Date: Thu, 26 Nov 92 05:06:07 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #460 To: Space Digest Readers Precedence: bulk Space Digest Thu, 26 Nov 92 Volume 15 : Issue 460 Today's Topics: Dante on "Nightline" GPS handheld receivers (2 msgs) hypergolics (was Re: Pumpless Liquid Rocket?) manned vs. unmanned spaceflight Not at Caltech? (was Re: NASA Daily News for 11/24/92 (Forwarded)) (2 msgs) Shuttle replacement (10 msgs) Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: 25 Nov 92 17:36:18 From: Steinn Sigurdsson Subject: Dante on "Nightline" Newsgroups: sci.space In article <1f01stINN850@nuala.hal.COM> juan@hal.COM (John Thompson Reynolds) writes: Just out of curiosity, is there any valid Science being done by this NASA "mission" to Antartica, or is this just showboating to get some network coverage? Assuming that science is in fact being done, what does it have Why science? Is NASA now forbidden from doing engineering development and testing? to do with Aeronautics and Space? Why is NASA getting involved in oceanography? I can see them supporting other organizations such as NOA, but I can't see why they would be "stealing the limelight". Because they're paying for it? | Steinn Sigurdsson |I saw two shooting stars last night | | Lick Observatory |I wished on them but they were only satellites | | steinly@lick.ucsc.edu |Is it wrong to wish on space hardware? | | "standard disclaimer" |I wish, I wish, I wish you'd care - B.B. 1983 | ------------------------------ Date: Tue, 24 Nov 92 21:58:39 EST From: Dan Shoop Subject: GPS handheld receivers Newsgroups: sci.space dhopkins@gpsemi.lincoln.com (Dave Hopkins) writes: > Is the market for GPS handheld receivers is really as big as we've been > lead to believe? What use will long, lat and alt be to anyone unless it > it is fully integrated into a navigation system? The New York - New Jersey Trail Conference uses them for mapping trails. FARSEF | The Dan Shoop | Far Side shoop@horton.farsef.com | Expeditionary ATTnet: 201.612.0895 | Force PagerNet: 800.225.0256 #92664 Snail: 127 E Prospect 07463 Give your child mental blocks for Christmas. ------------------------------ Date: 26 Nov 92 04:05:00 GMT From: Philip Young Subject: GPS handheld receivers Newsgroups: sci.space In article dhopkins@gpsemi.lincoln.com (Dave Hopkins) writes: >Is the market for GPS handheld receivers is really as big as we've been >lead to believe? What use will long, lat and alt be to anyone unless it >it is fully integrated into a navigation system? On Tuesday night (22nd NoV) "Beyond 2000" (*) showed a segment on smart cars which had GPS receivers mounted as a navigation aid. Evidently the folks who are test driving the vehicles are wrapped. Not exactly hand-held, but small & mobile, and could conceivably become ubiquitous. * Science and technology show in Australia, on channel 7. Best show on TV, IMHO. -- Philip R. Young Data General Australia Pty. Ltd. ------------------------------ Date: 26 Nov 92 02:32:23 GMT From: "Charles R. Martin" Subject: hypergolics (was Re: Pumpless Liquid Rocket?) Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: If you're willing to settle for a hybrid liquid/solid combination, water and aluminum foil work once you get them started. Aluminum is difficult to ignite but is a *ferocious* fuel, enough so to rip oxygen out of water molecules. Oooh, I like the sound of this. I have this image of Our Hero improvising a rocket out of materials available in the USS Enterprize's kitchen. (Old Generation, of course. NG people would just use the replicator.) What would it take to light it off? Would thermite be sufficient? -- Charles R. Martin/(Charlie)/martinc@cs.unc.edu Dept. of Computer Science/CB #3175 UNC-CH/Chapel Hill, NC 27599-3175 3611 University Dr #13M/Durham, NC 27707/(919) 419 1754 "Oh God, please help me be civil in tongue, pure in thought, and able to resist the temptation to laugh uncontrollably. Amen." -- Rob T ------------------------------ Date: Thu, 26 Nov 1992 03:05:23 GMT From: Robert W Murphree Subject: manned vs. unmanned spaceflight Newsgroups: sci.astro,sci.space jregehr@topper.ksu.ksu.edu (John David Regehr) writes: >Sorry if this is a dead subject, but I've only been reading this group for a >week or so. I'm writing a paper contrasting manned and unmanned spaceflight. >I'm in the middle of a couple of books, but I haven't been able to come up >with a good thesis statement yet. I would appreciate hearing from people who >have opinions on the subject, or who can suggest some good reference material. >I am trying to approach this from a practical and philosophical standpoint, >rather than detailing the historical controversy on whether the focus of space >exploration should be on manned or unmanned flights. Thanks. Your really going to get overwhelming pro-manned space from these groups. Nick Szabo sometimes posts antimanned stuff. Have you read "and the heavans and the earth" by Walter Mcdougall, Bruce Murray's new memior Journey to the Planets and his old book, before he became a politician, navigating the future, there's a new book by somebody burrows who wrote "deep black" on the politics of satellite reconaissance. The burrows book, whose title excapes me, is probably the best single peice. If you haven't read "the right stuff" by Toma Tom Wolfe on how astonauts became somebody instead of nobody you should either read it or watch the movie. I have an extensive anti-manned bibliography that I would be willing to share if you'll give me your address. Since your in Kansas you might call me, I',m in oklahoma my number is (405)-447-7590. I have shared my bibliography with others who have written policy statements on men vs machines, here at OU. Also, I lobbies against the space station in 1991. ------------------------------ Date: 25 Nov 92 19:50:35 -0600 From: Bill Higgins-- Beam Jockey Subject: Not at Caltech? (was Re: NASA Daily News for 11/24/92 (Forwarded)) Newsgroups: sci.space In article <1992Nov25.002729.8201@news.arc.nasa.gov>, yee@atlas.arc.nasa.gov (Peter Yee) writes: > Daily News > Tuesday, November 24, 1992 24-hour audio service at 202/755-1788 > % Fourth Town Meeting to take place in Pasadena Thursday, Dec. 3; Urk! This may not be true. > The fourth in NASA's series of Town Meetings will take place next > Thursday, Dec. 3, on the Pasadena campus of the California Institute of > Technology in the Ramo Auditorium. The Town Meetings include > presentations by top NASA officials and invited individuals from > universities and industry in the region of the meeting. Members of the > audience have several opportunities during the 4 1/2-hour long events > to raise questions or comment on the presentations. As with the > previous three meetings, the Pasadena Town Meeting will be covered live > on NASA Select television. At the Indianapolis town meeting on Friday, Goldin mentioned that they had moved it from Caltech to another campus. Sorry, my notes don't show just where. I think somebody forgot to inform the PAO apparatus at NASA HQ. If you intend to go to the LA-area meeting (I encourage it, it was more interesting than I thought it would be, and I think NASA should hear from Our Kind Of People), check with the Town Meeting Office at (202)453-3006, or fax a request to (202)755-0207. Of course, they'll be closed Thursday, and I'm not sure about the rest of the weekend. But you can get them Monday. Also, beware of location info in these Daily News reports. They got the location wrong on the Indianapolis meetings, too. Bill Higgins, Beam Jockey | "I'm gonna keep on writing songs Fermilab | until I write the song Bitnet: HIGGINS@FNAL.BITNET | that makes the guys in Detroit Internet: HIGGINS@FNAL.FNAL.GOV | who draw the cars SPAN/Hepnet: 43011::HIGGINS | put tailfins on 'em again." --John Prine ------------------------------ Date: Thu, 26 Nov 1992 10:19:13 GMT From: Ron Baalke Subject: Not at Caltech? (was Re: NASA Daily News for 11/24/92 (Forwarded)) Newsgroups: sci.space In article <1992Nov25.195035.1@fnalf.fnal.gov>, higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes... >In article <1992Nov25.002729.8201@news.arc.nasa.gov>, yee@atlas.arc.nasa.gov (Peter Yee) writes: >> Daily News >> Tuesday, November 24, 1992 24-hour audio service at 202/755-1788 >> % Fourth Town Meeting to take place in Pasadena Thursday, Dec. 3; > > >Urk! This may not be true. > The location for the Dec. 3 Town Meeting has been changed to Cal State Dominquez Hills. I've already informed Charles Redmond who puts out the NASA Daily News. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Learn to recognize the /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | inconsequential, then |_____|/ |_|/ |_____|/ | ignore it. ------------------------------ Date: 25 Nov 92 17:47:43 From: Steinn Sigurdsson Subject: Shuttle replacement Newsgroups: sci.space In article <1992Nov25.192740.634@iti.org> aws@iti.org (Allen W. Sherzer) writes: In article <25NOV199211262560@judy.uh.edu> wingo%cspara.decnet@Fedex.Msfc.Nas.Gov writes: >>To date it has never been done. Shuttle flights are so expensive >>that it isn't likely it can ever be done. You would need to return >>at least five or so satellites. >I seem to remember several satellites that were returned and later launched >on other vehicles. You are referring to the two Palpa communication satellites. It was about all the Shuttle could do and it cost the taxpayers hundreds of millions in launch subsidies. We spent half a billion $$ to recover $75 million worth of satellites. Only a NASA employee could consider that a good deal. Come on Allen, you can't charge the whole cost of the flight to the rescue, this has been hashed out a dozen times - >Also there was LDEF that is contributing greatly to >lowering the cost of all of the other spaceflight missions due to the >information gathered ERROR: You are assuming LDEF as is was the one and only way to get this infromation. This is incorrect. True, but just exactly who was doing it a different way? As LDEF is it as of now should not all the benefit derived from it be credited to the shuttle program? Irrespective of whether it would have been better&cheaper some mythical other way? >>Would you consider a pickup truck which only worked one day a week and >>cost $200 per mile to operate 'working hardware'? I wouldn't which is >>why I don't consider Shuttle working hardware. >We are not talking about pickup trucks It's called an analogy. If you don't know what that is or can't deal with it, then remove this part of the thread. Otherwise tell us all if you think the truck works. Ooh, I love analogies: so, Allen, would you argue that an Aircraft carrier is best left anchored in mid-ocean and the planes flown in? After all, it seems silly to sail the thing back and forth all the time when what you really want is a launch platform for aircraft (somewhere) in the ocean, no? Delta Clipper is fully reusable. That means it isn't likely the controller was miswired. If it was miswired, the DC couldn't have flown to the spaceport. Maybe we should wait for the thing to fly before making these claims? +----------------------150 DAYS TO FIRST FLIGHT OF DCX----------------------+ | Steinn Sigurdsson |I saw two shooting stars last night | | Lick Observatory |I wished on them but they were only satellites | | steinly@lick.ucsc.edu |Is it wrong to wish on space hardware? | | "standard disclaimer" |I wish, I wish, I wish you'd care - B.B. 1983 | ------------------------------ Date: Mon, 23 Nov 92 17:42:47 PST From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space.shuttle,sci.space >By the way Henry, I found out some interesting stuff there are three versions >of the Saturn V first Stage. These are as follows > >S1C-T Test Stage for Manufacturing and Ground firings > This is the one at the Alabama Space & Rocket Center > >S1C-D Dynamic Test model. Was later scrapped at the end of > the program. > >S1C-1,2,3.... Flight Saturn S1 C stages. > I don't know the true designations, but I think that the S1C-D that you said was scrapped is presently on display near the VAB at Kennedy Space Center. It was part of the AS-500F vehicle used to test the Kennedy facilities in 1966. At least, I'm pretty sure that AS-500F is on display at the Cape. -Brian ------------------------------ Date: Tue, 24 Nov 92 18:05:51 PST From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >>Shuttle certainly does not have 'twice the lift capacity' of Titan IV as >>an earlier poster contended, but it does have about one-third more, I >>believe. > >The new Titan SRMs will close most if not all of that gap. > Allen As long as we're talking about future upgrades (the new Titan SRMs) then we can also consider the Space Shuttle's Advnaced Solid Rocket Motors. Titan IV / IUS maximum payload: 49,000 lbs. Space Shuttle maximum payload: 55,000 lbs. Titan IV / Solid Rocket Motor Update maximum payload: 55,000 lbs. Space Shuttle / Advanced Solid Rocket Motor maximum payload: 65,000 lbs. I won't argue with you other points, but this one is more than "most if not all of the gap". -Brian ------------------------------ Date: Tue, 24 Nov 92 21:17:20 PST From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >I think (USSR?) Shuttle is only rocket to have killed crew during >the boost phase. We've got to replace it before it happens >again. Get rid of those damn SRBs. If they're no good on a titan >then they're no good on the shuttle. Everytime I watch a launch >I find myself holding my breath for the 2 minutes it takes to >expend the SRBs. > >-- >Thomas Clarke Oh, now stop harping on the SRBs. It wasn't the Solid Rocket Booster which led to the loss of Challenger, it was those ninnies in NASA and Thiokol management. They're the ones that said "37 degrees? Sure, let's go ahead and launch it..." On a related topic, why on Earth didn't NASA just put those joint heaters on the SRB back in '86 and start flying again, fixing the other problems one at a time through a reduced flight rate? Ah... politics. -Brian ------------------------------ Date: Tue, 24 Nov 92 21:18:43 PST From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >In article <1992Nov24.062745.4287@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) w r >ites: >Notice NASA is funding the 4 great >observatories. if ASTRO was so great, they'd fly it more. > Actually, the AXAF has been broken down into two missions, with a third, (X-ray Timing Explorer) now being planned, too. It's a "Good Observatory" now, but not "Great". :-) Meanwhile, the Space Infrared Telescope Facility in unfunded. >judging how often >LDEF, ASTRO and SPacelab have flown over the last 12 years, i dont think >people are dying for those missiions. > Spacelab has flown ten times, in it's various configurations. That's about one flight per year the Shuttle has been flying. Shuttle has been flying eleven years. By the time the 12th anniversary comes around next April, we'll have added two more Spacelab missions. (D-2 and ATLAS-2) Hopefully. We can do better, of course, but that's not so bad. >>wasteful. Might as well bring down a satellite or two at the marginal >>cost of a little maneuvering fuel. > >I think this is easier said then done. Henry, Alan???? > See my previous post. STS-41C sort-of did that, STS-51A really did. >Nonsense. a booster destroyed by the RSO is part of a planned process. >All previous manned missions had emergency escape provisions for the >crew during boost. I cant remember wether apollo used a escape rocket >or the SM engines, but the crew could get clear. certainly not fun, >but probably no worse then ejection seats. certainly any manned vehicle >would have this capacity. Henry, does the Soyuz have an escape rocket???? > >>>>the idea of a powered descent and vertical >>>>landing gives me the willies... >>> >>>Much safer than airplanes for most people. A DC crash will only affect the >>>Spaceport. When aircraft crash they tend to kill people on the ground. >> >>And a Shuttle crash landing is that of a glider, no boom, and perhaps >>survivable by the crew. Plus who says the SSTO will crash on the Spaceport >>grounds, few aircraft do. If they have a guidance failure, it might be >>downtown Disney World. All those kids, consumed in flaming rocket fuel, >>I can see the headlines now. >> >remember it is a piloted >powered vehicle. if the ILS screws, the crew is still able to visualy >guide as well as get instructions from ground control. At Mach 24, it doesn't take long for things to get out of hand. Remember that Scott Carpenter missed his landing zone by so much that Walter Cronkite was about to pronounce him gone. There are many incidences of off-target returns in the Russian space program too. What would that do to Delta Clipper? ("Ah! Set her down in Golden Gate Park! Everybody remember where we parked!") >Besides, a DC flies on LOX/LH. coming in it should be low fuel and >LOX/LH does not really explode effficiently. Actually, I'd rather it have enough fuel to buzz around in search of a clearing. We don't want a repeat of Apollo 11's 20-seconds-of- fuel-left when they're are populations down here! Besides, most of that explosion we saw on 28 January 1986 was the result of uncontrolled burning of LH2/LOX. I watched that from my back yard, and I wouldn't want one of those on top of Orlando. -Brian ------------------------------ Date: Tue, 24 Nov 92 21:17:58 PST From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >In article <1992Nov24.062745.4287@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) w r >ites: >>Deadheading is never cost effective. But that's a management problem, >>not a Shuttle problem per se. If you have to charge an entire Shuttle >>mission against a satellite return, then it is expensive, > >To date it has never been done. Shuttle flights are so expensive >that it isn't likely it can ever be done. You would need to return >at least five or so satellites. Not exactly, Allen. The Solar Max repair mission came pretty close to this in 1984. If the STS-41C crew had been unable to repair Max, they would have brought it home. This flight had carried the LDEF satellite into orbit and then gone on to repair Solar Maximum Mission. And then there is the STS-51A mission in November, 1984 which did EXACTLY that. STS-51A launched the Anik D-2 and Syncom IV-1 satellites for commercial organizations. A couple of days later, the crew captured and stowed Westar VI in the payload bay. Then they captured and stowed Palapa B-2 in the payload bay. Both were returned to Earth. By the way, both satellites were relaunched in 1990 by a Long March III and a Delta. >So? When a Titan goes boom the crew has a very good chance of surviving. >There hasn't been a Titan failure which would have resulted in loss of >crew for at least 10 and more likely 20 years. > Oh, PLEASE! Do you HONESTLY believe a crew would have survived the April, 1986 Titan 34-D launch failure? Like Challenger, there was no warning... only close scrutiny of the telemetry indicated a problem (well after the fact). I doubt even an Apollo LES would have been able to fire before that cataclysm enveloped the spacecraft, assuming, of course that a crew would have known to pull the lever. This failure occured so close to the ground, that the Vandenberg launch pad was wrecked. >If your in Shuttle, true enough. On the other hand if your in a Delta >Clipper made of much simpler components (less likely to fail) and with >abort modes throughout the entire flight envelope it is a great deal >of comfort. > > Allen Except of course, the RL-10 engine, which has now failed in flight twice in the past eighteen months. Remember what I said about 'rocket engines having a way of conking-out at innoportune times?' -Brian ------------------------------ Date: Thu, 26 Nov 1992 03:29:17 GMT From: "Allen W. Sherzer" Subject: Shuttle replacement Newsgroups: sci.space In article <70245@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) writes: >As long as we're talking about future upgrades (the new Titan SRMs) then >we can also consider the Space Shuttle's Advnaced Solid Rocket Motors. Not quite what was said. >Titan IV / IUS maximum payload: 49,000 lbs. >Space Shuttle maximum payload: 55,000 lbs.... Both configurations are fairly close in terms of weight especially considering that Titan today can launch almost anything. How about this comparison: Shuttle cost: ~10,000 per pound Titan cost: ~ 3,000 per pound Now if YOU where paying the bills (and as a taxpayer, you are) which do you consider the better buy? Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------150 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Thu, 26 Nov 1992 03:46:44 GMT From: "Allen W. Sherzer" Subject: Shuttle replacement Newsgroups: sci.space In article <70267@cup.portal.com> BrianT@cup.portal.com (Brian Stuart Thorn) writes: > Not exactly, Allen. The Solar Max repair mission came pretty close to > this in 1984. If the STS-41C crew had been unable to repair Max, they > would have brought it home. I'm not sure but I doubt they could have returned Solar Max that mission. I don't see how they could have put both LDEF and the fixtures for Solar Max in the payload bay. > This flight had carried the LDEF satellite > into orbit and then gone on to repair Solar Maximum Mission. Fine. Split the costs 50% each way. Your still only breaking even (and to do that you had to ignore billions in shuttle costs). But even if you did show a small profit, it was the only time in 10 years of operation. Does that justify the $50 billion of so Shuttle has cost us? > And then there is the STS-51A mission in November, 1984 which did > EXACTLY that... Sure but at great cost to the taxpayers. We spent half a billion $$ to recover $75 million worth of satellites. Does that sound like a wise way to spend the taxpayers money? > By the way, both satellites were relaunched in 1990 by a Long March III > and a Delta. FYI, both those launches put together cost less than 20% of the cost of ONE shuttle flight. > Oh, PLEASE! Do you HONESTLY believe a crew would have survived the > April, 1986 Titan 34-D launch failure? Yes I think they would have had a 50/50 chance. When they take off one guy always has his finger on the abort button. Less than 1/5 a second would have been enough. >Except of course, the RL-10 engine, which has now failed in flight twice >in the past eighteen months. As has already been pointed out, similar failures on a DC1 would not have resulted in loss of either spacecraft or crew. > Remember what I said about 'rocket engines >having a way of conking-out at innoportune times?' Not the same thing. Reused components don't fail as often as re-used components. The fact that the spacecraft survives malfunction so problems can be repaired adds to reliability. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------150 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Thu, 26 Nov 1992 03:18:50 GMT From: Rich Kolker Subject: Shuttle replacement Newsgroups: sci.space In article jbh55289@uxa.cso.uiuc.edu (Josh 'K' Hopkins) writes: >gary@ke4zv.uucp (Gary Coffman) writes: > >(Henry Spencer) writes: >(Allen W. Sherzer) writes: >>>>>the idea of a powered descent and vertical >>>>>landing gives me the willies... >>>> >>>>Much safer than airplanes for most people. A DC crash will only affect the >>>>Spaceport. When aircraft crash they tend to kill people on the ground. >>> >>>And as any Harrier pilot will tell you, a vertical powered landing is >>>safer than a horizontal powered landing. And either one is *much* safer >>>than a Shuttle-style horizontal landing *without* power. > >>As any glider pilot will tell you, gliders don't burn on impact. Nor >>do they pinwheel across the sky when a thrust diverter fails. > >The only thing a shuttle landing has in common with a standard glider landing >is that neither uses engines. I've heard astronauts describe the shuttle >while it's landing as performing like a greased brick. If I recall correctly, >a 747 with engines off can glide better than a shuttle. To make a Gulfstream fly like ths huttle (to act as Shuttle Training Aircraft) they drop the gear, drip the flaps (make that drop), and... run the Engines in REVERSE! Needless to say, the orbiter aint much of a glider! ++rich ------------------------------------------------------------------- rich kolker rkolker@nuchat.sccsi.com It's been a long, long time -------------------------------------------------------------------- ------------------------------ Date: Wed, 25 Nov 92 20:55:50 PST From: Brian Stuart Thorn Subject: Shuttle replacement Newsgroups: sci.space >Most gliders have no fuel on board. The shuttle, however has a considerable >amount of hypergolic fuels on board for the OMS and RCS thrusters. >Which means a big explosion w/toxic gas clouds, as well as the loss of the >crew. I think that most of the OMS/RCS fuel is dumped after the de-orbit burn, leaving just enough for the maneuvering during re-entry. By the time the Shuttle touches down, it'c close to bone dry. The STS-45 landing last April test-dumped the remaining fuel in the tanks to see if it adversely effected Shuttle control. It didn't. -Brian ------------------------------ id AA06638; Thu, 26 Nov 92 00:16:47 EST Received: from crabapple.srv.cs.cmu.edu by VACATION.VENARI.CS.CMU.EDU id aa12361; 26 Nov 92 0:03:21 EST To: bb-sci-space@CRABAPPLE.SRV.CS.CMU.EDU Newsgroups: sci.space Path: crabapple.srv.cs.cmu.edu!fs7.ece.cmu.edu!news.sei.cmu.edu!cis.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!utcsri!utzoo!henry From: Henry Spencer Subject: Re: What comes after DC-1 Message-Id: Date: Wed, 25 Nov 1992 22:58:20 GMT References: Organization: U of Toronto Zoology Lines: 55 Sender: news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU In article deanr@sco.COM (Dean Reece) writes: >How long can the DC-1 stay on orbit? Will the Cryo fuels boil off? It's hard to answer detailed questions about DC-1, because it's a design concept rather than a finished design. The current notion is for a stay time of a few days. Some boiloff will occur, but the problem is not disastrous. Not a lot of fuel is needed for retrofire and landing, and modern insulation works pretty well. (IRAS and COBE were both cooled by liquid *helium*, with orbital lifetimes measured in *months*.) >How hard (how many mods) would need to be made to re-fuel a DC-1 on >orbit? Assume the fuel is there for starters. At least some of the people involved would like to see this part of the specs from the start. There is limited experience in moving large amounts of cryogenic fuels around in orbit, but it shouldn't be that hard to do. >What is the highest (circular) orbit that the DC-1 can attain if it >doesn't need to worry about fuel for landing? GEO? Not a prayer. The fuel requirement for retrofire and landing is nowhere near what's needed for that. A slightly higher LEO would be all you'd get. >Is there any technical reason that a DC-1 couldn't make it to the moon >if it could be fully re-fueled at this (maximum) orbit? Hard radiation, >Too much thermal stress...? Refuel it in (low) orbit and it should be feasible, modulo issues of in-space stay time and the details of the landing. >Assuming fuel stores (or production) on the moon, could the DC-1 support >its own weight fully fueled on luna, or would a launch cradle need to be >constructed there? At 1/6 G, it should be able to support its weight with something close to full tanks, and they won't be full after the landing. >Would it be able to return to Earth on a single >fillup, or would it need to attain Earth orbit and refuel again? The only real question is whether its thermal protection is adequate for a lunar reentry. Making Earth orbit is *more* expensive than going into the atmosphere and landing, because the atmosphere does all the braking for the landing. >Again, assuming high orbit refueling, could DC-1 make Mars? Could it >return? (a 1 way trip might still be plenty useful if the DC-1 is in >mass production and fairly cheap, compared to a custom Mars lander) For this I'd have to check numbers in more detail. I suspect you'd need some fairly serious work on stay times and the like to make this viable. Not ridiculous but not obviously practical. -- MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology -Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry ------------------------------ End of Space Digest Volume 15 : Issue 460 ------------------------------