Return-path: 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 ; Wed, 2 May 90 01:43:59 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 2 May 90 01:43:29 -0400 (EDT) Subject: SPACE Digest V11 #342 SPACE Digest Volume 11 : Issue 342 Today's Topics: Re: Galileo entry probe Re: Re: Fermi paradox Navstar GPS Status Reports on WWV and WWVH Re: Galileo entry probe I need an engineer. Re: Navstar GPS Status Reports on WWV and WWVH Re: Hubble Telescope Radiation Effects on Spacecraft Computers (How to get rid of) space garbage Satellite Dish Recommendations? Re: Niven's inertialess drive (was Re: Dyson spheres, heat flow) ---------------------------------------------------------------------- Date: Tue 1 May 90 12:43:23-PST From: Jay Glass Subject: Re: Galileo entry probe Mail-System-Version: >Does the Galileo probe that is going to enter the Jovian atmosphere >have a camera on board? What other sensors are present? The Galileo probe doesn't have a camera, but the orbiter does. There are six instruments on board the probe, each with one or more sensors. Rather than list pages of specifications on the net, interested parties can request a technical brochure from: Benny Chin, Manager, Galileo Probe Operations Mail Stop 244-19, NASA-Ames Research Center, Moffett Field, CA 94035-1000 or email to bchin@nasamail.nasa.gov . Incidentally, I couldn't find Mary Shafer *anywhere* Sunday morning...when asked where the Usenet RDV was, her boss looked blank... Jay Glass glass@pluto.arc.nasa.gov ------- ------- ------- ------------------------------ Date: Tue, 1 May 90 20:16:33 EDT From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: Re: Re: Fermi paradox >From: usc!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca!neufeld@ucsd.edu (Christopher Neufeld) >Subject: Re: Fermi paradox > No, I think you can say that the probability that there is exactly >one life-bearing planet in the universe is no more than 1/e. > Assume that the probability that a given star will harbour one >life-bearing planet is some value r where r << 1. > Now, what is the probability that out of N stars, exactly one will be >life-bearing? It's: P(1) = choose(N,1) * r * (1 - r)^(N-1). > Apply the familiar calculus techniques to find the maximum value of >this function for 0 <= r <= 1. It turns out that the critical value >which maximizes P(1) is r = 1/N. For this value of r, P(1) = 1/e, >assuming that N is very large. For any other value of r, P(1) < 1/e. >Hence, the probability that there is exactly one life-bearing planet in >the universe is no greater than 1/e, or about 37%. I think at best you're overanalyzing the situation. The 1/N principle is very common in probability analysis. (If you have three cows, of a breed in which the chances of the animal being white are one in three, how many of the cows would you expect to be white? - and so on.) What we're looking for is a conditional probability - if we know A, B, and C, what is the probability that D is true. For the presence of life on other planets, we know so little about the conditions that trying to assign a probability at this point is little more than number-pushing. There are a number of logical fallacies or weaknesses in many of the estimates of life elsewhere. One of the most common is the assumption that the earth is representative of conditions elsewhere. We say, "Well, we're here, so it stands to reason that that there must be other folks somewhere else." The problem with this is that it makes no allowance for the calculated probability (as seen at some point in the distant past) of our coming into existance. It could have been only by a very slim chance that life developed on Earth. If we were't here, we wouldn't be able to speculate. (This concept is very difficult to express - maybe someone else can do a better job?) Another fallacy is that the universe is large - it is by most standards, but not by the laws of probability. One rough estimate is that the observable universe has about a hundred billion galaxies of about a hundred billion stars each. Which is greater - the number of stars in this volume, or the number of possible ways to shuffle a deck of 52 cards? It's the cards. (In fact, if every one of those stars had a planet with a billion people shuffling cards for a billion years, it's still very unlikely that any specific sequence would come up.) If the odds of life developing around an average star are comparable to the odds of shuffling a deck of cards into a specific sequence, then it's wildly improbable that life would develop anywhere. The fact that we're here *could* be a case in which the wildly improbable happened (or it could be due to divine intervention - there's currently no way to determine this objectively :-). It is often assumed that given the right environmental conditions, it is highly probable that life will arise within a few billion years. That could be correct - there's no way to tell with what we know now. While we're just beginning to understand the mechanisms of life, there are at least two things that can be said with considerable confidence - all the organisms we've looked at which fully fit our definition of independent life are *extremely* complex, and there is as yet *no* completely described sequence of events that would lead to the spontaneous formation of living organisms as we know them from nonliving matter. Thus we really can't say what the odds are. In fact, it has been speculated that the chances could be so slim that that the unlikely possibility that life came to Earth from somewhere else in the galaxy would still give better odds than local development. My opinion is that given our current level of knowledge, calculating the probability of life elsewhere may provide useful insights, but that's about all. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: Tue, 01 May 90 11:21:36 ADT From: LANG%UNB.CA@vma.cc.cmu.edu Subject: Navstar GPS Status Reports on WWV and WWVH National Institute of Standards and Technology time signal radio 00000100 stations WWV and WWVH transmit brief reports on the status of the 00000110 Navstar Global Positioning System. These reports are prepared by the 00000200 U.S. Coast Guard's Omega Navigation Systems Center (ONSCEN) in 00000300 Alexandria, VA. The broadcast from WWV is at 15 minutes past each hour.00000400 A brief description of GPS is given in the preceding minute. The 00000500 broadcast from WWVH is at 44 minutes past each hour with the 00000600 introduction during the preceding minute. The broadcasts are updated 00000700 nominally once a day. 00000800 00000900 WWV, Fort Collins, CO, transmits continuously on 2.5, 5, 10, 15, and 20 00001000 MHz. WWVH, Kauai, Hawaii, transmits continuously on 2.5, 5, 10, and 15 00001010 MHz. Only a simple shortwave receiver is needed to pick up these 00001100 broadcasts. 00001110 00001200 Both stations also transmit solar activity and geomagnetic field reports00001300 as well as Omega navigation system status reports and weather. The 00001400 "program" schedule for WWV and WWVH is as follows: 00001500 00001600 WWV 00001700 H:08 North Atlantic weather 00001800 H:09 North Atlantic weather cont'd. 00001900 H:10 East Pacific weather 00002000 H:14 GPS message introduction 00002100 H:15 GPS status report 00002200 H:16 Omega status report 00002300 H:18 Solar activity / geomagnetic field report 00002400 00002500 WWVH 00002600 H:43 GPS message introduction 00002700 H:44 GPS status report 00002800 H:45 Solar activity / geomagnetic field report 00002900 H:47 Omega status report 00003000 H:48 Pacific weather 00003100 H:49 Pacific weather cont'd. 00003200 H:50 Pacific weather cont'd. 00003300 H:51 Pacific weather cont'd. 00003400 ================================================================================ Richard B. Langley BITnet: LANG@UNB.CA or SE@UNB.CA Geodetic Research Laboratory Phone: (506) 453-5142 Dept. of Surveying Engineering Telex: 014-46202 University of New Brunswick FAX: (506) 453-4943 Fredericton, N.B., Canada E3B 5A3 ================================================================================ ------------------------------ Date: 1 May 90 16:17:13 GMT From: news-server.csri.toronto.edu!utgpu!utzoo!henry@rutgers.edu (Henry Spencer) Subject: Re: Galileo entry probe In article <1990Apr30.161227.14460@axion.bt.co.uk> apengell@axion.bt.co.uk (alan pengelly) writes: > Does the Galileo probe that is going to enter the Jovian atmosphere >have a camera on board? What other sensors are present? There's no camera on the probe, as I recall, just an assortment of atmospheric instruments. (Sorry, I don't have a list handy.) Pity. -- If OSI is the answer, what is | Henry Spencer at U of Toronto Zoology the question?? -Rolf Nordhagen| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Tue, 01 May 90 13:10:31 EST From: Dennis_Grant%CMR001.BITNET@vma.cc.cmu.edu Subject: I need an engineer. I am doing some research for a program that I am going to write as a (potential) graduate project in computer science. I am wrting a game *blush* that takes place in the near future, and I want to make it as realistic as possible. (within certain limits) I therefore would like to talk with an indulgent aero engineer about various space-related topics. (esp. power sources, drive systems, and weapons) I'd use our library for this, but all the books I can find are either too simplistic, or are 4000 page journals written in technospeak that I (as a poor helpless computer science student :) ) can't understand. If someone out there would like to help me, or could point me in the direction of some good documentation, please respond to me E-mail. ALSO: I need a starmap of the local area of the galaxy (local = nearest 50 stars or so) as seen from an observer from "above" (ie if the orbital plane of the earth is on the x,y plane, with the sun at the origin, the observer would be at the point (0,0,n) with n large enough to see about 50 stars or so) I have never seen a map of this sort- all the maps I can find are of the earthbound-observer variety. Thanks in advance, Dennis Grant CMR, Quebec, Canada Comp Sci 92 DETUD595@CMR001.BITNET ------------------------------ Date: 1 May 90 07:11:35 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Navstar GPS Status Reports on WWV and WWVH In article LANG@UNB.CA writes: >National Institute of Standards and Technology time signal radio 000100 >stations WWV and WWVH transmit brief reports on the status of the 000110 >Navstar Global Positioning System. These reports are prepared by the 000200 . . . >H:49 Pacific weather cont'd. 003200 >H:50 Pacific weather cont'd. 003300 >H:51 Pacific weather cont'd. 003400 On reading this, I had the most overwhelming urge to //PUNCH it out, pick up the deck, drop it it on the floor, collect the cards, stick them in the card sorter and admire the results! Ahh, for the good old days! I'll be back in my cave -- Hollerith you need anything. -- The genius of you Americans is that you never make ** Tom Neff any clear-cut stupid moves, only complicated stupid ** tneff@bfmny0.UU.NET moves that leave us scratching our heads wondering if we might possibly have missed something. -- Gamel Abdel Nasser ------------------------------ Date: 1 May 90 18:08:43 GMT From: swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!elroy.jpl.nasa.gov!jato!mars!baalke@ucsd.edu (Ron Baalke) Subject: Re: Hubble Telescope In article <299.263BF427@ofa123.FIDONET.ORG> Russ.Tillman@ofa123.FIDONET.ORG (Russ Tillman) writes: >Viewing the 1969-70's lunar sites with the Hubble would be a great PR tool to >display it capabilities to the common non-scientist person (aka taxpayer). >Most people know how far the moon is from earth but not many can relate to the >Hubble view the edge of the universe so hit em up on it capabilities with >something they understand. I remember back in the 70's, that while enroute to >Jupiter, Pioneer took a picture of both the earth and the moon in the same >frame. A picture like that get's people thinking! > There are a couple of space movies planned mainly to be used for PR purposes. When Galileo transmits back its Venus science data this November, the images will be put together to form a movie of Venus. In December, 1992, when Galileo makes it 2nd earth flyby, it will takes pictures of the Earth/Moon every 20 minutes, which also be put together to form a movie. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | Go Lakers! ------------------------------ Date: 1 May 90 21:07:40 GMT From: shlump.nac.dec.com!renoir.dec.com!klaes@decuac.dec.com Subject: Radiation Effects on Spacecraft Computers The following message is from Hema Murty, who is currently unable to post to USENET. Please send all messages to her. Thank you. - Larry Klaes ############# Can anyone give me references or information on how radiation from the Van Allen Radiation belts surrounding Earth affects computers on spacecraft which spend a long time in that region of space? There must have been studies done on previous missions, yet all I am able to find so far are the ALOUETTE results from the 1960s. Thank you very much for your help. Hema Sandhyarani Murty, Institute for Aerospace Studies, University of Toronto Reply-To: murty@mv03.ecf.UUCP (Hema Murty) murty@ecf.toronto.edu Organization: Engineering Computing Facility, University of Toronto ------------------------------ Date: 1 May 90 23:55:35 GMT From: thorin!homer!leech@mcnc.org (Jonathan Leech) Subject: (How to get rid of) space garbage In light of the current 'life of HST' discussion, maybe we could talk about ways to get rid of orbital debris. First off the wall suggestion: use high-powered lasers to accelerate decay from the Poynting-Robinson effect. If this thread takes off, I'll run some numbers on this suggestion. -- Jon Leech (leech@cs.unc.edu) __@/ ``Thus Mathematics helps / our brains and hands and feet and can make / a race of supermen out of us.'' - The Education of T. C. Mits ------------------------------ Date: 2 May 90 02:22:10 GMT From: sam.cs.cmu.edu!vac@pt.cs.cmu.edu (Vincent Cate) Subject: Satellite Dish Recommendations? Our cable TV costs us $21/month (no movie channels). My personal line of credit account only needs payments $23 for every $1,000 owed. If I could get a dish for $1,000 it would cost me about as much per month as cable. I am willing to pay much more than this for a dish, since the payments will not go on forever. Also, I could turn around and sell the dish later to get back some of this money. Another thing is that cable will probably cost me more than $21/month if I am still getting it next year. Anyway, I am very interested in buying a satellite dish to pick up TV signals. What should I look for? Can anyone recommend a good one? Any that I should avoid? Is Radio Shack's 9 foot dish for $2,000 a reasonable deal? (it can move from satellite to satellite) Are there still plenty of unscrambled channels? Is this going to continue to be the case? Is there something like HBO or Showtime that is unscrambled? Can I get plenty of channels with a dish that does not move or do I need to get one that can switch from satellite to satellite? What are the price ranges for each? Thanks for any info, -- Vince ------------------------------ Date: 2 May 90 02:39:17 GMT From: zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!uluru6!danielce@tut.cis.ohio-state.edu (Daniel Ake CAROSONE) Subject: Re: Niven's inertialess drive (was Re: Dyson spheres, heat flow) In article , clive@ixi.co.uk (Clive Feather) writes: > In article <1990Apr30.050759.17885@uokmax.uucp> spcoltri@uokmax.uucp (Steven P Coltrin) writes: [Talking about the inertialess drive being neutrino-reaction drive] > >because the exhaust is thrown where it cannot be seen. (Though in _The > >Ringworld Engineers_ it is revealed that ships using thrusters can be tracked > >by their neutrino exhaust.) > But in "Flatlander" an Outsider ship accelerates Beowulf and Elephant to 0.9c > in a matter of minutes. This can't be a simple reaction drive; it has to act > on the occupants as well as the ship, or they'd be squashed. Indeed. Having made the awful blunder recently of forgeting that drives need a power supply, I am now qualified to say that the neutrino exhaust in question would come from the fusion plant that powers the ship. > I always assumed that man had reinvented the drive. Beowulf seemed to think > that the price was too high, and anyway, knowing it can be done is 90% of the > battle. Interesting thought, It has been so long since I read most of the books that I cannot remember the details at all. I disagree that knowing it can be done makes the rest trivial. What happened to "Success is 1% inspiration, 99% perspiration."? Knowing it can be done makes it a hell of a lot easier to convince yourself that it is not impossible (!!) but does not really help much more. Knowing roughly *how* it is done is of much more use. ------------------------------ End of SPACE Digest V11 #342 *******************