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 ; Sun, 22 Apr 90 01:44:58 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sun, 22 Apr 90 01:44:28 -0400 (EDT) Subject: SPACE Digest V11 #301 SPACE Digest Volume 11 : Issue 301 Today's Topics: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things) Re: NASA Headline News for 04/20/90 (Forwarded) Re: Decompression and 2001 Re: Large Format CCDs for astronomy (was Re: release of images) Digests and status postings Re: Drake Equation (was Re: Interstellar travel) Voyager/Neptune images request. Re: Decompression and 2001 Re: Interstellar Radio Communications (long) Re: Apollo 13, STS-1, Vostok 1 anniversaries Re: SETI ---------------------------------------------------------------------- Date: Sat, 21 Apr 90 06:18 CST From: Bill Higgins-- Beam Jockey Subject: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things) Original_To: SPACE vsi1!hsv3!mvp@apple.com (Mike Van Pelt) wrote: >Nope, "Silent Running" goofed, too. The nuclear explosions, though >visually very good, made noise -- the "bang" *BEFORE* the flash! I >could accept some kind of tenuous shock wave hitting the ship some time >after the explosion, but *BANG*FLASH* is just stupid. Well, Mike, I am getting old and the memory is going fast, but I am *pretty* sure that back in the unlamented Seventies, I saw prints of *Silent Running* that had it BOTH ways. There was a version with silent nuclear explosions. There was a version, I think later, where noises had been dubbed in. It would take a real scholar of film to track down the truth. But this is the way I remember it. And, yes, the explosion effect was very convincing: a bright sphere that faded to dimmer and dimmer reds as it expanded. None of your puffs of smoke and whirling debris that have been so popular in the post-*Star Wars* era. They did have other sounds in outer space, though. It seems that once you pass the orbit of Saturn, you begin to hear Joan Baez singing. /// Bill Higgins E /// |8D:O: occc))))<)) Fermi National Accelerator Laboratory E /// /// Bitnet: HIGGINS@FNALB.BITNET Bumper sticker seen on a Soyuz: SPAN/Hepnet/Physnet: 43011::HIGGINS DON'T LAUGH-- IT'S PAID FOR Internet: HIGGINS@FNALB.FNAL.GOV ------------------------------ Date: 21 Apr 90 16:59:39 GMT From: mtndew!friedl@uunet.uu.net (Steve Friedl) Subject: Re: NASA Headline News for 04/20/90 (Forwarded) Peter Yee reports: > With the batteries up to "full charge" the > Shuttle launch team will have up to April 28 to launch before the > batteries need to be charged again. Why can't the batteries be trickle-charged from the orbiter directly? > During the rollout the huge crawler-transporter will rack up > its 1000th mile. Maybe time for an oil change? :-) Steve -- Stephen J. Friedl, KA8CMY / Software Consultant / Tustin, CA / 3B2-kind-of-guy +1 714 544 6561 voice / friedl@vsi.com / {uunet,attmail}!mtndew!friedl "The UNIX PC 3B1: 75% of the power of a VAX-11/780" - Technology Resource Ctr ------------------------------ Date: Sat, 21 Apr 90 12:12:04 PST From: shimeall@cs.nps.navy.mil (Tim Shimeall) To: henry@zoo.toronto.edu, space+@andrew.cmu.edu Subject: Re: Decompression and 2001 It just so happens that SHOWTIME rebroadcast 2001 this morning, and I watched it especially to see this seen. The interval between when Dave blew the pods hatch and when he pulled the switch was VERY short. He blew into the lock, bounced off the back wall, and pulled the swich. It was closer to 3 seconds than 8. Tim P.S. But he was still too "clean" in the next seen (no nosebleed, etc.) ------------------------------ Date: 21 Apr 90 23:13:56 GMT From: portal!cup.portal.com!mmm@apple.com (Mark Robert Thorson) Subject: Re: Large Format CCDs for astronomy (was Re: release of images) Does anybody every sell these things? How much do they cost? Do they have any special requirements, like cooling in liquid nitrogen? Are they designed by the semiconductor house, or the observatory? How long are they exposed to collect an image? ------------------------------ Date: 22 Apr 90 01:25:55 GMT From: portal!cup.portal.com!J_STEPHEN_HALL@apple.com Subject: Digests and status postings I will be adding Usenet to my BBS in the next month or so. Was wondering what space items I could subscribe to and pass on to my users. Many thanks, Steve ................................................................. .UUCP: ucbvax!sun!portal!cup.portal.com!j_stephen_hall| . .ARPANET and INTERNET domains please use: | . . portal!j_stephen_hall%cupertino.pcc@suncom | ;-) . .SYSOP: The 19th Hole (813) 378-5602 Sarasota, Florida| . . Fido: 1:137/208 Eggnet: 99/9008/208| . ................................................................. ------------------------------ Date: 20 Apr 90 17:45:14 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Drake Equation (was Re: Interstellar travel) In article <3619@minyos.xx.rmit.oz> rxtajp@minyos.xx.rmit.oz (Andrew Pettifer) writes: >What about all those 50Hz power grids? >They would cause some beat frequencies, and i'm sure that the phase >relationships are drifting all the time, which would help to make the signal(?) >seem more random. The 10 Hz beat would be interesting. The phase relationship probably doesn't change very much, since most grids are phase-locked to a coordinated time base. The time bases are stable enough that a simple AC line-synchronous mechanical clock is more accurate than most quartz crystal time bases (ie, watches). As long as they don't lose power. ------------------------------ Date: 18 Apr 90 20:21:53 GMT From: usc!elroy.jpl.nasa.gov!zardoz.cpd.com!dhw68k!ofa123!rick@ucsd.edu (Rick Ellis) Subject: Voyager/Neptune images request. In a message of , pcarew@stsusa.com writes: > I am interrested in obtaining the images from the Voyager Neptune > flyby from last summer. I have a modest collection here available for downloading. They are all in .GIF format. -- Rick Ellis ...!{dhw68k,zardoz,lawnet,conexch}!ofa123!rick rick@ofa123.FIDONET.ORG 714 544-0934 2400/1200/300 ------------------------------ Date: 21 Apr 90 06:41:06 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Decompression and 2001 In article <1990Apr19.232315.5862@athena.mit.edu> abennett@athena.mit.edu (Andrew Bennett) writes: >I have read (from multiple sources) that an individual should be able to >survive about 30 sec. in a vacuum (give or take, depending on the individual). >Your ear drums would probably rupture, you'd get a bloody nose and you'd have If you happen to have a pressure gauge lying about, try this experiment: put the open end in your mouth and arrange to view the dial. See if you can blow 14.7 PSI. See how long you can hold it. See how it makes you feel. This is what the pressure differential effects of going from a 1ATM "shirt-sleeve" environment to hard vacuum would do to you if you held your breath. It would probably _not_ rupture the eardrums unless the decompression was very rapid, or the eustachean tubes were blocked. The partial pressure effects -- bends, localized boiling, and rapid drying of delicate tissue -- are a different matter on which my speculations would not be particularly valuable. In SCUBA, you lose one atmosphere of pressure for every thirty feet, a distance you can cover rather rapidly in a panic ascent. A good SCUBA class drills one simple but important rule into you: "blow bubbles". You exhale continuously any time you aren't inhaling. If your air passages are open enough to make a stream of bubbles you probably won't embolize. Air embolism, passage of air into the bloodstream through pressure trauma in the lungs, is a killer. Unless I _knew_ better, if I suddenly found myself in Dave's situation I'd start blowing bubbles. ------------------------------ Date: 21 Apr 90 17:46:14 GMT From: calvin.spp.cornell.edu!johns@cu-arpa.cs.cornell.edu (John Sahr) Subject: Re: Interstellar Radio Communications (long) 76 lines total --- you may wish to hit 'n' now. More thoughts on a: why we don't hear anything, and b: why no one may be hearing us, and c: a possible explanation to Fermi's "paradox." Humans have been radiating a fair amount of electromagnetic power for the last 50 years or so. As our electronics art has improved, we have begun to rely more and more on "tricky" schemes to efficiently use bandwidth and power. For example, AM radio is a mode that carries around its own local oscillator, in the sense that the carrier frequency component has a substantial fraction of the transmitter power. It also has two technically redundant sidebands. Because better, stable oscillators can be built, and tricky filter or mixing circuits can pass 2.4 khz at several MHz operating frequency, single sideband (no carrier, one sideband) has become a popular mode for some kinds of radio communication. Another relatively new idea is to use "spread spectrum" techniques to aid interference reduction (and perhaps to impede detection). This is roughly related to code-domain multiplexing techniques as well. Even in radar waveforms, which may have repetition times of a few milliseconds, the actual transmitted wave may not be a simple pulse. Incoherent scatter radars use fairly elaborate techniques of frequency hopping, "random" pulse spacing, and "pseudo-random" codes to improve their operation, while increasing the bandwidth and complexity of the signal. I don't know much about military radars, but I can imagine several reasons for using complex waveforms there as well. The point is, there are advantages to using modulation techniques which make our radio emissions look more and more noiselike, which is one way of expressing a fundamental result of Claude Shannon's work. The abundant radio power we emit, while growing larger in absolute size, is also growing in complexity. Our own signals may not seem particularly interesting, because they look like everything else. Clearly this is not literally the case, but on the average, I suspect that our "energy per radiated bit" is decreasing, even if our total radiated power is increasing. That the "energy per bit" is decreasing makes the detection of Earth-origin signals harder, and is ultimately more relevant than the total power we radiate. Basically, my postulate is this: A civilization "discovers" radio, and spends fifty years learing how to occupy the spectrum and make high power transmitters. As their electronic prowess increases, so does their net irradiated power, but the "energy per bit" drops dramatically, so that two hundred years after the discovery of radio, the civilization is transmitting signals that are largely indistinguishable from noise, rendering them rather invisible against the background of stars. Thus, rather than having "enlightened" civilizations continuously radiating signs of their presence, they may in fact only emit a two hundred year thick shell of "detectibility." This would allow some very old civilizations to be quite near to us, without being spotted by us, and also without any specific attempts to hide from us. Suppose that at 50 ly there is a 10,000 year old "radio capable" civilization. Their "shell of detectibility" will have long passed us, while ours will be just reaching them. Pure speculation; food for argument, that's all. -- John Sahr, | Electrical Engineering - Space Plasma Physics johns@alfven.spp.cornell.edu | Cornell University, Ithaca, NY 14853 ------------------------------ Date: 20 Apr 90 17:59:53 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Apollo 13, STS-1, Vostok 1 anniversaries In article <1227@urbana.mcd.mot.com> rnoe@urbana.mcd.mot.com (Roger Noe) writes: >spacecraft. I think it was Grissom, the mission commander, who had pulled >himself up and out of his side seat toward the hatch in an attempt to >undo the bolts. Before he got very far he passed out because there was There wasn't any way for them to get out. The fire rapidly raised the interior pressure, and the door mechanism was designed to be monkey-proof with a positive pressure differential. Grissom had opened the bleed valve but the fire was producing extra gas volume much faster than it could be bled off. This is according to a conversation I had with one of the people who investigated the fire. The cause was eventually determined to be a glycol leak, which catalyzed on a metalic surface (silver?) releasing hydrogen, if I'm remebering the conversation properly. The gentleman has since left JSC for Boeing. >day in the history of space exploration than when Haise (I think) radioed, >"Houston, we've got a problem." According to this week's "roundup" (summary to follow when I get done with my circuits test) it was Swigert, and the exact quote was Swigert: "Okay, Houston, we've had a problem here." If the reporter didn't blow it this has to be a candidate for the all-time best-known misquotes list. Capcom Jack Lousma: "This is Houston. Say again please." Lovell: "Houston, we've had a problem. We've had a main B bus undervolt." The article continues... "And then, with the remorseless certainty of interconnected, highly complicated plumbing that has just had a wrench thrown into it, the CSM began to die." -- Steve Nuchia South Coast Computing Services (713) 964-2462 "The study of the art of motorcycle maintenance is really a miniature study of the art of rationality itself. Working on a motorcycle, working well, caring, is to become part of a process, to achieve an inner peace of mind. The motorcycle is primarily a mental phenomenon." -- Robert M. Pirsig ------------------------------ Date: 21 Apr 90 06:28:52 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: SETI In article <734@fsu.scri.fsu.edu> pepke@gw.scri.fsu.edu (Eric Pepke) writes: >It's not entirely that grim. We can determine some things for sure about >anybody who receives those signals. We know that they have figure out >radio. If they hadn't, they wouldn't be listening. There are a whole lot Maybe they are really big, or really small, and can see at those wavelengths. Maybe they build radiotelescopes like we build optical ones. Aren't maybes fun? >Now, there are a number of possible extreme theoretical objections to >this, if you really want to reach. Perhaps the BEMs do not understand the >concept of integers. However, even if they naturally think in continua If you understand radio, you understand integers. Harmonics are just too basic a pheonomenon to miss. The significance of primes might take a little longer, but if they are looking at the signal in the time domain they will eventually suspect it is of sentient origin. Fibonacci numbers are about the most non-obvious number sequence to occur naturally here, chances are they won't have any biology or geology that generates more than, say, a dozen primes. Geometry is probably a better place to look, nature isn't particularly fond of right angles but anyone doing hard-matter engineering will recognize Pythagoryan triples, and probably the face-orders of the regular solids. Could try the atomic number/atomic weight pairs for the stable isotopes. >Finally, perhaps C.M. Kornbluth was right, and at some point the machines >they built would acquire self-sustaining capability and the beings would >evolve into happy little technologically advanced morons, forgetting even >the basic principles that once they needed to survive. This one is a >little bit harder to laugh off. Like, what planets do we know of where that's happening right now? Sigh. Comment on carbon/silicon life: Don't forget that other temperature and pressure regimes are possible. We know staggeringly little about really high pressures, and less than we'd like about very low temperatures. Exotic combinations? Forget it. Just about anything could happen out there, but if it did we'd have a heck of a time finding anything in common on which to base a meaningful relationship. One new theme to emerge in science in the last few decades is that self-organizing systems aren't as unusual as we thought. The fact that all four of our gas giants have bands and great spots is a good example. (I think -- Neptune does, anyway.) At one of my clients' offices there is a small poster, apparently once part of a magazine ad. It is a picture looking across a mountain valley from the top of a very high, very rocky slope, looking over the handlebars of a motorcycle. The caption: "Never rule anything out." Words to live by. ------------------------------ End of SPACE Digest V11 #301 *******************