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Return-path: <ota+space.mail-errors@andrew.cmu.edu> 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 </afs/andrew.cmu.edu/usr1/ota/Mailbox/Aa91PHi00VcJ4M1U5V>; Thu, 12 Apr 90 01:49:08 -0400 (EDT) Message-ID: <8a91OVK00VcJ4Lzk4-@andrew.cmu.edu> Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Thu, 12 Apr 90 01:48:18 -0400 (EDT) Subject: SPACE Digest V11 #250 SPACE Digest Volume 11 : Issue 250 Today's Topics: Re: STS26 program Re: Ejection seats Re: Galileo Update - 04/10/90 Earthbound asteroid..... Interstellar travel Re: more on NASA redistribution of information re: releasing data / digitized images ---------------------------------------------------------------------- Date: 10 Apr 90 19:01:45 GMT From: mcsun!ukc!tcdcs!swift.cs.tcd.ie!ccvax.ucd.ie!h235_022@uunet.uu.net (Gordon T Gopher at CCVAX) Subject: Re: STS26 program In article <770@sppy00.UUCP>, cjs@sppy00.UUCP (Christopher Schaller) writes: > About a week ago, I recieved a copy of the STS26 program that has been > circulating. What version of ZIP do you use to uncompress this. > > Thankyou. > > Chris. -- I got the program too and PKZIP102 worked fine - but 110 should work even better (!!)... have fun with it.. Neil -------------------------------------------------------------------------------- Neil Conway H235_022@ccvax.ucd.ie | Disclaimer ? HA! I'll die of surprise if H235_022@ccvax.bitnet | this even makes it onto the net... :-) -------------------------------------------------------------------------------- ------------------------------ Date: 9 Apr 90 16:18:30 GMT From: zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!srcsip!jhereg!quest!viper!dave@tut.cis.ohio-state.edu (David Messer) Subject: Re: Ejection seats In article <384@mtndew.UUCP> friedl@mtndew.UUCP (Steve Friedl) writes: >Al Bowers writes: >> Your 25g estimate is in the ballpark. Older seats generated up to 40g >> and had consequent higher injury rates. > >So what causes these injuries? > >I find it easy to believe that ejecting is not A Fun Thing, but >where specifically is the danger? Have you every had 39 guys jump on top of you? Could be dangerous... :-> More specifically -- the danger is in two areas; the pilot may have some part of his body out of position, or the acceleration itself can cause an injury. If an arm or leg is not in the right place during ejection, it may get caught on something on the way out. The acceleration itself can compress vertibrae, dislocate joints, cause internal bleeding, and other nasty stuff. Then, of course, there are other things that can go wrong, like the paracute not opening... -- Remember Tiananmen Square. | David Messer dave@Lynx.MN.Org -or- | Lynx Data Systems ...!bungia!viper!dave ------------------------------ Date: 11 Apr 90 15:26:50 GMT From: usc!cs.utexas.edu!mailrus!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Galileo Update - 04/10/90 In article <1990Apr10.223630.29966@jarvis.csri.toronto.edu> wayne@csri.toronto.edu (Wayne Hayes) writes: >>The maneuver, which will slow the spacecraft by 24.8 meters per >>second or about 55 mph, will be carried out in four daily >>portions, each lasting more than 6 1/2 hours. ... >This seems like a rather large maneuver. Was it planned beforehand... No, it's just a tedious maneuver. :-) 25m/s is nothing by spacecraft standards, but the thrusters they're using are (a) miniscule, (b) on a spinning spacecraft that makes it impossible to fire continuously, and (c) *theoretically* cured of a nasty overheating problem that would make it unwise to fire them continuously anyway. -- With features like this, | Henry Spencer at U of Toronto Zoology who needs bugs? | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 11 Apr 90 16:32:05 GMT From: snorkelwacker!spdcc!rayssd!bea@think.com (Brian E. Alber) Subject: Earthbound asteroid..... ~r missed ------------------------------ Date: 11 Apr 90 22:12:01 GMT From: jb5v+@andrew.cmu.edu (Jeffrey Kirk Bennett) Subject: Interstellar travel I noticed a lot of talk about interstellar travel a while back, and I'm a little confused. Am I wrong, or is there a point to thinking about such things? It seems to me that there a a couple principles which make it completely impractical- but I'm not a physicist, so please expand or correct me if I'm wrong. 1. The goal is to find intelligent life and/or a habitable planet. It seems to me that both are extremely rare events. Though I've no doubt that there is life somewhere else in the universe, I'm sure it is an exceedingly rare event. But even if it's 1 in a trillion, the sheer number of stars makes it statistically likely. However, the probability of finding life or a good planet in any PARTICULAR star system is vanishingly small. Therefore, even if we could build a ship to visit a few nearby stars, we would probably have to investigate a few MILLION stars- several hundred thousand of which would be very remote- in order to find anything useful. 2. I don't see mankind inventing practical anti-matter propulsion or whatever the current idea is in the next century or two. But, since there are no theoretical reasons why a craft cannot fly arbitrarily close to c, assume that something will be developed which is capable of accelerating to, say, .9c within a reasonable (ship's) time. One related question is- are there thermodynamic efficiency considerations which limit the maximum possible speed? Would these depend on the method of propulsion used? The point is, due to relativistic mechanics, wouldn't it be a 1-way trip? If you travelled to a star 5 light-years away at .9c, wouldn't a few centuries or millenium pass on Earth? How severe is the time dilation effect? Again, I'm not a physicist. What happens to time during the acceleration and deceleration- when the velocity is not constant. And what happens when the ship stops accelerating and starts decelerating, when even the acceleration is not constant? Does anyone know how to figure that all out realistically, including all the non-constant terms. How long would a trip take at .1c, .5c and .9c in both ship's and Earth's time? 3. Assuming all the fuel is burned during the acceleration and deceleration phases, how would the craft return? 4. Even if it had the fuel to return, how would it find the Earth again, since it is not exactly standing still, and may have moved unpredictably due to passing stars, black holes, etc. in the path of the Sun. What I'm saying is basically this: We don't have the technology to do it. Even if we did, it would be a 1-way trip. Even if we accepted that and went anyway, how would we have fuel enough to get back? Even if we had fuel enough to get back, how would we even FIND the Earth again? Even if we surmounted all these difficulties, the probability of finding something useful is almost nil anyway. So who would fund this research, when the astronauts would be returning (if they ever returned) 20,000 years into the future when the Earth is ruled by dinosaurs or mutants or something, and most likely empty-handed? With AIDS, drugs and the deficit, such a Don Quixote exercise in futility wouldn't have a chance. So I don't see the point in even talking about it, but comments are welcome. On a related note- can't we dismiss UFO reports out of hand? My reasoning is this: 1. There are no little green men on the moon. Therefore, E.T.'s would have to come from outside the solar system = other stars. 2. If something is coming from another star, it would have to have near light-speed travel. 3. The aliens would never do this, since they would be faced with all the problems discussed above. Even if we assume a totally alien value system which would cause them to do it anyway... 4. Wouldn't something decelerating from near light-speed in our solar system have to shed all its relativistic mass as energy? In that case, it would probably be the brightest star in the sky, visible even in the daytime. Even if it's not so dramatic (I'm not a physicist- any estimates on this?), I'm sure we would pick up something, with all the tracking devices and telescopes we have pointed into space. Since we haven't seen this, doesn't that alone prove that there are no UFO's? 5. Even if I'm wrong there- if an alien makes a 1-way trip to another star and finds advanced life on a planet, wouldn't he at least LAND or something? What else can he do? He can't go home- everyone he knows is centuries dead at least- what does he have to lose? I can't imagine him just buzzing some farmer in Arkansas and heading off into the sunset. 6. 99% of the UFO reports can be explained by strange and rare meteorological events which are unfamiliar to most people. Nature is very strange indeed at times. I would say the other 1% (from reliable sources, Air Force pilots, etc.) are military craft or experimental weapons, etc. that don't officially exist and that we are not supposed to know about, and which the government covers up. I have no problem with that- they have to keep some secrets. These are things which have bugged me forever. I believe interstellar travel is probably impossible and certainly impractical, and UFO's don't exist. Am I missing something here? Jeff ------------------------------ Date: 11 Apr 90 21:35:50 GMT From: amelia!wilbur.nas.nasa.gov!eugene@ames.arc.nasa.gov (Eugene N. Miya) Subject: Re: more on NASA redistribution of information NASA isn't a very good place to store data...of any kind. I look at what happen to Landsat (now with the Eosat people), COSMIC, etc. These are long stories, many on going. Anonymous FTP, Center BBSs, and server daemons like netlib are a little like nightmares which the bureaucracy isn't aware. The Agency is still somewhat in the computer dark ages due to efforts by certain large computer (mainframes) companies and one large generally computer company. ;) There are also some antiquated ideas of how to use machines (If a SUN workstation has 16 users on it, this is 16 times better than if it has 1 user), fortunately the facility where I work is more enlightened (I have more machines than I know what to do with from a NeXT to some big iron). The real problem is software. The Internet is now a big International thing. We are an Agency of the US Government. We now have some VERY strict directives about export of American high technology. Numerous signatures and approvals are required just to ship a tape out from Ames. Certain countries and companies have been given extra looks, you can guess some of these: Japan, European countries: France, England, even Canada is regarded as "foreign" travel. I have a grad student from Mexico. I've also work with other researchers Here from France and Japan. Never mind the Soviet Union or China, in fact, they might be some sort of prefered status. Some of these countries regard Landsat and SPOT as spy apparatus (like the Philippines). If it comes on a tape or disk, don't think you can just get your hands on it. Launching cubes into space or running test craft in wind tunels, ain't cheap. Someone's going to pay on top of taxes. SO when you write to good ole Al Gore. Think about these issues, because the man knows about them. Us? We're just in the middle. --e. nobuo miya, NASA Ames Research Center, eugene@orville.nas.nasa.gov {uunet,mailrus,other gateways}!ames!eugene ------------------------------ Date: 11 Apr 90 05:12:10 GMT From: eagle!news@ucbvax.Berkeley.EDU (Ted Fabian) Subject: re: releasing data / digitized images I'd like to add a few comments to the recent discussion which has been going on here in SCI.SPACE about the releasing of images in formats that allow those images to be viewed on PCs.. however, I suspect that I'm liable to get negative feedback.. so let me preface my thoughts by first saying that I'm in no way connected to the HST Project, nor am I in any position that would provide me with access to their data or their images.. if I wanted the images, I'd have to wait like everyone else.. Many folks have been critical of policies which seemingly prohibit release of images until one year has passed.. I don't know if this is indeed a policy, or if someone has blown it out of proportion.. nor do I want to know.. but if it is, it has merit from a couple of persepctives... First and foremost, the overall goal of the spcae program and / or the particular mission (in this case, the HST) needs to be weighed against the benefits provided by releasing the images... will the release of the images benefit all of mankind?? will the immeadiate release of the images change a life, or provide some insight that will make someones life better?? I don't think that it will.. if you have a need to get the data, you're either already in such a position, or you know how to get the data without complaining openly to the world about it.. rather, I think the things we're seeing in SCI.SPACE as of late are from people who don't have a need to have the data.. they simply want the data either as a status symbol, or as some sort of ego booster.. several replies suggested writing to NASA and / or Congressmen to complain.. if you do, I doubt it'll help.. if you understood the processes of releasing data, (any data), as well as the reseach processes that are undertaken, you'ld realize that you're only talking to the wind... chances are, your Congressman will say something like "thanks for writing".. and "we'll be in touch"... and your letters to NASA will end up in the public affairs office.. there you'll get an offical reply that'll try to ex explain why they cannot honor your request.. but in neither case, will you have reached the folks who are capable of fullfilling your request.. rather, you'll be contributing to the problem.. meanwhile, a bigger question is whether the capability to provide the data in the format that you all desire even exists... and if so, who will pay for it... with the constant budget crunch, NASA as well as other government adgencies cannot expend resources randomly to satisfy everyone.. those whose requests best fit the overall program goal will be the ones who are answered... I don't want to start an arguement, nor do I want to hear from everyone who thinks he/she know better.. (I openly admit that I'm no expert at anything..) but I do ask that before you spout off your desires to have data made available to you, that you consider that you're asking for alot.. just off the top of my head to fulfill your requests, 1) data would need to be taken from the downlink data streams coming from TDRS (or whatever other source might be used) and then separated out.. at times, I've heard that this data rate can reach 300 megabits per second.. depending on the source, and the conditions.. so separating the digital images clearly is not a simple task.. 2) once separated, the data would need to be archived into a usable format.. specifically one that is understood by the most common graphics pacakges... again, given the density of the data, and the state of the art available today, putting something in one format will please some of the people, but not all.. so who picks the format?? or are multiple copies stored in different formats?? etc. etc... and where are the data files stored?? disk space is not cheap, nor readily availabe in many instances... 3) then, appropriate approvals to release the data would need to be obtained.. depending on what the data is, this process may require approval from several levels of management.. and then as someone pointed out, the offical release point of NASA is the Public Information Office.. so that data would need to be transferred to that office.. and the technology to release store and distribute that data in the formats desired would need to be made available to that office...if it isn't already there... 4) finally, we'ld be ready to let the world grab the pictures / images... OQ`OS remember, I don't speak for NASA, only myself.. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Thanks, * * Ted Fabian NASA Lewis Research Center * * Cleveland, Ohio * * * * phone: 216-433-6307 FTS 297-6307 | disclaimer: * * email: tpfabian@nasamail.nasa.gov | my opinions * * tfabian@mars.lerc.nasa.gov | are my own * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- ---------------------------------------------------- Thanks, Ted Fabian NASA Lewis Research Center tpfabian@nasamail.nasa.gov *my opinions tfabian@mars.lerc.nasa.gov *are my own.. ------------------------------ End of SPACE Digest V11 #250 *******************