STEREO Weekly Meeting Minutes for 2016-10-11 (Week 41) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned back to a monthly schedule. See below for details. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 40 (Oct 3-9) * On day 277 (Oct 3), during the DSS-15 support for Ahead, turbo decoder lock was lost intermittently at 1639z. This anomaly resulted in the loss of 237 frames of real-time telemetry data. See DR# N110396 for more information. * On day 279 (Oct 5), during the DSS-43 support for Ahead, turbo decoder lock was lost intermittently beginning at 2233z through 2234z. This anomaly resulted in the loss of 10 frames of SSR data. * On day 280 (Oct 6), during the DSS-34 support for Ahead, turbo decoder lock was lost intermittently between 2304z and 2339z. This anomaly resulted in the loss of 4 frames or SSR data. * On day 281 (Oct 7), during the DSS-15 support for Ahead, the transmitter tripped off-line at 2013z, just before EOT. While SECCHI was able to get the instrument back in operational mode following the earlier reset, several SCMs and a few MOps recovery commands where not transmitted as planned. The remaining recovery SCMs and MOps commands were successfully sent on the following track. See DR# G117534 for more information. * On day 281 (Oct 7), the SECCHI instrument reset at 07:37:02z. The SECCHI team reconfigured the instrument to operational mode by 1852z. This was the 41st reset of SECCHI on the Ahead observatory. * The average daily science data return for Ahead was 4.3 Gbits during this week. * Behind Observatory Status: From the last telemetry received on September 18th, low main bus voltage, 2 (#6 & 9) out of 11 battery cells are currently not functioning, attitude uncontrolled, rotating at a ~45 second period about its principal axis of inertia. Current orientation may support some solar array input. While propellant is suspected to be frozen, both propulsion tank latch valves are open and pressure transducer #2 is not functioning. EA mode is enabled. The battery charge rate is C/10. Necessary macro sequences have been tested to allow the peak power tracker in C&DH standby mode to protect the battery. These macro sequences will be loaded to EEPROM when the communications supports longer commands. * On day 277 (Oct 3), during the two hour support for Behind with DSS-63, no carrier was detected by the DSN. 200 commands were sent for battery state of charge recovery. This consisted of repeatedly sweeping a 3 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off, TWTA to standby, primary and secondary tank and -y panel (R4) heaters on. * On day 278 (Oct 4), during the two hour support for Behind with DSS-14, no carrier was detected by the DSN. 185 commands were sent for battery state of charge recovery. This consisted of repeatedly sweeping a 3 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. At 1530z, the transmitter lost modulation resulting in the aborting of 14 commands. The uplink was restored and command modulation was re-enabled. See DR# G117527 for more information. * On day 280 (Oct 6), during the two hour support for Behind with DSS-14, at 1350z, initial commanding was delayed 19 minutes due to sub reflector issue at the station. 155 commands were sent for carrier recovery. No carrier was detected by the DSN after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations which consisted of repeatedly sweeping a 3 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. See DR# G117532 for more information. * On day 281 (Oct 7), during a 4.5 hour support for Behind with the 34m station DSS-26 using the 80 KW transmitter to minimize 70m contentions, only 345 out of the expected 800 commands were transmitted during the support. A misconfiguration at the station prevented all commands within a block to be transmitted. Since each command block sends the same commands multiple times, the impact was minimal, other than not being able to maximize the amount of commands sent during the track. No carrier was detected by the DSN after attempting to power on the TWTA for 30 minutes; however, no detection is expected with the 34 meter stations. Transitioned to battery recovery operations which consisted of repeatedly sweeping a 3 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * On day 282 (Oct 8), during a 4.5 hour support for Behind with the 34m station DSS-26 using the 80 KW transmitter to minimize 70m contentions, 480 commands were transmitted during the support. No carrier was detected by the DSN after attempting to power on the TWTA for 30 minutes; however, no detection is expected with the 34 meter stations. Transitioned to battery recovery operations which consisted of repeatedly sweeping a 3 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * On day 283 (Oct 9), during a 5 hour support for Behind with DSS-14, 540 commands were transmitted during the support. No carrier was detected by the DSN after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations which consisted of repeatedly sweeping a 3 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. Week 41 (Oct 10-16) * The 92nd momentum dump on Ahead was carried out successfully last night (Oct 10), with ignition at 23:45 UT. This was the 11th dump without using the gyros. An estimated delta-V of 0.096 m/s was imparted. * Turbo decoder lock was lost briefly yesterday (Oct 10) at 15:38 UT during the station 25 pass for Ahead. This resulted in the loss of one frame of data. * Turbo decoder lock was lost briefly this morning (Oct 11) during the station 25 pass for Ahead. This resulted in the loss of five frames of data. * Ahead has 11 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 13.5 degrees. There are no passes scheduled for Behind during the week, as recovery attempts for Behind are back to a monthly schedule. Week 42 (Oct 17-23) * Ahead has 12 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, six at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 13.5 degrees. There are no passes scheduled for Behind during the week, as recovery attempts for Behind are back to a monthly schedule. Week 43 (Oct 24-30) * Oct 25 (Tuesday) the 10th STEREO Launch Date Anniversary. * Ahead has 13 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, four at 240 kbps, and five at 160 kbps. * Behind starts the week at an SPE angle of 13.6 degrees. There are no passes scheduled for Behind during the week, as recovery attempts for Behind are back to a monthly schedule. Week 44 (Oct 31-Nov 6) * Daily savings time in the United States ends on Sunday, Nov 6. * Ahead has 13 passes during the week, and overall coverage is nominal. An additional 70 meter track using station 43 for 2.4 hours was added on Monday, Oct 31. There are now two tracks at 720 kbps, six at 240 kbps, and five at 160 kbps. * Behind starts the week at an SPE angle of 13.6 degrees. There are no passes scheduled for Behind during the week, as recovery attempts for Behind are back to a monthly schedule. Week 45 (Nov 7-13) * The 12th and 13th uplink arrays for Behind are scheduled for Friday, Nov 11, and Sunday, Nov 13. The first 1.9 hours of each pass will use the Ahead spacecraft for calibration. The downlink rate will be 160 kbps. There will be no SSR playback or instrument commanding during these calibration passes. Station 26 will be below the 27.5 degree limit for the entire duration of the Ahead tracks; a waiver has been requested to transmit at 80 kW. * Following the Ahead tracks, there will be a 2.4 hour track for battery recovery on Behind on Friday, Nov 11, and a 3.2 hour track for carrier recovery on Sunday, Nov 13, with station 14 for 2.2 hours using the radio science receiver. Waivers have been requested for dropping below the 27.5 degree limit for 80 kW for 0.8 hours on Friday, and 1.5 hours on Sunday. * Mission operations is considering whether to change the uplink arrays to single-station 70 meter passes, considering the recent experience communicating with Behind. * Ahead has 9 tracks during the week, and overall coverage is nominal. There are four tracks at 720 kbps, three at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 13.8 degrees. There are no passes for Behind beyond the uplink array passes discussed above. Week 46 (Nov 14-20) * The 93rd momentum dump for Ahead is scheduled for Wednesday, Nov 16, with ignition at 14:30 UT. This will be the 12 dump without the gyros. * Ahead has 11 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, one at 240 kbps, and seven at 160 kbps. * Behind starts the week at an SPE angle of 13.9 degrees. There are no passes scheduled for Behind during the week, as recovery attempts for Behind are back to a monthly schedule. Week 47 (Nov 21-27) * Thursday, Nov 24, is Thanksgiving. Both Thursday and Friday are holidays at APL. * Ahead has 10 passes during the week. The schedule is currently short about 6 hours between Monday and Wednesday, Nov 21-23. However, support has been requested from ESA to fill in the missing time. There are currently four tracks scheduled at 720 kbps, three at 240 kbps, and three at 160 kbps. * Behind starts the week out at an SPE angle of 14.1 degrees. There are currently no passes scheduled for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 41: M Oct 10 (284) Ahead: Momentum dump, 23:45 UT T Oct 11 (285) W Oct 12 (286) T Oct 13 (287) F Oct 14 (288) S Oct 15 (289) S Oct 16 (290) ------------------------------------------------------------------------------- Scheduled activities for Week 42: M Oct 17 (291) T Oct 18 (292) W Oct 19 (293) T Oct 20 (294) F Oct 21 (295) S Oct 22 (296) S Oct 23 (297) ------------------------------------------------------------------------------- Scheduled activities for Week 43: M Oct 24 (298) T Oct 25 (299) W Oct 26 (300) T Oct 27 (301) F Oct 28 (302) S Oct 29 (303) S Oct 30 (304) ------------------------------------------------------------------------------- Scheduled activities for Week 44: M Oct 31 (305) T Nov 01 (306) W Nov 02 (307) T Nov 03 (308) F Nov 04 (309) S Nov 05 (310) S Nov 06 (311) Daily savings time ends in U.S. ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 07 (312) T Nov 08 (313) W Nov 09 (314) T Nov 10 (315) F Nov 11 (316) Behind: Uplink array pass for battery recovery S Nov 12 (317) S Nov 13 (318) Behind: Uplink array pass for carrier recovery ------------------------------------------------------------------------------- Scheduled activities for Week 46: M Nov 14 (319) T Nov 15 (320) W Nov 16 (321) Ahead: Momentum dump, 14:30 UT T Nov 17 (322) F Nov 18 (323) S Nov 19 (324) S Nov 20 (325) ------------------------------------------------------------------------------- Scheduled activities for Week 47: M Nov 21 (326) T Nov 22 (327) W Nov 23 (328) T Nov 24 (329) Thanksgiving F Nov 25 (330) S Nov 26 (331) S Nov 27 (332) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * Dec Behind: Resume LGA downlink capability on 70 m DSN 2017: 2018: * Mar 5 Ahead: Mercury transit 2019: * Mar Ahead: Switch downlink rate to 240 kbps for 34 meter * Apr Behind: Switch downlink rate to 240 kbps for 34 meter 2020: * May Behind: Switch downlink rate to 360 kbps for 34 meter * Jun Ahead: Switch downlink rate to 360 kbps for 34 meter * Jun Behind: Switch downlink rate to 480 kbps for 34 meter * Sep Ahead: Switch downlink rate to 480 kbps for 34 meter 2021: * Jul Behind: Switch downlink rate to 720 kbps for 34 meter * Aug Ahead: Switch downlink rate to 720 kbps for 34 meter