Date: Tue, 18 May 93 05:43:44 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #584 To: Space Digest Readers Precedence: bulk Space Digest Tue, 18 May 93 Volume 16 : Issue 584 Today's Topics: Billboards in space I want to be a (NASA) space cadet No. Re: Space Marketing would be wonderfull. Satellite Capabilities-Patriot Games (4 msgs) Space billboards Space Marketing would be wonderfull. (9 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: 17 May 93 15:05:45 From: Michael C Voorhis Subject: Billboards in space Newsgroups: sci.space > downs: > 1. astheticaly disgusting to a certain percent of the country (how > many we dont you know...) > 2. cant be "walked around", you have to go quite a distance (either up > or around the planet) Additional down-point: 1. Risk of fallout from missiles and other items launched by irate stargazers, attempting to destroy said `billboards' I think that these billboards would be found disgusting by mroe than just a trivial minority of the population. How many miles long/high would a billboard have to be to be seen from orbit, anyway? I can't imagine how large a billboard would have to be to be legible from geostationary orbit... Mike. ------------------------------ Date: Mon, 17 May 93 16:47:41 EDT From: CZ45000 Subject: I want to be a (NASA) space cadet Subj: I want to be a (NASA) space cadet or do I....? Judging from the response to "What does weightlessness feel like?" I wonder if someone on this list can authoritatively answer these questions: How much of an astronaut's (mission specialist) time is spent acting as a subject for medical experiments, as opposed to controlling physics/astronomy/remote sensing experiments and equipment? What does a mission specialist really do - both during a mission and between them? Why does NASA seem to prefer candidates with Ph.D.'s? From the astronaut's point of view is his scientific training used or wasted? Steve. ------------------------------ Date: 17 May 93 11:52:19 From: Tim Conrow Subject: No. Re: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,k12.chat.teacher In article <1993May17.061128.23196@ucsu.Colorado.EDU> fcrary@ucsu.Colorado.EDU (Frank Crary) writes: Sorry, it seems quite clear to me: If you object to such things, you are wasting your time worring about one minor aspect of the problem. Either openly oppose growth in general or accept its consequences. (I'm not sure if that is "kneejerk" by your standards. It's avoiding hypocracy by mine.) Frank Crary CU Boulder Either we must allow advertisers to impose themselves on our lives in any way they desire, or we must forego economic growth? Is that it, Frank? That's what's known in the rhetoric business as a false dichotomy. There are other options available. Reasonable restraint such as we might expect of neighbors, for example. I would think a reasonable person -- such as you clearly pride yourself on being, based on the wording of the paragraph above -- would have a somewhat less self-centered approach to such problems. Perhaps the appearence of the night sky is of no concern to you, but it is to other people. This rather unsocial indifference to others works out fine until *your* toes are stepped on. By the way, it's "hypocrisy". "Hypocracy" might be "government by hypodermic needle" maybe. I dunno, maybe we're headed for that too ;-) -- Tim ------------------------------ Date: Mon, 17 May 93 10:28:18 PDT From: Charlie Prael Subject: Satellite Capabilities-Patriot Games Newsgroups: sci.space england@helix.nih.gov (Mad Vlad) writes: > Hello netters, > > I'm new to this board and I thought this might be the best place > for my post. I have a question regarding satellite technology seen > in the movie Patriot Games. In the movies, the CIA utilizes its > orbitting sats to pinpoint a specific terrorist camp in N Africa. > The photos taken by the sats are stunning! I know that sats are > capable of photographing the license plates of vehicles. My > question is this: The camp in question was taken out by the > British SAS. And while the SAS was in action, the CIA team was > watching in the warroom back in Langley, VA. The action of the SAS > was clear and appeared to be relayed via a sat. The action was at > night and the photography appeared to be an x-ray type. That is, > one could see the action within the tents/structures of the camp. > Does such techology exist and what is it's nature? i.e., UV, IR, > x-ray, etc. > > PS Who wrote the book Patriot Games? > > Mad Vlad Vlad-- Yes, that kind of technology *does* exist. That sort of thing is short with IR imaging equipment, though in the film's case it was shot by simply fly-netting the tops of the tents, and making it *look* like it was shot by IR. The author of PG was Tom Clancy, who's done a number of other, similar Technothrillers based in the same series. ------------------------------------------------------------------ Charlie Prael - dante@shakala.com Shakala BBS (ClanZen Radio Network) Sunnyvale, CA +1-408-734-2289 ------------------------------ Date: Mon, 17 May 1993 19:07:17 GMT From: Thomas Clarke Subject: Satellite Capabilities-Patriot Games Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: > In article england@helix.nih.gov (Mad Vlad) writes: > >The photos taken by the sats are stunning! I know that sats are > >capable of photographing the license plates of vehicles... > > The satellite imagery is treated semi-realistically in the *book* > version of Patriot Games. I haven't seen the movie, but I expect > Hollywood has exaggerated for dramatic effect. X-ray vision from > orbit is just not available. I think the imagery was supposed to be in the infrared. I have seen films where soldiers can be seen through camoflage in infrared. Although I think to go through a tent it would have had to have been far-infrared (FLIR) which is an order of magnitude longer wavelength than visible. The resolution would thus have been a lot lower ~1 m rather than 10 cm. Hollywood did get the degraded resolution wrong. Hmm. The 10 cm is atmospherically limited, maybe at FLIR wavelength the "seeing" is better so that with enough aperture the resolution is not degraded ?? -- Thomas Clarke Institute for Simulation and Training, University of Central FL 12424 Research Parkway, Suite 300, Orlando, FL 32826 (407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu ------------------------------ Date: Mon, 17 May 1993 20:28:10 GMT From: Mark Elowitz Subject: Satellite Capabilities-Patriot Games Newsgroups: sci.space In article <1993May17.190717.14834@cs.ucf.edu>, clarke@acme.ucf.edu (Thomas Clarke) writes: > In article henry@zoo.toronto.edu (Henry Spencer) > writes: > > In article england@helix.nih.gov (Mad > Vlad) writes: > > >The photos taken by the sats are stunning! I know that sats are > > >capable of photographing the license plates of vehicles... > > > > The satellite imagery is treated semi-realistically in the *book* > > version of Patriot Games. I haven't seen the movie, but I expect > > Hollywood has exaggerated for dramatic effect. X-ray vision from > > orbit is just not available. > > I think the imagery was supposed to be in the infrared. I have > seen films where soldiers can be seen through camoflage in infrared. > Although I think to go through a tent it would have had to have > been far-infrared (FLIR) which is an order of magnitude longer > wavelength than visible. The resolution would thus have been a > lot lower ~1 m rather than 10 cm. Hollywood did get the degraded > resolution wrong. > > Hmm. The 10 cm is atmospherically limited, maybe at FLIR wavelength > the "seeing" is better so that with enough aperture the resolution > is not degraded ?? > -- > Thomas Clarke > Institute for Simulation and Training, University of Central FL > 12424 Research Parkway, Suite 300, Orlando, FL 32826 > (407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu Adaptive optics technology tends to work better in the IR, so IR imaging using adaptive optics works better then using adaptive optics in the visible. However, using Rayleigh's criterion, you get higher resolution in the UV given a certain optical configuration. Most likely, some of the newer KH satellites, use IR CCD imaging technology. ------------------------------ Date: Mon, 17 May 1993 19:38:45 GMT From: Henry Spencer Subject: Satellite Capabilities-Patriot Games Newsgroups: sci.space In article <1993May17.190717.14834@cs.ucf.edu> clarke@acme.ucf.edu (Thomas Clarke) writes: >Hmm. The 10 cm is atmospherically limited, maybe at FLIR wavelength >the "seeing" is better so that with enough aperture the resolution >is not degraded ?? The "few cm" I quoted is the diffraction limit for a circa 2m mirror in visible light, ignoring atmosphere issues entirely. You'd need a monstrous mirror to get centimeter-range resolution in thermal infrared from orbit, unless the NRO lads have discovered some entirely new physics. -- SVR4 resembles a high-speed collision | Henry Spencer @ U of Toronto Zoology between SVR3 and SunOS. - Dick Dunn | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 17 May 93 09:34:00 PST From: thomsonal@cpva.saic.com Subject: Space billboards Newsgroups: sci.space dnash@uxa.cso.uiuc.edu (David Nash) quotes somebody else quoting the NYT: >In the New York Times on Sunday May 9th in the week in review >section there was a report of a group called "Space Marketing" >in Atlanta, Georgia who is planning to put up a one mile wide >reflective Earth orbiting satellite which will appear as large ^^ ^^^^^ >and as bright as the Moon and carry some sort of advertising. ^^^ ^^ ^^^^^^ Excuse me if someone has already done the arithmetic on this, but something seems not particularly right with these figures. If "as large as" == "of the same angular extent as," then the sign, subtending 0.5 degree of arc, would be at an altitude of 115 miles (presumably statute), or 185 km. There is still a lot of air at that altitude, and normal satellites in circular orbit that low only last a very few days before reentering. I would imagine the sign would have a frontal area/mass ratio at least as large as other satellites, and so it would only last a week or so, if that. (There are ways of getting around this: for example, put the sign in an eccentric orbit with apogee at several thousand km and perigee at 200 km over the market area. Cosmos 398, a LEMski from the FSU's lunar landing program, is in just such an orbit, and has been flirting with incineration for several years as it dips below 200 km at perigee.) Of course, the "one mile" may not be quite right, and the sign might be higher and bigger, perhaps in a Mir-like orbit at a little under 400 km and twice as large as stated. However, in order to be seen, I would assume that the sign would have to be illuminated by sunlight -- self-illumination doesn't strike me as practical. As people who have seen the Moon during the day know, the sign would be visible in the daytime sky, but presumably this wouldn't offend astronomers as much as a bright Moon-like object whipping across the night sky -- and there's the catch. In order to be a bright object in the nighttime sky, the sign has to be illuminated by the sun while the ground observers are in darkness. This is just the pre/post-twilight observing condition amateur satellite watchers need for seeing other satellites, and we can use satellite prediction programs to get an idea of how much of a nuisance the sign would create for astronomers through light pollution. Firing up such a program (TRAKSAT), and using Mir and Cosmos 398 as surrogates for the sign, we see that for a 90 day period starting now, a site in Hawaii would see the illuminated sign for a few minutes per night every few days at times near nautical twilight. Details will vary with orbit, observing site, and time of year, but this table should be generally representative of how often and for how long the sign would be visible from a given observatory. As for occultation, remember that the sign is moving at orbital velocity: around 7500 m/sec. Even if it is 3 km in diameter, it will occult a given point in the sky for less than a half a second. Perhaps the practicing astronomers (amateur and professional) among the readership could comment on how much an over-flight schedule like this would affect their observations. TRAKSAT Version 2.80 Analytical Solution Tracking Station: HONOLULU,HI (Local time assumed to be UT - 10) [ Optical Visibility ]Twilight setting = -12.0 Pass Satellite UTC Time Local Time Azimuth Max Min Duration Date HR:MN:SC Date HR:MN:SC Ele Range HR:MN:SC deg km Mir Complex 18May93 06:30:11 17May93 20:30:11 NW TO SE 47 506 00:06:11 20May93 06:13:30 19May93 20:13:30 W TO S 17 1039 00:04:30 30May93 14:50:13 30May93 04:50:13 S TO E 14 1158 00:03:13 01Jun93 14:30:55 01Jun93 04:30:55 S TO NE 37 615 00:05:55 01Jun93 14:12:35 03Jun93 04:12:35 SW TO NE 71 405 00:06:35 04Jun93 14:53:59 04Jun93 04:53:59 NW TO NW 10 1372 00:01:59 22Jun93 07:14:54 21Jun93 21:14:54 W TO N 22 869 00:05:54 23Jun93 06:16:34 22Jun93 20:16:34 SW TO NE 72 406 00:06:34 24Jun93 06:57:12 23Jun93 20:57:12 NW TO NW 11 1354 00:02:12 25Jun93 14:08:36 25Jun93 04:08:36 N TO E 19 961 00:04:36 26Jun93 14:46:19 26Jun93 04:46:19 NW TO SE 46 510 00:05:19 16Jul93 06:37:19 15Jul93 20:37:19 NW TO SE 78 394 00:06:19 18Jul93 06:17:00 17Jul93 20:17:00 NW TO S 28 742 00:05:00 30Jul93 14:16:57 30Jul93 04:16:57 SE TO E 11 1261 00:02:57 31Jul93 14:52:16 31Jul93 04:52:16 SW TO NE 79 388 00:06:16 Cosmos 398 17May93 07:33:25 16May93 21:33:25 W TO SW 10 4768 00:06:25 26Jun93 07:22:57 25Jun93 21:22:57 SW TO NE 59 677 00:09:57 27Jun93 07:08:12 26Jun93 21:08:12 SW TO NE 55 732 00:09:12 28Jun93 06:53:15 27Jun93 20:53:15 SW TO NE 52 789 00:09:15 29Jun93 06:37:57 28Jun93 20:37:57 SW TO NE 50 856 00:10:57 30Jun93 06:22:30 29Jun93 20:22:30 SW TO NE 48 902 00:10:30 01Jul93 06:06:50 30Jun93 20:06:50 SW TO N 47 954 00:10:50 31Jul93 06:24:00 30Jul93 20:24:00 NW TO SE 53 337 00:04:00 01Aug93 06:01:12 31Jul93 20:01:12 NW TO SE 69 303 00:05:12 13Aug93 15:03:32 13Aug93 05:03:32 S TO NE 37 2894 00:22:32 14Aug93 14:38:02 14Aug93 04:38:02 S TO NE 34 3015 00:21:02 15Aug93 14:12:23 15Aug93 04:12:23 S TO NE 30 3138 00:20:23 Allen Thomson SAIC, Inc. McLean, VA -------------------------------------------------------------------------- No one would believe me if I claimed to speak for SAIC, and rightly so: I don't. ------------------------------ Date: 17 May 93 18:09:42 GMT From: Richard J Shank Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines HEY!!!! YOU PEOPLE!!! PLEASE!!! Edit your newsgroup line. This has nothing to do with misc.invest and it is all we get now that this thread has started. It's not that people are not interested (most are not though) but it does not belong here and our BW is getting swamped with garbage. Thank you for your concern and assistance. ------------------------------ Date: Mon, 17 May 1993 17:45:26 GMT From: Frank Crary Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,misc.legal In article kkobayas@husc8.harvard.edu (Ken Kobayashi) writes: > But here's an idea - what if the billboard was not composed of a single >gigantic 'thing' but instead of hundreds of little, high-quality mirrors? >Then they can just point the reflected light towards a particular city, >and the area outside will not be severely affected. Of course, it will >reduce effectiveness and probably increase cost, but that would be a >reasonable compromise wouldn't it? The Russians have been playing with a similar idea for a decade or so. Not to advertise, but to replace street lights. In a nation where most of the cities are regularly in darkness for over 16 hours a day, that almost makes sense. Frank Crary CU Boulder ------------------------------ Date: 17 May 93 18:24:16 GMT From: Richard J Shank Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,misc.legal Who needs space marketing to mess things up? All it takes is a few morons to tag 10 or more newsgroups together in a posting and everybody has to tolerate it. What the hell has misc.invest got to do with 99% of this thread? Please remove our newsgroup from this *.* listing. It is getting annoying beyond belief. ------------------------------ Date: Mon, 17 May 1993 17:41:49 GMT From: Frank Crary Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,k12.chat.teacher,misc.legal In article jhart@agora.rain.com (Jim Hart) writes: >If anybody has a strong claim to control of the the night sky, it is >astronomers. Check out the common law. In the days when wild lands >weren't scarce, pioneers laid claim to the land by putting it to >use, eg clearing and growing a crop. The law always required the used to improve the land in some way (building a house there, planting crops, etc...) Further, this only applied to the individual involved. An entire profession couldn't make a collective claim. >Even trespassers can lay claim to >the right of passage if if they've done it for long enough and the >owners have not complained or taken steps to stop them. Usage >begets property rights. Use does. But legally simply looking at a plot of land doesn't count as "use." To apply these laws you have to at least walk across the land regularly. >Astronomers have been using the night sky for thousands of years -- >they own it. If they don't complain now against scenic trespassers >(eg light polluters), they will lose their common-law right of ownership. We have no such common law ownership since we: Are an unorganized group, not a single individual or chartered company; have made no improvements to the property; have only observed, as opposed to directly used the property. If you really want to apply common law property rights, I think the Russians "own" the 65 deg. inclination orbits between 200 and 300 km altitude and various nations and companies own parts of the geostationary orbit. The rest of space would be either unused or contested (i.e. used by many people, so no one has a valid claim.) You could probably use the contested status of most orbits to oppose things like anti-satellite weapons tests which would produce dangerous orbital debris: Since ownership is contested, no one can do things which prevent the traditional uses (analogous to putting up a fence across a path traditionally used by trespassers.) Frank Crary CU Boulder ------------------------------ Date: 17 May 1993 20:23:14 GMT From: Pawel Moskalik Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,sci.astro,talk.environment,sci.space,rec.backcountry,misc.rural The notion that visible light astronomy is getting obsolete is just plain silly. Look, people are doing observations in X-ray or IR not because thy are "better" than visual light, but because thay are complementary. They carry DIFFERENT information about the object. We need this information, as well as information carried in visual light. More and more often people arrange multiwavelength campains, when they observe the same object simultaneously in ALL wavelengths (from gamma, through X-ray, UV, visual, IR to radio). And that is EXTREMELY useful and scientifically productive. There is still plenty of data aquired invisual an many, many papers published. For one thing, visual, ground-based astronomy is far cheaper than space-based non-visual astronomy. Visual detectors are also very numerous. There are things that can be done in visual, but cannot be done in any other wavelenght !! Examples?? you can observe photometrically one chosen star continuously for 2 weeks (passing it from telescope to telescope as the Earth rotates). This has been actually done by several group succesfully. With this kind of data you can tell a great deal about the star simply by analysing the temporal variations of the brightness. Scientific results have been outstanding. But to do that, you need to have CONTINUOUS data lasting for 10 days or more. You cannot get this kind of data from space-based X-ray or UV telescopes, simply because thare are not enough of them in orbit. Pawel Moskalik ------------------------------ Date: 17 May 1993 19:32:09 GMT From: "David M. Palmer" Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,k12.chat.teacher fcrary@ucsu.Colorado.EDU (Frank Crary) writes: >In article <1993May17.021717.26111@olaf.wellesley.edu> lhawkins@annie.wellesley.edu (R. Lee Hawkins) writes: >>>because of his doubtfull credibility as an astronomer. Modern, >>>ground-based, visible light astronomy (what these proposed >>>orbiting billboards would upset) is already a dying field: The >>Ahh, perhaps that's why we've (astronomers) have just built *2* 10-meter >>ground-based scopes and are studying designs for larger ones. >Exactly what fraction of current research is done on the big, >visable light telescopes? From what I've seen, 10% or less >(down from amlost 100% 25 years ago.) That sounds like "dying" >to me... Grabbing an issue of 'Astronomical Journal' at random (May '93), I get 21/34 papers are optical. The 34 includes computational astronomy. I don't think any of the optical papers were Hubble-based. >>Seriously, though, you're never going to get a 10-meter scope into orbit >>as cheaply as you can build one on the ground, and with adaptive optics >>and a good site, the difference in quality is narrowed quite a bit >>anyway. >That would be true, if adaptive optics worked well in the visable. >But take a look at the papers on the subject: They refer to anything >up to 100 microns as "visable". I don't know about you, but most >people have trouble seeing beyond 7 microns or so... There are >reasons to think adaptive optics will not work at shorter >wavelengths without truely radical improvements in technology. Adaptive optics, speckle, etc. works well in the optical. Or at least a lot better than old-fashioned, slap-a-plate-into-the-holder-and-point optics. >>What deparment are you in anyway, Philosophy? You obviously are not >>qualified to speak about astronomy... >The sign the office door says, "Astrophysical, Planetary and >Atmospheric Sciences." Although perhaps my degree in astrophysics >from Berkeley doesn't qualify me either... On the other hand, >I just might not be too attached to one particular way of collecting >astronomical data. What field are you in? -- David M. Palmer palmer@alumni.caltech.edu palmer@tgrs.gsfc.nasa.gov ------------------------------ Date: 17 May 1993 19:40:22 GMT From: "David M. Palmer" Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,misc.invest,sci.astro,talk.environment,talk.politics.space,sci.space,rec.backcountry,misc.rural,misc.headlines,k12.chat.teacher fcrary@ucsu.Colorado.EDU (Frank Crary) writes: >That's extremely doubtfull: Adaptive optics require moving the >optical elements around with cycle times (including time for >vibrations to die down) of order 10-50 miliseconds. Unless you >make "the largest telescopes" out of tens of thousands of seperate >pieces, active corrections will be of limited value to these >telescopes (judging from the expense and development problems >associated with the new, 36-element mirror, I don't think >thousands of elements is likely.) You don't have to move the primary mirror. The movable elements can be in the secondary or tertiary. Or in post-processing in some schemes. And most of the trouble with Keck has been in the mirror grinding, not in the element positioning. >>To say that "visible light astronomy is already a dying field" is >>pure hokum... >If you say so, but most of the papers I see are based on spacecraft, >orbital telescope, radio telescope or high-altitude infrared >observations. And most of my work uses space-based and balloon-borne gamma-ray instruments. But I don't believe that we should stop all observations below 1 keV just so that Proctor & Gamble can sell more tampons. -- David M. Palmer palmer@alumni.caltech.edu palmer@tgrs.gsfc.nasa.gov ------------------------------ Date: Mon, 17 May 1993 20:33:14 GMT From: Devon E Bowen Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,sci.astro,talk.environment,sci.space,rec.backcountry,misc.rural Those interested might look into joining the Dark Sky Association which is a group that educates the public about light pollution and helps for those interested in getting local light pollution laws passed. They do good work and don't take the us-them approach. Sorry, but I don't have the address handy. I can get it if there is interest. Devon ------------------------------ Date: 17 May 93 13:50:29 From: Matt Austern Subject: Space Marketing would be wonderfull. Newsgroups: sci.environment,misc.consumers,sci.astro,talk.environment,sci.space,rec.backcountry,misc.rural In article <1t8s7iINNa60@no-names.nerdc.ufl.edu> pam@wombat.phys.ufl.edu (Pawel Moskalik) writes: > There are things that can be done in visual, but cannot be > done in any other wavelenght !! > Examples?? you can observe photometrically one chosen star continuously > for 2 weeks (passing it from telescope to telescope as the > Earth rotates). This has been actually done by several group > succesfully. With this kind of data you can tell a great > deal about the star simply by analysing the temporal > variations of the brightness. In fact, many of the astronomy results that are relevant to my own field are obtained using this sort of method. For example, this type of observation is used for automated supernova searches, and for attempts to see gravitational lensing due to certain types of dark matter. The two searches that I've mentioned both involve looking at visible light from extremely faint sources---extragalactic sources, in fact. What a non-astronomer would think of as small amounts of light (street lights from 30 miles away, for example) are major interferences. I'd hate to see all of this scientifi work forced to end just for the sake of another advertising campaign. Remember: just because someone calls something "progress" doesn't mean it necessarily is. [I first saw this thread on rec.backcountry, so I'll try to say something marginally relevant to that group. I'm in the middle of Desert Solitaire right now; I've just finished the chapter where Abbey discusses road-building in National Parks. I think Abbey would have some very unsympathetic comments about intrusive advertising in the night sky.] -- Matthew Austern Maybe we can eventually make language a matt@physics.berkeley.edu complete impediment to understanding. ------------------------------ End of Space Digest Volume 16 : Issue 584 ------------------------------