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, 24 Mar 90 01:29:49 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 24 Mar 90 01:29:21 -0500 (EST) Subject: SPACE Digest V11 #181 SPACE Digest Volume 11 : Issue 181 Today's Topics: Re: Shuttle escape systems, was Challenger's Last Words Re: Solar System Questions from a Novice Re: Strange Flash of Light Galileo Update - 03/23/90 Re: What was Challenger really up to? Railgun ... Re: Intelsat / Titan failure Voyager Update - 03/23/90 Re: Shuttle escape systems, was Challenger's Last Words RE: SPACE Digest V11 #93 Re: Solar System Questions from a Novice ---------------------------------------------------------------------- Date: 23 Mar 90 05:19:27 GMT From: crash!orbit!pnet51!schaper@nosc.mil (S Schaper) Subject: Re: Shuttle escape systems, was Challenger's Last Words I think I remember reading that the shuttle floats like it flies - like a brick. If they did ditch, they would have to get out _fast_. The SRB's did _not_ steer straight in the Challenger accident, if the exhaust plumes on that memorable picture mean what they seem to mean. UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper ARPA: crash!orbit!pnet51!schaper@nosc.mil INET: schaper@pnet51.cts.com ------------------------------ Date: 23 Mar 90 16:58:18 GMT From: cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Solar System Questions from a Novice In article <6362@blake.acs.washington.edu> wiml@blake.acs.washington.edu (William Lewis) writes: > I can think of at least one stable orbit around binary stars of >approximately equal mass and large separation ... The two >stars are separated by about 1 AU, and the planet orbits in the point >which could be called the L4 or L5 point, equidistant from the suns. Sorry, this is *not* stable. The L4 and L5 points are stable only if the two major bodies have very *unequal* masses. I don't remember the number for sure, but I have a vague recollection that the big one has to be something like 30 times the mass of the small one. Please don't ask for the intuitive explanation; as far as I know, there isn't one. You just have to grit your teeth and do the math. -- US space station: 8 years | Henry Spencer at U of Toronto Zoology and still no hardware built. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Fri, 23 Mar 90 15:39:53 CST From: marco@ncsc.navy.mil (Barbarisi) Subject: Re: Strange Flash of Light Several posters have discussed a large, lightning-like, flash of light which occured over large parts of Missouri. It was described as occuring on a clear winter night. Further it was omnidirectional; it had no apparent point of origin and observers recorded the same intensity of light reqardless of the direction in which they viewed the event. This sounds like one of four phenomena: 1) Clear air lightning - which I have observed on many a winter night in Minnesota. Clear air lightning is a diffuse, large scale discharge of static electricity, not associated with a storm system. When I've seen it, it was a flash that enveloped the whole sky and there was no discernable thunder. 2) St. Elmo's Fire - which may be related to clear air lightning. St. Elmo's is a form of static discharge which emits bright light and, when observed closely, a "crackling" sound. For lack of knowledge, I won't say more about it. Perhaps someone out there can comment on the likelihood of this event being a discharge of St.Elmo's Fire. 3) A distant massive thunderstorm - I recall there were some truly nasty tornadic thunderstorms South of Missouri on the night of the flash. Flashes from such storms may be visible hundreds of miles away - the light propagates by reflection off high altitude ice crystal clouds. The result at a distance is a diffuse flash of light that encompasses the entire sky. 4) Laser beams bouncing off Elvis' sequined jacket. Marco Barbarisi Naval Coastal Systems Center Panama City, Florida marco@ncsc.navy.mil ------------------------------ Date: 24 Mar 90 00:09:16 GMT From: snorkelwacker!usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@tut.cis.ohio-state.edu (Ron Baalke) Subject: Galileo Update - 03/23/90 GALILEO MISSION STATUS REPORT MARCH 23, 1990 As of noon Friday (PST), March 23, 1990, the Galileo spacecraft is 70,023,320 miles from the Earth, 11,852,790 miles from Venus and is traveling at a heliocentric velocity of 85,320 miles per hour. Round trip light time is 12 minutes, 26 seconds. The spacecraft's spin configuration continues at 3.15 rpm with a spacecraft attitude sun point angle of 0.5 degrees. Three SITURNS to lead the sun were successfully performed on March 19, 21, and 23. Spacecraft performance for these activities was as expected and without incident. A NO-OP command was sent on March 19 to reset the Command Loss Timer to 288 hours consistent with the plan for this mission phase. The Venus-Earth (VE-2) sequence memory load was sent on March 22; the load was successfully transmitted and received by the spacecraft without incident. The VE-2 sequence controls spacecraft activities from March 26 to April 23. This sequence includes 12 SITURNS, 1 Retro-Propulsion Module (RPM) flushing activity, several cruise science Memory Readouts (MROs) for the Magnetometer (MAG), Extreme Ultraviolet Subsystem (EUV), Dust Detector Subsystem (DDS) and Energetic Particles Dectector (EPD), and a telemetry data rate switch back to 40 bps from 10 bps. During early April, from April 9 thru April 12, time windows have been established for the planned Trajectory Course Manuever (TCM-4A). The -x RTG (T4) temperature measurement which began acting erratically on March 8 went to full saturation on March 21 indicating an open circuit somewhere between the transducer and the Command and Data Subsystem (CDS); other CDS measurements routed to this CDS tree switch are all reading as expected. The loss of these measurements does not pose a threat to the RTG or the spacecraft since power performance parameters (V, I) are measured separately by the power subsystem electronics. The AC/DC bus voltage imbalance measurements have varied only slightly. The DC measurement has fluctuated between 21.31 and 21.62 volts; the AC measurement has fluctuated between 48.56 and 48.75 volts. All other power-related measurements (bus voltages, bus currents and shunt current) and other subsystem measurements have all been as expected. Deep Space Network (DSN) support for Galileo continues at 10 bps without problems, although the B-string telemetry at the stations experience difficulty in maintaining lock due to the currently unfavorable ratio of bit rate to subcarrier frequency transmitted by the spacecraft. The problem is recognized and is considered acceptable at present. Characterization of the problem by DSN Operations is in progress. The impact of the DSN plan for elevation bearing maintenance on Galileo, particularly the Trajectory Correction Maneuver for Earth Encounter #1 (TCM-4) is being evaluated by the DSN and Galileo. It appears that some impact may be inevitable, but the outcome of the first Goldstone inspection is awaited before any final maintenance decisions can be made. A Mission Readiness Test (MRT) with the 34 meter antenna in Australia was completed successfully, and the Galileo project participated in a Multi-Mission Verification Test to establish compatibility of the new DSN Telemetry Processor Assembly (TPA). The new TPA software is scheduled to begin operational support on April 29. The Galileo project released about 4.5 hours of its scheduled tracking coverage on March 22 allowing the International Cometary Explorer spacecraft (ICE) to collect valuable solar flare data from the recent event on March 21. The tracking coverage was released only after successful uplink transmission and total verification of the VE-2 load on the Galileo spacecraft was completed. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: 23 Mar 90 05:19:15 GMT From: crash!orbit!pnet51!schaper@nosc.mil (S Schaper) Subject: Re: What was Challenger really up to? I think that that is about as likely as my initial theory, that I didn't take at all seriously at the time, that Khaddafy had a laser on a fishing trawler off shore (remember the geopolitics at that time?) What was Christa McAuliffe doing on board if it was a weapons-capable laser mission? UUCP: {amdahl!bungia, uunet!rosevax, chinet, killer}!orbit!pnet51!schaper ARPA: crash!orbit!pnet51!schaper@nosc.mil INET: schaper@pnet51.cts.com ------------------------------ Date: 23 Mar 90 10:45:22 GMT From: ogicse!blake!wiml@ucsd.edu (William Lewis) Subject: Railgun ... I thought I'd repost this from sci.electronics in case anyone was interested ... From: pahsnsr@nmtsun.nmt.edu (Paul A. Houle) Newsgroups: sci.electronics Subject: Re: Rail Guns Message-ID: <4007@nmtsun.nmt.edu> Reply-To: pahsnsr@nmtsun.nmt.edu (Paul A. Houle) Lines: 23 Posted: Thu Mar 22 20:32:26 1990 Actually, the fastest railgun in the world is powered by a huge bank of ordinary car batteries; According to an article in Av Week about six months ago or so, a company in California has an electromagnetic gun, either a railgun or coilgun, that has a high enough terminal velocity to put something into orbit. Actually doing it is a problem, because you'd need something that weighs about a gram that can perform an orbital insertion maneuver - never mind air resistance. Another story in last week's Av Leak was about a coil gun proposed to be based in Hawaii; the goal is to toss kilogram quantities of matter into polar orbit. Of course, the only reason to launch something into a polar orbit is for surveillance applications... Looks like Cheney and the .mil bunch aren't ready to pay off a peace dividend. It seems to me that we could use something that could throw sand, ice, and metals into LEO or G-sync at $10 /lb. In fact, that's a hell of a way to build a space station. Outer layer is a kevlar baloon, and the inner layer is Kevlar and something kinda like Saran wrap; blow in a foot of sand, and you've got a cheap and simple space station / long-rasnge spacecraft with excellent radiation and meteorite resistance... -----------------------end of repost------------------------------ -- JESUS SAVES | wiml@blake.acs.washington.edu Seattle, Washington but Clones 'R' Us makes backups! | 47 41' 15" N 122 42' 58" W ------------------------------ Date: 23 Mar 90 13:54:18 GMT From: mailrus!sharkey!itivax!vax3!aws@tut.cis.ohio-state.edu (Allen W. Sherzer) Subject: Re: Intelsat / Titan failure In article <1990Mar22.215135.18932@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >There is also the >question of whether you want to bring it back down or tack a fresh upper >stage onto it and send it on its way. I very strongly suspect the latter. Wouldn't tacking on a fresh upper stage using the shuttle cost more than the Intelsat and launch are worth? I assume that would take a dedicated shuttle flight. That plus the cost of the stage plus the cost of training seems like it would cost a lot more than an new Intelsat and launch. Allen ----------------------------------------------------------------------------- | Allen W. Sherzer |Archie: These guys are terrorists. Know what that means?| | aws@iti.org |Lorenzo: No prisoners! | | |Recce: You say that like there was some other way. | ------------------------------ Date: 23 Mar 90 17:26:41 GMT From: elroy.jpl.nasa.gov!forsight!jato!mars.jpl.nasa.gov!baalke@decwrl.dec.com (Ron Baalke) Subject: Voyager Update - 03/23/90 Voyager Mission Status Report March 23, 1990 Voyager 1 Voyager 1 continues to collect routine cruise science data. High-rate Ultraviolet Spectrometer Subsystem (UVS) observations were conducted on HD 206165 (March 2) and Markarian 509 (March 6 & March 13). One frame of high-rate Plasma Wave Subsystem (PWS) data was recorded on March 5 and March 12. An AGC/Command threshold test was executed on March 7. This is the first time that this particular test was performed on Voyager 1. A number of verification alarms were experienced during the uplink of the AGC/Command Threshold test, but the alarms did not appear to have any adverse impact on the test, and the test was completed successfully. The processing and analysis of Planetary Radio Astronomy Subsystem (PRA) Experiment Data Record (EDR) data continues daily, for the purpose of observing and logging radio events of interest to the PRA team. On March 13, a Magnetometer (MAG) sequence was executed by the spacecraft. No problems were encountered and the spacecraft performance was nominal. The instruments responded satisfactorily. Images from the "family portrait" have been transmitted back to Earth. Uranus and Neptune images were successfully sent back on March 16, and Saturn images on March 20. The remainder of the images are scheduled for transmission from the spacecraft's tape recorders for tonight (Mars) and for March 27 (Jupiter, Earth and Venus). Spacecraft performance for all the sequenced activity has been nominal. Voyager 2 Voyager 2 continues to collect routine cruise science data. One frame of high-rate PWS data was recorded on March 5 and March 12. The AB gyro pair was turned on on March 5. Thermal events (AB gyros on) induced a command moratorium that resulted in approximately two days of this period being unavailable for acquisition of ranging or coherent Doppler data. High-rate UVS observations were conducted on HD 212571 (March 5) and NGC 7027 (March 7, 12, 13 and 14). Most of this data was lost due to the limited Deep Space Network (DSN) coverage. An Attitude and Articulation Control Subsystem (AACS) test and Computer Command Subsystem (CCS) timing offset determination were performed on March 7. A Cruise Maneuver (CSRMVR) was performed on March 14 and a PLSCAL on March 15. Commands to update the AACS yaw and roll axes were also transmitted in preparation for the mini-CRSMVR executed on March 14. The update was verified by an AACS Memory Read Out. Spacecraft performance for all the sequenced activity has been nominal. Ron Baalke | baalke@mars.jpl.nasa.gov Jet Propulsion Lab M/S 301-355 | baalke@jems.jpl.nasa.gov 4800 Oak Grove Dr. | Pasadena, CA 91109 | ------------------------------ Date: 23 Mar 90 16:51:22 GMT From: zaphod.mps.ohio-state.edu!samsung!cs.utexas.edu!news-server.csri.toronto.edu!utgpu!utzoo!henry@tut.cis.ohio-state.edu (Henry Spencer) Subject: Re: Shuttle escape systems, was Challenger's Last Words In article <2209@orbit.cts.com> schaper@pnet51.orb.mn.org (S Schaper) writes: >I think I remember reading that the shuttle floats like it flies - like a >brick. If they did ditch, they would have to get out _fast_. More to the point, the shuttle ditches like it somersaults: in pieces. It's too fragile to survive a ditching or belly landing. The STS-1 flight plan (which I have a copy of) has a number of contingency branches, involving things like multiple engine failures and the like, which involve coming down in water... every one of them ends with "EJECT". (If this confuses anyone, note that Columbia had ejection seats for the first four flights.) -- US space station: 8 years | Henry Spencer at U of Toronto Zoology and still no hardware built. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Fri, 23 Mar 90 16:16 GMT From: "P D JONES, CRU" Subject: RE: SPACE Digest V11 #93 Please do not send any more messages to this account. Its previous owner, Mike Salmon, no longer works here. Thank you. ------------------------------ Date: 23 Mar 90 10:16:19 GMT From: ogicse!blake!wiml@ucsd.edu (William Lewis) Subject: Re: Solar System Questions from a Novice In article <221@puma.ge.com> jnixon@andrew.ATL.GE.COM (John F Nixon) writes: >neufeld@physics.utoronto.ca (Christopher Neufeld) writes: >>3) A given planet revolves around one star then the other in a figure eight >>pattern, while the suns revolve around each other. I believe this situation >>is unstable. > >No, there are stable orbits around binary stars! I wish I could remember the >reference, if you are interested I'll try and find it. Since a lot of stars >are members of binary systems, this can really increase the number of planetary >systems which might exist 8-). I can think of at least one stable orbit around binary stars of approximately equal mass and large separation ... I suppose it could be viewed as a degenerate case of either case 1 or 2, above. The two stars are separated by about 1 AU, and the planet orbits in the point which could be called the L4 or L5 point, equidistant from the suns. More general is the configuration I *think* is called a "Kemplerer rosette", in which all the stars/planets/what-have-you rotate at equal distances from a common center of mass, spaced equally around the edge of a circle ... symmetry shows that it's at least sort of stable, although I don't know how stable it would be against perturbations. Other situations spring to mind, but again they're (a) sort of unlikely, as they're not planar; and (b) I have no idea at all how they would respond to perturbations ... such as, two stars, rotating about a fixed point, while the planet "bobs" up and down perpendicular to the plane of rotation, passing through the center of mass on each orbit. It might be possible to cancel out perturbations with some sort or resonance between the orbits of the stars and the planet, but it's probably not worth the trouble. I think the planet's orbit would tend to widen out into an ellipse ... if things matched up, the planet could miss the stars on every orbit, but again I don't know about perturbations (or even of any situation which could give rise to such a bizarre configuration...) Don't quote me on any of this, as the last contact I had with taught orbital mechanics was an introductory physics course some time ago ... -- JESUS SAVES | wiml@blake.acs.washington.edu Seattle, Washington but Clones 'R' Us makes backups! | 47 41' 15" N 122 42' 58" W ------------------------------ End of SPACE Digest V11 #181 *******************