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 ; Mon, 6 May 91 02:30:21 -0400 (EDT) Message-ID: <0c9DTqO00WBwI=9k53@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 6 May 91 02:30:15 -0400 (EDT) Subject: SPACE Digest V13 #493 SPACE Digest Volume 13 : Issue 493 Today's Topics: Re: Galileo works? Re: "more appropriate questions" (was: Why the space station?) Solar Power Re: Why the space station? What about ozone as an oxidant? Re: Galileo works? Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster) SPACE Digest V13 #474 Re: Another Galileo Sulution 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: 2 May 91 23:34:39 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!uakari.primate.wisc.edu!samsung!rex!rouge!dlbres10@ucbvax.Berkeley.EDU (Fraering Philip) Subject: Re: Galileo works? In article jpc@fct.unl.pt (Jose Pina Coelho) writes: [I wrote:] pg> I don't know, but maybe because the radio waves could become focused in pg> such a way as to interfere with the spacecraft electronics. I don't know pg> how much radio-frequency interference the circuits can take. and Jose Pina Coelho wrote: >They better be able to take a lot of it or they won't survive >Jupiter's radiation belts (I mean, they are *strong* radiation >fields, World War III would be peanuts arround Jupiter). I think you're confusing different sorts and frequencies of e-m radiation. And things work differntly at different frequencies. -- Phil Fraering dlbres10@pc.usl.edu Joke going around: "How many country music singers does it take to change a light bulb? Four. One to change the bulb, and three to sing about the old one." ------------------------------ Date: 2 May 91 19:30:07 GMT From: newton.cs.jhu.edu!callahan@umd5.umd.edu (Paul Callahan) Subject: Re: "more appropriate questions" (was: Why the space station?) In article <21623@crg5.UUCP> szabo@crg5.UUCP (Nick Szabo) writes: >>2. Why Space Station Freedom? > >If it isn't useful, and isn't really that entertaining (despite the >astronauts), it has to have some very good PR. Snappy names are key. >Even most of the engineers on the project realize the ridiculous >irrelevence between the name to the project, and have taken to calling >it "Fred". I always assumed the name was chosen to add a charming Orwellian touch to the whole enterprise. After all, the main result of such an undertaking will probably be to limit the "freedom" of those who want to do serious space exploration. From a more optimistic perspective, I believe that a lot of research fundamental to future space travel can be done without leaving this planet and without dealing with NASA at all. Automation is still getting better and better, primarily because it has uses other than space travel. Maybe by the time the world wakes up and decides it's time to seriously look into, say, mining the asteroid belt, we will have enough automated machinery for the job that the notion of setting up a human colony will seem dangerous and ridiculous. I have nothing against humans in space, but I think that a huge industrial infrastructure in the near solar system will be necessary to make regular space-travel feasible (as distinguished from dare-devil stunts like the Apollo program). There is no reason to believe that space industry, including such things as mines and factories, will need any humans on the spot at all, assuming sufficiently sophisticated computers controlling it all. The goal of a fully autonomous factory (complete with the ability to fix errors that were not explicitly predicted) is a good deal less ambitious than a lot of AI goals. There are people interested in these kinds of problems, they are not all being funded by the government, and they can work without the cost of expensive boosters or the risk of having their equipment blow up. It is clear from the problems that occur, for instance, with antenna deployment on satellites that we have not reached a very high level of system reliability, but this is far from a proof that it is impossible. In my opinion, if the human race ever does become a space-faring civilization, the late 20th century will not be seen as a long dry-spell, but rather as a period when some of the most essential background research was being performed (on Earth!). This is not a substitute for a sensible space program, of course, but it's at least a cheerful note to add to this otherwise depressing issue. -- Paul Callahan callahan@cs.jhu.edu ------------------------------ Date: 3 May 91 01:29:01 GMT From: mcsun!ukc!slxsys!ibmpcug!demon!news@uunet.uu.net (Ian Stirling) Subject: Solar Power All of the thermal solar power schemes I have seen use moving mirrors,moving mirrors are expensive,Why not use stationary mirrors? This idea would work best in high or low latitudes. ###\/ / #######\| \___ / ########\| \___/ #########\| / \___ ####HILL##\| / ^ \___ ###########\\ / reflected \___ ############\\ / rays> \___ #############\\------------------------\-O 20K)mail messages as Printf@cix.compulink.co |I get charged for them. Printf@cix.uucp | one of these may work | ------------------------------ Date: 5 May 91 19:25:24 GMT From: agate!headcrash.Berkeley.EDU!fcrary@ucbvax.Berkeley.EDU (Frank Crary) Subject: Re: Why the space station? In article <803@newave.UUCP> john@newave.mn.org (John A. Weeks III) writes: >I really do not understand this argument. How can Fred help us get to >the moon? The only help that I think Fred might be is as a rest stop >on the way. You are not going to be building moon ships in orbit (Fred >is not going to be an assembly hanger), and I doubt that you are going to >see Fred used as a gas station. As far as testing the crew modules, you NASA thinks about things in an unusual way... In the late 1960's and early 1970's they thought: "We want a lunar base, and manned Mars missions. What can we do to make this cheap and reasonable?" The answer they came to was that a space station, supporting in-orbit tugs/shuttles (e.g. specialized zero-g transports) would drastically lower the cost of a lunar base. They also decided that a lunar base could return Lunar oxygen to the orbital station (a debatable point). This oxygen could go to supporting a Mars mission. Finally they concluded that an orbital station would need a re-usable ground-to-orbit craft to build/support the station. From these conclusions, NASA went to Congress and President Nixon. Neither wanted to pay for the whole package... So NASA thought "Well, the first thing we will need is the reusable Earth-to-orbit transport. Lets get that done first." So NASA focused on the Space Shuttle (without really remembering why they needed it). They got Congress to pay for it, but the final product is not well suited for its origional purpose: building and supporting a space station. Now, having the shuttle, NASA wants to proceed with their origional plan: The "Next Logical Step" is a space station. So NASA, again forgeting WHY it wants the station, is cutting whatever deals with Congress and/or the station users that are required to get the station. This results in a design that does not fit into the "grand plan" any better that the shuttle does. Frank Crary UC Berkeley ------------------------------ Date: Fri, 03 May 91 21:41:23 EDT From: Richard Ristow Subject: What about ozone as an oxidant? There's been some discussion about alternative propellant chemistry. Does anybody know the current thinking on using ozone as the oxidant? I haven't kept current (!), but back in 1957 Willy Ley wrote, ... a tank that holds 6 pounds of liquid oxygen holds almost 10 pounds of liquid ozone ... [and] calculation shows that a fuel burned with ozone would produce an exhaust velocity some 10 percent higher than ... the same fuel burned with oxygen. [Ozone is dangerously unstable, but there may be a way to counteract this;] all one can say at the moment is that the other characteristics of liquid ozone are worth some effort. (1) Now, some comments. First, the '10% increase in exhaust velocity' has to be an average; ozone will contribute a fixed amount of energy per weight of oxygen consumed. It will contribute a smaller increment in a higher-energy propellant combination (the extra energy adds a fixed amount to the SQUARE of the exhaust velocity, and is a smaller absolute, not just relative, addition to a larger exhaust velocity), but a larger amount when the greater proportion of the propellant weight is oxygen. (Actually, since the two changes are in opposite directions as one moves from hydrcarbons to hydrogen as fuel, they may roughly cancel.) Higher density -- smaller tanks -- is always valuable, but of relatively low importance with hydrogen as fuel, as the tankage is so dominated by the hydrogen already. On the other hand, while reducing the size of first- stage tanks (and so dry weight) is always useful, it's precisely in the first stage that accepting some extra weight to avoid exotic techniques pays best. There ought to be a place for ozone, however, where performance is crucial. Obvious cases are upper stages, where ozone ought to increase payload or performance of a given booster significantly; and SSTO, hydrogen-fueled or dual-stage, which are at the edge of the performance envelope at best With a large launch market to amortize the cost of making them work, hydrocarbon-ozone (perhaps propane-ozone) first stages should be significantly smaller, and so cheaper, than equivalent oxygen-hydrocarbon stages. All high-energy oxidants (including LOx) are hard to manage, and ozone would be no exception. Spontaneous decomposition, especially rapid, is a hazard most others do not present. In other respects ozone should be more benign than, say, flourine-containing oxidants. It is toxic, but the toxicity can be ended by reconverting it to oxygen. The exhaust from an ozone rocket should be similar to that from a rocket burning the same fuel with oxygen. Most launch accidents end in fires that consume the large bulk of the propellants. Routine boil-off could probably be handled by catalytic converters. Large-scale spills during transport and storage would seem the worst hazard. Ley's statement that "the other properies of ozone could use some work" seems to stand. What thinking and work has been done since? (1) Ley, Willy, *Rockets, Missiles and Space Travel: Revised Edition*, The Viking Press, New York, 1957, pp. 307-308. ------------------------------------------------------------------------- Richard Ristow AP430001@BROWNVM.BROWN.EDU (BROWNVM on BITNET) ------------------------------ Date: 3 May 91 17:02:40 GMT From: dog.ee.lbl.gov!hellgate.utah.edu!caen!uakari.primate.wisc.edu!samsung!rex!rouge!dlbres10@ucbvax.Berkeley.EDU (Fraering Philip) Subject: Re: Galileo works? In article <1991May3.130053.18480@lth.se> magnus%thep.lu.se@Urd.lth.se (Magnus Olsson) writes: >It's even worse: He's confusing radio waves with ionizing radiation. The >radiation belts of Jupiter, like the earth's Van Allen belts, contain >a lot of electrically charged particles - electrons, protons etc. Making >a piece of harware resistant to ionizing radiation like this is a totally >different thing from making it resistant to radio frequency interference. Yes, but I couldn't tell whether he was talking about _that_ or the synchotron radiation caused by said particles. More and more people are throwing around words like "electromagnetic fields" or "electromagnetic radiation," as in the recent 60 minutes spot on "stray voltage" (which they never explained in physical terms) without realizing that the terms encompass everything from gamma rays and x-rays through visible light (yes, you spend your whole day bathed in e-m radiation!) to microwaves and radio waves. -- Phil Fraering dlbres10@pc.usl.edu Joke going around: "How many country music singers does it take to change a light bulb? Four. One to change the bulb, and three to sing about the old one." ------------------------------ Date: 4 May 91 02:39:35 GMT From: news-server.csri.toronto.edu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: Saturn V and Design Reuse: Saturn VI? (RBB: Real Big Booster) In article <1991May3.161528.29165@en.ecn.purdue.edu> irvine@en.ecn.purdue.edu (/dev/null) writes: >No, life DOES NOT have a value that can be estimated. The LEGAL >COSTS of a trial does not equate to a human life. Life may not have a value that can be estimated, in some theoretical sense, but for practical planning one *must* assign it some specific value. There is *NO LIMIT* to how much you can spend making the hardware a little bit safer. If you want to get anything done, sooner or later you have to say "enough". Whether you like it or not, when you say that, you have set the value you put on life. "For perfect safety... sit on a fence and watch the birds." --Wilbur Wright -- And the bean-counter replied, | Henry Spencer @ U of Toronto Zoology "beans are more important". | henry@zoo.toronto.edu utzoo!henry ------------------------------ ReSent-Message-ID: Resent-Date: Wed, 01 May 91 13:49:22 EDT Resent-From: Tommy Mac <18084TM@msu.edu> Resent-To: space+@andrew.cmu.edu Date: Sun, 28 Apr 91 02:02:40 EDT Reply-To: space+%ANDREW.CMU.EDU@msu.edu From: space-request+%ANDREW.CMU.EDU%CARNEGIE.BITNET@msu.edu Subject: SPACE Digest V13 #474 Comments: To: space+@ANDREW.CMU.EDU To: david polito <15432DJP@MSU.BITNET>, Tom McWilliams <18084TM@MSU.BITNET> >Subject: Orbital Elements of Saturnian system >Does anyone have a table of orbital elements for the moons of Saturn? >I would love to have the elements for all 17, but I doubt they've been >computed yet. >I need: The longitude of the perigee, longitude of the ascending node, and the >mass. (All geocentric) ^^^^^^^^^^ I think he meant "chronocentric" Acknowledge-To: <18084TM@MSU> ------------------------------ Date: 1 May 91 17:24:53 GMT From: mintaka!think.com!rpi!uupsi!pbs.org!pstinson@bloom-beacon.mit.edu Subject: Re: Another Galileo Sulution In article <0DA4D13D00402195@UALR.BITNET>, RDBROWN@UALR.BITNET writes: > Although putting a communications relay satellite in orbit around Jupiter > is a good idea, one must remember that Jupiter's position changes during > it's year, sometimes making it even further away from Galileo than Earth > would be. > > Another possibility would be to launch a relay station into a trajectory > aimed directly at Galileo, thus the relative position between it and > Galileo remain unchanged. Relay-1 can then take on the task of tracking > Earth. Later, as Relay-1 gets far enough away from Earth, Relay-2 can > be launched to follow behind Relay-1 making it theoretically possible to > follow Galileo as long as we keep launching relay probes. While this might work, it is a more complicated and costly solution than necessary. I don't believe the concern is so much about loosing data while in transit to Jupiter, but once Galileo arrives there and goes into orbit. The easiest way to solve this concern would be to have a relay comsat ready and waiting in orbit there, as was already suggested. I believe JPL may even be prepared to give up some of the later transit data. The main mission is after all at Jupiter. It is irrelevant how many times that planet may be father away from Galileo than Galileo is from Earth during the transit stage, since the planned for mission doesn't really start until Galileo is in orbit around Jupiter. ------------------------------ End of SPACE Digest V13 #493 *******************