STEREO Weekly Meeting Minutes for 2016-05-17 (Week 20) ANNOUNCEMENTS ------------- * None INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * There are currently no communications with the Behind spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 19 (May 9-15) * On day 130 (May 9), during the DSS-45 support for Ahead, telemetry lock was lost intermittently between 0339z and 05585z due to heavy rain at the Canberra complex. This anomaly resulted in the loss of 11,041 frames of real-time and SSR data, which is the equivalent of about 10-15 minutes. See DR# C112055 for more information. * On day 130 (May 9), during the DSS-24 support for Ahead, turbo decoder lock was lost intermittently beginning at 1814z through 2039z. This anomaly resulted in the loss of 19 frames of SSR data. * On day 132 (May 11), during the DSS-65 support for Ahead, turbo decoder lock was lost intermittently between 0934z and 0942z due to heavy rain at the Madrid complex. This anomaly resulted in the total loss of 11,573 frames of real-time and SSR data. As there was sufficient track time, SSR pointers were repositioned on the next support and all SSR data were recovered. See DR# M109356 for more information. * On day 133 (May 12), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently between 2022z and 2024z. This anomaly resulted in the loss of 8 frames of SSR data. * On day 134 (May 13), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently between 0916z and 1058z. This anomaly resulted in the loss of 9 frames of real-time telemetry and SSR data. * The Ahead observatory operated nominally during this week on the center of the HGA main lobe. The HGA feed assembly was at 98 degrees C and decreasing with the HGA angle at 10.8 degrees and increasing, with respect to the spacecraft-Sun line. * On day 130 (May 9), the 34th SECCHI stepped calibration on Ahead was executed at 1200z to recalibrate the COR1 imager. This was the 3rd SECCHI stepped calibration roll to be conducted without gyro use. Note that the G&C control bandwidths that were loaded on day 055 for improving roll error were in effect for each data collection step. * On day 133 (May 12), at 1710z, Fault Protection release 2.3.19 and MOps macro release 1.1.29 were loaded to C&DH RAM on Ahead and verified. These releases contain a new autonomy rule for detecting a loss of battery state of charge quicker and commands for correcting a wheel over speed reset condition. * On day 134 (May 13), the Ahead observatory was used to phase calibrate the 4th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind battery recovery. At 1559z, the transmitter at DSS-26 tripped off-line for 11 minutes due to a coolant temperature issue. See DR# G117166 for more information. An 11.5 dB gain in uplink AGC was observed in the spacecraft transponder data. No SSR playback was conducted as the phasing of transmitters would have caused periodic dropped frames. * On day 135 (May 14), the Ahead observatory was used again to phase calibrate the 5th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind battery recovery. A 12 dB gain in uplink AGC was observed in the spacecraft transponder data. No SSR playback was conducted as the phasing of transmitters would have caused periodic dropped frames. * On day 136 (May 15), the PLASTIC instrument increased their record rate to a nominal 3.3 kbps at 0000z. The actual telemetry rate appears to be close to 3 kbps, and so far everything to seems to be working well. * The SSC pointed out that telemetry return has been generally much better than was originally expected at the nominal 160 kbps rate. This is because of the telemetry boosts that are implemented for passes at high elevation, for passes with station 26, and the increased use of the 70 meter stations. There was some concern earlier in the year about contentions with other missions, and the fact that the 70 meter station 14 was going down for maintenance. However, station 14 is back online again, and this is a good time for the instrument teams to consider whether or not to increase their telemetry usage. * The average daily science data return for Ahead was 5.4 Gbits during this week. * On day 134 (May 13), the 4th uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26. The uplink array was phase calibrated using the Ahead observatory first for 1.9 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of the three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters incorporating the frequency segmented acquisition sequence with the MOC sending commands for battery recovery. Initial commanding was delayed by two minutes due to software issue with the command bind at the station. This anomaly resulted in four commands being aborted. 283 commands covering 36 frequency segments were sent for battery state of charge recovery. * On day 135 (May 14), the 5th uplink array for STEREO Behind recovery was conducted using DSS-24, 25, and 26. The uplink array was phase calibrated using the Ahead observatory first for 1.9 hours then the arrayed stations were switched to point to the Behind observatory. The configuration consisted of with the three 34m stations at the Goldstone complex using the 80 kW and two 20 kW transmitters incorporating the frequency segmented acquisition sequence with the MOC sending commands for transmitter carrier recovery. At 2342z, the DSN command state did not transition operational for the last segment due to a known software issue. See DR# G117169 for more information. 680 commands covering 34 frequency segments were sent. The DSN 70m station, DSS-14, and the Allen Telescope Array observed concurrently. Intermittent carrier locks were reported by both DSS-26 and DSS-14, but at different times. No downlink signal was detected by the Allen Telescope Array. Use of the DSN radio science receiver recording during the monthly carrier recovery uplink array recovery supports for definitive signal verification has been requested. * The next uplink array attempt will be June 11, 12. * As time goes by, the ephemeris error increases, degrading DSN antenna pointing. However, with time the spacecraft range also decreases, improving RF communications and the ability for other assets to acquire data on Behind. Analysis indicates that the total RF gain change is significant and the probability of command success increases with time. Week 20 (May 16-22) * Ahead has 13 tracks during the week, and overall coverage is nominal. There are two tracks at 720 kbps, two at 360 kbps, five at 240 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 14.6 degrees. There are no tracks for Behind during the week. Week 21 (May 23-29) * The MOC will switch over the restricted IONET connect for three hours starting at 12:00 on Thursday, May 26. This should have no effect on operations. * Electrical maintenance will be carried out at the MOC during Memorial Day weekend. During this time, the MOC will be on generator power, starting at 5:00 PM EDT on Friday, May 27, through 8:00 PM EDT on Monday, May 30. Operations will not be affected. * Ahead has 14 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, seven at 240 kbps, and four at 160 kbps. * Behind starts the week at an SPE angle of 14.8 degrees. Recovery efforts for Behind are on Friday-Sunday, May 27-29. The battery recovery tracks will be undertaken with the 80 kW transmitter on station 26. The Allen Telescope Array will also be listening during the transmitter recovery track, along with station 14. Week 22 (May 30-Jun 5) * Monday, May 30, is Memorial Day, which is an APL holiday. * The 88th momentum dump on Ahead will be carried out on Tuesday, May 31, with ignition at 20:00 UT. This will be the seventh momentum dump without using the gyros. * Jun 2, the MOC will be loading new C&DH fault protection rules and macros to EEPROM. These changes are designed to provide better protection in case of the loss of one of the reaction wheels, or low solar array voltage. * Ahead has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, three at 360 kbps, five at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 15.0 degrees. There are no passes for Behind during the week. Week 23 (Jun 6-12) * Ahead has 9 passes during the week, and overall coverage is nominal. There are 4 passes at 720 kbps, one pass at 360 kbps, three passes at 240 kbps, and one pass at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. * Uplink array attempts to recover Behind are scheduled for June 11, 12. Each pass will start out with Ahead for 1.9 hours for phase calibration. There will be no instrument calibration or SSR playback during these calibration passes. Following calibration, the stations will attempt to command Behind for 3.3 hours on June 11 for battery recovery, and for 5.3 hours on June 12 for carrier recovery along with station 14. The last 35 minutes will be below the 27.5 degree elevation limit, so a waiver has been requested. Otherwise, the broadcast power would be reduced from 80 to 60 kW. Week 24 (Jun 13-19) * Ahead has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, four at 360 kbps, five at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. There are no tracks for Behind during the week. Week 25 (Jun 20-26) * Ahead has 10 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, two at 360 kbps, four at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 15.2 degrees. Recovery efforts for Behind are Monday-Wednesday, Jun 20-22. The batter recovery tracks will be undertaken with the 80 kW transmitter on station 26. Week 26 (Jun 27-Jul 3) * The 5th battery discharge operation on Ahead is scheduled for Monday, Jun 27, for about 2 hours starting at 17:00. * Ahead has 12 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, two at 360 kbps, four at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 15.2 degrees. There are no tracks for Behind. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 16 (137) T May 17 (138) W May 18 (139) T May 19 (140) F May 20 (141) S May 21 (142) S May 22 (143) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 23 (144) T May 24 (145) W May 25 (146) T May 26 (147) F May 27 (148) S May 28 (149) S May 29 (150) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 30 (151) Memorial Day T May 31 (152) Ahead: Momentum dump, 20:00 UT W Jun 01 (153) T Jun 02 (154) F Jun 03 (155) S Jun 04 (156) S Jun 05 (157) ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 06 (158) T Jun 07 (159) W Jun 08 (160) T Jun 09 (161) F Jun 10 (162) S Jun 11 (163) Behind: Phased array recovery attempt S Jun 12 (164) Behind: Phased array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 13 (165) T Jun 14 (166) W Jun 15 (167) Ahead: STEREO Subsystem Assessment Review T Jun 16 (168) F Jun 17 (169) S Jun 18 (170) S Jun 19 (171) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 20 (172) T Jun 21 (173) W Jun 22 (174) T Jun 23 (175) F Jun 24 (176) S Jun 25 (177) S Jun 26 (178) ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 27 (179) Ahead: Battery maintenance, 17:00 UT T Jun 28 (180) W Jun 29 (181) T Jun 30 (182) F Jul 01 (183) S Jul 02 (184) S Jul 03 (185) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 2016: * Jul 5 Juno arrival at Jupiter * 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