Date: Thu, 1 Mar 1990 15:11-EST From: space-tech-request@cs.cmu.edu To: "~/st/lists/stdigest" Subject: Space-tech Digest #50 Contents: Henry Spencer Re: No Waste In Space [ heavy launchers; ET use ] Henry Spencer Re: No Waste In Space Edward Wright Re: No Waste In Space Edward Wright Re: No Waste In Space Henry Spencer Re: No Waste In Space Henry Spencer Re: No Waste In Space Edmund Hack ETs, Debris & Orbital Mech. George Herbert Re: No Waste In Space Jim Meritt Re: No Waste In Space Rich Schroeppel Is orbital popcorn a problem? Henry Spencer Re: No Waste In Space George Herbert ET/Bootstrap Station ------------------------------------------------------------ From: henry@zoo.toronto.edu Date: Tue, 27 Feb 90 12:22:42 EST To: space-tech@CS.CMU.EDU Subject: Re: No Waste In Space > Shuttle-C will cost less to develop and come online faster > than the Saturn V only because NASA's phony "estimates" say > the Saturn would take ten years to redevelop. Bologna -- > that's longer than it took the first time! Not bologna; the agency that would be doing it this time is not the same one that did it the first time. Oh, it has the same name, and still uses some of the same buildings, but that's about the only resemblance. Many bureaucratic arteries have hardened since then, and many good people are gone. Just not having Wernher Von Braun to run the development probably adds years to the time. Worse than that, you'd have to rely much more heavily on contractors now, because all of NASA's in-house manufacturing capability (used very heavily during the Saturn program) was scrapped in the post-Apollo cutbacks. Times have changed, and NASA has changed... not for the better. If you want a concrete example, the pacing item in booster development is usually considered to be the engines. The F-1 got started when Del Tischler wrote the specs in 24 hours, had them checked and approved within a couple of days, had them to the contractors within weeks, and had major development contracts underway within months. Does anyone seriously believe that could happen at NASA today? > I'd like to see a private company start to build and sell the > Saturn V. I think you could probably finance such a project > through a public stock offering... Where's the return on investment going to come from? Who are the paying customers going to be? Re-developing and re-testing the booster and building your own launch facility is going to cost a bundle, remember. You're going to have to sell a bunch of them to pay that back. Who's buying? Not NASA, not after you've embarrassed them like that. They'll tell you "the shuttle meets our current needs, but we'll certainly consider your bid for any future project that calls for heavier launch capability"... except that you'll grow a long gray beard waiting for them to start such a project. Not the USAF, they want boosters they control. Not ESA or JSA or Glavcosmos, they have their own booster industries to support. Commercial customers? How many of them need such capacity? You're gambling that a market will develop. With luck you could get cost per kilo well below current offerings, which would help. But it's still a massive gamble. If you want to get into the booster industry, think small, not big. I'd be overjoyed to see someone revive the Saturn V -- if for no other reason, because I'm really grieved that I never got to see a launch -- but it doesn't look commercially viable right now. Small boosters are a different story. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ From: henry@zoo.toronto.edu Date: Tue, 27 Feb 90 12:54:55 EST To: ocf.berkeley.edu!gwh@zoo.toronto.edu Cc: space-tech@CS.CMU.EDU Subject: RE: No Waste In Space > Henry, you lack Faith :-) "Faith can move mountains only if it gets a bit of help from engineers." :-) > The amount of debris that an ET's insulation will > produce in orbit isn't a problem for your station; > it ought never come back and nail you any faster than > it was 'popped' off the outside... It's not a problem for your station, but it's a problem for everyone else. The odds are you will never be allowed to do it, because shedding that much debris is no longer considered acceptable, and you will not get a tank unless you revise your plans to contain the junk. We have enough trouble with unintentional debris; the last thing we need is people *knowingly* putting up hardware that will pollute near-Earth space that badly. > Orienting it for low drag and such will take some > fuel...but the drag that Freedom will produce with those > nice aerodynamic open structures will be worse. :-( > It's a factor in any design you fly, an ET based one no > worse than others. Unfortunately it *is* worse than others. What matters is mass per unit frontal area, and a big empty tank is lots worse than an open framework made out of relatively dense materials, carrying small dense modules. Molecular aerodynamics is not the same as viscous aerodynamics: what matters is frontal area, and shape is almost irrelevant. In dense air, an open framework is really bad because it drags all sorts of nasty vortexes behind it and those create lots of drag. At orbital altitude, air density is so low that the molecules don't interact with each other very much. Result: no vortexes, just individual molecules bouncing off your structure. This changes the rules. A hole in a framework doesn't cause any drag at all, the molecules just zip straight through and don't interact with the structure in any way. The frontal area matters a lot, the orientation of the frontal area matters some, and the mass of the object determines how much it is affected. A shuttle tank in gravity- gradient orientation loses on all three grounds: lots of frontal area, much of it more or less at right angles to the velocity vector, and quite low mass. Orienting the tank for low drag is the thing to do, but it requires a continuous expenditure of fuel -- the stable state is broadside-on, and you'll be fighting that constantly. That was a contributing factor in Skylab's demise. There have been proposals to use tethers in one way or another to stabilize the tank in a low-drag orientation. That would help a lot. > I do agree with not letting the tank lie around in orbit. > If we were to actually build one of these i would launch > the Titan stuff first and then fly the shuttle up to > it. Yes, that is definitely the way to do it. Among other considerations, it avoids the need to fly a remote-controlled rendezvous and docking, something the US has no experience with. On another topic, by the way, someone brought up the need for a hatch. No need; there are already inspection hatches in the tanks. I think they are covered up by the spray-on insulation, so you'll need some way to cut through it. The GRIT folks have looked at just pulling out wires previously imbedded in the insulation. This looks like it would work. (Just for laughs they tried nylon fishing line; it turned out to work better than their fancy stainless-steel wire...) Incidentally, another reason you may want to do something about that damned insulation is that it will outgas, which will upset people who want to use your tank-based station for experiments that need clean vacuum. The Space Studies Institute people have looked at using a hot-wire system to slice the stuff off, and my recollection is that it seemed workable. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Tue, 27 Feb 90 10:38:55 CST From: "Edward V. Wright" To: gwh@ocf.berkeley.edu, henry@zoo.toronto.edu, space-tech@CS.CMU.EDU Subject: RE: No Waste In Space A few days ago I noticed something in notes sci.space about NASA signing a contract with a company called Global Outposts to put five external tanks into orbit. This was part of a NASA press release, so I have to assume its official. So apparently NASA can/has found launches where it can put an external tank into orbit. ------------------------------ Date: Tue, 27 Feb 90 12:05:06 CST From: "Edward V. Wright" To: henry@zoo.toronto.edu, space-tech@CS.CMU.EDU Subject: Re: No Waste In Space > Where's the return on investment going to come from? Who are the paying > customers going to be...? Not NASA, not after you've embarrassed them > like that. Not the USAF, they want boosters they control. Not ESA or > JSA or Glavcosmos, they have their own booster industries to support. SDIO? They've bought commerical launches and are *very* happy with them, and plan to buy a lot more. If the USAF buys a Saturn V from Big Boosters Inc., don't they control it? The "Looking Glass" nuclear control center is a model 747 the AF bought from Boeing, and the Air Force seems happy enough with the degree of control they have over it. Remember, too, that commercial air freighters do handle military cargoes, some of which are even classified. You're probably right about NASA. But, despite what government bureaucrats would like, government agencies do not control their own budgets. If the Saturn V was significantly cheaper than Shuttle C, then perhaps OMB or maybe even the taxpayers would have something to say about it. ESA *might* be a customer, if they had something big to launch. Even Ariane 5 will be to small to compete with the Saturn. Japan I think would be an interesting possibility. The Japanese have been manufacturing license-built Deltas for years, but are forbidden by contract from selling them internationally. If a Japanese company bought the rights to build the Saturn V and to sell it on the global market, then you might start to see some real competition for NASA, ESA, Glavcosmos, etc. ------------------------------ From: henry@zoo.toronto.edu Date: Tue, 27 Feb 90 14:50:35 EST To: convex.com!ewright@zoo.toronto.edu Cc: space-tech@CS.CMU.EDU Subject: Re: No Waste In Space > > Where's the return on investment going to come from? Who are the paying > > customers going to be...? > > SDIO? They've bought commerical launches and are *very* happy with > them, and plan to buy a lot more... The only thing that would make them buy Saturn-V-class launches would be a decision to deploy an SDI system, which hasn't a snowball's chance in Hell of getting past Congress. (Note, this is not an invitation to debate the merits of SDI -- not appropriate for this mailing list -- but I think both pro-SDI and anti-SDI people can agree that the current Congress does not support SDI strongly enough to spend billions on deployment.) The big reason why ALS is sliding rapidly towards oblivion is that SDI no longer looks like a likely customer for lots of large launches. >If the USAF buys a Saturn V from >Big Boosters Inc., don't they control it? If they buy the *hardware*, yes, but not if they buy *launch services*. Which is one big reason why they were never very keen on the shuttle. The apple of the USAF's eye in launchers these days is Titan 4, which is entirely theirs. (If NASA wants a Titan 4, it has to go begging to the USAF for one -- the USAF, not Martin Marietta, owns Titan 4.) In any case, what does the USAF need Saturn-V-class lift for? > ...government agencies do not control their > own budgets. If the Saturn V was significantly cheaper than Shuttle > C, then perhaps OMB or maybe even the taxpayers would have something > to say about it. Unless HR2674 passes, NASA and the USAF will continue running their own launch shops at considerably higher cost than buying equivalent commercial launches, and neither OMB nor the taxpayers has yet succeeded in doing anything about this. Government agencies, and their pet contractors, do not control their own budgets, but they have considerable clout with Congress, which does. > ESA *might* be a customer, if they had something big to launch. > Even Ariane 5 will be to small to compete with the Saturn... You don't understand: as long as ESA has Ariane 5, all major ESA projects will be *defined* in such a way that they can fit on Ariane 5. Sure, they might be a customer if they had something too big for Ariane 5, but you can bet almost any amount of money that that situation will never be allowed to arise. > Japan I think would be an interesting possibility. The Japanese have > been manufacturing license-built Deltas for years, but are forbidden > by contract from selling them internationally... And they're in the process of doing something about this. Their H-2 booster will be entirely their own with no annoying licensing restrictions. It won't be Saturn-V-class, but it will be *theirs*. They are officially silent so far about whether it will be available commercially, but they are being very secretive about certain aspects of the technology, and it sure smells like they are at least preserving the option of joining in the competitive market. > If a Japanese > company bought the rights to build the Saturn V and to sell it on > the global market, then you might start to see some real competition... Remember who owns the rights to the Saturn V: the US government. Any agreement allowing use of existing plans etc. will almost certainly carry a clause forbidding major foreign involvement. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ From: henry@zoo.toronto.edu Date: Wed, 28 Feb 90 12:39:08 EST To: space-tech@CS.CMU.EDU Subject: Re: Shuttle-C economies of scale? > > ... where are the customers? The list of approved missions that could > > use heavy-lift capability is really short. > > But I thought the entire point of the Shuttle-C was that it is mostly > composed of standard Shuttle components, so that building only 3 or 4 > of them to use for space station launches would be economical? It > should require many fewer launches than the ALS to ammortize... This depends on how many wonderful new ideas are piled in as part of the project. At one point, a little bird told me that there was pressure to bundle in a major reworking of some of the ground-support facilities, which would run the bill up a lot. Nobody is going to build a new launcher just for the space station. Especially since the space-station project believes it cannot count on any new launchers, so it is still planning to cope using the vanilla version of the shuttle. If Shuttle-C is built, it will be as a generic heavy launcher for future projects. The trouble is, there aren't very many of those which actually have approval. Of course, what we have here is the standard chicken-and-egg problem, since all the project people figure they'd better not count on heavy launchers. Short of a (funded!) major new initiative that obviously has to have it, Shuttle-C is going to have to get started as a gamble, and then try to attract firm customers once it starts to look like it will actually fly. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Tue, 27 Feb 90 14:21:09 PST From: Edmund Hack Subject: ETs, Debris & Orbital Mech. To: space-tech@CS.CMU.EDU Recently sent out on space-tech: > The amount of debris that an ET's insulation will > produce in orbit isn't a problem for your station; > it ought never come back and nail you any faster than > it was 'popped' off the outside... Actually, the debris from the ET _is_ a big problem if you are in an orbit at another inclination. If you are in a polar orbit or high inclination, the debris is coming at a large angle to your flight path - a problem for the USSR and for earth observers that are in polar or sun-synchronous orbits. Or if in equatorial orbit, the debris from polar launches hits you and you get hit in any case as you climb up or drop down. Another problem with the ET/Progress scenario is that the two are in orbits that have an inclination difference of 20-30 degrees, leading to a delta-V needed that is relatively high: delta-V = 2 * orbital-V * sin (angle/2) if they are at the same altitude, with angle = difference in inclination. For LEO, orbital velocity is about 26000 fps. If angle = 20, delta-V = 9,000 fps; angle = 30, delta-V = 13,500 fps. Note that according to the Prox Ops Handbook from STS Crew Training, the Shuttle has only 750 fps of delta-V, so it can't do more than a degree or so of plane change. Another problem is that even if the objects are in the same orbit, the phases of the orbits will be different. This makes for all sorts of nasty problems in orbital transfers. For example, if you are in a 200 nm orbit and need to get to something in 1 day or less that is 180 deg. out of phase, you will need to change your orbital altitude by 75 nm. This requires (for Hohmann transfer) a total delta-V of 530 fps to drop to 125nm orbit, catch up and go back up to 200 nm. Then, you need to go back to the Station, needing another 530 fps and about another day. This is why the windows for some of the launches (like LDEF) are so tight, so that the phase differences are small. Another wrinkle to the phasing problem is that the thing you want to recover needs to have 2 days of life/thermal/power support available, more if it is life-critical. (So if the transfer vehicle breaks you can send your backup - you do have a backup don't you? It might hit a piece of debris and be disabled!) The problem with space operations blue-skying is that orbital mechanics is subtle and unforgiving. (Read "Those Pesky Belters and Their Torch Ships" in _A Step Farther Out_ by Jerry Pournelle for an interesting semi- technical essay on this.) To do things fast requires lots of delta-V - to do things efficiently takes lots of time. Edmund Hack Intelligent Systems Department Lockheed Engineering & Sciences - supporting NASA/JSC hack@lock.span.nasa.gov ------------------------------ Date: Tue, 27 Feb 90 19:56:09 PST From: gwh@ocf.berkeley.edu To: gwh@ocf.berkeley.edu, henry@zoo.toronto.edu Subject: RE: No Waste In Space Cc: space-tech@CS.CMU.EDU re. Henry's quote on faith and engineers: that's why i'm going to BE an e engineer :-) [thanks tho, Henry] With regards to the relative drags on the current space station and my proposal: Henry is of course right [silly me...] that an open framework won't be as bad in low orbit as in a real atmosphere; however, anyone who actually knows, if you can find the actual surface area of the Freedom designs, in the direction of orbital motion, I would like to compare the density per surf. area of the d two ideas [I don't have this, someone in NASA?] ANd about insulation; henry seems to have solved my problem for me :-) If it can be stripped off in orbit, then we can shove the garbage into the intertank area, or deorbit it if we have to. And about the fuel situation re. keeping oriented correctly; if we can save several billion compared to Freedom, we can buy a lot of Atlas and Titan launches with fuel :-) It's a trade off, and i have a feeling that it wouldn't be uneconomical to resupply a higher stationkeeping fuel useage than to pay for ten to thirty shuttle flights. -george william herbert gwh@ocf.berkeley.edu ------------------------------ Date: Wed, 28 Feb 90 09:24:47 EST From: Jim Meritt To: space-tech@CS.CMU.EDU Subject: RE: No Waste In Space Question on insulation: Assume that all the data from the LDEF is available. Please comment on making the tank insulation out of one of the things that apparently subliminated with the exposure/sunshine/atomic oxygen/whatever. Jim Meritt ------------------------------ Date: Wed, 28 Feb 90 09:13:03 PST From: Richard Schroeppel To: space-tech@CS.CMU.EDU Subject: Is orbital popcorn a problem? Is popcorn debris from the insulation of a shuttle external tank a real problem? It should have low mass/area, and reenter fairly quickly. Rich Schroeppel rcs@la.tis.com ------------------------------ From: henry@zoo.toronto.edu Date: Wed, 28 Feb 90 13:03:18 EST To: ocf.berkeley.edu!gwh@zoo.toronto.edu Subject: RE: No Waste In Space Cc: space-tech@CS.CMU.EDU > ...about insulation; henry seems to have solved my problem for me :-) If it > can be stripped off in orbit, then we can shove the garbage into the intertank > area, or deorbit it if we have to. This is definitely the best thing to do. However, it does add another complication, because now a fair bit of work has to be done on the tank pretty much immediately after it's orbited. > ... the fuel situation re. keeping oriented correctly... > ...It's a trade off, and i have a feeling that it wouldn't > be uneconomical to resupply a higher stationkeeping fuel useage than to pay > for ten to thirty shuttle flights. Actually, if you can pay for two shuttle flights, the problem can be solved fairly well: put up *two* tanks and trusswork to connect them. Then you can build a structure whose long axis (in mass terms) is perpendicular to the tank axes rather than parallel to it, so you can have a stable orientation with the tanks pointed along the velocity vector. You might be able to do the same thing with one tank and a counterweight of sufficient mass. (The obvious counterweight is the battery pack -- any low-orbit solar-powered station needs energy storage, since it spends nearly half its time in the Earth's shadow.) You'll still need some attitude-control fuel to keep the thing from rotating on the Earth-sky axis due to stray torques, but that's a much less demanding requirement since you're not constantly fighting gravity-gradient effects. Henry Spencer at U of Toronto Zoology uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Wed, 28 Feb 90 22:03:23 PST From: gwh@ocf.berkeley.edu To: space-tech@CS.CMU.EDU Subject: ET/Bootstrap Station Cc: gwh@ocf.berkeley.edu Just finished talking to someone from Locheed, a engineering manager in the group that they have working on the Freedom station. He had a bunch of interesting details about how his group is going to do things [mostly interiors but a hand in lots of parts]. He also was very candid about other designs that have been advanced, and i took the opportunity to ask him quite a bit about the External Tank based designs that have been done. He said that there were a number of very good ideas based on using ET's, one of which was that he likes the ET concept a LOT. For a cheap boostrap, he would have liked to have flown a shuttle with a bay full of fittings and such; the whole station would have taken a couple of shuttle flights to assemble but would be faster and easier than what Freedom will be. One concept that he was big on was orienting two ET's with a connecting structure such that the tidal pull oriented it with the tanks actually pointing into the orbital motion. I told him of my idea to fly the majority of the fittings seperately thus not making mission dependent of the shuttle [well not a lot] and he agreed with that being a good operational concern. All in all he likes that concept, and it sounded like he thought that if it wouldn't cost Locheed most of it's contracts for Freedom he would have pushed through a proposal on it. -george william herbert gwh@ocf.berkeley.edu ------------------------------ End of Space-tech Digest #50 *******************