Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Wed, 13 Dec 89 01:36:11 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 13 Dec 89 01:35:46 -0500 (EST) Subject: SPACE Digest V10 #341 SPACE Digest Volume 10 : Issue 341 Today's Topics: Re: Satellites in E-W orbits Pegasus launch? Payload Status for 12/12/89 (Forwarded) Re: Relative distances and sizes in the Universe. ---------------------------------------------------------------------- Date: 12 Dec 89 22:05:12 GMT From: zaphod.mps.ohio-state.edu!brutus.cs.uiuc.edu!ux1.cso.uiuc.edu!uxh.cso.uiuc.edu!jep@tut.cis.ohio-state.edu (John E. Prussing) Subject: Re: Satellites in E-W orbits > >This is something I have been thinking about some time: > >I live far up in the northern part of Sweden ( Lat 65 35' - not so far >from the arctic circle). When we have dark nights here (no moon or >aurora (yes there is aurora outside right now - but the full moon >takes off the spectacular effect) there is no problem seeing >"satellites" orbiting. If You stand outside, looking up, for 15 >minutes there are always several of them. > >Now to my question: It seems that they are going mainly in two >directions - either north-south (or vice versa) or east-west. I dont >know very much about orbits for satellites but I can understand the >N-S orbits. What I'm wondering about is if it is possible for an >object to have an E-W orbit lying 2/3 from the equator?? > >One solution I have thought about is that what I'm seeing is just >satellites on the top of their "sine"-shaped orbits (whatever they're >called). This is just a guess - what is the answer? > >--Borje >----------------------------------------------------------------------------- >Borje Josefsson, Computer centre, University of Lulea, S-951 87 Lulea, Sweden >Tel: +46 920 91 262 (direct), +46 920 91 000 (operator). Fax: +46 920 972 88 > >Domain: bj@dc.luth.se Path: {uunet,mcvax}!sunic!dc.luth.se!bj What you say is basically true. It is impossible to have something completely in an E-W orbit except for an equatorial orbit. The orbit plane must contain the center of the Earth. The N-S orbits you see are polar orbits (90-degree inclination to the equator) and the west-to-east is the top of the *sine wave* which is the groundtrack of the satellite (intersection of line from center of Earth to satellite with surface of Earth). The maximum latitude of the groundtrack is equal to the inclination of the orbit; the groundtrack is essentially a sine curve about the equator with equal excursions into the northern and southern latitudes. Near the maximum latitude the satellite is travelling essentially west-to-east. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= John E. Prussing Aeronautical & Astronautical Engineering University of Illinois at Urbana-Champaign ------------------------------ Date: 13 Dec 89 00:09:34 GMT From: concertina!fiddler@sun.com (Steve Hix) Subject: Pegasus launch? Last I heard, Pegasus was supposed to launch around December 8. Did it? Another slip? ? ------------ "...Then anyone who leaves behind him a written manual, and likewise anyone who receives it, in the belief that such writing will be clear and certain, must be exceedingly simple-minded..." Plato, _Phaedrus_ 275d ------------------------------ Date: 12 Dec 89 18:23:40 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Payload Status for 12/12/89 (Forwarded) Daily Status/KSC Payload Management and Operations 12-12-89 - STS-31R HST (at VPF) - The HST SIC & DH was removed and the suspected faulty CU/SDF was taken to CCAFS for analysis. The high gain antenna coupler and off load booms were removed. Today there will be a performance demonstration test (PDT #8) in support of data link validation. - STS-32R SYNCOM (at Pad A) - SYNCOM battery charging will continue after orbiter hyper load. - STS-35 ASTRO-1/BBXRT (at O&C) - Completed the mission sequence test yesterday. Today will be IPR troubleshooting on the HDRR cable and the RAU 5. Plan to remove the counter balance weights today which were used during the IPS motion test. - STS-40 SLS-1 (at O&C) - Gas component test stand prep and validation was completed. Pyrell foam panel work continues. Eddy current checks were post- poned until this morning and rack rotations were rescheduled for this evening. - STS-42 IML (at O&C) - No activity. ------------------------------ Date: 13 Dec 89 05:21:12 GMT From: cs.utexas.edu!jarvis.csri.toronto.edu!csri.toronto.edu!wayne@tut.cis.ohio-state.edu (Wayne Hayes) Subject: Re: Relative distances and sizes in the Universe. In article <8912121730.AA22210@decwrl.dec.com> klaes@wrksys.dec.com (CUP/ASG, MLO5-2/G1 6A, 223-3283 12-Dec-1989 1233) writes: > If the solar system out to the > orbit of Pluto could fit in a coffee cup, the Milky Way Galaxy > would be the size of the North American continent. > > Also, if the solar system were 2.54 centimeters (one inch) across, > the Milky Way Galaxy would be 161,000 kilometers (100,000 miles) wide. These two don't jibe. One inch is smaller than a coffee cup, but 161,000 km is definitely larger than North America. The proper ratios (using 4.2 light hours and 100,000 light years) is one to about 200 million, and 208 million inches is 3156 miles, so the coffe cup vs North America analogy is the "correct" one. The ratio of 1 inch to 100,000 miles is about the ratio of the *Earth's* orbit to the Galaxy. Other than that, the article was fascinating. I've often tried to convey to friends the vastness of the solar system alone, and then the galaxy... and the Universe... Some of the analogies wowed me yet again. Gosh, this is a BIG place. -- The 'C' programming language is, at worst, the second best language for any given application. Usually, however, it is the best. -- anon Wayne Hayes INTERNET: wayne@csri.toronto.edu CompuServe: 72401,3525 ------------------------------ End of SPACE Digest V10 #341 *******************