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, 31 Mar 90 02:12:41 -0500 (EST) Message-ID: Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 31 Mar 90 02:12:16 -0500 (EST) Subject: SPACE Digest V11 #205 SPACE Digest Volume 11 : Issue 205 Today's Topics: Galileo Update - 03/30/90 Galileo Updates Re: "Brilliant Pebbles" vs. "Smart Rocks" (was Re: Railgun ...) Re: SUSI (Was Re: Austrailian Reduced Wobble telescope) Re: Ejection seats Re: Solar Cells ---------------------------------------------------------------------- Date: 31 Mar 90 00:13:58 GMT From: jarthur!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@uunet.uu.net (Ron Baalke) Subject: Galileo Update - 03/30/90 GALILEO MISSION STATUS REPORT March 30, 1990 As of noon Friday (PST) , March 30, 1990, the Galileo spacecraft is 75,701,420 miles from the Earth, 12,872,890 miles from Venus traveling at a heliocentric velocity of 82,650 miles per hour. The spacecraft continues at a steady 3.15 rpm in a cruise mode-dual spin. Round trip light time is 13 minutes, 28 seconds. Three SITURNS to lead the sun were successfully performed on March 26, 28, and 30. Spacecraft performance for these activities was as expected and without incident. The Venus-Earth (VE-2) sequence load went active as planned on March 26. This sequence controls spacecraft activities to April 23 and contains 12 SITURNS, 1 Retropropulsion Module (RPM) flushing event, several cruise science memory readouts (MROs) for the Magnetometer (MAG), Extreme Ultraviolet instrument (EUV), and Dust Detector Subsytem (DDS). During early April, from April 9 through April 12, time windows have been established for the planned TCM-4A (Trajectory Course Maneuver). Commands were sent on March 28 to reconfigure the Command and Data Subsytem (CDS) and Telemetry Modulation Unit (TMU) for 40 bps coded telemetry data transmission. The data rate switch from 10 bps to 40 bps was accomplished without incident and involved commanding the CDS spun critical controllers to route the generated 40 bps data stream to the TMUs. TMU commands were sent to reset the telemetry modulation index value to a level compatible with the 40 bps data rate. Subsequent to the data rate switch, telemetry link performance was as expected and near predicted levels. A massive power failure for about 5 hours occurred at the Signal Processing Center (SPC-40) in Canberra, Australia, on March 28. The power loss resulted in the loss of planned cruise science MRO data reception from MAG, EUV and DDS instruments. Later that same day, a planned SITURN was performed from the VE-2 stored sequence without flight team monitoring since the 70 meter antenna (DSS-43) was still down. Upon resumption of DSS-43 tracking coverage, later that day, telemetry data indicated that the spacecraft executed the SITURN properly and that spacecraft performance was as expected and without incident. Science Team members pointed out that nearly all DDS and MAG science data collected for the last three weeks was still retrievable if a real time MRO could be performed on March 29. To assess the risk of doing a MRO, a careful review of the VE-2 scheduled spacecraft activities was performed; the risk was found to be acceptable and the MROs were successfully completed. When the power failure occurred, the station immediately switched to generator power but was unable to properly configure any links due to damage to the Network Configuration Facility and other interface related problems. It was reported that the power outage was due to a failure in a 22 kv commercial power distribution transformer. During this power failure voice communication with the station was available. The Energetic Particles Detector (EPD) instrument was powered again on March 29, the first time since the Venus flyby, in preparation for planned motor maintenance activities. Prior to instrument turn on, however, Delay Action Commands (DACs) were transmitted on March 28 to reset the EPD input current threshold limit to a level consistent with expected instrument operation in order to preclude science safing system fault protection execution. The AC/DC bus voltage imbalance measurements have fluctuated slightly. The DC measurement has ranged between 20.9 and 21.62 volts; the AC measurement has ranged between 47.8 and 48.7 volts. All other power-related measurements (bus voltages, bus currents and shunt currents) and other subsystem measurements have all been as expected. Impact to both TCM-4A and TCM-4B has been eliminated in the current version of the Deep Space Network (DSN) schedule for elevation bearing rework throughout the DSN network. Although this schedule is contingent on satisfactory bearing conditions at DSS-43 and DSS-63 (70 meter antennas at Australia and Spain, respectively) following their inspections, it will allow work to proceed on the basis of what is known at present and relieves the immediate concern for Galileo. New software for the DSN Telemetry Processor Assembly (TPA) that provides consistent telemetry time tagging between different support configurations went into "soak" on March 29th and is now being used for Galileo support. 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: 30 Mar 90 11:33:34 GMT From: shelby!csli!jkl@decwrl.dec.com (John Kallen) Subject: Galileo Updates Are the Galileo Updates archived? If so, are they accessible by anonymous FTP? I'm interested in tracking the probe given the data provided by Yee and Balke (btw, thank you for keeping us in touch with the status of the probe) _______________________________________________________________________________ | | | | |\ | | /|\ | John K{llen Computer: kom-pyu'-t:r (n) | |\ \|/ \| * |/ | |/| | | PoBox 11215 device to speed and | |\ /|\ |\ * |\ | | | | Stanford CA 94309 automate errors. _|_|___|___|____|_\|___|__|__|_jkl@csli.stanford.edu__________________________ ------------------------------ Date: 29 Mar 90 14:25:28 GMT From: att!tsdiag!davet@ucbvax.Berkeley.EDU (Dave Tiller N2KAU) Subject: Re: "Brilliant Pebbles" vs. "Smart Rocks" (was Re: Railgun ...) In article <244@puma.ge.com> jnixon@andrew.ATL.GE.COM (John F Nixon) writes: -stealth@caen.engin.umich.edu (Mike Pelletier) writes: ->Whence this silly nomenclature "Brilliant Pebbles"? - ->Whatever happened to the succinct, professional sounding "Smart Rocks"? - -Actually, I am proposing "Savant Sand" as an SDI weapon.... -jnixon@atl.ge.com ...steinmetz!atl.decnet!jnxion How about: -Intelligent Igneous -Loquatious Limestone -Precocious Perovskovites -Brainy Boulders -Cerebral Coral Any more? -- David E. Tiller davet@tsdiag.ccur.com | Concurrent Computer Corp. FAX: 201-870-5952 Ph: (201) 870-4119 (w) | 2 Crescent Place, M/S 117 UUCP: ucbvax!rutgers!petsd!tsdiag!davet | Oceanport NJ, 07757 ICBM: 40 16' 52" N 73 59' 00" W | N2KAU @ NN2Z ------------------------------ Date: 23 Mar 90 02:51:48 GMT From: munnari.oz.au!csc!ccadfa!usage!metro!news@uunet.uu.net (Robert Minard) Subject: Re: SUSI (Was Re: Austrailian Reduced Wobble telescope) From article , by K_MACART@UNHH.BITNET: > > Awhile back on the Discovery Channel, I saw a piece on these guys > down under at one of the universities that had crafted an optical telescope > that had the capability to adjust for the wobble of stars due to the air. Sounds like you're talking about us! The Chatterton Astronomy Department of the University of Sydney has built a prototype of one such instrument and is completing a full scale version called SUSI (Sydney University Stellar Interferometer) this year. The instruments are optical interferometers formed by combining the light from two computer-controlled plane mirrors at either end of a "baseline". The mirrors are called "siderostats" because they reflect starlight towards the centre of the baseline, where the two beams are combined in a maze of mirrors, periscopes and beamsplitters. Two of these mirrors are piezoelectrically driven to compensate for the small rapid (~10 ms) wavefront tilts introduced by the atmosphere. The tilts are measured by splitting off some of the light and focusing it onto position detectors each containing four photomultiplier tubes. Another important aspect of the combination process is that the distances travelled by the two beams are adjusted dynamically so that they travel roughly equal distances (to within a few wavelengths) before being combined. When the wavefronts are parallel they are allowed to interfere and the strength of the interference (the "visibility") is measured. This measurement allows us to determine the angular diameter of the star. The prototype first measured visibility on 1 October 1985 and the angular diameter of Sirius was measured during February/March 1986 as 5.63 +/- 0.08 marcsec confirming a result obtained by the Narrabri Intensity Interferometer (that's another story) but requiring substantially less observing time. The result was published in Nature ("New determination of the angular diameter of Sirius", J. Davis and W.J. Tango, Nature 323, pages 234-235). The specifications of the prototype and SUSI are as follows: prototype SUSI baseline: 11.4 m 5 to 640 m wavelengths: 442 nm 400 to 900 nm angular resolution: 8 marcsec .05 to 15 marcsec siderostat diameter: 100 mm 140 mm Note: marcsec = milli arcsec = 5 x 10^-9 rad The angular resolution is a function of the baseline length, and is the same as for a conventional telescope with a diameter equal to the baseline (can you imagine a telescope 640 m in diameter?). The downside is that we don't form images of the star, we only obtain its visibility and because our input aperture is so small we don't have anything like the sensitivity of large telescopes. However no other optical instrument being constructed has such resolution and similar resolution at radio wavelength cannot be achieved by ground-based antennas because the diameter of the earth does not provide a long enough baseline. -- Robert Minard Telephone: +61 2 692 3679 Chatterton Astronomy Department, Facsimile: +61 2 660 2903 School of Physics A28, Telex: AA 26169 UNISYD University of Sydney, NSW 2006, AUSTRALIA. ACSnet: minard@extro.ucc.su.oz.au ------------------------------ Date: 30 Mar 90 22:05:30 GMT From: skipper!bowers@ames.arc.nasa.gov (Al Bowers) Subject: Re: Ejection seats In article <9003292359.AA26727@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: >>Subject: Hermes crew escape system >> For the European Hermes spaceplane it was decided (according to newspaper >> reports) to buy the russian ejection seats developed for Buran. >> The ejection seats will enable the crew to eject during the first 90 seconds >> of the flight, placing them 500 m away from Hermes in 2 seconds. >> Ejection will be possible up to 30 km altitude and a velocity of >> 3000 km/h. >That's a pretty abrupt trip! Are US ejection seats comparable? What's the peak >acceleration? (It would have to be 25g minimum, probably greater.) >I presume the crew are ejected head first, in a sitting position. Higher >accelerations have been employed in a rocket sled, but I don't think the >force was applied in this direction. Your 25g estimate is in the ballpark. Older seats generated up to 40g and had consequent higher injury rates. The Ari Force publishes their ejection seat statistics every year and two years ago the sucessful ejection rate was ~85% or so. Another 10% or so caused some debilitating injury such that the pilot was not flight capable within a month. The remaining were fatalities. These stats were only for seats used within the envelope prescribed for them. There was one freak accident in which an F-16 jock on an FCF (functional check flight) out over water ejected at the edge of the envelope. About 10000 ft msl, 700 knots (just supersonic), the seat was specified for subsonic below 10000 ft. During the ejection the pilot broke both arms and collar bones. Chute deploy worked fine, unfortunately the pilot was unable to inflat his life vest and drowned. -- Albion H. Bowers bowers@elxsi.dfrf.nasa.gov ames!elxsi.dfrf.nasa.gov!bowers NASA Ames-Dryden Flight Research Facility, Edwards, CA Aerodynamics: The ONLY way to fly! Live to ski, ski to live... ------------------------------ Date: 30 Mar 90 02:13:15 GMT From: bfmny0!tneff@uunet.uu.net (Tom Neff) Subject: Re: Solar Cells Since the "31% efficient" GaAs photovoltaics are really two distinct layers of cells with complementary spectrum coverage, I would first check the WEIGHT vis a vis current technology. Understand that this is much more efficient per surface area, but how much weight do we save. -- "UNIX should be used :: Tom Neff or as an adjective." -- AT&T :: ...uunet!bfmny0!tneff (UUCP only) ------------------------------ End of SPACE Digest V11 #205 *******************