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 ; Sat, 28 Apr 90 02:00:36 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 28 Apr 90 01:59:44 -0400 (EDT) Subject: SPACE Digest V11 #324 SPACE Digest Volume 11 : Issue 324 Today's Topics: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things) Re: Dyson spheres, heat flow Satellite receiver NASA Headline News for 04/27/90 (Forwarded) Re: Dyson spheres? Re: Vandeburg Launch Schedules Re: Our galaxy Re: Barium Releases Payload Status for 04/26/90 (Forwarded) Re: Fermi paradox ---------------------------------------------------------------------- Date: 27 Apr 90 00:24:51 GMT From: agate!sag4.ssl.berkeley.edu!daveray@ucbvax.Berkeley.EDU (David Ray) Subject: Re: Not-so-Silent Running (Was Re: a bunch of other irrelvant things) >If *I* remember correctly, they had 4 separate nuclear explosions. >It never made sense that the first bomb didn't explode or disable >the other three. Actually, they did have 4 explosions, each for nuking one of the four "space greenhouses". In the movie they planted the bomb, then jettisoned (separated) the greenhouse module and let it drift some distance away from the mother ship before it exploded. In the movie they only waited a couple minutes before exploding the bombs. One can only speculate how far away they were from the mother ship when the bombs exploded, but with current technology the modules couldn't have been more than a mile or two away, and so it would have made more sense for them to have felt serious effects from the explosion. In the movie they implied that they were exploding the bombs when they were far enough away not to ba a danger. Well, OK, so they did have greenhouses in space, and their technology WAS beyond current capabilities. Maybe they had advanced propulsion systems that could move these very heavy modules more quickly. Maybe the spaceship had advanced resistance to radiation. The movie sucked. It didn't make sense that a NASA-like space federation would have gone to all the expense and planning to build these space greenhouses, maintain them, have them work perfectly, and then decide to nuke then for beaurocratic reasons. I don't think that that kind of reasoning would permit such technological advances to progress to the point that they could have been able to build them in the first place. This is the aspect of the movie that upset me the most. ------------------------------ Date: 27 Apr 90 06:10:07 GMT From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!ria!uwovax!2011_552@ucsd.edu (Terry Gaetz (Astronomy, U. Western Ontario)) Subject: Re: Dyson spheres, heat flow In article <3770@munnari.oz.au>, danielce@uluru3.ecr.mu.oz (Daniel Ake CAROSONE) writes: > Another thought. Someone said that you could use a balck hole as a heat sink > within a Dyson sphere. Tell that to Hawking, who said that even black > holes produce balckbody radiation. It would work, but you would have > to get the hole out through the sphere after a while (long while) or > you would still radiate. The Hawking radiation from a black hole has an effective temperature inversely proportional to the black hole mass (about 1/10^7 K for a solar mass black hole). Provided that the black hole is massive enough, it could be used as a heat sink. For example; a black hole with the mass of Mercury would have a temperature of roughly 0.5 K. It would have an interesting property, though: the black hole would become increasingly efficient as a heat sink as heat energy is dumped into it. (The added energy increases the mass of the BH; this lowers the effective temperature because of the inverse mass dependence.) -- Terry Gaetz -- gaetz@uwovax.uwo.ca -- gaetz@uwovax.bitnet ------------------------------ Date: Fri, 27 Apr 90 11:57 GMT From: "Joe Desbonnet, UCG Ireland." Subject: Satellite receiver A long time ago (early 89?) someone posted the schematic for some sort of satellite receiver. Can any one remember what the vol/issue numbers were ? Joe. ------------------------------ Date: 27 Apr 90 21:17:21 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 04/27/90 (Forwarded) ----------------------------------------------------------------- Friday, April 27, 1990 Audio Service: 202/755-1788 ----------------------------------------------------------------- This is NASA Headline News for Friday, April 27... The Hubble Space Telescope is open for business. The robot arm is powered down. Now released from the Hubble Space Telescope, the orbiter Discovery is preparing to return home following the successful opening of the aperature door. At approximately 9:45 A.M. EDT, the Goddard Space Telescope Operations Control Center received confirmation the telescope aperature door began to open. The top side of the telescope is pointing toward the sun and the aperature door is pointing 90 degrees in relation to the sun. The motion of the aperature door opening put the software subsystem computer into a software sunpoint safe mode, similar to the safe mode the telescope was in during the time the door was opened. During this morning's transition to the safe mode there was no real action that occcured. The HST is safe and stable while the control center is in full communication with the telescope. ******** Observers are looking forward to the first Hubble Space Telescope test image. It is expected the media can view star field NGS 3532 from the Goddard Space Flight Center in Greenbelt next week. Prior to NASA's reception of this first test image, a briefing will provide information on how the telescope is focused and how the image is captured. The next series of maneuvers during the orbital and science verification period will ensure all systems and instruments are functioning properly. This is expected to extend over the next 8 months. ******** As Discovery is now on its way home, preparations continue on schedule at Kennedy Space Center for the launch of space shuttle Columbia and its payload Astro-1 scheduled for May 16. The Terminal Countdown Demonstration Test began on time this morning at 8:00 A.M. at the T minus 24 mark. The test will culminate with a simulated engine start and cutoff at the T minus 5-second mark tomorrow at 11:00 A.M. EDT. ******** Aerospace Daily said the Aerospace Industries Association released a report yesterday recommending NASA and the Space Council establish an independent Space Exploration Initiative study group. It would be split into teams that would consider strategies and objectives, rules and technology evaulations. And, the study group would consist of 70 persons from industry, universities and government agencies. ******** ----------------------------------------------------------------- Television coverage on NASA SELECT TV of the STS-31 mission will continue through landing scheduled Sunday, April 29. Discovery's arrival will be covered from 10:00 A.M. to 12:00 Midnight EDT. Today.... FLIGHT DAY #4 12:29 P.M. Crew Choice TV Opportunity (Orbit 48) Houston TV 1:49 P.M. Middeck Activities (Orbit 49) Houston TV 4:30 P.M. STS-31 Change of shift news conference. Goddard Space Flight Center. 7:00 P.M. STS-31 Change of shift news conference. Johnson Space Center. 8:00 P.M. Replay of STS-31 Flight Day 4 Saturday, April 28.....FLIGHT DAY #5 3:00 A.M. Change of shift news conference Johnson Space Center 4:00 A.M. Downlink of crew choice TV Opportunity (Orbit 57) 6:59 A.M. Protein Crystal Growth Experiment. 7:34 A.M. Crew news conference (Orbit 60) Houston TV 7:59 A.M. Crew Network Interview 8:30 A.M. Change of shift news conference. Goddard Space Flight Center 11:00 A.M. Change of shift news conference. Johnson Space Center 4:30 P.M. Change of shift news conference. Goddard Space Flight Center 7:00 P.M. Change of shift news conference. Johnson Space Center 8:00 P.M. Replay of STS-31 Flight Day 5 ---------------------------------------------------------------- All events and times are subject to change without notice. These reports are filed daily, Monday through Friday, at 12:00 Noon, EDT. Additional reports are provided during mission operations. ---------------------------------------------------------------- A service of the Internal Communications Branch, NASA Headquarters. ------------------------------ Date: 28 Apr 90 00:10:26 GMT From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!physics.utoronto.ca!neufeld@ucsd.edu (Christopher Neufeld) Subject: Re: Dyson spheres? In article <9004271901.AA08396@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: > >With nonreflecting sails, you *have* to allow radiation in both directions, or >else the photon pressure of the radiation (dependent only on energy, not >wavelength) will offset the photon pressure of the incident light, and there >will be no net force. > No. The reasoning is almost right, but you have to consider geometric effects. The light radiated as heat from your habitat doesn't go only parallel to the light incident on it from the Sun. Consider the following case: I have a spherical habitat near the Sun. The temperature of the surface is regulated by circulating a coolant fluid or something, and the temperature is essentially constant over the front and back surfaces. Now, there is obviously no net force on the sphere due to its own radiation, since that is spherically symmetric. Add in the effect of the Sun, which puts an unbalanced force on the sphere, and the sphere must experience a net force. Essentially, you argued that the waste heat would radiate ONLY to the outside, and then only straight away from the Sun. In fact, the inside would also radiate heat. By the way, even if we ignored the effect of radiation back toward the Sun, the non-parallel nature of the heat radiation on the far side of the habitat would result in a lower net force than the force incident from the Sun's side. -- Christopher Neufeld....Just a graduate student | "Like most neufeld@helios.physics.utoronto.ca | intellectuals he is cneufeld@pro-generic.cts.com Ad astra! | intensely stupid." "Don't edit reality for the sake of simplicity" | Marquise de Merteuil ------------------------------ Date: 27 Apr 90 23:38:37 GMT From: acad!johns@uunet.uu.net (John Sergneri) Subject: Re: Vandeburg Launch Schedules In article <1074@manta.NOSC.MIL>, simpkins@manta.NOSC.MIL (Michael A. Simpkins) writes: > > 408 765-4279 > In all my years growing up there I can't say that I remember any of the > launches being "officially" announced. Everyone on base knows that there is > going to be a launch, so most of their families know there's going to be a > general it's no big deal to the locals (except the TITAN IV's of course!) so > the news media just doesn't seem to find out about it. If I wasn't afraid > of being dragged off by the men in dark suits I'd give y'all the heads up. > I'd imagine that someone on the net who reads this group knows what's going on at Vandenburg and could tell us when the UNCLASSIFIED launches are. But then again, maybe there isn't. I'd guess that all annoucements from a AFB would have to be coordinated via some public affair office, screened for classified information, stamped, buried in peat for three months, dusted off, restamped, rereviewed, then posted. I think that the launch may have already happened. -- John Sergneri "Final Note: Capitalism, for good or ill, is the uunet!acad!johns river in which we sink or swim, and stocks the supermarket." ROZZ-TOX Manifesto - Gary Panter ------------------------------ Date: 26 Apr 90 14:51:02 GMT From: mcsun!ukc!acorn!ixi!mike@uunet.uu.net (Mike Moore) Subject: Re: Our galaxy >wmartin@STL-06SIMA.ARMY.MIL (Will Martin) writes: > >| In a related topic, is there any "better" name for our galaxy than "the >| Milky Way"? Something that sounds more like a proper name and is more > The Japanese call it "Heaven's River". See the sci-fi book "Beyond Heaven's River" by Greg Bear. -- -------------------------------------------------------------------------- Usual disclaimer..... etc | mike@ixi.uucp True Intelligence is not knowing all the answers, | it's knowing the right questions. | ------------------------------ Date: 27 Apr 90 15:56:03 GMT From: sdd.hp.com!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Barium Releases In article <2502@syma.sussex.ac.uk> nickw@syma.susx.ac.uk (Nick Watkins) writes: >>NASA's Pegsat released its first barium canister on Apr 15... >Is this related to the CRRES barium releases or part of a completely >separate campaign ? ... If I recall correctly, the Pegsat barium canisters are some of the ones that were originally meant to fly on CRRES, back before it got redesigned for expendable launch and had to shed a whole bunch of weight. NASA is getting them up any way they can. -- 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: 27 Apr 90 21:06:36 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Payload Status for 04/26/90 (Forwarded) Daily Status/KSC Payload Management and Operations 04-26-90. - STS-31R HST (at Pad-B) - Post launch GSE removal will be performed today. - STS-35 ASTRO-1 (at OPF) - ASTRO-1/BBXRT landline validation was performed Wednesday and will continue today. Also today, the payload bay doors will be opened and igloo connectors will be safety wired. - STS-40 SLS-1 (at O&C) - Experiment train interface testing continues. - STS-42 IML-1 (at O&C) - Module pyrell foam replacement, floor staging, and rack staging were worked Wednesday and will continue today. - STS-45 (Atlas-1)- Bracket installations will continue today. - STS-46 TSS-1 (at O&C) - No activities are scheduled for today. - STS-55 SL-D2 (at O&C) - Rack 12 staging will continue today. - HST M&R (at O&C) - ORUC interface testing continues today. ------------------------------ Date: 27 Apr 90 03:27:21 GMT From: crdgw1!sixhub!davidsen@uunet.uu.net (Wm E. Davidsen Jr) Subject: Re: Fermi paradox You can do a lot of speculating about the probability of having civilizations meet, though. For example, the Earth is more or less 4.6 billion year old, and we have been able to detect and generate signals for about 100 years of that time (all ballpark numbers). A lot of the probability depends on how long you think we will retain that capability, and if you believe that we will get a breeding population to another habitable planet. I do believe that a race which bred more slowly and was highly sensitive to polution would have a better chance of expanding, due to a longer time in which feeding or protecting the population was not a major sink for resources. -- bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen) sysop *IX BBS and Public Access UNIX moderator of comp.binaries.ibm.pc and 80386 mailing list "Stupidity, like virtue, is its own reward" -me ------------------------------ End of SPACE Digest V11 #324 *******************