Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.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, 26 Jun 91 05:16:35 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Wed, 26 Jun 91 05:16:31 -0400 (EDT) Subject: SPACE Digest V13 #718 SPACE Digest Volume 13 : Issue 718 Today's Topics: Re: IGY and the beginning of the Space Age Re: Fermi Paradox Re: Space heros? NASA Prediction Bulletins: Space Shuttle Re: Democracy: Easy Come, Easy Go Earth Gravity Assist and Aerobraking Safety Re: Fermi Paradox Re: talk.politics.space (was Re: sci.space.moderated) Re: Crary's Quick Debunkings Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 9 Jun 91 00:53:08 GMT From: cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!ox.com!hela!aws@ucbvax.Berkeley.EDU (Allen W. Sherzer) Subject: Re: IGY and the beginning of the Space Age In article <1991Jun8.063806.28077@sequent.com> szabo@sequent.com writes: >There was no space race and very little space research funding until the >Soviets launched Sputnik for the IGY, shocking the U.S. into joining a >space race. Read your history Nick. The space race began a LONG time before Sputnik. >That the astronauts and their groupies managed to gain >power is a relic of Kennedy's Apollo ... The decision to send people up happened long before Kennedy ever got to the White House. Project Mercury began and even had flown before Kennedy hit on the idea of Apollo. >The Astronauts did not contribute positively towards NASA's funding; indeed >NASA funding started to drop after 1966 when the astronaut flights started >to swing into full gear. Funding dropped because development was nearing completion. BTW, funding needs to go up before it can go down. How did it get up if those nasty astronauts where so unpopular? >NASA's funding cut from 1968 until the mid-1970's when manned spaceflight >was replaced by automated exploration. Sorry. NASA fudning went up to pay for the Shuttle, not for unmanned probes. Allen -- +---------------------------------------------------------------------------+ |Allen W. Sherzer | DETROIT: Where the weak are killed and eaten. | | aws@iti.org | | +---------------------------------------------------------------------------+ ------------------------------ Date: 8 Jun 91 18:16:15 GMT From: agate!headcrash.Berkeley.EDU!gwh@ucbvax.Berkeley.EDU (George William Herbert) Subject: Re: Fermi Paradox While proposing what amounts to a Star Trek transporter may sound great for solving the Fermi paradox, it's questionable if it's feasable to manufacture such a device or if it's possible to make something like you described work. This is essentially science fiction. I'm going to argue that something this comple falls under the 'suffeciently advanced technology == magic' rule and that debating it from a scientific point of view is pointless. -george william herbert gwh@ocf.berkeley.edu ------------------------------ Date: 8 Jun 91 07:06:07 GMT From: sequent!muncher.sequent.com!szabo@uunet.uu.net Subject: Re: Space heros? In article <".7-Jun-91.11:13:48.EDT".*.Eric_Florack.Wbst311@Xerox.com> Eric_Florack.Wbst311@XEROX.COM writes: > >To obtain the >public's support, and therefore, an easier time at obtaining public funding, >at least a certain degree of the space exploration should be manned... This is total BS. The civilian space program was originally motivated by the automated IGY satellites, the first being Sputnik which shocked the U.S. into funding spaceflight. The correlation between astronaut flights and NASA funding is negative. NASA funding started to drop in 1966 after Gemini swung into full gear, and dropped most precipitously during the Apollo flights which the American public increasingly opposed. Polls have always showed roughly equal public support for "unmanned" and "manned" endeavors, even when stated with that falsely dichotomous terminology. The myth that astronauts somehow motivate space funding is the last refuge for those who can't find any other rationale for the wasteful astronaut toys the NASA leadership (astronauts) are pushing. -- Nick Szabo szabo@sequent.com "If you understand something the first time you see it, you probably knew it already. The more bewildered you are, the more successful the mission was." -- Ed Stone, Voyager space explorer ------------------------------ Date: 8 Jun 91 13:21:19 GMT From: udecc.engr.udayton.edu!blackbird.afit.af.mil!tkelso@tut.cis.ohio-state.edu (TS Kelso) Subject: NASA Prediction Bulletins: Space Shuttle The most current orbital elements from the NASA Prediction Bulletins are carried on the Celestial BBS, (513) 427-0674, and are updated several times weekly. Documentation and tracking software are also available on this system. As a service to the satellite user community, the most current elements for the current shuttle mission are provided below. The Celestial BBS may be accessed 24 hours/day at 300, 1200, or 2400 baud using 8 data bits, 1 stop bit, no parity. STS 40 1 21399U 91 40 A 91158.22557870 .00106961 00000-0 25599-3 0 85 2 21399 39.0070 322.2320 0013304 4.9358 248.6192 15.95228336 263 -- Dr TS Kelso Assistant Professor of Space Operations tkelso@blackbird.afit.af.mil Air Force Institute of Technology ------------------------------ Date: 8 Jun 91 17:42:11 GMT From: prism!ccoprmd@gatech.edu (Matthew DeLuca) Subject: Re: Democracy: Easy Come, Easy Go In article <22244@cbmvax.commodore.com> ricci@cbmvax.commodore.com (Mark Ricci - CATS) writes: >In article <30754@hydra.gatech.EDU> (Matthew DeLuca) writes: >>If you want to lobby, fine, but you have to do it >>on your own money. NASA has to use its own money... >Gee Matt, whose money do you think NASA's is? NASA's money is NASA's money. I've been trying to make a fairly subtle point that people aren't picking up on: NASA is not the government. It is an organization created by the government, and it is funded by the government, but it is *not* the government. If they were, there wouldn't be all the bickering and fighting and backstabbing we see come budget time...it would all be one big happy family. -- Matthew DeLuca Georgia Institute of Technology "I'd hire the Dorsai, if I knew their Office of Information Technology P.O. box." - Zebadiah Carter, Internet: ccoprmd@prism.gatech.edu _The Number of the Beast_ ------------------------------ Date: 9 Jun 91 05:46:53 GMT From: sequent!muncher.sequent.com!szabo@uunet.uu.net Subject: Earth Gravity Assist and Aerobraking Safety In article DLOWE@UA1VM.UA.EDU (David Lowe) writes: > >I have been enduring all the romance about imminent asteroid >mining and waiting for someone to discuss safety. I have posted perhaps a dozen times on this subject over the last two years. To summarize, there is no way we can tolerate bringing a dinosaur-killer sized asteroid anywhere near Earth. Reentry of c. 100 ton Shuttles is safely performed and tolerated towards inhabited areas, and natural fireballs and meteorites massing several tons each hit the Earth harmlessly every year. Somewhere between these two extremes, we need to figure out the margins of safety and enforce them. There are several techniques for using Earth to change the orbital trajectory of objects: * fast aerobraking (eg Shuttle, Apollo) * slow aerobraking (eg Hiten) * gravity assist (eg Galileo) All three of these can play important roles in reducing the costs of capturing space materials from comet fragments and asteroids into various Earth orbits. The delta-v savings are roughly up to an order of magnitude for gravity flyby, and up to two orders of magnitude for aerobraking. For gravity assist, the following need to be considered: * what is the margin of error due to fringe atmospheric density, gravity anomaly and trajectory measurement error * how quickly and precisely can the on-board engines compensate for trajectory errors directly preceeding and during the flyby * can the operation be timed so that a worst-case error will cause reentry over an uninhabited area (eg the ocean) * are there any strongly toxic or nuclear materials on board * what is the worst-case scenario wrt the mass, composition, and worst-case error trajectory of the payload For slow aerobraking, we must also consider the above points, paying close attention to the fringe atmospheric density, since that is what we are using to change the trajectory. For fast aerobraking, we need to pay very close attention to upper atmospheric density at all levels. The error margins are much less. Unless the worst-case scenario is trivial or the spacecraft is well-controlled aerodynamically, fast aerobraking is much more dangerous than slow aerobraking or gravity flyby. Given these data points, we must then determine whether the project is ethically and politically tolerable, and whether it can be insured. For the sake of discussion, I make the following initial proposed rules of thumb: gravity assist & slow aerobrake * <.0001% chance of trajectory error sufficiently large for reentry * if reentry, >98% chance it will occur over & towards uninhabited area * payload mass limits: solid metallic materials: 5,000 tons stony materials: 10,000 tons carbonaceous materials or loose regolith: 30,000 tons volatile materials: 50,000 tons fast aerobrake: * aerobrake must contain control surfaces sufficient to give <.001% chance of reentry due to error * if reentry, >98% chance it will occur over & towards uninhabited area * no strongly toxic or nuclear materials on board * mass limits: solid metallic materials: 200 tons all other materials: 400 tons (note: ceramic heat shield will be significant % of mass for any payload) Significant amounts of simulation, study of real-life artificial and natural reentries, and benefit/risk analysis need to go into determining the actual safety margins. -- Nick Szabo szabo@sequent.com "If you understand something the first time you see it, you probably knew it already. The more bewildered you are, the more successful the mission was." -- Ed Stone, Voyager space explorer ------------------------------ Date: 9 Jun 91 06:15:46 GMT From: ogicse!milton!wiml@uunet.uu.net (William Lewis) Subject: Re: Fermi Paradox In article <6013@lectroid.sw.stratus.com> tarl@sw.stratus.com (Tarl Neustaedter) writes: >In article <300@hsvaic.boeing.com>, eder@hsvaic.boeing.com (Dani Eder) writes: >> [stuff about sending people to other stars via information and replicators] >> >> Conclusion: The Fermi Paradox is very much with us. > >Nope. Several problems with your scenario: > [several good points deleted] And 7, it might be against the hypothetical aliens' hypothetical religion to get scanned (destructively, no doubt) and sent across the galaxy to be reconstructed. It certainly gives *me* the creeps. Once you have the technology to easily fabricate arbitrary objects (which you postulate) the only real limit to the population of the solar system is the amount of matter in it. (As for energy, it's easier just to scoop up some of the Sun's atmosphere or a gas giant and fuse it than go to some distant star.) While this is a limit, it's a pretty big limit, and a natural disaster can always convert some of the poopulation back into raw material ... -- wiml@milton.acs.washington.edu Seattle, Washington (William Lewis) | 47 41' 15" N 122 42' 58" W "Just remember, wherever you go ... you're stuck there." ------------------------------ Date: 10 Jun 91 05:54:16 GMT From: tm2b+@andrew.cmu.edu (Todd L. Masco) Subject: Re: talk.politics.space (was Re: sci.space.moderated) pthomas@arecibo.aero.org (Peter L. Thomas) writes: > (has anyone thought that space-tech is ready to graduate to > sci.space.tech? just a side-note) I doubt it. One, the traffic doesn't warrant it. Two, Space-tech is for people who are actually willing to do some calculations before posting. Marc, the moderator, seems to shy away from larger local redistributions of the list (such as the andrew machines). Making such a newsgroup would with defeat the purpose, if unmoderated, or if moderated would just mean rejecting a couple of orders of magnitude more posts than would be accepted. Hardly worth the effort on anybody's part. -- Todd Masco | tm2b@andrew.cmu.edu | "Free speech is the right to shout CMU Physics | tm2b@andrew.BITNet | 'theatre' in a crowded fire." ------------------------------ Date: 8 Jun 91 07:35:11 GMT From: mcsun!ukc!edcastle!hwcs!sfleming@uunet.uu.net (Stewart Fleming) Subject: Re: Crary's Quick Debunkings In article <8188@testeng1.misemi>, stanfiel@testeng1.misemi (Chris Stanfield) writes: > >Anybody care to list other terran formations that resemble faces, etc.? >I know >they exist all over the planet... Mount Rushmore. Of course, you can debate whether this shows existence of intelligent life or not. >Chris Stanfield, Mitel Corporation: E-mail to:- uunet!mitel!testeng1!stanfiel :-) STF -- sfleming@cs.hw.ac.uk ...ukc!cs.hw.ac.uk!sfleming "Hope my metabolic functions cease before I feel the effects of time. I am communicating about my contemporary peer group." ------------------------------ End of SPACE Digest V13 #718 *******************