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 ; Mon, 12 Feb 90 01:30:56 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 12 Feb 90 01:30:34 -0500 (EST) Subject: SPACE Digest V11 #35 SPACE Digest Volume 11 : Issue 35 Today's Topics: Soviet Soyuz TM-9 mission begins to Mir space station RE: SSX and Propellants Re: Spacecraft drives and fuel efficiency Re: Spacecraft drives and fuel efficiency Re: Galileo Update - 02/06/90 (Forwarded) Re: Nasa Freq. Re: metric vs. imperial units Re: Spacecraft drives and fuel efficiency Easy come, easy go (was Re: Spacecraft drives and fuel efficiency) Re: Spacecraft drives and fuel efficiency Re: Recreation in Space ---------------------------------------------------------------------- Date: Sun, 11 Feb 90 13:40:55 EST From: Glenn Chapman To: biro%hydra.enet.dec.com@decwrl.dec.com, klaes%wrksys.dec@decwrl.dec.com, lepage%vostok.dec.com@decwrl.dec.com, space-editors-new@andrew.cmu.edu, yaron@astro.as.utexas.edu Subject: Soviet Soyuz TM-9 mission begins to Mir space station The USSR successfully launched its Soyuz TM-9 mission on Feb. 11th (though the launch time was only stated as this morning). The crew for this 6 month mission are Anatoly Solovyov (Soyuz TM-5/Mir Jun. '88 for 9 days) and Alexander Balandin, a new cosmonaut, as expected. The Soyuz TM-9 will rendezvous with Mir on Feb. 13th. There they will replace the current cosmonauts Alexander Viktorenko and Alexander Serebrov who have been in orbit for 159 days, since Sept. 5, 1989. The original schedule for the current crew called for them to come down on Feb. 24th but the Feb. 9th announcement said that it may be Feb. 19th. One of the more important items that Viktorenko and Serebrov will be bringing down in the Soyuz TM-8 capsule will be the crystallization protein experiments paid for by Payload Systems of Cambridge, MA. One of the main tasks of the new crew will begin with the docking of the Kvant 3 or Technology module which will occur in March/April this year. This 17.2 Tonne expansion section will dock with the front axial docking port of Mir, then be swung to the side port using a robot arm to dock opposite to the Kvant 2 module. Kvant 3 will be 13.7 meters (45 ft.) long (the same length as Kvant 2) but has a huge solar array some 36 meter (118 ft.) in span that is planed to generate some 20 Kilowatts of power. By comparison Mir itself has only a 29.7 meter (97 ft.) spanning array, and the total of its power, plus that of arrays added on Kvant 2 and erected during space walks, is only 20 Kilowatts itself. The main task of Kvant 3 is material processing, especially the growth of super pure crystals. The Soviets argue that this module will begin the point where materials processing on Mir will pay for the missions. (Radio Moscow Feb. 8-11) One interesting point has been pointed out about the next mission, Soyuz TM-10, scheduled for July '90. As noted in my previous posting one of the stated crew members is Vitally Serastyanov, an old time cosmonaut, selected in 1967, flew Soyuz 9 in June 1970 for 17 days, Soyuz 18/Salyut 4 in May 1975 for 63 days and was a manager in the Soviet Lunar Landing training program. However, Jonathan McDowell of the Harvard Smithsonian Observatory, pointed out to me that Serastyanov retired in 1975 and became a well known science journalist on Russian television/radio. This suggests that he is the Soviet reporter to fly to Mir to beat the Japanese journalist which been moved up from 1991 to the fall of this year. At 55 years old this probably makes him the first astronaut/cosmonaut to retire, take on other tasks, then to return again to space to make use of his old training in a new field. Definitely the Soviet manned program is becoming more commercial. Let us see if they can, in their own minds, make a profit in space. Glenn Chapman MIT Lincoln Lab ------------------------------ Date: 11 Feb 90 00:03:33 GMT From: zaphod.mps.ohio-state.edu!van-bc!rsoft!mindlink!a752@tut.cis.ohio-state.edu (Bruce Dunn) Subject: RE: SSX and Propellants Having watched this discussion unfold for a while, i would like to do something absolutely horrible to those of you who have been hopping up and down excitedly about high-density propellants: I'm going to break out some Numbers. For instance: The space shuttle ET The space shuttle's external tank weighs 78,100 lbs [nominal] when empty. when filled with the full fuel load of 1,359,000 lbs LOX and 226,000 lbs of LH2, the total tank mass is 1,663,000 approx and the fraction of this that is the tank itself is one part in 21. Liquid hydrogen is by far the lowest density fuel around. That the tankage for it is negligible compared to the fuel mass sort of knocks holes in the idea of getting more mileage out of higher density fuels. Counterarguements of the type that any decrease in the final mass [rocket eqn] is a significant advantage can as far as i can tell be effectively countered by the decrease in Isp for the denser fuels compared to LH2. If anyone out there has a more in-depth analysis showing me wrong, please post it and/or email me. But all my design studies are staying LH2 burners for the time being :-) *********************************************************************** ***** George William Herbert | UCB Naval Architecture [On schedule? at UCB? Yes!] I agree with this line of reasoning only as long as the objective is to lower the total gross mass of a vehicle. However, it is usually the dry mass of a rocket which costs a lot, not the propellant. To a first approximation, the cost of a vehicle is proportional to its dry weight. For first stage use in a multi-stage vehicle, a pencil and paper calculation will quickly show you that hydrocarbon fuels will give a lower dry mass than LH2 would. Granted, the total stage mass will be higher because of the lower specific impulse, but this increased mass is cheap fuel and oxidizer, not expensive hardware. However, for upper stage use or for stages where a lot of delta V is required from a single stage, specific impulse becomes more important than density. Researchers who have been modeling two stage or single stage to orbit vehicles have generally found that burning subcooled propane during the first part of the flight reduces total hardware masses by 5 to 10% over the mass of an all hydrogen vehicle. This is not a huge difference, but it is real. In practice, as Henry Spencer has pointed out, the availability of suitable engines may be much more important than theoretical considerations in determining how a vehicle is to be built. Certainly, if hydrogen is to be used for the upper stage of an ascent and the engine can be adapted for lower stage work by modifying its expansion ratio, it may be desirable to go with a single engine design rather than have the complication of two engine types. The most promising engines for future vehicles are dual fuel engines which can burn both a hydrocarbon and hydrogen. The relative proportion of thrust and propellant used in each mode can then be fine tuned to a specific vehicle and ascent profile. For anyone wishing to persue this topic further, I can E-mail them some literature references. - Bruce ------------------------------ Date: 11 Feb 90 22:18:33 GMT From: ogicse!unicorn!n8741572@decwrl.dec.com (Matthew Skinner) Subject: Re: Spacecraft drives and fuel efficiency In article <19452@nuchat.UUCP> steve@nuchat.UUCP (Steve Nuchia) writes: >Robert Forward's solution to this excersize (_Flight_of_the_Dragonfly_) >was to release the main reflector at turnover and use the reflected >(and refocused) beam to deccelerate the ship using a smaller secondary >reflector. The former main reflector is of course accelerated further >on the outbound axis. This was a one-way mission, [...] Dr. Forward describes a two way trip in his book _Future_Magic_ which uses the outermost ring to decelerate the ship, then a middle ring to reflect the laser to accelerate the center sail back home. -- Matthew Skinner skinner@ [ nessie | unicorn ].wwu.edu ------------------------------ Date: 11 Feb 90 19:22:02 GMT From: nuchat!steve@uunet.uu.net (Steve Nuchia) Subject: Re: Spacecraft drives and fuel efficiency In article <26734@cup.portal.com> hkhenson@cup.portal.com (H Keith Henson) writes: >energy to laser light. Lasers will levitate against 1g, and as someone >(Henry?) recently said, a year at one gee is the speed of light. >(How to stop is left as an exercise) Keith Henson Robert Forward's solution to this excersize (_Flight_of_the_Dragonfly_) was to release the main reflector at turnover and use the reflected (and refocused) beam to deccelerate the ship using a smaller secondary reflector. The former main reflector is of course accelerated further on the outbound axis. This was a one-way mission, and involved a lot of coasting since the deceleration phase has limited delta-v. As in most light sail problems the bulk of the reflector (or thrust/mass ratio if you prefer) is one of the biggest remaining exercizes. -- Steve Nuchia South Coast Computing Services (713) 964-2462 "If the conjecture `You would rather I had not disturbed you by sending you this.' is correct, you may add it to the list of uncomfortable truths." - Edsgar Dijkstra ------------------------------ Date: 11 Feb 90 23:41:13 GMT From: cs.utexas.edu!sun-barr!newstop!texsun!convex!convex.com@tut.cis.ohio-state.edu (Richard A. Schumacher) Subject: Re: Galileo Update - 02/06/90 (Forwarded) This is also the first time a probe will approach the earth-moon system from a great distance, which should permit the best determination to date of the Earth's mass (right, Henry, Ron?) ------------------------------ Date: 10 Feb 90 21:20:29 GMT From: mtndew!friedl@uunet.uu.net (Steve Friedl) Subject: Re: Nasa Freq. > For all you space fanatics, here is a listing of all of the radio frequencies > that NASA uses. It's 463 lines long. I assume that there are all kinds of data streams going to and from the Shuttle (and to other things like Voyager or Galileo). Does NASA ever get worried about electronic sabotage over these frequencies? Is everything encrypted? 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 "Winning the Balridge Quality Award is as easy as falling off a horse." - me ------------------------------ Date: 12 Feb 90 01:06:32 GMT From: eru!luth!sunic!sics.se!pd@bloom-beacon.mit.edu (Per Danielsson) Subject: Re: metric vs. imperial units In article <1294@otc.otca.oz>, gregw@otc (Greg Wilkins) writes: >You guys just keep making excuses!!!! Yes an entire country can convert >from imperial to metric -> Eg Australia and we have the safest airline in >the world. If any airline or spaceflight relies on the pilots ability to >do mental arithmetic in his native units, then it aint safe!! I'm quite sure that aviation in Australia uses feet for altitudes and nautical miles for distances, just as the rest of civilian aviation in the world (with a few exceptions: the USSR being the one really important one, but russian pilots have to use feet and nm when they fly outside the USSR. (The other group I know of using meters and km in the air is the Swedish Air Force)). It's of course not impossible to convert everyone to meters (witness the co-use of air space and Air Traffic Control of civilian and military traffic in Sweden), but it will be *very* expensive in large parts of the world. Converting to SI (i.e. "metrics") in other areas is another matter. I'm all for it. ("The U.S. is going metric inch by inch.") >The whole point is that metric has many big points in its favour: > > - The rest of the world is using it Agreed. > - To some extent, when designing physical systems, recurring decimal > places can be avoided, hence round off errors can be reduced. This I don't understand. Why is any measurement system better than another here? > - To do any sort of calculation by computer, metric is by far better than > imperial, thus reducing the possibility of program error. This, too, I fail to understand. Computers don't care about measurement systems. >... >[Stuff deleted] >... >Anyway, to sum up, stop making excuses, start making changes, put a bit >of effort in , and maybe, just maybe you will be able to talk technical >with the rest of the world in twenty years or so! I agree completely. The U.S. is becoming more and more dependent on cooperation with the rest of the world, since it is not as dominating in the world economy nowadays as 20-30 years ago. This alone should make americans a little worried about the lack of progress in converting to SI. -- Per Danielsson UUCP: pd@sics.se (or ...!enea!sics!pd) Swedish Institute of Computer Science PO Box 1263, S-164 28 KISTA, SWEDEN ------------------------------ Date: 11 Feb 90 21:32:29 GMT From: rochester!dietz@rutgers.edu (Paul Dietz) Subject: Re: Spacecraft drives and fuel efficiency In article <10166@hoptoad.uucp> tim@hoptoad.UUCP (Tim Maroney) writes: >You have to realize just how enormous the energy costs are in >interstellar travel. They are certainly enormous compared to current energy usage. But then, the energy cost of sending a spacecraft to the moon is large compared to the energy used by stone-age man. The energy resources of the solar system are more than adequate for interstellar travel, given sufficiently massive engineering. The sun produces about 4e26 watts of power. At 100% efficiency, this power is enough to launch, every *second*, a 15 million ton starship at half the speed of light. Implementation details are left to the reader :-). Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: 12 Feb 90 03:00:29 GMT From: zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!xanth!xanth.cs.odu.edu!paterra@tut.cis.ohio-state.edu (Frank C. Paterra) Subject: Easy come, easy go (was Re: Spacecraft drives and fuel efficiency) In article <19452@nuchat.UUCP> steve@nuchat.UUCP (Steve Nuchia) writes: In article <26734@cup.portal.com> hkhenson@cup.portal.com (H Keith Henson) writes: >>energy to laser light. Lasers will levitate against 1g, and as someone >>(Henry?) recently said, a year at one gee is the speed of light. >>(How to stop is left as an exercise) Keith Henson >Robert Forward's solution to this excersize (_Flight_of_the_Dragonfly_) >was to release the main reflector at turnover and use the reflected >(and refocused) beam to deccelerate the ship using a smaller secondary >reflector. The former main reflector is of course accelerated further >on the outbound axis. This was a one-way mission, and involved a lot >of coasting since the deceleration phase has limited delta-v. As in >most light sail problems the bulk of the reflector (or thrust/mass >ratio if you prefer) is one of the biggest remaining exercizes. Assuming you guys have solved all the problems of accelerating the ship, how about when you reach the half way point, pointing the solar sail at the destination star and using it to decelerate the ship? >-- >Steve Nuchia South Coast Computing Services (713) 964-2462 >"If the conjecture `You would rather I had not disturbed you >by sending you this.' is correct, you may add it to the list of >uncomfortable truths." - Edsgar Dijkstra Simple idea from a simple mind. Frank Paterra paterra@cs.odu.edu -- Frank Paterra paterra@cs.odu.edu ------------------------------ Date: 11 Feb 90 07:58:48 GMT From: pasteur!sting!scott@ucbvax.Berkeley.EDU (Scott Silvey) Subject: Re: Spacecraft drives and fuel efficiency > Unfortunately, the speculative "gate" approaches such as the Kerr > metric warp are even worse. Has anyone done any estimates on the > energy needed to keep a Kerr warp contained and spinning? What is a "Kerr metric warp", who is Kerr, and what sort of physics does this involve? Is this merely some science fiction conjecture or is it based on reputable theory? How do you estimate how much energy it takes to induce one? Scott ------------------------------ Date: 11 Feb 90 23:35:55 GMT From: zaphod.mps.ohio-state.edu!rpi!crdgw1!sixhub!davidsen@tut.cis.ohio-state.edu (Wm E. Davidsen Jr) Subject: Re: Recreation in Space In article <1037@watserv1.waterloo.edu> a1wrkshp@watserv1.waterloo.edu (WATMOST Groups 9) writes: | Finally, do what would YOU like to do if you were a crewman on the Space | Station? Could zero gravity itself be entertaining enough, or would you | desire some form of activity? Can you suggest an object, such as a | gyroscope, that would be interesting to use in zero-g, and should be provided? Let me give you a hint... if I were going to be on a multiyear mission, I would want female astronauts. -- bill davidsen - sysop *IX BBS and Public Access UNIX davidsen@sixhub.uucp ...!uunet!crdgw1!sixhub!davidsen "Getting old is bad, but it beats the hell out of the alternative" -anon ------------------------------ End of SPACE Digest V11 #35 *******************