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 ; Fri, 27 Jul 1990 02:39:28 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Fri, 27 Jul 1990 02:38:51 -0400 (EDT) Subject: SPACE Digest V12 #137 SPACE Digest Volume 12 : Issue 137 Today's Topics: Galileo Update - 07/26/90 NASA Headline News for 07/26/90 (Forwarded) Re: Balloons, anyone? Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 26 Jul 90 23:15:55 GMT From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Galileo Update - 07/26/90 GALILEO MISSION STATUS REPORT July 26, 1990 As of noon (PDT) Thursday, July 26, 1990, the Galileo spacecraft is 81,154,850 miles from the Earth and traveling at a heliocentric velocity of 50,620 miles per hour. The spacecraft is spinning at 3.15 rpm with a sun point angle of 4.7 degrees. Round trip light time is 14 minutes, 36 seconds. Commands were sent on July 20 to disable the Plasma Wave (PWS) magnetic field sensor/electronics heater control algorithm and to power off the 3-watt thermal control heater. These actions were taken to eliminate concerns for solder joint degradation due to higher than expected heater on/off cycling observed over the past two weeks. A comparison of actual flight temperature data with predicted temperatures indicated that the heater can be safely powered off with no risk to the PWS. A plan is being developed to determine how soon after High Gain Antenna (HGA) deployment it will be safe to repower the heater. Attitude and Articulation Control Subsystem (AACS) acquisition sensor threshold parameters were changed on July 20 as a result of calibration data collected in June. The updated threshold levels are consistent with expected signal amplitude levels for this mission phase. The maneuver Profile Activity (PA) which previously had not properly set the thruster temperature monitor bit has been fixed and could cause a maneuver abort if the algorithm remained enabled. The Retropropulsion Module (RPM) thruster temperature algorithm was therefore disabled on July 23. This action was taken to assure that a faulty transducer interface would not abort a burn activity and cause safing of the spacecraft (Z1A, P1A, and L2B transducer interfaces have already failed). Late on July 19 and then again early on July 23, a recurrence of the despun Command Data Subsystem (CDS) Critical Controller (CRC) Power on Reset (POR) A telemetry indication was noticed in CDS telemetry. The signature was the same as that observed in the previous two occurrences in late February and late April of this year. Recovery actions to reset the indications were taken on July 20 and July 23, respectively. Actions were the same as for the previous two CRC POR telemetry indications. After the command recovery actions, NO-OP commands were sent to properly reset the Command Loss Timer. There is no concern for the health of the Spacecraft as a result of these POR telemetry indications. The cause for the CRC A POR telemetry indication is presently unknown, however several possibilities have been identified. One promising explanation involves electrical noise coupling from 2.4khz power interfaces to the despun CDS CRC POR A interface. These interfaces are all routed through the Spin Bearing Assembly (SBA) and are adjacently located. For noise coupling to occur, both brushes in the CDS POR interface must momentarily (about 50 microseconds) present a high resistance (greater than 10 kohm) in the interface and an AC bus imbalance condition must exist. The Orbiter AC bus imbalance telemetry has indicated the existence of AC bus imbalance since December 1989. Ground test data on a flight-like slip ring assembly has shown that high resistance can exist for greater than 1 msec even after 1.3 million SBA revolutions. The number of inflight SBA revolutions to date in the mission is about 1.1 million. If the noise coupling model is valid and the flight slip rings perform similar to the ground test assembly, it is reasonable to expect several more CDS CRC A POR telemetry indications. Investigative actions into the other possible causes are in process. The AC/DC bus imbalance measurements remained relatively stable with only slight variations observed. All other power-related and subsystem telemetry measurements were as expected. The AACS Flight Software must be changed to allow for the pulse mode spin up to 10 rpm required for Probe Release and for Jupiter Orbit Insertion which is to occur in December 1995. These changes will not be uplinked to the spacecraft until much later in the mission. To accommodate the required changes, the existing AACS software must be scrubbed. Prior to launch, the project had developed a set of possible scrubbs which will, if implemented, free up adequate memory. The AACS Flight Software team has examined each of the scrubb candidates in detail and has presented its recommendation to the project in a series of meetings over the past several weeks. Total unused memory after the implementation of the approved scrubbs is expected to be 772 words. No existing functional capability has sacrificed as a part of this scrubbing effort. Two additional scrubbs which could yield an additional 190 words of memory have been deferred. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 26 Jul 90 19:18:47 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: NASA Headline News for 07/26/90 (Forwarded) ----------------------------------------------------------------- Thursday, July 26, 1990 Audio Service: 202/755-1788 ----------------------------------------------------------------- This is NASA Headline News for Thursday, July 26........ The first commercial Atlas rocket was successfully launched at approximately 3:21 P.M. EDT yesterday from Cape Canaveral, Fla. carrying the Combined Release and Radiation Effects Satellite (CRRES). Separation of the CRRES spacecraft from the Centaur upper stage occurred at 28 minutes after liftoff. From a geoshycnronous transfer orbit, the spacecraft will study the interaction of the ionosphere and magnetosphere, as well as the effects of space radiation on microelectronic components. NASA Deputy Administrator James R. Thompson said yesterday's launch of the CRRES aboard a General Dynamics Atlas-1 was an "important step forward in the 'new way' in which NASA is doing business with the private sector for expendable launch vehicle services." ******** Following yesterday's tanking test on the Atlantis, Associate Administrator for Space Flight Dr. William Lenoir held a Space Shuttle Status Media Briefing. He said that the orbiter would be rolled back from the launch pad. Due to the liquid hydrogen leak that may be in the 17-inch disconnect flange, the orbiter will be demated in order to further examine the area. ******** The launch of the Space Shuttle Columbia/Astro-1 mission is now scheduled for early September. It will be followed by the launch of the Space Shuttle Discovery/Ulysses mission in mid-October. ******** Aerospace Daily reports two Soviet cosmonauts are scheduled to repair an airlock hatch in a space walk this afternoon. They will also retrieve a ladder that they used to help them fix loose thermal blankets on the Soyuz Spacecraft. ******** --------------------------------------------------------------- Here's the broadcast schedule for Public Affairs events on NASA Select TV. All times are Eastern Daylight. Thursday, July 26..... 11:00 A.M. U.S. and Soviet crew members of the Apollo-Soyuz Space Mission-- 15-year reunion news briefing at the Kennedy Space Center. 12:30 P.M. NASA Update will be transmitted. 2:00 P.M. Magellan Status Press Conference. A summary on the Venus encounter scheduled August 10. 6:00 P.M. NASA Video Productions. Friday, July 27...... 1:00 P.M. Exobiology briefing at Ames Research Center tape replay from Wednesday, July 25. -------------------------------------------------------------- All events and times may change without notice. This report is filed daily, Monday through Friday at 12:00 P.M., EDT. This is a service of the Internal Communications Branch, NASA HQ. Contact: JSTANHOPE or CREDMOND on NASAmail or at 202/453-8425. -------------------------------------------------------------- NASA Select TV: Satcom F2R, Transponder 13, C-Band, 72 Degrees West Longitude, Audio 6.8, Frequency 3960 MHz. JSNEWS7-26 --------------------------------------------------------------- ------------------------------ Date: 26 Jul 90 21:33:58 GMT From: voder!dtg.nsc.com!andrew@ucbvax.Berkeley.EDU (Lord Snooty @ The Giant Poisoned Electric Head ) Subject: Re: Balloons, anyone? ahiggins@pequod.cso.uiuc.edu (Andrew Higgins) writes: > This idea of a "rockoon" has been around for quite a while. i prefer "ballette". sounds better. "ballet" wouldn't work. -- ........................................................................... Andrew Palfreyman Incidentally, in English, the name of the planet andrew@dtg.nsc.com is "Earth". - Henry Spencer ------------------------------ End of SPACE Digest V12 #137 *******************