lot harder; notably, the energy per kilogram doubles (or worse; I'm not sure how atmospheric effects will scale). Vertical launch means less air to go through. Requires a short gun though. More to the point, any of these approaches means serious complexity -- onboard navigation and maneuvering -- because they all need precision guidance. In particular, a lunar flyby is a good example of a mission that really has to have midcourse corrections, because even small velocity errors at injection get magnified horrendously as you coast up out of Earth's gravity well. (The Moon is 99% of the way to escape.) The whole point of using a railgun (etc) for launch is small dumb payloads. It's cheaper to just add a kick motor and accept some loss in payload. The complexity might be concentrated in a few collection-tugs. Radar track the dumb payload as it leaves the atmosphere; this information is used to plot the tug's course. We reduce average payload to include tug fuel, but the projectiles can remain dumb. Rich Schroeppel rcs@cs.arizona.edu ------------------------------ From: ssi!lfa@uunet.UU.NET (Louis F. Adornato) Subject: Re: Railgun to orbit To: uunet!cs.cmu.edu!space-tech@uunet.UU.NET Date: Thu, 29 Oct 92 6:27:23 CST Rich Schroeppel (rcs@cs.arizona.edu) writes: > Vertical launch means less air to go through. Requires a short gun though. . . . > > The complexity might be concentrated in a few collection-tugs. Radar track > the dumb payload as it leaves the atmosphere; this information is used to plot > the tug's course. We reduce average payload to include tug fuel, but the > projectiles can remain dumb. Vertical launch means that the closing speed between the tug and the projectile will be orbital velocity (minus 900 mph rotational speed of the earth at launch point). Absorbing the shock of this impact would be on the impossible side of "pretty hard". Also, the launch timing would be critical - the tug would have to be positioned perfectly to catch the projectile as it passed through the orbital altitude. You wouldn't want the tug to be orbiting at less than 150 miles or so, and the orbital period at that altitude is around 90 minutes, plus "time off station" for the tug to deliver the projectile (although it could gather a bunch of them before changing to a "delivery" orbit. If the projectile wasn't equipped with a guidance and control system, the winds aloft would add a significant error locus to the position of the projectile at altitude, which, even with a pretty nimble tug (i.e., lots of delta-v, which means lots of payload diverted to fuel), would mean a high number of missed catches. Lou Adornato uunet!ssi!lfa | The secretary (and the rest of the company) Supercomputer Systems, Inc | have disavowed any knowledge of my actions. Eau Claire, WI | ** Space IS our future! ** ------------------------------ Date: Thu, 29 Oct 1992 12:09:59 MST From: "Richard Schroeppel" To: space-tech@cs.cmu.edu Subject: Re: Railgun to orbit Louis F. Adornato points out that vertically launched projectiles will be hard to collect in low-earth orbits. The original thread of the discussion assumed aphelions vaguely near the moon's orbit. Henry Spencer remarked on the extra launch energy required (about double the energy required for low orbit), and I remarked that there would be some savings in the air-burden, compared to an oblique or tangential launch. I note that the velocity of a circular orbit falls as R^-1/2. At the moon's distance, ~60Re, circular velocity is about 2500mph. So the collection tug will have to maneuver for rendezvous. It takes five days to fall from the moon's orbit, so there's planty of time. Alternatively, we add a bit more launch energy, making the aphelion say 10x lunar orbit; the fall time goes as R^3/2, so we have months to do the collecting. At some distance, solar gravity becomes an important factor, but I don't know the distance. I once worked out the following slightly related problem: Assume we are rail-gun launching to low earth orbit, from the surface; ignore the atmosphere. I decided that you achieved minimum "impact" velocity with your collector/space-station by making the projectile have an aphelion double that of the station, so that the semi-major axes matched, with the orbits intersecting 90 degrees after launch. In this geometry, the station sees the projectile approaching from below, at about 500mph. Someone else claimed that the best geometry was to go for tangency instead, but the arguments were inconclusive. I envisioned a catcher based on either a big net, or a bolo (the payload splits into two halves after launch, held together by a 100 meter cable; the catcher has a hook on a long cable; the payload is slowed gradually, then reeled in). Any opinions on the maximum feasible "impact velocity" for any catching scheme? Rich Schroeppel rcs@cs.arizona.edu ------------------------------ Date: 29 Oct 1992 15:23:36 -0500 (EST) From: "GORDON D. PUSCH" Subject: Re: Railgun to orbit To: space-tech@cs.cmu.edu Richard Schroeppel writes: >Louis F. Adornato points out that vertically >launched projectiles will be hard to collect in low-earth orbits. >The original thread of the discussion assumed aphelions vaguely near the >moon's orbit. Henry Spencer remarked on the extra launch energy required >(about double the energy required for low orbit), and I remarked that >there would be some savings in the air-burden, compared to an oblique or >tangential launch... > [...Discussion of how HEO-collection eases ] > [ required tug delta-V and agility deleted...] > True; it also has an additional advantage: you don't need to find as much real-estate, and you'll bother fewer of your neighbors with the shockwave- footprint, UV and/or x-rays ;-). However vertical launch makes building the railgun/coilgun/DIL harder (you need a bloody deep hole, for example...). Seriously, what is the difference in the air-burden between horizontal and vertical launch? I vaguely remember a _Physics Today_ news article on railgauns that claimed that if you launched a solid steel "telephone-pole" horizontally, you'd lose about a foot; whereas vertically, you'd only lose about *half* a foot --- not a tremendous savings (the article was discussing railgun-launching of big, robust *REALLY*-dumb payloads...). Anybody got data and/or references on this? >...I envisioned a catcher based on [...] a bolo (the payload splits into >two halves after launch, held together by a 100 meter cable; the catcher has >a hook on a long cable; the payload is slowed gradually, then reeled in)... > How about a smallish Morovec rotating skyhook in MHEO (middling-high earth orbit :-) with a modest delta-v tug on the end? The payload approacheth; the tug drops off at near-zero relative velocity to the 'load, makes a short dash to snatch it up, then scoots back to the 'hook and grabs on... One might also make the "skyhook" a circumferentially rotating *loop* rather than a single "spoke" as is usually proposed; this would require significantly more material (\pi times the saving gained by tapered cables) but simplifies timing a bit, as one could grab on *anywhere* rather than just the end-points as in a single-spoke design... I don't have my skyhook references handy, so I don't know how much mass tapering saves... I vaguely remember it's a *lot*, though; perhaps a "rimless multi-spoked wheel" would be a better design ... Gordon D. Pusch ! BITnet: TASCC A&D, Stn. 49a ! AECL, Chalk River Laboratories ! Phone: (613) 584-3311, X-4107 (off.) Chalk River, Ont. CANADA ! (613) 584-2368 (hm.) K0J 1J0 ! ------------------------------ Date: Fri, 30 Oct 1992 11:02:44 MST From: "Richard Schroeppel" To: space-tech@cs.cmu.edu Subject: Radio Frequency Allocation I snipped the message below from Space Digest. Rich Schroeppel rcs@cs.arizona.edu ============== Date: 28 Oct 92 10:48 PST From: Public Service Telecommunications Consortium Subject: Post WARC Newsgroups: sci.space On the assumption there are people on the conference concerned with telecommunications and space, I would like to solicit some views, especially from European readers. The World Administrative Radio Conference (WARC) provided a variety of allocations for new services. I am especially interested in LEOs, and the set asides for their operation. The U.S. delegation to WARC came home claiming victory; it had obtained what was wanted for Motorola's IRIDIUM and others like it. The European post- WARC view was that the U.S. should not be so sure of itself; one delegate was quoted as saying, "the devil is in the details." The "details," in this case, were the many footnotes and reservations not seen by all when the Final Acts were signed in a frenzy of late night activity. I know it is difficult to make predictions, especially about the future, but I'd be interested in informed views of how things are going to shape up, especially in light of European displeasure with the results the U.S. thinks it obtained. If you'd care to answer via e-mail, many thanks and I'm Bert Cowlan, Public Service Telecommunications Corporation, a nonprofit thinktank. Address . ------------------------------ End of Space-tech Digest #128 *******************