Aucbvax.6224 fa.space utcsrgv!utzoo!decvax!ucbvax!space Fri Feb 19 04:08:17 1982 SPACE Digest V2 #109 >From OTA@S1-A Fri Feb 19 03:37:32 1982 SPACE Digest Volume 2 : Issue 109 Today's Topics: Heinlein short-story Heinlein story/ Luna City "home" "All those lovely Titans going to waste" Using Titans L-5 Society KING can't get this, so rerouting to digest instead MARCH '82 SHUTTLE LAUNCH DATE? Twisting of orbital platforms Re-Ring / my ring better than yours Re: Re-Ring / my ring better than yours ---------------------------------------------------------------------- Date: 02/18/82 1129-EDT From: GNC at LL Subject: Heinlein short-story To: space @ mit-mc I believe that the Heinlein story to which Tom Wadlow referred is "It's Great to be Back", from "The Green Hills of Earth" collection. Joe Baldassini ------- [That's the one. Thanks, Joe. --Tom W.] ------------------------------ Date: 18 Feb 1982 09:56 PST From: Ciccarelli at PARC-MAXC Subject: Heinlein story/ Luna City "home" To: SPACE-ENTHUSIASTS at MIT-MC cc: Ciccarelli ----- ...(where home will be, after a long tour in Luna City is an interesting question. Heinlein wrote a marvelous story about precisely that, whose name I can't recall) ----- Tom Wadlow -- you may be thinking of "The Menace from Earth", or of the novel "The Moon is a Harsh Mistress". Regarding "losing touch with the folks" -- regardless of the video bandwidth used to "call home", Luna citizens have the unavoidable two-seconds-plus delay between action and reaction. I think it's something you'd get used to, especially with video, but I know how annoying the 500msec "hop" delay for today's satellite-relayed long-distance phone calls can be [I got delays occasionally when calling from Arizona to Florida, when I lived in Arizona recently]. Speculation -- would cheap "picturephone" service keep people *here on the planet* from "losing touch with the folks"? /John ------------------------------ Date: 18 Feb 1982 10:23 PST From: Ciccarelli at PARC-MAXC Subject: "All those lovely Titans going to waste" To: Space at MIT-MC cc: Ciccarelli Making an analogy with computer science, I think of "finding uses for" all the computer hardware built just SEVEN years ago (memory boards with 256-bit chips, "4004" processors) that's now languishing somewhere in DOD's basement. And I soon dismiss the possibility for several reasons that are applicable to ANY quickly-evolving technology, i.e. launch vehicle design. Though the Titan would be "expendable" -- no need to "fix it" -- these arguments still hold some water [1] Spare parts availability. You cannot find replacements for many of the electronic components (logic chips, for example) incorporated into even fairly recent designs, let alone 30-year-old Titans. And even "slight" redesign (to work around parts you can't get) is out of the question. [2] Documentation. The "science" of documentation of large systems has been maturing rapidly; it may be prohibitively expensive to educate those who will be required to learn the equipment. [3] Basic advances in the state of the art. The equipment may not have the functions you need, because it was designed when those functions were too expensive, or not technically realizable, or simply not yet thought of! Likewise, your support equipment (tracking stations; telemetry programs...) may use a later, more advanced technology incompatible with the stuff you'd like to "reuse". I think we'd better total up the "hidden costs" of reusing ANYTHING before doing so. The money, time and energy might be better spent on creating low-cost spinoffs of Shuttle technology. We may find the Titan is no bargain even for FREE! /John ------------------------------ Date: 18 Feb 1982 1045-PST From: Tom Wadlow Subject: Using Titans To: space at MIT-MC Unfortunately, the computer analogy is not quite on the mark. We have Titans, but they are not in mothballs. They are in silos, surrounded by people who know the intricacies of Titan maintenance and launch procedures. If we had to re-furbish them, I would agree, but they are *supposed* to be flight-ready today. If we allow the technical expertise to disappear, they will be impossible to use. But that should not be the case yet. Admittedly, I am in favor of developing Shuttle related launch systems in any event. But the Titan scheme should be looked at before they are replaced, to see if the cost is not prohibitive. An interesting question might be: If we suddenly acquire a massive launch capability, what would we do with it?? ------------------------------ Date: 18 Feb 1982 09:00:59-PST From: E.jeffc at Berkeley To: v:space@mit-mc Subject: L-5 Society Checking over the latest Silicon Gulch Gazette, it appears that the L-5 Society has a booth at the next West Coast Computer Faire in San Francisco. I guess I have no choice but to visit their booth, as I am dying of curiosity as to what they have to say to a bunch of hackers. ------------------------------ Date: 18 February 1982 15:57-EST From: Robert Elton Maas Subject: KING can't get this, so rerouting to digest instead To: SPACE at MIT-MC COMSAT@MIT-MC 02/18/82 04:04:41 Re: Msg of Wednesday, 10 February 1982 01:51-EST To: REM at MIT-MC FAILED: KING at KESTREL; Host appears to be permanently down or not accepting mail. Failed message follows: ------- Date: 10 February 1982 01:51-EST From: Robert Elton Maas Subject: half-time power from the moon To: KING at KESTREL It would be rather silly to put a power station on the far side of the moon and make an electrical conduit to bring the electricity 1500 miles to the polar region where it would face Earth half the year, and not bring it a few hundred more miles so it'd face the Earth year around. I think your design is a straw man. The expense of that extra few hundred miles of conduit would be small compared to the money already invested, and would double the uptime. ------------------------------ From: HQM@MIT-ML Date: 02/18/82 16:34:34 Subject: MARCH '82 SHUTTLE LAUNCH DATE? HQM@MIT-ML 02/18/82 16:34:34 Re: MARCH '82 SHUTTLE LAUNCH DATE? To: SPACE at MIT-MC DOES ANYONE KNOW THE PROJEECTED LAUNCH DATE FOR THE NEXT SHUTTLE MISSION? AND POSSIBLY ANY INTERESTING GOALS OF THIS FLIGHT? (PLEASE SEND A REPLY TO HQM@AI, AS I AM NOT ON SPACE MAILING LIST) THANK YOU HENRY MINSKY ------------------------------ Date: 18 February 1982 18:21-EST From: Robert Elton Maas Subject: Twisting of orbital platforms To: CARLF at MIT-AI cc: SPACE at MIT-MC A long thin rope doesn't work because it provides only longitudinal force, no torque. If the weight pulls sideways in an effort to restore the SPS to its correct attitude, the rope just bends instead of applying torque at the other end where it attaches to the SPS or other object. You need either a small weight on the end of a long rigid object such as a beam with supports: **********-------- * * -------- * * -------- * S P S *========================WEIGHT * * -------- * * -------- **********-------- or a larger weight closer: **********====********* * * * VERY * * S P S *====* LARGE * * * * WEIGHT* **********====********* In either case the supports must be resistant to torque, thus with a long weight with support wires tapering back to opposite sides of the SPS (first diagram above) the force on the guide wires will be several times the sidewards force on the conter-weight. Does anybody have figures on the total mass of an SPS capable of supplying 10% of USA electricity needs, on the restoring torque needed to maintain its angular position within 10 degrees either way from center, the diameter of the SPS capable of holding the support wires, the proposed mass of the counterweight and its proposed distance from the SPS, and thus the tension needed in the guy wires? ------------------------------ Date: 18 February 1982 18:44-EST From: Robert Elton Maas Subject: Re-Ring / my ring better than yours To: HAGERTY at RUTGERS cc: SPACE at MIT-MC Date: 16 Feb 1982 2146-EST From: HAGERTY at RUTGERS Since then, REM and I have exchanged a couple of thoughts on the matter (COSMOS Ringed Planet...)- he feels that it would not be practical around a star for energy capturing reasons. No, you have it backwards. I said a ring around a planet as shown in Cosmos (located about 1/2 radius above the surface where orbital speed is about 12 orbits per day, but complete with about 40 columns reaching down to the surface forcing it to go only 1 orbit per day thus forcing the columns to support it from below), wouldn't be especially good for catching energy, and would be too dangerous but a ring of SPSs around the Sun would be dandy. (Sagan's planet-ring would span 8000 miles across whereas a ring around the sun would span 292,000,000 miles and thus collect 36,000 times as much sunlight if it had the same width in the polar direction and the same optical density and efficiency. Other factors are that putting stuff in orbit around the Sun costs more than putting in LEO around Earth, but putting up rigid ring with lots of physical support beams is probably much more expensive than just orbiting stuff anywhere in the solar system, so I think the ring-around-sun would be better than a ring-around-planet. Re use of ring-around-planet as spaceport. I wonder if it would be any cheaper than building a dome around the Earth to keep in the atmoshere, evacuating the air above the dome, and launching spaceships by mass drivers above the dome?? (Just for fun, imagine the environmental impact report for EITHER.) ------------------------------ Date: 18 Feb 1982 2011-EST From: C. Greg Hagerty Subject: Re: Re-Ring / my ring better than yours To: REM at MIT-MC cc: : ; In-Reply-To: Your message of 18-Feb-82 1844-EST Well, that makes sense. A dome would be quite expensive and REALLY throw off the environmental balance. One may wonder how fragile this balance really is: How much arisol-spray do you use. If you throw too many pennies into Odell Lake, fish type B will die, causing fish type A to die.. Skylab? .. NOW, Skylabs (instead of threatening the last two KooKoo birds in existance (on a hidden island of course)) along with the other falling/unfalling junk and satellites, could be harnessed togeather in the days of the space shuttle.[Yielding a ring with production possibility, political controvercy and all] Instead of killing the last 2 KooKoo birds with fallout from fusion-powered spacecraft (which could be built on the ring), we can kill them with the trivial shade of our ring (a thin ring), falling nuts and bolts, possibly the ring itself (after the explosion of a fusion-powered space ship) - but have enough fusion-powered spaceships to find another habitable planet (to breed KooKoo birds on). /Greg: ------- ------------------------------ End of SPACE Digest ******************* ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.