Date: Thu, 29 Oct 92 05:04:39 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #356 To: Space Digest Readers Precedence: bulk Space Digest Thu, 29 Oct 92 Volume 15 : Issue 356 Today's Topics: administrivia Any information on GPS ? Comet calendar Dyson's Spheres pocket satellite receivers (was Re: QUESTIONS: Apollo, Earth, Moon Re:Swift-Tuttle Comet a threat to earth? Relativistic Shuttle timing Solar Sails (2 msgs) Two-Line Orbital Element Set: Space Shuttle 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: Wed, 28 Oct 92 23:33:38 EST From: digests (Email Digest Server) Subject: administrivia Some of the messages in today's digest are 3 weeks old. Sorry about that, our mailer has been having problems, and they got queued up at a remote site. Better late than never, right? <:-) Also, apologies for the "subscription" message(s). I'd hoped the heuristic filter I installed would catch all such requests, but the long signature did me in. I've since changed the heuristics, so maybe we can go another 5 months without any sneaking by.... Mark Maimone space-request@isu.isunet.edu ------------------------------ Date: Thu, 29 Oct 1992 04:06:45 GMT From: Rafael & Subject: Any information on GPS ? Newsgroups: fj.sci.geo,fj.sci.misc,sci.aeronautics,sci.astro,sci.geo.meteorology,sci.misc,sci.space Hello out there. Sorry if I am posting this in the incorrect newsgroups, but I want some informations on GPS (Global Positioning Systems), specifically: - Limitations to work in another countries, for example, satellite orientation/disponibility, power requirements, etc. - Data capabilities (storage, communication with computers, memory, etc). - any other information. A friend of mine is very interested in buying one, to take to Brazil. I got a catalog from Sony but it was an old model, and in Japanese, so any information will be welcome. Any informations/addresses/e-mails of companys/users will be nice, too. Please e-mail it directly to me. Thanks in advance, Rafael. ------------------------------ Date: Wed, 28 Oct 92 23:18:09 EST From: John Roberts Subject: Comet calendar -From: flb@flb.optiplan.fi ("F.Baube x554") -Subject: Comet => Millennial Madness ? -Date: 27 Oct 92 12:16:49 GMT -Let's not be too Euro-centric here. -Does anyone know whether Wednesday 14 August 2126 -corresponds to any nice, round number in any *other* -calendar systems ? -I'm thinking, something like 31 Urgtember 4999. If I recall my 10th-grade history class correctly, sometime around the time of the French Revolution, France was experimenting with a weird "metric" calendar (probably ten months per year). The only month I ever heard the name of was "Thermidor"(sp?), around July or August. Apparently it didn't catch on. Perhaps some of the French readers of sci.space could comment. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 28 Oct 92 22:16:02 GMT From: Marc Fournier - Admin Subject: Dyson's Spheres Newsgroups: sci.space In article <1992Oct26.202658.154145@zeus.calpoly.edu> jgreen@zeus.calpoly.edu (James Thomas Green) writes: >Why not make the radius of the DS larger than 1 AU to avoid heating >up the inside too much? I'm not a scientist, but how would that help?? The energy would still be trapped, wouldn't it? Supposing a solid sphere, that is. Marc -- Marc G. Fournier | R-node Public Access Unix running UnixBBS 1.10 Etobicoke, Ontario | 416-249-5366 24hrs 7 days/week network email voice: 249-4230 | shell accounts available 1900+ newsgroups FREE marc@r-node.pci.on.ca | Telebit WorldBlazer/SupraModem2400/Cardinal 2400 ------------------------------ Date: 29 Oct 92 03:26:10 GMT From: Anthony J Stieber Subject: pocket satellite receivers (was Re: Newsgroups: comp.sys.hp48,comp.sys.palmtops,sci.space In article <10292302.63825.14415@kcbbs.gen.nz> Steve_Grant@kcbbs.gen.nz (Steve Grant) writes: >Company: Gessa > 45a, route des Acacias > 1227 Geneve > Switzerland > TEL: +41 (22) 427800 > FAX: +41 (22) 427805 > Contact: Eric Heiniger Thanks for posting the extra information. Here's some more that was mailed to me. GESSA is refferring calls for non-aviation calls to PALMTREE:617-871-7050. GESSA has the 'moving map' for aviation users. I would guess that their receiver uses a serial interface so it could be used an any suitable machine. Hopefully they document whatever protocol they use. -- <-:(= Anthony Stieber anthony@csd4.csd.uwm.edu uwm!uwmcsd4!anthony ------------------------------ Date: 29 Oct 92 02:33:25 GMT From: Wan Ngai Wayne Lee Subject: QUESTIONS: Apollo, Earth, Moon Newsgroups: alt.sci.planetary,sci.astro,sci.space I am posting the following questions for a friend who don't have access to the net. I will forward your electronic answers to him. You can also mail him the answers. His address is at the end. .-----------------------------------------------------------------------. | name: Lee, Wan Ngai Wayne | internet: wlee@csd4.csd.uwm.edu | | mail: 2121 E. Newport Ave.|compuserve: >internet:wlee@csd4.csd.uwm.edu| | Milwaukee, WI 53211| | |phone: (414) 963-4157 | | `-----------------------------------------------------------------------' ====================QUESTIONS=========================================== 1. QUESTION ABOUT (APOLLO) LUNAR MODULE DESCENT PROCEDURE I have read that during the descent (from lunar orbit to surface) that the astronauts passed through a "dead man's zone" during which a descent stage failure could not be solved by using the ascent stage to return to orbit. The descriptions I have read are not full. 3 questions: a. Did this only apply to the early missions or did the "dead man's zone" possibility apply to all of the moon shots? The J-missions had increased maneuvorability. b. If the descent stage would have failed, would the procedure have been for the astronauts to continue dropping to the surface or attempt an abort to orbit? c. Is the "dead man's zone" a matter of geometry, timing with CSM, fuel, or some combination? 2. RADAR TRACKING OF LUNAR-ORBITING CRAFT During the Apollo missions, was it ever possible for Earth-based radar to determine where moon-orbiting craft were? It is my impression that the answer was no. Were radio signals (from CSM or LM) ever used to pinpoint where craft were? 3. EARTH's MAGNETIC FIELD Has the prehistoric "flip" of Earth's magnetic field been proven? What may cause this in the future? Does the Moon has its own magnetic field? If I had a compass on the moon, how would it behave? 4. LUNAR FEATURES At the northern end of the Imbrium Basin, there are two pronounced natural pyramids. What is the best explanation of how Pico and Piton were formed? How was the Straight Wall formed? Can anyone steer me to an article on it (size, length, origin?) Have any low-orbit/oblique viewpoint photos been taken of the pyramids or the Straight Wall? 5. LUNAR WATER In the 1970's, I read that Apollo 12 & 14 ALSEP sensors (ION) picked up what seemed to be a water vapor emission near Fra Mauro. What would be an alternative explanation for such readings? How respectable is the notion that frozen water may exist on the moon and how would such a discovery related to moon's origin & history? By the way, Arthur C Clarke has put moon water in his 2061 novel. 6. MOON TRADING CARDS I am writing an historical survey of space gadgets. In 1969, a major trading card company issued a series about the Apollo moon landings. One of the cards showed the testing of a phone-booth-sized shower, which was in the zero-gee simulating NASA airplane. a. What company issued the cards? b. Could anyone mail me a xerox copy of the shower test? I will mail back $1.00 in postage to the first few respondants. Chris Roth P.O. Box 71065 Milwaukee, WI 53211-1065 ------------------------------ Date: 29 Oct 92 03:46:10 GMT From: "Steven Green (+61 6 276 6813" Subject: Re:Swift-Tuttle Comet a threat to earth? Newsgroups: sci.astro,sci.space In article alti@dcs.ed.ac.uk (Thorsten Altenkirch) writes: >I understand that it is pretty unlikely that Swift-Tuttle will hit >earth in 2126. However, I would like to know what would happen in the >case such a big object would collide with our planet? I am not sure >whether my memory is right but in the discussion about the >disappearance of the dinosaurs an object of a size like 200m was >mentioned. Now, Swift-Tuttle is supposed to be much bigger (10 km?)... It'd probably ruin your whole day ! -- * Steve Green * "Hey Rocky, watch me pull a rabbit outa my hat!" * * Comms Group * "That trick never works" * * ITS Branch * "Nothin' up my sleeve - PRESTO" * * CSIRO Australia * "No doubt about it - I gotta get another hat" * ------------------------------ Date: Wed, 28 Oct 92 23:30:22 EST From: John Roberts Subject: Relativistic Shuttle timing -From: bbbehr@sunspot.noao.edu (Bradford B. Behr) -Subject: Re: Smith-Tuttle Comet a threat to earth? -Date: 27 Oct 92 18:37:05 GMT -Organization: National Solar Observatory/SP, Sunspot NM, USA ->One can extrapolate on this one since the shuttle is rougly doing ->28,000 km/hr, is NASA taking into account the time distortion between ->the crew and JSC? -Shuttle velocity = 28000 km/hr = 7.78e3 m/s -Lightspeed = 3.00e8 m/s -v/c = 2.60e-5 -Time dilation formula: -T = T0 / sqrt(1 - (v/c)^2) -so dilation factor = 1 - 3.37e-10 -Mission duration = 10 days = 8.64e5 sec -so Shuttle clocks will lag JSC clocks by 2.91e-4 sec at mission end. -A third of a millisecond? Significant? Some timing links might -conceivably get thrown off by a deviation of this magnitude. But -presumably they resync throughout the mission... Since the Shuttle is moving in a circular path, you probably have to use general relativity to get a more accurate answer. Also, the fact that the Shuttle is less deep in Earth's gravity well than the surface of the Earth would cause the difference to be less than you would otherwise think. (Time passes more slowly in a gravity well than in "free space".) Atomic clocks have been placed in high-altitude aircraft, and a time difference has been measured. If NASA wants their measurements tagged with a 100-nanosecond timestamp like we use here, then they have to take the difference into account. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: Thu, 29 Oct 1992 00:13:23 GMT From: Josh 'K' Hopkins Subject: Solar Sails Newsgroups: sci.space rbw3q@rayleigh.mech.Virginia.EDU (Brad Whitehurst) writes: >In article <1992Oct28.165504.15346@ptdcs2.intel.com> greason@ptdcs2.intel.com (Jeff Greason ~) writes: >>Well, so solar sails are just "driven by radiation pressure". I'd heard >>that (as well as solar wind) before. >> >>However, If you look at the original post, you'll see my concern -- >>radiation pressure seems 2-3 orders of magnitude too small to be useful >>for drive. Recalling that F=P/c for light pressure, and that power >>density P is roughly 1.4kW/m^2 at Earth orbit, you get a pretty trivial >>4.7 MICRONEWTONS per square meter. >... > Well, I don't have any numbers, but don't forget the "solar >wind" of particles streaming from the sun. I would think it would >have a significant contribution. Actually, solar wind is pretty insignificant. Solar sails really do have low accelerations. However, since they don't require fuel, the can keep speeding up "forever." Try calculating the final speed after a year of constant acceleration. The power density also increases dramatically as you get closer to the Sun, so using 1.4 kW/m^2 for a trip to Mercury, for example, would be a very bad approximation. Using suitably huge sails, it's possible to achieve some impressive trip times for certain destinations. Jerome L. Wright has a recent book out on sail design. It's worth reading if you're interested in the details. He knows what he's talking about, though I'd like to fire his editor. -- Josh Hopkins jbh55289@uxa.cso.uiuc.edu "We can lick gravity, but the paperwork's a bit tougher." Wernher von Braun ------------------------------ Date: Wed, 28 Oct 1992 23:55:58 GMT From: Frank Crary Subject: Solar Sails Newsgroups: sci.space In article <1992Oct28.202753.10814@murdoch.acc.Virginia.EDU> rbw3q@rayleigh.mech.Virginia.EDU (Brad Whitehurst) writes: >>Well, so solar sails are just "driven by radiation pressure". I'd heard >>that (as well as solar wind) before. > Well, I don't have any numbers, but don't forget the "solar >wind" of particles streaming from the sun. I would think it would >have a significant contribution. The particle momentum is less than 1% that of the radiation pressure. However, there is a idea for using it (Zubrin's Magsail): The particles are charged, and interact with magnetic fields. In theory, a loop of current-carrying wire would refelect particles out to a few times the radius of the loop. While the momentum transfer from the solar wind is low, the mass of a wire loop (as opposed to a reflective sheet in a solar sail) is _much_ lower. This system should get overall accelerations higher than those of a solar sail, if you can use a passively-cooled superconductor for the loop (that is, a nitrogen-temperature superconductor farther from the sun than, roughly, Venus.) Frank Crary CU Boulder ------------------------------ Date: Thu, 29 Oct 1992 04:43:02 GMT From: TS Kelso Subject: Two-Line Orbital Element Set: Space Shuttle Newsgroups: sci.space The most current orbital elements from the NORAD two-line element sets are carried on the Celestial BBS, (513) 427-0674, and are updated daily (when possible). Documentation and tracking software are also available on this system. As a service to the satellite user community, the most current elements for the current shuttle mission are provided below. The Celestial BBS may be accessed 24 hours/day at 300, 1200, 2400, 4800, or 9600 bps using 8 data bits, 1 stop bit, no parity. Element sets (also updated daily), shuttle elements, and some documentation and software are also available via anonymous ftp from archive.afit.af.mil (129.92.1.66) in the directory pub/space. STS 52 1 22194U 92 70 A 92302.25000000 .00103295 00000-0 25599-3 0 184 2 22194 28.4667 79.1129 0006424 326.8112 244.4425 15.94356950 889 -- Dr TS Kelso Assistant Professor of Space Operations tkelso@afit.af.mil Air Force Institute of Technology ------------------------------ End of Space Digest Volume 15 : Issue 356 ------------------------------