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 Oct 89 16:40:34 -0400 (EDT) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 21 Oct 89 16:40:10 -0400 (EDT) Subject: SPACE Digest V10 #152 SPACE Digest Volume 10 : Issue 152 Today's Topics: A small voice, a small plan Re: Trying to build a fluxgate magnetometer -- help! Re: More whining about Galileo (nope) Re: More whining about Galileo re: plutonium aboard galileo Re: Galileo--- history repeats itself Amroc Helium Pressurization system Re: Leap Second Re: Titius Series / Quantum orbits? ---------------------------------------------------------------------- Date: 13 Oct 89 23:40:41 GMT From: oliveb!mipos3!omepd!inteloa!snidely@apple.com (David P. Schneider) Subject: A small voice, a small plan [I originally posted this under the subject line, "Subject: a small step for a goal-setter, a giant leap for planning..." but decided afterwards that that was too facetious. Since I apperent- ly screwed up the distrbution, I can still hope that you see only this copy. dps, Friday ] My own space goals are to experience the adventures Robert Heinlein described so beautifully to teen-agers of the 50's and 60's (I was into aircraft then, too, and I have yet to take a flying lesson). But to ad- dress a more practical set of goals, how about the following? Design the space station for intermittent occupation. Perhaps the Spacelab module could be modified to provide crew quarters for visits of 2-6 weeks, assuming provisions seperately launched. Permanent parts of the station would be for maintaining orbital stability, power, and untended experiments. Actually, the untended experiments are most likely to go up in medium-term modules. I've had wild pictures of plugging the Spacelab module into an ET, then filling the tank with water for shielding (cosmic rays). But what could be done realistically to shield Spacelab to a reasonable level? The current space station plans are based on not losing any shuttles or station components over a lengthy construction period. It would be a good idea if we could reduce the risk to the project by making components replacable (e.g., reducing their cost) and by reducing the number of flights required to make a stable platform. Re-assign the shuttle fleet. Assign N-1 shuttles to manned flight support (currently, N=3). Assign the Nth shuttle for experimental equipment tests. That is, it would be used to test new SSME designs, new control equipment, etc. If the design change is suc- cessful, roll it back into the support pool, and pick the most out-of-date orbiter to try the next change on. One problem with this is that structural changes probably re- quire a new airframe. Already there has been some of this going on. Remember how each new orbiter has been better than the previous? Such as using thermal protection blankets to replace many areas of tiles? Question: could the current shuttle be adapted to a hor- izontal launch system, or is better lift required than is available? Of course, I want to continue planetary probes. I don't have any specific suggestions, but the current trend to smaller satellites may also help the probes. The idea is to launch a fleet of small, specific, and hence cheap probes by pointing out how each one saves money over a general purpose multi-mission unit. Of course, the cumulative costs may not be lower (probably higher), but if funding is cut for 50% of a fleet, you're better off than if funding is cut for a single multi-mission unit. Also, the design trade-offs become easier. Anyway, a shot from someone with no deep insights and no inside knowledge. I don't even have an regular science subscriptions outside of the net. David P. Schneider BiiN (tm) Tuesday, 10.10 ------------------------------ Date: 13 Oct 89 18:42:27 GMT From: rti!tijc02!jkl141@mcnc.org (John Leroy ) Subject: Re: Trying to build a fluxgate magnetometer -- help! From article <1914@sactoh0.UUCP>, by mahaun@sactoh0.UUCP (Mark A. Haun): > > I am trying to build a fluxgate magnetometer sensitive enough to > monitor variations in the Earth's magnetic field, mostly to observe > magnetic storms caused by big flares on the sun (March 13, 1989 > stuff especially :-) !). > > I would appreciate hearing from anyone who has built any sort of > fluxgate magnetometer, anyone who has seen a construction article > for one, or anybody with suggestions/ideas/etc. on the feasibility > of this project. Please email to any of the addresses below. My email to you bounces, so I'll post this. I just stumbled across "Simple Magnetometers or How to Measure Your Own K-Index" by Russell G. Wicker, W4WD in the Proceedings of the 22nd conference of the Central States VHF Society (1988). If you want a copy and can't find the proceedings let me know. -- -John LeRoy Packet Radio: WA4VLV @ WX4S Compuserve: 74136,401 UUCP: rti!tijc02!jkl141 Phone: 615-461-2440 ------------------------------ Date: 16 Oct 89 04:13:24 GMT From: gem.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!jhunix!c05_ta06@tut.cis.ohio-state.edu (Ta06) Subject: Re: More whining about Galileo (nope) In article cr10+@andrew.cmu.edu (Christopher John Rapier) writes: >Actually, The Christic Institute is more than an environmental impact >group. They are actually a liberal law frim doing what they consider >good work on a pro-gratis basis. They are a lot like, from what I >understand, the ACLU. They are voicing a valid concern. 40 pounds of >plutonium ain't just a chest X-Ray. A couple mics will give your brain >them funky tumors. Yes. Al you have to do is cut open someone's head, put the plutonium in, and close them up, and they might get brain tumors from it. Alpha particles are not very penetrating. _Why_ do so many people post from ignorance? >I personally don't agree with them on this BUT I do >support them in their investigations into the actions of the CIA and the >government in Nicaragua and the Palenca bombings ... La Penca. -- "The workers ceased to be afraid of the bosses. It's as if they suddenly threw off their chains." -- a Soviet journalist, about the Donruss coal strike Kenneth Arromdee (UUCP: ....!jhunix!arromdee; BITNET: arromdee@jhuvm; INTERNET: arromdee@crabcake.cs.jhu.edu) ------------------------------ Date: 16 Oct 89 03:37:32 GMT From: terry@astro.as.utexas.edu (Terry Hancock) Subject: Re: More whining about Galileo In article <15137@bloom-beacon.MIT.EDU> dbwilson@athena.mit.edu (David B Wilson) writes: >2) How does a planet capture an asteroid? Sling shot effect in reverse > with a moon or two to help out? > This isn't so mysterious. I assume you're having trouble because it is difficult to have such a thing happen in the two-body problem (an object approaching from infinity will recede to infinity, it can't have a closed orbit). However, the problem is really best considered as a restricted three-body problem, with the Sun and the Planet being the two substantial masses and the captured asteroids the negligible-mass object which may follow a very complicated orbit if you get it in the right place. The asteroid starts from (approximately) a two-body orbit around the Sun. As the planet perturbs the orbit, it eventually reaches an unstable orbit from which it must be treated as a three-body problem. Then it settles into a more or less stable two-body orbit around the planet -- having "passed the hump." It may then be perturbed into a tighter orbit (probably by tidal effects) which will then be more stable, or it will be perturbed back over the hump and into solar orbit. The grouping of Jupiter's outer satellites into two families suggests to me that the details of this problem are probably pretty interesting, but to my knowledge this has not been explained, and I don't happen to know of anyone who's studying it (anyone know?). > >Q: How many members of the Christic Institute does it take to screw in a > light bulb? >A: 21. 1 to screw it in and 20 to perform the environmental impact study. Cute :-). But I'd rather you didn't put down environmental impact studies -- they're very important, even when they say everything's OK after all. Most of the time, the point is to find the minimum-impact way of doing what you want, not putting you out of business. And when they DO put you out of business, it's usually for a good reason, though you probably won't appreciate it then. Uncontrolled industry is a dangerous thing, we all have to face the Human future -- Space flight is one way, Environmentalism is another, and we need both. PS -- This is not to say I support the Christic Institute, I think they're full of .... *************************************** Terry Hancock terry@astro.as.utexas.edu *************************************** ------------------------------ Date: 16 Oct 89 14:31:10 GMT From: f.gp.cs.cmu.edu!bjm@pt.cs.cmu.edu (Bret Musser) Subject: re: plutonium aboard galileo Re: danger of plutonium It is only dangerous when not handled properly, which NASA has provided sufficient data to the EPA and to the courts saying that they are handling it safely. For those who like examples: (From Academic American Encyclopedia under Plutonium -- Uses) "The isotope (238)Pu powers such sophisticated devices as batteries in implanted heart pacemakers, which consequently operate for up to 10 years." I'll let you draw your own conclusions. bjm .sig ahead! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Bret J. Musser --- Carnegie-Mellon University | Why bother with dis- Pittsburgh, Pa | claimers on rec.arts.- Internet: bjm@f.gp.cs.cmu.edu | startrek? Do companies Bitnet: bjm%f.gp.cs.cmu.edu@cmccvb | hold official policies Work Phone: (412) 268-8751 | on TOS vs. TNG? =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= ------------------------------ Date: 12 Oct 89 15:39:45 GMT From: gem.mps.ohio-state.edu!uakari.primate.wisc.edu!pikes!udenva!isis!csm9a!japplega@tut.cis.ohio-state.edu (Joe Applegate) Subject: Re: Galileo--- history repeats itself In article <22983@cup.portal.com>, mmm@cup.portal.com (Mark Robert Thorson) writes: > The Christic Institute is (or was) on the net; I remember seeing some > postings from them in sci.environment. Perhaps someone could post their > net address and invite them to give a statement? (Perhaps sci.space.flame > could be created in advance for this purpose?) > > I thought I heard that they are funded by a number of Christian churches, > hence the name. Of course, this could just be a cover story. I have heard that they are funded by various New Age and several extremely liberal "Christian" denominations... and that their calling is to bring the "Christ" consciousness into politics... this is of course New Age theology and has no resemblance to Biblical Christianity. I would appreciate any real information as to the theology and specific supporters of the Christic institute as I am going primarily on hearsay... - Joe Applegate - ======================STANDARD DISCLAIMER============================ All views and opinions are my own and do not represent the views or opinions of the Colorado School of Mines, whatever they might be. ===================================================================== ------------------------------ Date: 12 Oct 89 06:11:19 GMT From: zephyr.ens.tek.com!tektronix!psueea!parsely!bucket!loop!keithl@uunet.uu.net (Keith Lofstrom) Subject: Amroc Helium Pressurization system More information about the AMROC LOX tank pressurization system: The pressurization tanks contain a mix of room temperature helium and hydrogen gas at 6000 PSI. This mixture leaves the tank and expands adiabatically to 400 PSI or so. This cools the gas down a lot, so it doesn't expand as much as it would if it stayed at room temp, or was heated. The gas mixture passes over a bed of (Platinum?) catalyst, combines with ambient oxygen (this is the LOX tank, remember) and heats up to 700K or so; this yields about 10x the volume of pressurized gas. Of course, when the gas hits the LOX and the tank walls it starts cooling again; I don't know how fast that process is, or whether sloshing in the tank would accelerate it, but apparently the effect wasn't large on the test stand. - - - - In reply to Henry about the safety of LOX: Of course the LOX is just as dangerous on a hybrid as it is on a liquid; but it is explosions from the rapid mixing of fuel and oxidizer in a liquid rocket accident that AMROC points to as a danger. The LOX can't rapidly mix with the hybrid fuel, though of course it can still support combustion in the wrong places. Fires are (as demonstrated) still a threat - large explosions aren't. This will hopefully lead to lowered costs for pad design and vehicle handling systems; in the longer term it should simplify the design of emergency escape systems. One safety aspect of a rubber fuel that was mentioned after the briefing: "Well, if the rocket goes out of control and lands in Los Angeles, it might not hit anything *on the first bounce*, but ... " :-) I'm not sure I buy the idea of hybrid rockets myself, but it seems a clever way to cheaply develop a new rocket, and crazier things have succeeded with far worse performance tradeoffs. Hybrids seem more believable than MSDOS, for example :-) -- Keith Lofstrom keithl@loop tektronix!psueea!qiclab!loop!keithl Launch Loop, P.O. Box 1538, Portland, Oregon 97207 (503)-628-3645 ------------------------------ Date: 13 Oct 89 14:53:00 GMT From: ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!m.cs.uiuc.edu!kenny@iuvax.cs.indiana.edu Subject: Re: Leap Second joe@hanuama.Stanford.EDU (Joe Dellinger) writes: >Does anyone know if we'll ever get a negative leap second? I know the general >trend must be for more positive than negative ones being needed. I guess >when the day lengthens to 24.03 hours or so, we'll have "leap hour parties" >at the end of every month... Yes, it is possible that negative leap seconds will be required at some future time; the slowdown in the Earth's rotation is pretty irregular. Here are estimated differences (in minutes) between Universal Time and Ephemeris Time over the years (data tken from Jan Meeus, _Astronomical Formulae for Calculators): Year UTC-ET Year UTC-ET Year UTC-ET Year UTC-ET 1710 -0.2 1840 0.0 1912 0.2 1971 0.7 1730 -0.1 1870 0.0 1927 0.4 1977 0.8 1750 0 1880 -0.1 1940 0.4 1770 0.1 1895 -0.1 1950 0.5 1800 0.1 1903 0.0 1965 0.6 As you see, things went backwards between 1800 and 1840, and again between 1870 and 1880. Kevin | / o Kevin Kenny (217) 333-5821 |< /) | | | |/\ Illini Space Development Society o , o , | \ X_ \/ | | | P.O. Box 2255 40 07 N 88 13 W kenny@cs.uiuc.edu Station A uunet!uiucdcs!kenny Champaign, IL 61825 AD ASTRA PER ARDUA k-kenny@uiuc.edu kenny%cs@uiucvmd.bitnet ------------------------------ Date: 13 Oct 89 16:49:43 GMT From: thorin!alanine!leech@mcnc.org (Jonathan Leech) Subject: Re: Titius Series / Quantum orbits? In article <6421@pt.cs.cmu.edu> vac@sam.cs.cmu.edu (Vincent Cate) writes: >The general equation is: > > R = R0 * b^N >... >It seems clear to me that this is not due to chance. I think it's not at all surprising that you can choose the free parameter b to get a good fit. If you had the *same* b for Uranus, Jupiter etc., *that* would be noteworthy. -- Jon Leech (leech@cs.unc.edu) __@/ ``The tuba recital is one of the most memorable experiences of music school.'' - Seen on a bulletin board in the UNC Music School ------------------------------ End of SPACE Digest V10 #152 *******************