Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from corsica.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 ; Fri, 23 Jun 89 05:16:56 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 23 Jun 89 05:16:48 -0400 (EDT) Subject: SPACE Digest V9 #506 SPACE Digest Volume 9 : Issue 506 Today's Topics: HST update - from the horse's mouth Military and Civilian Space Re: Ozone depletion, atmospheric models, and public policy RE: SPACE Digest V9 #494 Re: Ozone depletion, atmospheric models, and public policy How does one subscribe to this... Re: Orbital queries Re: Chaotic orbits Re: Outer Space Committee subscribe ---------------------------------------------------------------------- Date: Sat, 17 Jun 89 22:00 EST From: Subject: HST update - from the horse's mouth The following is amalgamated from my notes taken at the recent (last week) American Astronomical Society meeting. The talk was given by A. Boggess from NASA/Goddard, and was an update on everything that is going on with the Hubble Space telescope at this time. My notes of the talk are chicken scratches, so forgive any errors. The HST is set to launch March 26, 1990, but is actually ready to go at any time before that. As mentioned earlier, it is currently at Lockheed in California and will be moved via an Air Force C5-A to Cape Kennedy. Certain final checks still need to be done before moving (and are currently in progress). These are: - The cataloguing and closing off of all boxes on the HST. (I guess that these are the accessible compartments on the outside of the HST.) These will then not be opened again until the HST is in space, and then only if repair work need be done. When this is completed, the only opening will be the main mirror aperture. - It will then be moved into a horizontal position to be ready for packaging (into a special box designed by the Air Force) and shipping. - Three potentially loose bolts on the secondary mirror must be checked. These will be replaced, with the new bolts being affixed with epoxy. As of June 1, 1989, the schedule for the HST is the following: July 10-11 Turn horizontal - replace nuts/bolts. July 24-28 Optical tests. - illuminate with white light to look for dust/clean - turn on the instruments, flood with white light, and do final instrument alignment October 7-12 Ship to launch site. October 26 onward Functional tests at Kennedy Space Centre. March 10 Place in shuttle and move to launch site March 26 Launch - deploy within 2 days (thank you, now go away :-) ) 2 months of turn on testing - power, maneuvering capability, then instruments Next 5 months - basic calibrations, simple basic science (3 months, 2 months respectively, but intermingled) 7 months after launch - telescope is `open' for business to the general observing public - currently, there is a 10-1 oversubscription for the available observing times (first year) There were also some comments made with respect to questions from the audience. Even with the solar maximum expected in the next few years, NASA figures that HST will only require about 1 reboost every 5 years. Any reboost would require a shuttle flight by itself (someone explain this to me - I didn't get a chance to ask), with the first one tentatively set for about 5 years down the road. However, if it turns out that reboosts are required more often, the HST would become uneconomical. In fact, the suggestion was made to move back the launch date if newer simulations show this to be the case. Nothing much else was said about that matter. For those of you who dislike the idea of spending so much money on space-based research, you should be glad to hear that the 8-meter ground-based telescopes look like they have a good chance of getting the funding needed. Currently, the US will build one of them, and Canada and Great Britain will split the second. One will go to Mauna Kea, the other to Chile, with a 2:1:1 subscription ratio for the two instruments going to the countries involved. Cost is currently estimated at about $60 million for the Hawaiian telescope, and about $48 million for the Chilean one. Some of the difference is due to the Chilean instrument being built second, the rest, I think, is due to the difference in labour costs. By the way, don't quote me on the numbers, I didn't write them down - they are accurate within $10 million (a lot better than the government is capable of doing!). There are, of course, 4 other telescopes of the 8-meter class being built - by the Keck group, ESO, and Japan. -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Arnold Gill | If you don't complain to those who | Queen's University at Kingston | implemented the problem, you have | BITNET: gill@qucdnast | no right to complain at all ! | -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ------------------------------ Date: 17 Jun 89 17:24:17 GMT From: agate!web%garnet.berkeley.edu@ucbvax.Berkeley.EDU (William Baxter) Subject: Military and Civilian Space Should military and civilian space programs be separate in the US? If so, how can this be accomplished? If not, what objections do you have? Please e-mail replies to me. I'll post a summary. William Baxter ARPA: web@{garnet,brahms,math}.Berkeley.EDU UUCP: {sun,dual,decwrl,decvax,hplabs,...}!ucbvax!garnet!web ------------------------------ Date: 17 Jun 89 23:40:49 GMT From: visdc!jiii@uunet.uu.net (John E Van Deusen III) Subject: Re: Ozone depletion, atmospheric models, and public policy In article <8906141936.AA14067@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: > > In article <386@v7fs1.UUCP> mvp@v7fs1.UUCP (Mike Van Pelt) writes: >> I suspected from the beginning that the so-called 'ozone hole' was >> just part of a natural cycle that we would have been seeing all along >> if we had had satellites for decades. It makes no sense whatsoever >> that a fluorocarbon-induced hole would first appear over the south >> pole. According to the Jan 1988 issue of Scientific American, pg 32., the decline in springtime ozone levels over Antarctica was first identified by Joseph C. Farman and his colleagues at the British Antarctic Survey. They have monitored ozone levels directly over Halley Bay since *1956*. Their work continued until the results were published in 1985. Satellite observations beginning in 1971 completely confirm their work. The mean value of 300 Dobson Units declined precipitously starting in 1976 and reached a low of 160 in 1985. > ... the proposed "fix" is to undertake a presumably expensive switch > to alternate products, with us as consumers or taxpayers expected to > foot the bill. ... John Roberts seems to be in general agreement with Mike Van Pelt's statements. > - It is generally agreed that an increase in the short wavelength > ultraviolet light reaching the surface is undesirable. This light can > be blocked by O3 (ozone) or by O2 (regular oxygen). (The books don't > really go into the relative effectiveness of the two.) For much of the following see "The Astrophysics of Suntanning" by Bradley E Schaefer, NASA-Goddard Spaceflight Center, in SKY and TELESCOPE, June 1988, pg. 595. The most destructive UV-C radiation has a wavelength shorter than 2800 Angstroms. It is so strongly absorbed by the earth's atmosphere that it is seldom observed on the surface. The observation that O2 absorbs "short wavelength ultraviolet light" is not relevant, because UV-C does not reach the earth. The burns, skin cancer, wrinkles, blotchy pigmentation, and leathery skin resulting from prolonged exposure to Sun light are the result of UV-B rays, 2800-3200 angstroms. Oxygen does NOT block UV-B. For a standard ozone layer, (300 Dobson Units or 3 mmm STP), UV-B is dimmed 4.6 magnitudes per air mass. Other factors include scattering by air molecules, 1.2 magnitudes, and scattering by dust, 0.2 magnitudes. > CFCs tend to break down very slowly, with an expected lifetime of > 50-100 years. The free chlorine atoms last only a relatively short > time, before combining with other substances and drifting back toward > the troposphere. CFCs are almost impervious to breakdown by normal atmospheric processes, and they persist until they diffuse into the stratosphere. CFCs break apart when they absorb UV radiation. The result is the release of a free Chlorine atom. When the free Chlorine encounters ozone, Chlorine monoxide and an oxygen molecule are formed. Once Chlorine monoxide encounters a free oxygen molecule, the Chlorine atom is released, and another molecule of O2 forms. The Chlorine atom thus acts as a *catalyst* for the destruction of ozone. The only interference reaction that removes the Chlorine atom is the reaction of Chlorine monoxide with Nitrogen dioxide to form Chlorine Nitrate. > - Ozone depletion by chlorine is expected to be effective only in the > upper atmosphere. If the current ozone layer were depleted, it is > expected that more ozone would form lower down ... Ozone forms when UV radiation cracks an Oxygen molecule. If the Ozone layer is depleted, then this process should occur at lower elevations. As stated above, the production of free Chlorine from CFCs uses exactly the same mechanism. > - There is very little interest in measuring the short wavelength > ultraviolet light at the surface. Because it does not exist. See above. > Many (but not all) researchers seem to feel that depletion of the > current ozone layer would be directly proportional to increase of > ultraviolet at the surface. The fraction of light reaching the ground is 10^-kM/2.5 where k is the absorption coefficient, shown above to be about 6.0, and M is the number of Air Masses, 1 at zenith. A ten percent reduction in Ozone results in over *50* percent increase in UV-B radiation reaching the earth. > - I would assume that the winter holes in the ozone layer at the poles > are caused by depletion of the ozone when there is not much sunlight > present. The ozone builds back up in the spring when the sun reappears. The Antarctic Ozone hole forms in the spring! -- John E Van Deusen III, PO Box 9283, Boise, ID 83707, (208) 343-1865 uunet!visdc!jiii ------------------------------ Date: Sun, 18 Jun 89 03:43 CST From: IH04@vaxb.acs.unt.edu Subject: RE: SPACE Digest V9 #494 Re: GANYMEDE I am a writer working on a project that puts life on Ganymede, and I'm trying to decide what kind of differences a Ganymedan would have to have to live on a giant ice-covered moon with low density, no atmosphere to speak of and a greatly distant sun. It seems to me that there could be underground oceans heated by Ganymede's core, and some kind of life could exist there, but my lack of expertise is really showing as I develop this. Can anyone help? Also, I'd like to know how I can find out if there are gold deposits on Ganymede or any other body in our solar system. Many thanks, Rogers (IH04@NTSUVAXB) ------------------------------ Date: 17 Jun 89 23:19:49 GMT From: amdahl!pacbell!ditka!bucket!loop!keithl@ames.arc.nasa.gov (Keith Lofstrom) Subject: Re: Ozone depletion, atmospheric models, and public policy In article <8906141936.AA14067@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: > > - There is very little interest in measuring the short wavelength ultraviolet > light at the surface. Many (but not all) researchers seem to feel that > depletion of the current ozone layer would be directly proportional to > increase of ultraviolet at the surface. There was an article in *Science* last year or so (Ref?) about actual, long term measurements of biologically active UV at various sites around the US. There has been a *slight decrease*. The sites included both rural and urban measurements - the decrease is not due to local pollution. Decreasing CFC use is still a good idea, as long as people show a little perspective in what they replace it with, and how nasty they get about it. Keith -- Keith Lofstrom keithl@loop tektronix!tessi!qiclab!loop!keithl Launch Loop, P.O. Box 1538, Portland, Oregon 97207 (503)-628-3645 ------------------------------ Date: Sun, 18 Jun 89 12:01:47 MDT From: gavron%dac@lanl.gov (Ehud Gavron, MS H828 (505)665-1131) To: GOV@"space@angband.s1.gov", GAVRON%beta@lanl.gov Subject: How does one subscribe to this... subscribe How does one subscribe to this space digest? EG ------------------------------ Date: 17 Jun 89 23:49:00 GMT From: ux1.cso.uiuc.edu!uxe.cso.uiuc.edu!ahiggins@uxc.cso.uiuc.edu Subject: Re: Orbital queries From rsmith@udel.edu: > 2) Why do most space launches orbit west-to-east relative to the earth's > surface? Obviously other possibilities exist (e.g., geosynchronous > and polar). Nonetheless, I don't know of any that go east-to-west. > How come? Many satellites *do* orbit in east-to-west (or retrograde) orbits. Most are in orbits which are just barely retrograde (i.e., an inclinations of just greater than 90 degrees). The only relatively equatorial retrograde satellite in my recent recollection (and the most news worthy) is Ofek-1 launched by Israel last September using a Shavit rocket. If you consider Israel's geographic position relative to the Mediterranean, it's fairly obvious why it was launched in this manner. > Thanks in advance for any insights - You're welcome. -- Andrew J. Higgins | Illini Space Development Society ahiggins@pequod.cso.uiuc.edu | a chapter of the National Space Society phone: (217) 359-0056 | at the University of Illinois P.O. Box 2255 - Station A, Champaign, IL 61825 "We are all tired of being stuck on this cosmical speck with its monotonous ocean, leaden sky and single moon that is half useless....so it seems to me that the future glory of the human race lies in the exploration of at least the solar system!" - John Jacob Astor, 1894 ------------------------------ Date: Sun, 18 Jun 1989 11:38-EDT From: Dale.Amon@H.GP.CS.CMU.EDU Subject: Re: Chaotic orbits > of the "new science of chaos" (of which I understand nothing) as opposed > to the sense in which "chaos rules my desk" (which I understand far too Look for the book by Gleick ("Chaos"). There is also a reasonably stuffy "historical/philosophical" treatment by Ilya Prigogine himself. I recommend them both. A chaotic orbit is one that is bounded but never repeats exactly, ie it is described by a strange attractor. Normal orbits are just cases where the attractor has not bifurcated at all. There is a series of bifurcations leading to chaotic regions. The limits are still predictable and the object is well behaved, not "random" in a gaussian sense. It is just impossible (in a mathematically provable sense) to predict its future position at an arbitrary time t in the future. The accuracy of the prediction is sensitively dependant on the conditions at t0, and two points arbitrarily close together at t0 will be arbitrarily far apart at time t sufficiently far in the future. You cannot measure better than Heisenberg allows, therefore you cannot predict a chaotic orbit arbitrarily far in the future. ------------------------------ Date: Sun, 18 Jun 89 14:34:47 EDT From: "Keith F. Lynch" Subject: Re: Outer Space Committee To: ccnysci!patth@nyu.edu Cc: KFL%AI.AI.MIT.EDU@MINTAKA.lcs.mit.edu, Space@andrew.cmu.edu > The Committee on the Peaceful Uses of Outer Space ... With China, the USSR Cuba, and other butchers as members. Right. I hope the US isn't involved. ...Keith ------------------------------ Date: Sun, 18 Jun 89 22:34:29 MDT From: gavron%dac@LANL.GOV (Ehud Gavron, MS H828 (505)665-1131) To: GOV@"space+@andrew.cmu.edu", GAVRON%beta@LANL.GOV Subject: subscribe subscribe space Ehud Gavron set ack sub Ehud Gavron ------------------------------ End of SPACE Digest V9 #506 *******************