Aucbvax.6130 fa.space utcsrgv!utzoo!decvax!ucbvax!space Tue Feb 9 03:40:16 1982 SPACE Digest V2 #102 >From OTA@S1-A Tue Feb 9 03:16:30 1982 SPACE Digest Volume 2 : Issue 102 Today's Topics: Re: sri-unix.707: Horseshoe Orbits RE: dennis' reply to Horseshoe Orbits half-time power from the moon Politics of Space Scramjet Request horseshoe orbits polar lunar solar power ---------------------------------------------------------------------- Date: Sun Feb 7 10:51:10 1982 To: Space at MIT-MC From: hplabs!menlo70!ucbvax!ihnss!cbosg!harpo!chico!duke!phs!dennis at Berkeley Subject: Re: sri-unix.707: Horseshoe Orbits Source-Info: From (or Sender) name not authenticated. Nope -- it's not ignorance, it's just a point of view problem. Higher orbits are slower only in terms of angular velocity (speed relative to the surface). In linear velocity (yeah, orbits are ellipses, but that's the idea) higher orbits are faster. You need to accelerate from a low orbit to achieve a higher one. The ground speed is slower because the circumference grows quickly wrt speed and it has more distance to cover than it has extra speed to do it with. Thus, the two moons exchange kinetic energy (orbital speed) via gravitational attraction, and they BOTH (mutual and opposite) change orbits. The higher moon (the one caught up on) is decelerated and the lower moon is accelerated, causing them to exchange orbits. This will collapse eventually (tidal forces ALWAYS eat some of that kinetic energy), and either they will collide or just take up the same orbit; I suspect collision. ------------------------------ Date: Mon Feb 8 00:24:53 1982 To: Space at MIT-MC From: hplabs!menlo70!ucbvax!ihnss!houxi!houxg!lime!gdg at Berkeley Subject: RE: dennis' reply to Horseshoe Orbits Source-Info: From (or Sender) name not authenticated. speaking, angular velocity is the rate at which an orbiting body subtends a given angle relative to the orbital *focus* (CG), which, in the case of relatively light moons orbiting relatively round, heavy planets, can be considered to be the center of the planet. Simply put, radians/second. *It has nothing to do with speed relative to the surface.* For example, a geosynchronous satellite has no motion relative to the Earth's surface, yet its angular velocity is considerable. If the earth suddenly stopped rotating, the satellite's angular velocity would remain the same (360 degrees/day), and it would remain in orbit at the original altitude. (Of course it would no longer be geosync either.) We just tend to think of orbital speeds as relative to the planet surface, but that is *apparent* angular velocity. Luckily for us, that's all it is. If the earth had no angular velocity (spin) of its own we wouldn't be able to have geosync satellites at all because no matter what orbit we put them in they'd always have some velocity relative to the surface. - Glenn Golden ------------------------------ Date: Monday, 8 February 1982 08:07-PST From: KING at KESTREL To: Jerry E. Pournelle cc: SPACE at MIT-MC, King at KESTREL Subject: half-time power from the moon In that case, unless the moon's equator happens to coincide almost exactly with the ecliptic (does it?) the power station will be out of service for six months out of the year. (There is NO pointof the Earth's surface that has continuous sunlight.) In addition, note that the sun's angle changes. If the moon's equator IS aimed at the sun, then only half of the sun is visible from the poles, and you would need a tall tower (built againstgravity, don't forget) and a rotator to take advantage of the continuous power available. Dick ------------------------------ Date: 8 Feb 1982 0926-PST Sender: WARD at USC-ISIF Subject: Politics of Space From: Craig E. Ward To: SPACE at MIT-MC Cc: Ward at USC-ISIF Message-ID: <[USC-ISIF] 09:26:10.WARD 8-FEB-82> Yesterday I got around to reading my copy of "The Planetary Report" and I found a reprint of an article by James Van Allen. I contend that this article illustrates one of the problems we have in getting the space program funded, namely, that many of the big names of the scientific community are politically naive and give the political opponents of science weapons to use against us. Very quickly, the article contends that we can not complain about the level of funding of the space program (6 billion NASA and 3 billion DoD), that if several scientific probes have been cancelled, we must remember that it is because the nation spends almost all its money on manned space flight. He hints that he thinks the space shuttle is going to be a "financial monstrosity" being 20-50 years ahead of its time. I disagree on several of his points. The NASA budget is not by any reasonable accounting adequate, nor is the general level of scientific funding. For something so vitally important to the country to receive such a small piece of the pie is a disgrace. I also contend that the manned space program has more than justified itself by its returns in science and technology. And finally, to illustrate my point, to assume that money taken from the manned program will go to the unmanned demonstrates great political naivity. Van Allen's arguments sound rather similar to those made by people like Senator Proxmire (a real tail-gunner if there ever was one). I think that Proxmire's statements have shown that he lacks an understanding of the scientific method and such statements as those of Van Allen allow him to claim allies in the scientific world (See, even their own agree with me). The battle over funding must be fought in the political arena and we must learn how to fight there if we are going to get anywhere. I do not want to give the impression that I think either Dr. Van Allen or Senator Proxmire are stupid or evil. I would very likely like both if I were to meet them. I would, however, like to caution people in positions like that of Dr. Van Allen to be careful of what they say and to whom they say it. The budget you save may be your own. /Craig ------------------------------ Date: 8 Feb 1982 1313-CST From: John Otken Subject: Scramjet Request To: Space at MIT-MC Could anyone supply some references to SStO technology? ------- ------------------------------ Date: 8 Feb 1982 06:47:05-PST From: menlo70!sytek!intelqa!murray at Berkeley HOORAY!!!!!! Finally some REAL space news! Please keep it up. ------------------------------ Date: Mon Feb 8 10:10:52 1982 To: Space at MIT-MC From: ucbvax!decvax!duke!phs!dennis at Berkeley Subject: horseshoe orbits Source-Info: From (or Sender) name not authenticated. Nuts. I fell into the point-of-view trap myself. Anyway, correcting for that, my remarks still apply, unless somebody who has taken more than one astrophysics course can correct me. ------------------------------ Date: Mon Feb 8 11:01:44 1982 To: Space at MIT-MC From: ucbvax!decvax!duke!cjp at Berkeley Subject: polar lunar solar power Source-Info: From (or Sender) name not authenticated. I can see problems with moon-based solar power stations even at the poles. If you could get continuous power there, I could maybe see beaming it to earth from such a close tangent to the lunar surface. The moon's orbit is the problem. It is not quite in the same plane as the earth's orbit around the sun. So, the polar regions will cycle in and out of sunlight on a yearly basis. Even when the sun lights the pole, it is low on the lunar horizon. This means that the collectors would have to be huge and/or highly tilted, relative to the amount of power you'd get. And you would still have to build a power station at both poles to get year-round power. ------------------------------ 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. 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