Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from holmes.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr1/ota/space/space.dl) (->ota+space.digests) ID ; Tue, 6 Jun 89 03:16:35 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 6 Jun 89 03:16:24 -0400 (EDT) Subject: SPACE Digest V9 #473 SPACE Digest Volume 9 : Issue 473 Today's Topics: Re: Private Space Companies OSC Hercules Launch Information Re: Venus & the Greenhouse effect.. Re: Venus & the Greenhouse effect.. Wanted: software to predict satellite sightings Smith appointed Deputy Director, NASA Stennis Space Center (Forwarded) Re: Spiral arms Re: Venus & the Greenhouse effect.. Re: Venus & the Greenhouse effect.. ---------------------------------------------------------------------- Date: 2 Jun 89 18:26:30 GMT From: jarvis.csri.toronto.edu!utgpu!utzoo!henry@rutgers.edu (Henry Spencer) Subject: Re: Private Space Companies In article shafer@drynix.dfrf.nasa.gov writes: >> the KC-135 and the 707 are **not** the same aircraft... > >This is not a popular misconception. Let's look at Jane's All the >World's Aircraft, which is a very authoritative source. On page 238 >of the 1976-77 edition we find the following... Note carefully what Jane's is saying: it is saying that the KC-135 and the 707 were both derivatives of the privately-funded "dash 80" prototype, that Boeing felt it advisable to ask USAF permission before building the 707, and that the 707 also entered military service as the VC-137 (and other related designations). >Thus we see that a privately developed prototype became the VC-137 >(probably A) which turned into the KC-135... Uh, please re-read your own excerpt from Jane's, carefully. The KC-135 order came first, after which Boeing asked for (and got) permission to work on a commercial dash-80 derivative in parallel, and said derivative eventually became the 707 and the VC-137. I did some digging in my library at home. Said library unfortunately runs more to fighters than transports, but I hit the jackpot in Bill Gunston's "USAF: The Modern US Air Force". For those who don't know the name, Gunston today is a freelance military-aviation author, but back in the mid-50s he was technical editor of Flight International, the British counterpart of Aviation Week. I think we can assume he knows what he's talking about. In his section on the C-135 family, he says: Boeing risked more than the company's net worth to build a prototype jetliner, first flown in July 1954. An important factor behind the gamble was the belief that the USAF would buy a jet tanker/transport to replace the Boeing KC-97 family, and this belief was justified by the announcement of an initial order for 29 only three weeks after the company prototype flew, and long before it had done any inflight refuelling tests. The KC-135A Stratotanker differed only in minor respects from the original prototype, whereas the civil 707 developed in a parallel programme was a totally fresh design with a wider fuselage, airframe of 2024 alloy designed on fail-safe principles and totally revised systems... And under VC-137: These aircraft bear no direct relationship to the prolific C-135 family but were commercial airliners... bought off-the-shelf... >The Air Force paid for the YC-14 prototypes, since this was back in >the era of fly-offs. This certainly contradicts the "Boeing has never >been paid by the government to build an aircraft" line... I don't think that I quite said that, given that the B-52, among others, was a Boeing product. But they've never had major government subsidies to build a later-successful airliner. (That last bit of weasel-wording is necessary because of an example you missed: the American SST.) >... Boeing is >much less concerned about ideological purity than some people on the >net are. Rather, they'll take any advantage they can (IMO as they >should) to continue building successful and profitable aircraft. Quite true. And more power to them. Unlike (say) McDonnell-Douglas, while they are happy to take government money if offered, they don't quake if the government scowls at them. -- You *can* understand sendmail, | Henry Spencer at U of Toronto Zoology but it's not worth it. -Collyer| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Sender: RPollard.ElSegundo@Xerox.COM Date: 2 Jun 89 10:43:20 PDT (Friday) Subject: OSC Hercules Launch Information From: RPollard.ElSegundo@Xerox.COM Cc: RPollard.ElSegundo@Xerox.COM Does anyone on the net have any info about where OSC is in their development of Hercules ? Specifically I was looking for the date that they expect to do the first launch. ------------------------------ Date: 2 Jun 89 17:50:45 GMT From: jacobs.CS.ORST.EDU!kstclair@cs.orst.edu (Kelly St.Clair) Subject: Re: Venus & the Greenhouse effect.. > [Is there any reason that Venus could not be cooled and terraformed?] Is there any reason (besides needing space so that we can keep breeding like flies)s) that we should? Most important of all: Is there anything that gives us the *RIGHT* to remake another world in our own image? (Old discussion, I know, but I thought it should be said...) ------------------------------ Date: 2 Jun 89 23:10:08 GMT From: haven!aplcen!arrom@ames.arc.nasa.gov (Ken Arromdee) Subject: Re: Venus & the Greenhouse effect.. >Is there any reason (besides needing space so that we can keep breeding like >flies)s) that we should? >Is there anything that gives us the *RIGHT* to remake another world in our >own image? The same thing that allows us to farm, mine, build houses on, etc... our own planet. "Is there any reason (besides needing space so that we can keep breeding like flies) that we should move out of the tropical regions in which we evolved into climates which require us to ruin the natural surroundings with dwellings to protect us from temperature extremes? Is there anything which gives us the *RIGHT* to build fires, grow plants, just to benefit our own selfish species, etc..." -- "The fact is self evident from the text and requires no supporting argument." --Tim Maroney Kenneth Arromdee (UUCP: ....!jhunix!ins_akaa; BITNET: g49i0188@jhuvm; INTERNET: arromdee@crabcake.cs.jhu.edu) (please, no mail to arrom@aplcen) ------------------------------ Date: 1 Jun 89 10:18:02 GMT From: mcvax!ukc!mucs!mario@uunet.uu.net Subject: Wanted: software to predict satellite sightings The regular postings of orbital elements sure *look* interesting, ... but does anyone have PD software that can use these elements to predict sightings? Anything for UNIX or IBM PCs would be appreciated... Mario Wolczko ______ Dept. of Computer Science Internet: mario@ux.cs.man.ac.uk /~ ~\ The University USENET: mcvax!ukc!man.cs.ux!mario ( __ ) Manchester M13 9PL JANET: mario@uk.ac.man.cs.ux `-': :`-' U.K. Tel: +44-61-275 6146 (FAX: 6280) ____; ;_____________the mushroom project____________________________________ ------------------------------ Date: 2 Jun 89 20:28:59 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Smith appointed Deputy Director, NASA Stennis Space Center (Forwarded) David W. Garrett Headquarters, Washington, D.C. June 2, 1989 RELEASE: 89-85 SMITH APPOINTED DEPUTY DIRECTOR, NASA STENNIS SPACE CENTER The appointment of Gerald Smith as deputy director of NASA's John C. Stennis Space Center (SSC), Miss., was announced today by Center Director Roy Estess. Smith will assume his new duties on June 17. Since 1986, Smith has managed the solid rocket booster project in the Shuttle Projects Office at NASA's George C. Marshall Space Flight Center (MSFC), Huntsville, Ala. In April 1985, he was detailed to NASA Headquarters, Washington, D.C., as acting chief, Engine Programs Branch, Shuttle Propulsion Division in the Office of Space Flight. Smith joined MSFC in September 1961 as a member of the former Structures and Mechanics Division. From 1961 to 1963, he served in the U.S. Army and was then re-employed at Marshall in the Propulsion Division of the former Propulsion and Vehicle Engineering Laboratory. In 1965, he left Marshall to work as a test and evaluation engineer in the Large Jet Engine Department at the General Electric Company. He returned to Marshall in 1967 as part of the center's structures and propulsion effort. In 1974, he was assigned to the Office of the Associate Director for Engineering in the Science and Engineering Directorate. In 1983, he became deputy manager of the Space Shuttle maine engine project in the Shuttle Projects Office. In September 1984, he was appointed deputy associate director for engineering in the Science and Engineering Directorate. Smith earned bachelor's and master's degrees in aeronautical engineering at Auburn University, Ala., and a master's degree in administrative science at the University of Alabama, Huntsville. ------------------------------ Date: 2 Jun 89 18:30:19 GMT From: frooz!cfa.HARVARD.EDU@husc6.harvard.edu (Steve Willner) Subject: Re: Spiral arms First, usc!csun!solaria!ecphssrw%bob.csun.edu@BLOOM-BEACON.MIT.EDU (Stephen Walton) wrote: >Contrary to popular belief, the steller density >(stars per cubic parsec) in spiral arms is the same as between the >arms; it is just that most of the new, hot, and therefore bright stars >are in the arms, causing them to stand out. Then in article <8906011842.AA08331@aristotle.Jpl.Nasa.Gov>, by pjs@ARISTOTLE-GW.JPL.NASA.GOV (Peter Scott) replied: > ... but I thought that arms in spiral galaxies were thought to be > compression waves and therefore at different times different parts > of the galaxy would be in the arms, which would preclude stellar > differentiation on the basis of age? Isn't the differentiation > between the disk and the halo, the Pop. I and II stars? These questions touch on a very active field of current research. As always, there is an interplay of theory and observation. I'll try to outline current ideas. We should know a lot more in five years. Spiral galaxies are conventionally considered to be made up of the following parts: the "bulge" in the middle (round, radius around 3000 light-years); the "disk", which is very thin (say 500 ly) but of large radius (say 50000 ly); and the "halo", which is roughly spheroidal and about the same radius as the disk. Some galaxies also have "bars," which are bigger than the bulge but smaller than the disk. The Sun is located in the disk of the Milky Way galaxy, about 25000 ly from the center. Halo stars generally have lower metal abundance than disk stars and are called "Population II" stars versus "Pop. I" in the disk. Less is known about bulge stars, but it now looks as though at least some of them have higher metal abundances than disk stars. Every star orbits in the gravitational field established by all the other mass of the galaxy. In the last several years, both theory and observation have come to agree that most of the mass of spiral galaxies is in the halo but is in some invisible form. There simply are not enough halo stars observed to add up to the necessary mass. (In describing these results for the Milky Way, the late Bart Bok used to refer to the "bigger and better Galaxy.") The nature of the invisible matter is unknown, though it cannot be stars (say 0.1 solar mass or greater). I think massive black holes (>10 solar masses) are also ruled out. (This "hidden mass" is NOT the same as the "missing mass" supposedly needed to close the Universe, though of course the two might be made out of the same stuff. The amount of "hidden mass" is only 1/50 to 1/10 of the "missing mass.") Theory says that perturbations to the mass distribution in galaxies can last for significant times if the perturbations have the right form. One form is spiral density waves. The "pattern" of the waves rotates at a different speed than do the actual stars in the disk, so any given star alternately passes through high- and low-density portions of the wave. The density contrast is modest but non-zero. An important research question today is how the observed spiral arms are related to these theoretical density waves. Spiral arms are much more conspicuous in blue light than in red light. The interpretation is that massive (thus blue and short-lived) stars are preferentially concentrated in the spiral arms, more concentrated in fact than stars of lower mass. The most likely explanation is that the density increase associated with spiral density waves somehow enhances star formation. The abundance of bright stars - stars so massive that their lifetimes are less than a galactic rotation period - is thus higher "downstream" of the density waves. Less massive stars, with long lifetimes, should be slightly concentrated in the density wave itself, but these stars are faint and thus hard to observe. (Most of the visible light of a "typical" galaxy comes from stars more massive than 2 solar masses, whereas most of the mass is in stars less massive than the Sun.) Infrared images, which are just now starting to be obtainable, should give a much better picture of the mass distributions in galaxies. I have cross-posted this to sci.astro and (with luck) directed follow-ups there. Please check the newsgroups line. (P.S. We have suffered two independent "system upgrades" in our mail path, so please try again if you recently have failed to reach me.) Steve Willner Phone 617-495-7123 Bitnet: willner@cfa 60 Garden St. FTS: 830-7123 UUCP: willner@cfa Cambridge, MA 02138 USA Internet: willner@cfa.harvard.edu ------------------------------ Date: 2 Jun 89 15:59:13 GMT From: asuvax!anasaz!scott@noao.edu (Scott Gibson) Subject: Re: Venus & the Greenhouse effect.. In article <1989May31.044452.19619@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: > >into the details and established that Earth would not have a runaway >greenhouse effect even with far more CO2 than it has now. There are >a number of complications, like the effect of clouds on climate (they >tend to cool the surface, on the whole). The "habitable zone" around I have seen this comment several times, and don't really understand it. The surface of Venus is *completely* obscured by clouds. While it makes sense (or seems to) that clouds, by shading the surface, cool it - this has not done much for the surface of Venus. Clearly, the presence of clouds does not necessarily stop a runaway greenhouse effect. Of course, Venus *is* a little closer to the sun...... Scott ------------------------------ Date: 3 Jun 89 22:09:51 GMT From: jarvis.csri.toronto.edu!utgpu!utzoo!henry@rutgers.edu (Henry Spencer) Subject: Re: Venus & the Greenhouse effect.. In article <285@bach.nsc.com> andrew@berlioz (Eraserhead @ The Noblest Explosion ) writes: >Is there any strong a priori reason why Venus could not be cooled by this >or any other terraforming idea? ... As I recall, from papers in JBIS and other places, the notion is not quite impossible but it is difficult. Getting rid of all that atmosphere is hard. There are other problems in making Venus habitable too, like a grave shortage of water and an excessively long rotation period. -- You *can* understand sendmail, | Henry Spencer at U of Toronto Zoology but it's not worth it. -Collyer| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ End of SPACE Digest V9 #473 *******************