STEREO Weekly Meeting Minutes for 2013-07-23 (Week 30) ANNOUNCEMENTS ------------- * The STEREO Behind transponder reset on Jul 18, causing space weather data to be unavailable for two days. See below for details. * Work will be done on the DMZ computers between 16-19 UT on Monday, Jul 29. This will require several reboots, and instrument teams can expect to need to reconnect. * See below for a discussion about the plans for reduced IMU operations. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 29 (Jul 15-21) * On day 198 (Jul 17), data file transfers failed from the DSN and to the SSC via the MOC SSH software. This failure was due to a new version of SSH that was deployed late Tuesday evening to comply with new security requirements. While this new version of SSH was deployed successfully to other APL missions, the STEREO implementation was unique. The old version of SSH was reinstalled on day 199 at 1430z and the SSC data transfers began working again. The DSN data files were retrieved manually by MOPS and the science data processing, level zero and other data products were made available later on day 199. Another attempt to deploy a new version of SSH will be made soon. * On day 200 (Jul 19), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently beginning at 201-0114z through 2010235z. This anomaly resulted in the loss of seven frames of SSR data. * On day 197 (Jul 16), during the DSS-34 support for Behind, the ranging data was degraded beginning at 0411z through 0740z due to weather. See DR #C109448 for more information. * On day 198 (Jul 17), during the DSS-14 support for Behind, the receiver unexpectedly went out of lock beginning at 1921z through 1925z due to antenna pointing errors. This anomaly resulted in the loss of 17841 frames of SSR data. See DR #G114086 for more information. * On day 199 (Jul 18), during the DSS-34 support for Behind, the station was unable to lock telemetry and ranging for the entire support (199:23:20z-200:03:30z) due to heavy rain over the Canberra complex. The bad weather delayed the detection of the spacecraft transponder reset anomaly, listed below. See DR #C109456 for more information. * On day 200 (Jul 19), during the DSS-54 support for Behind, the station was unable to lock telemetry until 1813z (1 hr. & 43 min. late) due to the Fault protection (Autonomy Rule #36) detection of the transponder reset and reconfiguring the transponder to emergency uplink and downlink data rates (11.71 bps) on the high gain antenna (HGA). The spacecraft was configured back to the nominal downlink data rate (120 Kbps) at 1857z and MOPS began the anomaly recovery procedure. * On day 199 (Jul 18), the Behind observatory autonomy rule #36 (Transponder Reset Detection) fired at 04:27:49z. Fault protection reconfigured the transponder to emergency downlink data rate (11.71 bps) on the high gain antenna (HGA). The observatory remained in operational mode, with all instruments collecting data. Unfortunately, the day 199 scheduled track at 2325z with DSS-34 was canceled due to heavy rain, which delayed the discovery of the anomaly until the next scheduled support at 200-1630z with DSS-54. The anomaly recovery was completed during the DSS-24 support at 201-0200z. Due to the lost track and anomaly recovery, approximately twelve hours of science data was lost for the PLASTIC and SWAVES instruments. The cause of the anomaly is currently under investigation by the engineer team. * Investigation of the transponder anomaly is hampered by the lose of some housekeeping telemetry. However, as far as the engineering team can tell, this appears to be a single event upset. Link margins were nominal after recovery, and there were no indications of problems. The engineering team is contacting the vendor to see if they can shed any light on the incident. The MOC wishes to express their appreciation to the DSN team at Madrid for their help during the recovery. * On day 200 (Jul 19), the SSR science partitions on Behind filled as follows: SWAVES (Part 13) reached 100% full at 1909z for 4.9 hours. PLASTIC(Part 17) reached 95% full at 2102z for 3.0 hours. The cause was the transponder reset anomaly and recovery on DOY 199-201. * On day 201 (Jul 20), the SSR science partitions on Behind filled as follows: SWAVES (Part 13) remained 100% full at 0000z for 2.4 hours. SWAVES (Part 13) reached 100% full at 0752z for 6.6 hours. PLASTIC(Part 17) remained 95% full at 0000z for 0.9 hours. PLASTIC(Part 17) reached 95% full at 0708z for 7.5 hours. The cause was the transponder reset anomaly and recovery on DOY 199-201. * The average daily SSR playback volume during the week was 4.4 gigabits for Ahead, and 3.0 gigabits for Behind. Week 30 (Jul 22-28) * A Project Interface Test will be carried out on station 26 with Behind on Wednesday, Jul 24, to test uplink software. There will be no SSR playback or instrument commanding during this test. * Ahead has 10 tracks during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Jul 23 (D14), Wednesday, Jul 24 (D43), Thursday, Jul 25 (D14), and Saturday, Jul 27 (D14 at 720 kbps). The station 26 pass on Sunday, Jul 28, will be carried out at 240 kbps. * Behind has 14 passes during the week, and overall coverage is nominal. A 70 meter pass is scheduled for Thursday, Jul 25 (D43 at 720 kbps). The station 26 pass on Saturday, Jul 27, will be carried out at 240 kbps. The following passes will be carried out at 160 kbps: Monday, Jul 22 (D26), Friday, Jul 26 (D26 twice), and Sunday, Jul 28 (D54). Week 31 (Jul 29-Aug 4) * DMZ work will be performed on Monday, Jul 29. See announcement above for details. * Autonomy release 1.1.16 will be loaded to EEPROM on Ahead on Tuesday, Jul 30, and on Behind on Wednesday, Jul 31. * An engineering demo using attenuators with the STEREO beacon broadcast on Ahead is scheduled for Thursday, Aug 1 (D34). * Ahead has 9 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Jul 29 (D14), Tuesday, Jul 30 (D14), Thursday, Aug 1 (D14), and Friday, Aug 2 (D14, D43). The following passes will be carried out at 160 kbps: Wednesday, Jul 31 (D54), and Saturday, Aug 3 (D25). * Behind has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Jul 30 (D14 at 720 kbps), and Wednesday, Jul 31 (D14). The following passes will be carried out at 160 kbps: Tuesday, Jul 30 (D55), and Sunday, Aug 4 (D55). Week 32 (Aug 5-11) * A return-to-service track for station 63 with the Behind spacecraft is scheduled for Tuesday, Aug 6. This track will be shadowing the station 55 track. * The 59th momentum dump on Ahead will be carried out at 16:30 UT on Wednesday, Aug 7. * The 54th momentum dump on Behind will be carried out at 17:00 UT on Wednesday, Aug 7. * Ahead has 10 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Aug 6 (D14), Wednesday, Aug 7 (D14), and Sunday, Aug 11 (D63). The following passes will be carried out at 160 kbps: Thursday, Aug 8 (D54) and Saturday, Aug 10 (D45). * Behind has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Thursday, Aug 8 (D14), and Sunday, Aug 11 (D63 at 720 kbps). The station 26 pass on Wednesday, Aug 7, will be carried out at 160 kbps. Week 33 (Aug 12-18) * An engineering demo using attenuators with the STEREO beacon broadcast on Behind is scheduled for Tuesday, Aug 13 (D45). * The station 25 pass for Behind on Tuesday, Aug 13, will be downlink only. * Ahead has 11 passes during the week, and overall coverage is nominal. A 70 meter pass is scheduled for Friday, Aug 16 (D14). The following passes will be carried out at 160 kbps: Tuesday, Aug 13 (D65), Saturday, Aug 17 (D65, D15), and Sunday, Aug 18 (D54). ESA New Norcia passes are scheduled for Monday and Tuesday, Aug 12, 13. * Behind has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Aug 12 (D43), Thursday, Aug 15 (D63 at 720 kbps), and Friday, Aug 16 (D14). The following passes will be carried out at 160 kbps: Monday, Aug 12 (D26), Tuesday, Aug 13 (D24), Saturday, Aug 17 (D25), and Sunday, Aug 18 (D65). Week 34 (Aug 19-25) * Ahead has 9 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Aug 20 (D14), and Thursday, Aug 22 (D43). The following passes will be carried out at 160 kbps, all using station 54: Monday, Aug 19, Saturday, Aug 24, and Sunday, Aug 25. * Behind has 10 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Aug 19 (D43), Wednesday, Aug 21 (D63), and Thursday, Aug 22 (D14). The following passes will be carried out at 160 kbps: Tuesday, Aug 20 (D65), and Saturday, Aug 24 (D25). Week 35 (Aug 26-Sep 1) * Ahead has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Aug 27 (D43), Friday, Aug 30 (D63), and Sunday, Sep 1 (D63). The following passes will be carried out at 160 kbps: Tuesday, Aug 27 (D54), Wednesday, Aug 28 (D55), and Thursday, Aug 29 (D54). * Behind has 8 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Aug 26 (D63), Wednesday, Aug 28 (D63), Thursday, Aug 29 (D63), and Friday, Aug 30 (D14 at 720 kbps). The station 24 pass on Sunday, Sep 1, will be carried out at 160 kbps. Other * A SECCHI proposal for additional telemetry has been circulated among the instrument teams. There's now a second draft. The consensus was that this should be passed on to the MOC. * A separate proposal concerning rolls will be discussed at the next telecon. * There was a discussion about the Reduced IMU Conops. There was a hiccup on the Ahead gyro a few weeks ago. The primary IMU on Ahead was lost soon after launch. Now the secondary IMU is giving signs of nearing the end of its lifetime. A plan is being put together to turn off the IMU for routine science observations to preserve the IMU lifetime. Part of this plan involves making necessary changes in the autonomy rules. Only minimal use is made of the IMU during normal science operations. Sun pointing information is based on the SECCHI Guide Telescope, which is much more accurate. The IMU is only used for roll information, which is also given by the star tracker. Under this new plan, the IMU would be turned on for special operations, such as rolls. The IMU would also be autonomously turned on if there were any problems with the star tracker. The goal is to make this change transparent to the instrument teams, and deliver the same level of pointing performance, which is currently exceeding the requirements. There will be a Go/No-go meeting at APL, probably sometime in the week of Aug 12. The instrument teams will be able to dial into this meeting. The focus of the meeting will be on the testing. If the go-ahead is given, then the change will probably be rolled out to the spacecraft early in the following week, e.g. Aug 19. * A question was raised about how often do star tracker hiccups occur. The answer was that 3-4 hiccups have been seen so far on both STEREO spacecraft together. More hiccups have been seen on MESSENGER. * The question was also raised whether this change would put any additional constraints on roll maneuvers. The plan is to turn the IMU on well before any planned roll events. * The engineering team estimates that the current IMUs have many months of useful operation left to them. Turning them off preserves their lifetime, and they are much more likely to start when turned back on than mechanical gyros. There's an open question as to whether the IMUs will need to be turned on during the conjunction period. If so, this would use a few months of their remaining lifetime. * A question was raised about the STEREO status in the Senior Review. STEREO was rated quite highly, and is good to go for the next two years at least, though ultimate funding is still up to Congress. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 30: M Jul 22 (203) T Jul 23 (204) W Jul 24 (205) Behind: PIT test with station 26 T Jul 25 (206) F Jul 26 (207) S Jul 27 (208) S Jul 28 (209) ------------------------------------------------------------------------------- Scheduled activities for Week 31: M Jul 29 (210) T Jul 30 (211) W Jul 31 (212) T Aug 01 (213) Ahead: Engineering demo with station 34 F Aug 02 (214) S Aug 03 (215) S Aug 04 (216) Notes: * DMZ maintenance, Jul 29, 16-19 UT ------------------------------------------------------------------------------- Scheduled activities for Week 32: M Aug 05 (217) T Aug 06 (218) Behind: Return-to-service track for D63 shadowing D55 W Aug 07 (219) Momentum dump, Ahead: 16:30 UT, Behind: 17:00 UT T Aug 08 (220) F Aug 09 (221) S Aug 10 (222) S Aug 11 (223) ------------------------------------------------------------------------------- Scheduled activities for Week 33: M Aug 12 (224) T Aug 13 (225) Behind: Engineering demo with station 45 W Aug 14 (226) T Aug 15 (227) F Aug 16 (228) S Aug 17 (229) S Aug 18 (230) Notes: * Significant telemetry shortage for the Ahead spacecraft expected during the week. ------------------------------------------------------------------------------- Scheduled activities for Week 34: M Aug 19 (231) T Aug 20 (232) W Aug 21 (233) T Aug 22 (234) F Aug 23 (235) S Aug 24 (236) S Aug 25 (237) ------------------------------------------------------------------------------- Scheduled activities for Week 35: M Aug 26 (238) T Aug 27 (239) W Aug 28 (240) T Aug 29 (241) F Aug 30 (242) S Aug 31 (243) S Sep 01 (244) ------------------------------------------------------------------------------- Upcoming events: 2013: * Nov 28 Both: Perihelion passage of Comet ISON http://stereo-ssc.nascom.nasa.gov/comet_ison/ * Dec 12 Ahead: Mercury transit 2014: * Jan 20 Behind: End use of 480 kbps on 70 m DSN subnet * Apr 21 Behind: Resume use of 480 kbps on 70 m DSN subnet * Apr 29 Behind: Mercury transit * Sep 07-Nov 15 Behind: Passage of Comet Siding Spring through HI2-B * Oct 15 Behind: End use of 480 kbps on 70 m DSN subnet * Oct 17 Behind: Comet Siding Spring encounter with Mars 2015: * Feb DAWN - Ceres arrival * Jan 20 - Mar 28 (TBC) Behind: Spacecraft behind Sun * Mar 17 - Jul 14 (TBC) Ahead: Spacecraft behind Sun * Jul 2 Behind: Resume use of 480 kbps on 70 m DSN subnet * Aug 25 - Oct 19 (TBC) Behind: Spacecraft behind Sun * Sep 25 Behind: End use of 480 kbps on 70 m DSN subnet * Jul DAWN - End of nominal mission 2016: * Apr 3 Behind: Resume use of 480 kbps on 70 m DSN subnet * Jul Juno arrival at Jupiter 2017: * Jul 11 Ahead: Switch downlink rate to 160 kbps * Jul 22 Behind: Switch downlink rate to 160 kbps 2018: * Mar 5 Ahead: Mercury transit