Space Digest Sun, 18 Jul 93 Volume 16 : Issue 889 Today's Topics: Ariane V.58 Mission Data Clementine (ref?) GPS in space (was Re: DC-1 & BDB) (2 msgs) ISECCo Update: Travels {Cont.} message from Space Digest Moon Cable/Beanstalk. problem w/ZHR equation Von Braun Team Work & DCX (Was Where is ESA's ERIN server? Why are meteor showers seasonal? (2 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: Sat, 17 Jul 93 12:40:16 GMT From: Dean Adams Subject: Ariane V.58 Mission Data Newsgroups: sci.space ARIANESPACE FLIGHT 58 The 58th Ariane launch is scheduled to place the INSAT 2B and HISPASAT 1B satellites into a geostationary transfer orbit (GTO) using an Ariane 44L launch vehicle equipped with 4 liquid strap-on boosters (PAL) and the Ariane Dual Launch System (Mini-SPELDA). It will be the 30rd launch of an Ariane 4 and the 13th in the Ariane 44L configuration. It will be launched from the Ariane launch complex ELA 2, in Kourou - French Guiana. The launch vehicle performance requirement is 4,615 kg, of which 4141 kg are the combined satellite masses. The total vehicle mass at liftoff is 480,529 kg. Required Orbit Characteristics: Perigee Altitude ..... 200 km Apogee Altitude ... 35,911 km at injection Inclination ............ 7 degrees The Ariane 44L lift-off for Flight 58 is scheduled on Thursday July 22, 1993, as soon as possible within the following launch window: Kourou Time GMT Washington, DC 19:47 - 20:52 22:47 - 23:52 18:47 - 19:52 Launch Vehicle: Ariane 44L. This is a three-stage liquid fueled launcher with liquid fueled strap-on boosters. The first stage (L220) is built by Aerospatiale, and is powered by 4 liquid fueled Viking V engines. The second stage (L33) is built by MBB Erno, and is powered by a single Viking IV engine. Both the Viking IV and V engines are manufactured by SEP. The first and second stages use a biliquid UH25/N2O4 fuel. The third stage (H10) is built by Aerospatiale, and is powered by a cryogenic H2/O2 fueled HM-7B engine built by SEP. The four strap-on boosters are each powered by a Viking VI engine, also built by SEP, which use the same biliquid fuel as the first and second stages. The fully assembled launch vehicle stands 58 meters high on the pad, and it is equipped with the Ariane payload fairing type 02. Flight Profile: +02:31 Liquid strap-on booster jettison +03:37 First stage separation +04:26 Fairing jettison +05:43 Second stage separation +05:49 Third stage ignition +18:16 Third stage shutdown / GTO injection +20:53 HISPASAT 1B separation +23:54 SPELDA top separation +25:55 INSAT 2B separation +25:59 Third stage avoidance maneuver +29:20 End of Ariane mission 58 Payloads: INSAT 2B is the second satellite of the second generation of the Insat program for the Department of Space of the Indian Government. It has been built by ISRO to serve multipurpose domestic needs of the Indian nation. Total mass at lift-off .... 1,931 kg Mass at GEO insertion ..... 1,187 kg Dry mass .................. 911 kg On-board power ............ 1,140 W (end of life) Nominal lifetime .......... 9 years On-Orbit position ......... 83 degrees east Transmission capacity: C-band .... 18 transponders S-band .... 2 transponders of 50 W In-flight operations: Apogee motor firing 1 ..... about 26 hours after lift-off, at 3th apogee Apogee motor firing 2 ..... about 58 hours after lift-off, at 5th apogee Apogee motor firing 3 ..... about 78 hours after lift-off, at 6th apogee Solar array deployment .... about 31 hours after last apogee firing East antenna reflector deploy ... 14 hours later West antenna reflector deploy ... 10 hours later Solar sail deployment ............ 1 hour later HISPASAT 1B is the second model of the first generation of telecommunications spacecraft for HISPASAT. It is built under the main contractorship of MATRA MARCONI SPACE Toulouse, France. The operational on-orbit location will be 7 degrees east. Total mass at lift-off .... 2,210 kg Mass at GEO insertion ..... 1,330 kg Dry mass .................. 1,052 kg On-board power ............ 4,700 W (end of life) Nominal lifetime .......... 10 years Span of solar panels ...... 22.3 m On-Orbit position ......... 30 degrees west Transmission capacity: 2 channels (110W), Spain to American coverage 2 channels for America to Spain coverage 2 X-band transponders 8 Ku-band transponders (55W) In-flight operations: East antenna deployment ... about 7 hours after lift-off Apogee motor firing 1 ..... about 37 hours after lift-off, at 4th apogee Apogee motor firing 2 ..... about 92 hours after lift-off, at 8th apogee Apogee motor firing 3 ..... about 157 hours after lift-off, at 11th apogee Solar array deployment .... about 183 hours after lift-off Launch coverage: All Ariane missions are broadcast live via satellite from Kourou. Coverage begins at 30 minutes before launch, and continues until all payloads have been deployed. -{ Dean Adams }- ------------------------------ Date: Sat, 17 Jul 1993 18:07:01 GMT From: Remi Cabanac Subject: Clementine (ref?) Newsgroups: sci.space,sci.astro Hello netters, I am currently following a summer session at ISU Huntsville Alabama, and I am involved in a project to design a Lunar Farside Observatory. We decided we needed a precursor orbiter and would like info on the Clementine mission. Any help will be appreciated. ------------------------------ Date: Sat, 17 Jul 1993 18:28:41 GMT From: fred j mccall 575-3539 Subject: GPS in space (was Re: DC-1 & BDB) Newsgroups: sci.space In <226do3$hcb@access.digex.net> prb@access.digex.net (Pat) writes: >Comments like "WATW" (We Are The World) Orbit does not sound like a >positive assessment. When there are numerous good reasons to push for >51 degree, 65 Degree, 73 Degree or even 90 or 97 degree orbits. Then people should be justifying those orbits based on their merits and talking about their drawbacks (like requiring some enhanced shielding, I gather) rather than trying to justify them as "the Soviets coulc play if we launch to high-inclination orbit". Having been *briefly* exposed to reasons why a high-inclination orbit would be better, practically all of the people trying to justify it seem to spend most of their time dwelling on how it lets other nations 'play' rather than on what we (the U.S.) gain from it. So the advantages of launching to high-inclination are there (as are the drawbacks). Why so little discussion of them from any of the proponents? >The whole point of 51 Degree or higher orbit is to avoid single >vehicle dependency. >At 28.5 degrees, only the shuttle could hit SSF with anything >approaching useful payload and with existing hardware. And only the Russians can if you launch it high-inclination. Remember, there are several modules that the Shuttle can't boost to higher inclination. You'd need an Energiya launch for those. >At 51 degrees, we open to launches out of both china and Baikonur. >Possibly from pletsesk, if you don't mind a big performance hit. >at 65 degrees you open Pletsesk fully. at 73 degrees you >add in Japan. Suddenly one has a whole diverse field of vehicles >available to supplement SSF activities that one does not have >at low incliniation orbit. See what I mean? If there are advantages other than the use of Russian and Chinese hardware and launch sites, why not discuss those instead of several paragraphs on how a high-inclination orbit lets those countries play? >The rpimary onjective of SSF is to enrich a bunch of contractors. You've been listening to Ken too much, Pat. ;-) >waiting for quarterly logistics flights from the shuttle (especially with >the risk of a shuttle accident and grounding being high) is not >conducive to good station management. Placing the station in an orbit >where other vehicles can support either materials flow or >even logistics (In case of shuttle unavailability) is >in my mind good business sense. And back to the 'high-inclination is better because it lets the Russians play' justification. This is a lose insofar as a justifcation for us assuming higher costs ($400 million, at least, remember?) goes. >>I would prefer to see a flyoff between a Soyuz and a U.S. designed ACRV. It is >>possible certain hungry (George) aerospace (Retro) startups might want a crack >>at a flyoff. >Well, NASA on their ACRV studies thought it was too expensive. >It seems a classic Make vs Buy decision on the ACRV. WE could make it >but it's cheaper to Buy. Now if the Soviets do Belly up on Us ( >the Unreliable Supplier Problem) then we merely need enough >inventory until we can gear up to Make. But Make vs Buy isn't a good paradigm if there is any sort of technology development involved in the alternatives. You have to count into the balance what sort of 'profit' we get from doing it ourselves and what kind of potential 'loss' there is if we don't do it ourselves (and hence lose ability in certain technology areas). That probably doesn't apply real strongly in this particular case, but I think you simplified right over it by simply trying to ignore the issue. >Given that you claim a degree in economics, i am surprised you aren't >aware of these choices. A cheap shot (and flame bait), and it also doesn't address the issue of loss of capability on our part caused by taking a 'buy' decision with regard to a piece of technology. >I like george, but as a taxpayer, i want best value for my money. >If that means buying from the soviets, why not? You obviate the asnwer by pretending that it's not an issue. 'Why not' is because it might (note -- I don't claim it will, just that it needs to be considered) be in our better long-term interest to spend more money up front and foster the development of the technology and capability here at home so that we will have our own capability and technology base going. >COnsidering we put 1/3rd of our GNP into relying on certain very unstable >arab countries to sell us Oil, I don't see what the problem is. You have an alternative? -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Ames Dryden ------------------------------------------------------------------------------ Fred.McCall@dseg.ti.com - I don't speak for others and they don't speak for me. ------------------------------ Date: 17 Jul 1993 15:42:03 -0400 From: Pat Subject: GPS in space (was Re: DC-1 & BDB) Newsgroups: sci.space In article <1993Jul17.182841.13504@mksol.dseg.ti.com> mccall@mksol.dseg.ti.com (fred j mccall 575-3539) writes: >In <226do3$hcb@access.digex.net> prb@access.digex.net (Pat) writes: > >>Comments like "WATW" (We Are The World) Orbit does not sound like a >>positive assessment. When there are numerous good reasons to push for >>51 degree, 65 Degree, 73 Degree or even 90 or 97 degree orbits. > >Then people should be justifying those orbits based on their merits >and talking about their drawbacks (like requiring some enhanced >shielding, I gather) rather than trying to justify them as "the >Soviets coulc play if we launch to high-inclination orbit". Having Reasons for a High Inclination Orbit : 1) Cheap Soviet flights available. 2) Improved Earth Observation Missions. 3) Improved Logistics Flow missions. 4) Improved space science/engineering base. ( hihg inclination, is a far more rigorous environment then low inclination. 5) Apparently ACRV return is simplified( This is what i was told, I can't see an intuitive reason why this is). > >But Make vs Buy isn't a good paradigm if there is any sort of >technology development involved in the alternatives. You have to >count into the balance what sort of 'profit' we get from doing it >ourselves and what kind of potential 'loss' there is if we don't do it > Make vs Buy is properly cognizant of the benefits of Technology developement. Nevertheless, Every company does Make this decision in it's business operations. IBM Buys Micro-processors. DEC buys 4M DRAMS. Certainly there are intangible benefits from spooling up to do things, but if that bleeds off developemnt money from more vital activities, that is equally a problem. Good Business people make these analyses. >>COnsidering we put 1/3rd of our GNP into relying on certain very unstable >>arab countries to sell us Oil, I don't see what the problem is. > >You have an alternative? More energy Conservation, Higher energy taxes, developemnt of low energy consumption Infra-structure. It's bizarre, that it is cash wise cheaper for me to drive to Chicago then to take the train ( The absolute lowest energy cost solution. Why is it, cheaper for me to drive to work in DC (Home to the best public transit system in AMerica) then to take metro. pat -- God put me on this Earth to accomplish certain things. Right now, I am so far behind, I will never die. ------------------------------ Date: 17 Jul 1993 09:03:48 -0800 From: FSRRC@acad3.alaska.edu Subject: ISECCo Update: Travels {Cont.} I left Rapid City (SD) almost 2 weeks ago. It was a one day drive to Minneapolis and the Browns (who I traveled with from Alaska) dropped me off at Patricia Wrede's. Pat put me up for 2 days, while I was seeing people and distributing information on ISECCo. Pat also had a number of real useful ideas on gaining new members. We are striving to get our membership up to 1,000 members, which will provide a broad enough membership base to fund construction. Those of you who are interested in joining do send us a note! We are still looking for innovative ideas for finding members, if you have any we'd like to hear about them. Also we are looking for magazines which cater to science-type (including SF) people in which we can put classified ads. If you know of any magazines like this please tell us! From Minneapolis I took a bus (this is a *very* low budget trip!) to Wichita KS, where I rented a car for 5 days. From there I went to a small town west of Hutchinson called Hudson where I visited Chandra Schaffer, who is an enthusiastic ISECCo volunteer. While I was in the area I went to the Cosmosphere in Hutchinson, which is an excellent exhibit on space technology. Naturally I left some of our literature there. After leaving Hudson I went south into Texas, and then back up through Lawton, Oklahoma City and then to Tulsa Oklahoma. This leg of the trip was primarily to pin up postcards on campus bulletin boards. The postcards have a blurb on ISECCo on the back and anyone who wants more information can simply put their address on the front and drop it in the mail. Any of you who could pin up some of these packets of postcards on bulletin boards please drop us a note so we can send you some! I had relatives in Tulsa who put me up for a couple of nights. When I left Tulsa I drove back to Wichita, returned the rented car (which was very handy, though an expensive way to travel). While waiting for the bus in Wichita I wrote about half this update. I'll upload it the next time I pause long enough at a place with a phone! The next stop was Cleveland Ohio, where I presented a seminar on our biosphere project to a group of NASA Lewis people. Since I am traveling light I didn't have a lot of notes (etc) with me, but the seminar went quite well in spite of that. I have been working on this project long enough so I know it by heart! When I left Cleveland I took the bus to Washington DC, where I shall be through the 19th of July meeting with people to discuss space, ISECCo and our biosphere. For those of you who are 'joining us late' I am on a trip around the country, primarily visiting people who are doing research in closed ecological life support technology. But I set aside a certain amount of time to visit members and other people who are interested in space. I am rapidly approaching the half-way point on the trip, and have accomplished a great deal, not to mention meeting many interesting people. To focus on my trip to the east coast and down to Florida (keeping in mind that these times are still pretty flexible and will change as needed): 7/17-7/19 visit people in the DC area (staying with Richard Kline) 7/20 leave DC & arrive in New York area 7/21-7/22 visit people in the NY area (staying with Richard Hope) 7/23 leave NY; travel to Lexington Kentucky 7/24-7/26 central Kentucky 7/27 travel to Huntsville Alabama 7/28 Huntsville area (staying with Peggy & Dale Hill) 7/39 travel to Kennedy Space Center 7/30-8/2 KSC (staying with Dennis Chamberlin) 8/3 travel to Houston Anyone who lives anywhere near this proposed travel path and would like to meet me please feel free to send me a note (include a phone number so I can contact you.) I'd be happy to talk with you about our organization, project or just space in general. ON OTHER MATTERS: For those of you who are familiar with our setup you know I own/manage rental properties. These travels are possible because of the efforts of those who have stayed behind to take care of my properties, as well as run ISECCo. I would like to thank Elisa Ballou and Scott Guse for keeping my company running smoothly, and stay on top of ISECCo activities like checking mail and weeding the garden. Debi Wilkinson has put in a considerable effort in arranging visits for me and many times acting as contact person and has been a great help keeping this trip in order, as well as pay ISECCo bills (including those I've generated on this trip). Her efforts are very much appreciated! We have an excellent group, and our projects move forward through their efforts. This is an ISECCo trip, and ISECCo is paying the majority of the expenses (i.e. everything that goes on the credit card). This is not a drain on the ISECCo funds though because I donated $2,000 to ISECCo before leaving, which will more than pay for the expenses of this trip. Indeed for the past year I have covered 100% of ISECCo's expenses--all the money donated by others in the last year has been set aside for construction. So our construction fund is growing! I am not sure how much longer I will be able to continue this (our expenses are continually rising), but so far I have managed. Would you like more information? Send me a note! My e_mail address is FSRRC@ACAD3.ALASKA.EDU and I answer every letter (some patience may be needed though, since I am traveling and can only log in occasionally.) Please include a postal mailing address for all initial correspondence--we occasionally have letters whose computer return address fails for one reason or another. --Ray :: President, ISECCo :::The International Space Exploration and Colonization Company::: :::P.O. Box 60885::Fairbanks::Alaska::99706::: Researching and Developing space oriented technology for the betterment of mankind. * * * * * * * * * * * * {end} ------------------------------ Date: 17 Jul 1993 15:52:39 -0400 From: Pat Subject: message from Space Digest Newsgroups: sci.space In article Date: 11 Jul 1993 08:58:04 -0400 |> Pat | |I don't know that I really want to go into that very extensively, Oh, why not start a little heated discussion :-) Here's one guaranteed to get wingos blood pressure going . Did Werner Von Braun have a habit of sieg heiling ? :-) | |But, as far as I know, the REQUIRED margins were exactly the |same for all stages. | Oh I was referring to something i saw in the literature. The as - built margins in the S-II were not as high as the other stages. |was settled, everyone had his own "bogie" and no "shaving" was |done, unless one exceeded the bogie. There were never any |changes in the S-IC made because we weren't meeting weight. What were the Safety Margins on the S-V? I heard somewhere there was a conflict on should it be 140% of design load or 105% of design load. | |>Henry S. Hillbrath |>Saturn V/S-1C Designer (with some assistance) | |> Really?????????? | |You seem surprised, why? Didn't think there were any of us old |codgers around any more? Didn't think we could find this |newsgroup? It is kind of rare to have "We Were There " Folks (Does anyone remember the books) on this news group. It tends to be over-run by under-grads. > >Surely, it couldn't be that you are doubting my word? I certainly hope not. No, just startled to see a real pro. The numbers in this group can be counted on ones fingers. (I don't aspire to the title Pro). > >Notice, I only said that I was "Designer" not "The Designer." Do you happen to know why there is no Saturn Stage marked S-III? There was the S-I, S-II then S-IV. kind of funny. > >I checked, none of the parts that I designed on the S-1C can be >seen in the largest scale Revell model that I could find. But, I >later calculated that the cost savings that my design concepts >produced were considerably more than my salary since I >started in the business, 30 plus years ago. (Oh, well, I blew it >all on the Shuttle.) These certainly sound like a good story. > >NO ONE believes an analysis... | EVERYONE believes a.test... > - except the guy who did it. | - except the guy who did it. > > T. M. ("Scotty") Davidson Who'se he? pat -- God put me on this Earth to accomplish certain things. Right now, I am so far behind, I will never die. ------------------------------ Date: 17 Jul 93 11:52:37 GMT From: Steve Linton Subject: Moon Cable/Beanstalk. Newsgroups: sci.space In article , henry@zoo.toronto.edu (Henry Spencer) writes: |> In article <1993Jul16.022120.1@aurora.alaska.edu> nsmca@aurora.alaska.edu writes: |> >Local govermental problems along the equator, since the Beanstalk would |> >need to be near the equator or on it.. The local government would ahve to |> >be appeased. |> |> If you've got the sort of money you would need to build a beanstalk -- |> remember, this is a high-tech structure tens of thousands of kilometers |> long, it *won't* be cheap -- you can just buy yourself a suitable local |> government while you're at it. :-) This will be a minor expense. |> -- Actually, you will need to buy up, or at least buy off ALL the local governements along the equator. In a worst-case catastrophe the cable will come down in pieces the whole way round. In one of his books (I forget the title) Charles Sheffield discribes an alternative to Arthur C. Clarke's "Start in orbit and build up and down" strategy for constructing an orbital tower. This is based on building the whole structure in deep space and spinning it up to 1 revolution/day. You then dig a LARGE hole where you want the base to be and put a suitable rock in an elliptical orbit tangent to the "orbit" you want the top of your tower to end up in. You then fly the tower into place just as the rock passes over the hole and QUICKLY fasten both ends. This works beautifully provided nothing goes wrong, but some of the failure modes are rather dramatic. In particular if you miss the rock at the top, but get caught at the bottom the tower whiplashes round the equator (I think) and, if it doesn't snap) the free end comes down VERY HARD INDEED. I think I'd like to this idea tested on a few uninhabitted planets first. ------------------------------ Date: 17 Jul 1993 13:43:14 -0400 From: Earl W Phillips Subject: problem w/ZHR equation Newsgroups: sci.space,sci.astro In trying to write a program around the recently posted ZHR equation, I am having trouble with 1 of it's components. The equation for "C" in my program doesn't give a result anywhere near the example of 1.72, I get something like 4.6. C=2.6 times exp(6.5-5.93)=1.72 Anybody got any idea what the problem is? ***************************************************************** * | ====@==== ///////// * * ephillip@magnus.ircc.ohio-state.edu| ``________// * * | `------' * * -JR- | Space;........the final * * | frontier............... * ***************************************************************** ------------------------------ Date: Sat, 17 Jul 93 04:48:00 BST From: h.hillbrath@genie.geis.com Subject: Von Braun Team Work & DCX (Was Paul Dietz Writes: > In article <21o1d9$qdn@agate.berkeley.edu> > gwh@soda.berkeley.edu (George William Herbert) writes: >> Pardon me, but didn't the J2 only get ike 365 Isp? Isn't this a bit low >> for SSTO purposes? > George, you really should get a copy of Sutton. On page 196 (5th ed.): > Engine Vac Isp Dry Weight (lb) Vac Thrust (lbf) Vac thrust/dry weight > SSME 455 6335 470,000 74.2 > J2 426 3454 230,000 66.6 Actually, one might say that he SSME has an Isp 363.2 +/- 1.8 seconds, in fact, the "ICD - 13M15000 Space Shuttle Orbiter Vehicle/Main Engine", sheet 4-4 says just that. That is sea level. But, then an SSTO has to start somewhere. Even Sutton doesn't tell you everything (and you do have to be able to read it, which is not always easy, as there is a lot "between the lines.") 363.2 +/- 1.8 is not that far from 365. George should not have backed down so easily. Actually, that is the SSME, of course. I could look up the J-2 Isp, but I won't. Arguably, the J-2 does not HAVE a sea level Isp, as it was not qualified to operate at that condition. (Without "cheaters".) Discussions of Isp are like those things on TV "Warning, do not try this at home, the performers are trained professionals." Isp is highly dependent on nozzle area ratio, the optimization of which is best left to those trained professionals. The SSME is a particularly complex case, as it has a nozzle much too long for best sea level performance (as long as anyone dared make it when it was designed) yet it does not get as much vacuum performance as it could if it did not have to run at sea level (or had an extendable cone.) The J-2 loses to the SSME two ways, one, it has a gas generator (GG), so there is a GG loss, and 2) it is much lower chamber pressure, so it cannot tolerate as long a nozzle with back pressure, nor have as high an area ratio in the same base area. Opinions on SSTO's are like navels. There are those that say that Thor's could have been SSTO's, they just didn't want to, and that kerosene is all you want for fuel. Having had some experience with engine/vehicle systems integration for SSTO's myself, I feel that the SSME does not have sufficient performance for "realistic" SSTO operation, and that engines, such as the J-2, RL-10 etc. are totally out of the question ("bad jokes" one might say.). We shall see, maybe, someday. It won't be this year, and I wouldn't count on it being this century. Henry S. Hillbrath -------------------------------------------------------------------- NO ONE believes an analysis... | EVERYONE believes a.test... - except the guy who did it. | - except the guy who did it. T. M. ("Scotty") Davidson ------------------------------ Date: 17 Jul 1993 17:20:47 GMT From: Troy Goodson Subject: Where is ESA's ERIN server? Newsgroups: sci.space,sci.astro I was reading the latest Earth Observation Quarterly (published by ESA) and it had a special section describing materials available from what I think was called ERIN. They gave the user name and password for guests to log on but did not give the address of the server. Does anyone know what that address might be? Troy. ------------------------------------- Troy Goodson ! The Georgia Institute of Technology ! ------------------------------------------------------------------- uucp: ...!{allegra,amd,hplabs,ut-ngp}!gatech!prism!gt5368a ! Internet: gt5368a@prism.gatech.edu ! ------------------------------------------------------------------- ------------------------------ Date: Sat, 17 Jul 1993 12:03:40 GMT From: Steve Linton Subject: Why are meteor showers seasonal? Newsgroups: sci.space ------------------------------ Date: Sat, 17 Jul 1993 12:05:58 GMT From: Steve Linton Subject: Why are meteor showers seasonal? Newsgroups: sci.space In article , daf@bbn.com (David Fagan) writes: |> I'm sure the answer to this must be simple, but it's been nagging at me |> for a long time. Why do particular metor showers recur at the same time of |> year? |> |> The simple answer is that there is a cloud of asteroids in the earth's |> orbit which the earth passes thru at the same time each year. However, |> don't I have to assume that the asteroids are in solar orbit as well? In |> that case it seems unlikely that the earth would repeatedly encounter those |> asteroids at the same point in its orbit. The only answer that leaves me is |> that there is an asteroid belt (or many belts) which cross the earths |> orbit. I've never heard anything to this effect, however. In essence you have it right. There are `belts' of gas and dust that intersect the Earth's orbit in various places. They are usuually in the orbits of comets, either existing ones or `dead` ones that have lost all their gas by too many close solar passages. ------------------------------ id AA00681; Sat, 17 Jul 93 01:33:34 EDT Received: from CRABAPPLE.SRV.CS.CMU.EDU by VACATION.VENARI.CS.CMU.EDU id aa26761; 17 Jul 93 2:26:27 EDT To: bb-sci-space@CRABAPPLE.SRV.CS.CMU.EDU Xref: crabapple.srv.cs.cmu.edu sci.space:67169 Newsgroups: sci.space Path: crabapple.srv.cs.cmu.edu!fs7.ece.cmu.edu!europa.eng.gtefsd.com!howland.reston.ans.net!usc!sdd.hp.com!saimiri.primate.wisc.edu!aplcen.apl.jhu.edu!wb3ffv!idsssd!bruce From: "Bruce T. Harvey" Subject: Re: Head NASA Select Guy (was Re: NASA SELECT and scrambling.) Message-Id: <1993Jul16.142934.11404@idsssd.UUCP> Organization: In*sight Distribution Systems, Inc. References: <1993Jul15.145900.57678@ns1.cc.lehigh.edu> Date: Fri, 16 Jul 1993 14:29:34 GMT Lines: 45 Sender: news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU in article <1993Jul15.145900.57678@ns1.cc.lehigh.edu>, tfv0@ns1.cc.lehigh.edu (Theodore F. Vaida ][) says: > > [deleted for brevity] >>Not so sure about his "trouble" conjecture; just because you get >>something for free doesn't mean you can't sell it to somebody! [deleted for brevity] > Ahh.. but considering the fact that you and I have already paid for it, > and the cable company didn't (least not in tune with what they might > make by selling it) it would be an attempt to sell you something you > already own! Personally I consider it theft of services (just like if > I descrambled HBO and sold it to my neighbors, and it was theft of services to > redistribute HBO when it was unscrabled, congress agreed to that by > allowing scrambling on the supposedly FREE airwaves of the sattelites > so...) So if you had an antenna capable of receiving the signal, you could get it for free. And a Community Access TV center has an antenna that can grab the signal (commercial free ... no income for the CATV center). But since it's commercial free, there is no income generated by this channel, as opposed to the local commercials that are often inserted on channels like USA and TNT (also 'free' kind of from our point of view) which bring revenue to the CATV center (rebroadcaster). Providing NASA Select would become a public service and would be a DRAIN on local resources without additional funding. It may not be able to be 'officially' classified as a public service ... don't know. It might be better to pursue alternatives that can try to avoid this argument, like getting one of the local schools to rebroadcast NASA Select when it doesn't have other programming (Baltimore County, MD ... Dundalk Community College does this admirably, even extending coverage during Shuttle flights), or have this and perhaps other types of government-sponsored broadcasts included in the realm that CSPAN covers, so that's it's paid for by all and available to all. You may be dead right in your arguments, but the reality of it is that if the CATV folks have to do it for free, they won't, if they have a choice. -- :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: Bruce T. Harvey (B-{>:: UUCP: ... {uunet|mimsy}!wb3ffv!idsssd!bruce Manager Appli. Devlopmt.:: INTERNET: wb3ffv!idsssd!bruce%uunet.uu.net@... INsight Distribution Sys::CompuServe: 71033,1070 (410)329-1100 x315, x352:: SnailMail: 222 Schilling Cir.,Hunt Valley, MD 21031 :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ------------------------------ End of Space Digest Volume 16 : Issue 889 ------------------------------