STEREO Weekly Meeting Minutes for 2011-06-07 (Week 23) ANNOUNCEMENTS ------------- * A flight software anomaly caused the IMPACT LET instrument to stop sending data on both spacecraft. See below for details. * SECCHI requests rolls of the Behind spacecraft to observe comet Elenin between Aug 1-12. See below for details. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 22 * On day 151 (May 31), during the DSS 54 support for Ahead, turbo decoder lock was lost briefly at 0659z. This resulted in the loss of three frames of instrument SSR data. See DR# N107368 for more information. * On day 153 (Jun 2), during the DSS 14 support for Ahead, initial telemetry acquisition was delayed four minutes due to a receiver and ranging processor anomaly. After processor was reset, telemetry lock was established at 1134z. The SSR playback was stopped and SSR pointers were repositioned. All SSR data were recovered. See DR# G111650 for more information. * On day 156 (Jun 5), during the DSS 54 support for Ahead, real-time telemetry was lost at 0409z. After the DCD software was reinitialized, real-time telemetry was received in the MOC at 0424z. Later in the support, turbo decoder lock was lost intermittently beginning at 0456z. These anomalies resulted in the loss of five frames of instrument SSR data. See DR# N107374 for more information. * On day 150 (May 30), the SECCHI instrument on Ahead reset at 03:41:57z. The SECCHI team reconfigured the instrument to operational mode at 150-1535z. This was the 22nd reset of SECCHI on the Ahead spacecraft. * On day 151 (May 31), during the DSS 25 support for Ahead, the wheel speed avoidance parameter was modified in G&C RAM, on the AHEAD observatory only, to reduce the jitter at the avoidance band at zero speed. * On day 152 (Jun 1), the 38th momentum dump on Ahead was successfully executed at 1430Z, which imparted a delta V of 0.0807 m/sec. * On day 151 (May 31), the IMPACT LET instrument on Behind stopped collecting data at 0020z due to a flight software anomaly. The same thing happened on the IMPACT LET instrument on Ahead on day 155 (Jun 4) between 1500z and 1800z. Diagnostic data were downloaded from both spacecraft and the anomaly is being investigated. A separate telecon to discuss the problem followed the weekly telecon. * On day 152 (Jun 1), during the DSS 15 support for Behind, telemetry frames were lost intermittently beginning at 0209z through 0328z. Later in the track, ranging lock was lost at 0333z through the remainder of the track. Again, later in the support, real-time telemetry was lost at 0404z due to a DCD anomaly. After the DCD failed over to the redundant side, real-time telemetry was received in the MOC at 0428z. These anomalies resulted in the loss of an hour of instrument SSR data and 77 minutes of ranging data. See DR# G111634 and N107374 for more information. * On day 152 (Jun 1), during the DSS 63 support for Behind, initial telemetry acquisition was delayed three minutes as the antenna was late in arriving on point. After the antenna was on point, telemetry lock was established at 1633z. This resulted in the loss of one frame of instrument SSR data. See DR# N107371 for more information. * On day 153 (Jun 2), during the DSS 63 support for Behind, initial telemetry acquisition was delayed 50 minutes due on going antenna maintenance. After the antenna was declared ready for service, telemetry lock was established at 1520z. The SSR playback was stopped and SSR pointers were repositioned. All SSR data were recovered. See DR# M106346 for more information. * On day 154 (Jun 3), during the DSS 63 support for Behind, real-time telemetry was lost at 1926z. After the DCD software was reinitialized, real-time telemetry was received in the MOC at 1941z. This anomaly resulted in the loss of 15 minutes of real-time data. All SSR data was recovered. See DR# N107373 for more information. * On day 155 (Jun 4), during the DSS 63 support for Behind, turbo decoder lock was lost intermittently beginning at 1313z and 1448z. This resulted in the loss of five frames of instrument SSR data. * On day 151 (May 31), the 32nd momentum dump on Behind was successfully executed at 1600z, which imparted a delta V of 0.067 m/sec. * The average daily SSR downlink volume was 5.4 gigabits on Ahead, and 5.8 gigabits on Behind. Week 23 * The IONET switches at APL will be upgraded. The upgrade of the backup switch originally scheduled for Jun 6 has been rescheduled for tomorrow (Jun 8) between 9-12 UT. The primary switch will be upgraded on Jun 8 between 14:40-15:00, after the Ahead pass. * Ahead has 720 kbps passes on Monday, Jun 6 (D14), Wednesday, Jun 8 (D63), Thursday, Jun 9 (D63), Friday, Jun 10 (D14), and Sunday, Jun 12 (D43). There are 12 passes during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Monday, Jun 6 (D63), Tuesday, Jun 7 (D63), Friday, Jun 10 (D63), Saturday, Jun 11 (D63), and Sunday, Jun 12 (D43). There are 14 passes during the week, and overall coverage is nominal. Week 24 * There will be a 2 hour return-to-service track on station 34 for Ahead on Jun 14. There will be no SSR playback during this track. Uplink will be enabled. * There will be test of the 160 kbps downlink during the station 25 pass for Ahead on Wednesday, Jun 15. The prior pass will be a 70 meter station, and a long 70 meter pass follows the test, so no data will be lost. Since the in-situ teams are planning to drop their telemetry rates for 160 kbps, this can be tested during the Jun 15 pass, but this is not required. The telemetry rates will drop to 160 kbps on Jun 27 for Ahead, and Jul 13 for Behind. At the same time that the nominal telemetry rate drops to 160 kbps, the telemetry rate for the 70 meter stations will drop from 720 kbps to 480 kbps. * Ahead has 720 kbps passes on Monday, Jun 13 (D63), Tuesday, Jun 14 (D63 and D14), Wednesday, Jun 15 (D63), and Thursday, Jun 16 (D43). There are 12 passes during the week, and overall coverage is 4.2 hours above nominal. * Behind has 720 kbps passes on Monday, Jun 13, Tuesday, Jun 14, and Wednesday, Jun 15, all using station 63. There are 14 passes during the week, and overall coverage is 1.5 hours above nominal. Week 25 * Macros for the 160 and 120 kbps downlink rates will be uploaded to RAM on both spacecraft on Tuesday, day 172 (Jun 21). * Ahead has a 720 kbps pass on Friday, Jun 24, using station 43. There are 10 tracks during the week, and overall coverage is 2.1 hours above nominal. * Behind has a 720 kbps pass on Sunday, Jun 26, using station 63. There are 14 tracks during the week, and overall coverage is 8 hours above nominal. Week 26 * Ahead switches downlink rate to 160 kbps on 35 meter stations, and 480 kbps on 70 meter stations on day 178 (Jun 27), starting with the station 15 pass. 480 kbps is the lowest rate that Ahead is projected to use with 70 meter stations--Behind will drop to 360 kbps for periods near the far side. * Modified macros for the 240 kbps rate will be uploaded to RAM on both spacecraft on Monday, day 178 (Jun 27). These changes are to bring down more spacecraft data prior to the uplink sweep for each pass. * Ahead has 480 kbps passes on Thursday, Jun 30 (D63), and Sunday, Jul 3 (D43). There are 10 passes during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Monday, Jun 27, Wednesday, Jun 29, Thursday, Jun 30, Friday, Jul 1, and Saturday, Jul 2, all using station 63. There are 12 passes during the week, and overall coverage is nominal. Week 27 * Monday, July 4 is a holiday. * Ahead has 480 kbps passes on Tuesday, Jul 5 (D63 and D14), Wednesday, Jul 6 (D63 and D14), Thursday, Jul 7 (D14), and Friday, Jul 8 (D63). There are 13 passes during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Tuesday, Jul 5 (D63), Friday, Jul 8 (D43), and Sunday, Jul 10 (D63). There are 12 passes during the week, and overall coverage is nominal. Week 28 * Behind will switch to the 160 kbps rate for 35 meter stations, and 480 kbps for 70 meter stations, starting with the station 55 pass on Jul 13. * Both spacecraft will have an HGA calibration on Jul 13, with Ahead starting at 15:00 UT, and Behind starting at 16:00 UT. * Behind will have the 33rd momentum dump on Tuesday, Jul 12, starting at 19:30 UT. * Ahead will have the 39th momentum dump on Thursday, Jul 14, starting at 15:00 UT. * Ahead has 480 kbps passes on Tuesday, Jul 12, and Saturday, Jul 16, both using station 43. There are 10 passes during the week, and overall coverage is 3.6 hours above nominal. * Behind has 720 kbps passes on Tuesday, Jul 12 (D43 and D63), and 480 kbps passes on Thursday, Jul 14 (D43), Friday, Jul 15 (D43 and D63), and Sunday, Jul 17 (D43). There are 15 passes during the week, and overall coverage is 4.1 hours above nominal. Other * The SECCHI team requests to roll the Behind spacecraft by 135 degrees for two hours per day each day between Aug 1 (or late on Sep 31) and Aug 12 to observe comet Elenin as it flies within 0.05 AU of the spacecraft. Observations of the comet at a wide variety of phase angles will provide information about composition. There's also a possibility that the in situ instruments on Behind will see the ion tail. The requested two hours per day will include the roll and settle times, with the roll starting on an even hour boundary, and then back to nominal roll and settled on the next even hour boundary. A more detailed plan will be sent to APL. COORDINATED OBSERVATIONS ------------------------ ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 06 (157) Ahead: 720 kbps downlink on station 14 Behind: 720 kbps downlink on station 63 T Jun 07 (158) Behind: 720 kbps downlink on station 63 W Jun 08 (159) Ahead: 720 kbps downlink on station 63 T Jun 09 (160) Ahead: 720 kbps downlink on station 63 F Jun 10 (161) Ahead: 720 kbps downlink on station 14 Behind: 720 kbps downlink on station 63 S Jun 11 (162) Behind: 720 kbps downlink on station 63 S Jun 12 (163) Ahead: 720 kbps downlink on station 43 Behind: 720 kbps downlink on station 43 ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 13 (164) Ahead: 720 kbps downlink on station 63 Behind: 720 kbps downlink on station 63 T Jun 14 (165) Ahead: 720 kbps downlink on stations 63 and 14 Behind: 720 kbps downlink on station 63 Ahead: Return-to-service track on station 34 W Jun 15 (166) Ahead: 720 kbps downlink on station 63 Ahead: Test of 160 kbps on station 25 Behind: 720 kbps downlink on station 63 T Jun 16 (167) Ahead: 720 kbps downlink on station 43 F Jun 17 (168) S Jun 18 (169) S Jun 19 (170) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 20 (171) T Jun 21 (172) W Jun 22 (173) T Jun 23 (174) F Jun 24 (175) Ahead: 720 kbps downlink on station 43 S Jun 25 (176) S Jun 26 (177) Behind: 720 kbps downlink on station 63 ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 27 (178) Ahead: Switch downlink rate to 160 kbps, 480 kbps for 70 m Behind: 720 kbps downlink on station 63 T Jun 28 (179) W Jun 29 (180) Behind: 720 kbps downlink on station 63 T Jun 30 (181) Ahead: 480 kbps downlink on station 63 Behind: 720 kbps downlink on station 63 F Jul 01 (182) Behind: 720 kbps downlink on station 63 S Jul 02 (183) Behind: 720 kbps downlink on station 63 S Jul 03 (184) Ahead: 480 kbps downlink on station 43 ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 04 (185) Independence day T Jul 05 (186) Ahead: 480 kbps downlink on stations 63 and 14 Behind: 720 kbps downlink on station 63 W Jul 06 (187) Ahead: 480 kbps downlink on stations 63 and 14 T Jul 07 (188) Ahead: 480 kbps downlink on station 14 F Jul 08 (189) Ahead: 480 kbps downlink on station 63 Behind: 720 kbps downlink on station 43 S Jul 09 (190) S Jul 10 (191) Behind: 720 kbps downlink on station 63 ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 11 (192) T Jul 12 (193) Behind: Momentum dump, 19:30 UT Ahead: 480 kbps downlink on station 43 Behind: 720 kbps downlink on stations 43 and 63 W Jul 13 (194) Behind: Switch downlink rate to 160 kbps, 480 kbps for 70 m HGA calibration, Ahead: 15:00 UT, Behind: 16:00 UT T Jul 14 (195) Ahead: Momentum dump, 15:00 UT Behind: 480 kbps downlink on station 43 F Jul 15 (196) Behind: 480 kbps downlink on stations 43 and 63 S Jul 16 (197) Ahead: 480 kbps downlink on station 43 S Jul 17 (198) Behind: 480 kbps downlink on station 43 Notes: * Dawn expected to achieve orbit about Vesta around Jul 16. ------------------------------------------------------------------------------- Upcoming events: 2011: * Jul 31 - Aug 12 Behind: Spacecraft rolls to observe comet Elenin 2012: * Jan 11 Both: HGA calibration * Jul DAWN - Vesta departure * Jul 11 Both: HGA calibration * Nov 4 Behind: Switch downlink rate to 120 kbps * Nov 13 Total solar eclipse, south Pacific 2013: * May 3 Ahead: Switch downlink rate to 120 kbps * 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 * Oct 15 Behind: End use of 480 kbps on 70 m DSN subnet 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 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