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, 21 Apr 90 02:39:11 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 21 Apr 90 02:38:41 -0400 (EDT) Subject: SPACE Digest V11 #298 SPACE Digest Volume 11 : Issue 298 Today's Topics: Re: Fermi paradox, SETI tomatoes, SETI Re: Decompression and 2001 Re: Pegasus launch planes - Altitude First, speed later? Re: Fermi Paradox Re: Apollo 13, STS-1, Vostok 1 anniversaries Re: Winch Launch as first stage. Re: Fermi paradox, SETI Re: Decompression and 2001 Pegsat barium drop ---------------------------------------------------------------------- Date: 21 Apr 90 02:14:30 GMT From: swrinde!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@ucsd.edu (Brian or James) Subject: Re: Fermi paradox, SETI AAAIIIEEE!!! A brief comment on the subject of 'stable deadends' in evolution. Lifeforms that do not change for a long time are not called 'dead ends', they are called 'well adapted'. Please note that the Victorian model of progress is not appropriate as a model of biology. JDN ------------------------------ Date: Fri, 20 Apr 90 16:54:32 EDT From: John Roberts Disclaimer: Opinions expressed are those of the sender and do not reflect NIST policy or agreement. Subject: tomatoes, SETI >From: pasteur!helios.ee.lbl.gov!hellgate.utah.edu!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!watserv1!watdragon!watyew!jdnicoll@ucbvax.Berkeley.EDU (Brian or James) Subject: Re: space tomatoes > Aren't tomatos related to plants like Deadly Nightshade? I wonder how >they came to be regarded as a foodstuff, since I know that as recently as >the 18th century people assumed they were as deadly as their relatives. Tomatoes are members of the nightshade family. They were grown for many years as ornamentals before they were widely regarded as a food. That's not unusual - today very few people eat dandelions ("dent de lion" in French), which I believe were introduced into America as a vegetable. Other members of the nightshade family are deadly nightshade, peppers, eggplant, potatoes, and tobacco. I get the impression that this family tends toward bad-tasting poisons that warn animals not to eat them. It might be a good idea to let adults taste the space tomatoes before letting children try them. ------------------------------ >Subject: Interstellar Radio Communications > Most of the discussion I've seen assumes that that communication >we're trying to 'eavesdrop' is only by chance detectable by us. If >you are trying to spot other technological cultures, it gets a >lot easier if they are trying to be heard [I have this mental image >of forty million civilisations listening carefully to the radio >bands while trying to be perfectly silent themselves]. > JDN Attempting to transmit [CETI?] is much more controversial than attempting to receive. After all, if there other intelligences out there, it could be useful to know about them, whether they're friendly or hostile. If they're hostile, there's no point in drawing attention to ourselves even more than is already being done with radar, television, etc. Some people seem to think that the potential for violence is some bizarre aberration of humanity, and that it's highly improbable that life arising in the rest of the universe would ever be violent. I don't have much confidence in this reasoning. Among the life forms we know, violence is a nearly universal behavioral trait among motile organisms, used to acquire food (hunting), or to compete for resources (food, shelter, status, territory, mates, etc.) We therefore have no actual example of a large-scale ecosystem that functions stably without violence. Humans have considerable capacity for aggression, much more than is probably needed in a technological society. To a large extent, this trait was probably inherited from ancestors who needed it to survive. Today we have to limit hostility in order to survive. There is a good chance that alien civilizations we encounter will have a similar background - descended from violent ancestors, but now at least cooperating with one another to build a civilization. It should not be assumed from this that they would get along well with us. The Nazis cooperated with one another, but were highly inimical to their neighbors. Before we announce our presence to the universe, it makes sense to listen for a while and find out what's out there. If we find someone who appears to be friendly, it's still important to learn to avoid what might be perceived as an insult or threat. John Roberts roberts@cmr.ncsl.nist.gov ------------------------------ Date: 20 Apr 90 16:29:26 GMT From: usc!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@ucsd.edu (Henry Spencer) Subject: Re: Decompression and 2001 In article <1990Apr19.232315.5862@athena.mit.edu> abennett@athena.mit.edu (Andrew Bennett) writes: >The most serious problem(s) are damage to your lungs (the avolii(sp?) don't >like low pressures) and the 'bends' (nitrogen nucleation in the body). So >holding your breath is a good idea, for your lungs' sake. As any scuba diver will tell you, holding your breath during decompression is a thoroughly bad idea. The alveoli don't object to low pressures much (remember 3psi of pure oxygen in pre-shuttle US spacecraft), but they are not mechanically strong and it's easy to damage them if there is more pressure inside than out. -- With features like this, | Henry Spencer at U of Toronto Zoology who needs bugs? | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: 20 Apr 90 15:37:06 GMT From: skipper!shafer@ames.arc.nasa.gov (Mary Shafer) Subject: Re: Pegasus launch planes - Altitude First, speed later? In article <8948@pt.cs.cmu.edu> vac@sam.cs.cmu.edu (Vincent Cate) writes: And how expensive is the Concorde to operate? Well, they sell one- way tickets from New York to London for $3,607. This is an expensive plane. I don't know many people who would pay $3,607 for a one-way ticket to London. There are about 100 seats so this comes to about $400,000/flight. Yes, this is alot of money; however, it is far below the the ~ $5,000,000 value of the increased payload to orbit!!!!! Even expensive planes are very cheap compared to rockets!!!! Maybe British Airways should stop selling tickets to people and start launching rockets. British Airways admits, quite cheerfully, that the cost of Concorde is subsidized. Looks like OSC may be planning on going just for altitude first off. As I said above, an extra 6 miles up is about equal in energy to an extra 1,000 MPH. So extra altitude probably gives the best return on investment at this time. My guess is that they want to use a DC-10 or a 747 to get their little payload up really high. A loaded 747 can go to 50,000 feet, so I would not be at all surprised if one with about half the flying weight (tanks not nearly full and little payload) could get to over 70,000 feet. This should be worth millions per flight and does not seem to be any where near as hard as using a supersonic plane. Service ceiling is limited by many factors, only one of which is weight. For example, how robust is the pressure vessel? Will the pressurization system work at this altitude? How's the stability? How big is the envelope? What happens to thrust at this altitude? Making the airplane light is just part of the problem. -- Mary Shafer shafer@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA ------------------------------ Date: Fri, 20 Apr 90 16:13:43 PDT From: greer%utdssa.dnet%utadnx@utspan.span.nasa.gov X-Vmsmail-To: UTADNX::UTSPAN::AMES::"space+@andrew.cmu.edu" Subject: Re: Fermi Paradox Subject: Re: Fermi Paradox In SPACE_Digest V11 #283, hoptoad!tim@ucbvax.Berkeley.EDU (Tim Maroney) writes: >It seems inevitable that within a thousand years, our own nature as a >species will have changed greatly -- through genetic engineering as >well as through the integration of artificial and biological neural ^^^^^^^^^^^^^^^^^ >networks. ^^^^^^^^^ You mean like a BRAIN? In a thousand years the speed of light will still be about 300,000 km/s and the radius of an atom will still be .1 nm. Not to say that the computers and software of tomorrow won't be vastly more powerful than today's, but at some point the curves that measure technological progress must break from their current exponential increase, and begin to approach an asymptote. As far as computers/software are concerned, this asymptote could lie above or below the performance of the human brain. Who can say at this point? Maybe the human brain can't create something smarter than itself. > I simply can't see how this could *not* be true within a It's also possible that a thousand years hence, our descendants might have figured out how to live happily with a minimum of technology, as many people do today. In the future they might even have competitions to see how little technology they can live with. What we think is normal now might be seen as aberrant in the future, as, for example, smoking used to be almost the norm, whereas today it seems insane. _____________ Dale M. Greer, whose opinions are not to be confused with those of the Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER While the Bill of Rights burns, Congress fiddles. -- anonymous ------------------------------ Date: 20 Apr 90 20:22:33 GMT From: altos!altos86!jerry@apple.com (Jerry Gardner) Subject: Re: Apollo 13, STS-1, Vostok 1 anniversaries }Trivia time: The nickname of the Apollo 13 command module was Odyssey, }after the ship in the movie "2001". The lunar module, which served as }the astronauts' "lifeboat", was nicknamed Aquarius. The ship in 2001 was named Discovery. -- Jerry Gardner, NJ6A Altos Computer Systems UUCP: {sun|pyramid|sco|amdahl|uunet}!altos86!jerry 2641 Orchard Parkway Internet: jerry@altos.com San Jose, CA 95134 Guns don't kill people, bullets do. (408) 432-6200 ------------------------------ Date: 20 Apr 90 00:37:31 GMT From: swrinde!cs.utexas.edu!texbell!uhnix1!nuchat!steve@ucsd.edu (Steve Nuchia) Subject: Re: Winch Launch as first stage. In article <6065.262cbf0a@jetson.uh.edu> ucc1q@jetson.uh.edu (A JETSON News User) writes: >You want a winch to do the job. Take a helicopter rotor hub, gearbox > and turbine engine. add a cable drum. should make one fast winch. Actually, one of the constraints on helicoptor design is that the rotor *tips* must be subsonic. You'd have to change the gearbox if you wanted it to pull the cable at a supersonic rate. We are still assuming we want to add about Mach 1 above the aircraft's speed, right? Then you wouldn't have enough torque. You'd also have to cope with the cable accumulating on the drum or a takeup reel/bin at supersonic speeds. My thought would be to pass the line around a pulley, hook a big parachute to the end, and toss it out. The chute goes backwards and the payload goes forwards at twice the speed. The load on the pulley attachment point is also twice the force on the payload, instead of equal to it. Better than an ordinary winch is a great big hydraulic cylinder with a large number of pulleys at each end, like a block-and-tackle in reverse. If there are N passes of the line along the cylinder and it is expanding at rate r then the line is coming in at Nr. The force exerted by the cylinder is also N times the force on the payload. The total length of the stroke is N times the stroke of the cylinder, and you can pay out extra line to keep the load from skewering you. You still have to cope with bearings carrying over twice the weight of the rocket turning at *very* high speeds. All of which is gold-plating on a silly idea. The right approach is to build an air-breathing horizontal take-off horizontal landing first stage. An aircraft on the scale of the Concorde but with a cargo area open to the rear, and able to fly with the door open, at least at altitude, would do the job. Carry the rocket internally to high altitude and ~Mach 2, then push it out the back in a second or so (-100 fps won't kill you) so your center of gravity doesn't move around. Use a small drogue chute on the rocket to keep it pointed the right way for ~5 seconds, then fire it. The key is to have the upper stages carried internally. If the upper stage stack is very narrow (no fins needed at altitude) you could even fire it through the nose of the first stage. One could envision fitting a C-5 with a flow-through cargo area and firing large stacks from it, but you probably couldn't design a supersonic flying sewer pipe. One solution to the aerodynamic problems that an opening to the rear in a supersonic aircraft might cause would be to build a disposable tailcone onto the back of the stack. Have the permanent tailcone attached to the payload sled so it pops into place as part of the separation sequence. Lots of fun. Who's going to build it? -- 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: 20 Apr 90 16:13:43 GMT From: usc!cs.utexas.edu!varvel@ucsd.edu (Donald A. Varvel) Subject: Re: Fermi paradox, SETI This is speculation and has very little to do with space, other than as a possible explanation of Why They Haven't Visited Us. Anyone who deals with computers knows that lacking input, computer systems either stop or stabilize in a loop. (At some level, they may be viewed as the same thing.) Similarly (and for the same reasons) biological systems left undisturbed long enough (possibly the catch) will reach a stable point -- possibly unchanging, but more likely cycling. Change requires either that stability has not yet been achieved or that the system is constantly being disturbed. The disturbance must be just enough to upset the stable state but not enough to destroy the entire system. Earth seems to provide that. How likely is it elsewhere? Let us accept for a moment, and as an example mechanism rather than as the sole explanation, the comet theory of periodic extinction. ``Disturbed stability'' requires that a comet impact the earth at intervals widely enough separated to allow some evolution, but close enough together that not too much time is wasted in stable deadends. Furthermore, the impact has to be big enough to break the equilibrium and small enough not to destroy all life. Assuming you think people are A Good Thing (rather than a noxious infection), don't you think Earth has been incredibly lucky? And how likely is it that another planet is similarly lucky? Moving on from biological systems to social systems, the same argument applies. If humanity ever achieves a stable, sustainable, global civilization, we can kiss technological innovation goodbye. Such a civilization simply can't allow it. I believe exactly that has happened in restricted areas, and the equilibrium has been disturbed by outside forces. In a global civilization there might be no external forces. How likely is it that an intelligent race can avoid that, while not destroying itself? Can we? -- Don Varvel (varvel@cs.utexas.edu) ------------------------------ Date: 20 Apr 90 19:56:46 GMT From: janus.Berkeley.EDU!bwood@ucbvax.Berkeley.EDU (Blake Philip Wood) Subject: Re: Decompression and 2001 In article <1990Apr20.162926.29153@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >As any scuba diver will tell you, holding your breath during decompression >is a thoroughly bad idea. The alveoli ... are not mechanically strong >and it's easy to damage them if there is more pressure inside than out. But this situation is not really analogous to decompression to a vacuum. In scuba you can have a differential of several atm, but in decomp to a vacuum the maximum is 1 atm. The proper question is whether something less than 1 atm can rupture the alveoli. In being exposed to a vacuum you certainly wouldn't want to simply open your mouth, because with no air in your lungs you have only about 15 sec of consciousness. The best strategy may be to exhale and hold that. Then you'd still have air, but the alveoli would only be exposed to some fraction (what is it?) of an atm. Blake P. Wood - bwood@janus.Berkeley.EDU Plasmas and Non-Linear Dynamics, U.C. Berkeley, EECS ------------------------------ Date: 20 Apr 90 06:52:17 GMT From: kirstein@boulder.colorado.edu (KIRSTEIN DALE) Subject: Pegsat barium drop What ever happened to the barium drop experiment launched on Pegsat? Was the first cannister dropped on schedule, did anyone see it, and what is the schedule for the second cannister drop i--------------------------------------------------------------------------- this .sig left intentionally blank ------------------------------ End of SPACE Digest V11 #298 *******************