STEREO Weekly Meeting Minutes for 2016-07-12 (Week 28) 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 27 (Jul 4-10) * On day 186 (Jul 4), MOps was alerted before the start of the DSS-54 support for Ahead that the transmitter had been declared red. The support remained one-way for the duration and all SSR data were received. This anomaly resulted in the loss of 4.3 hours of commanding and two-way tracking data. See DR# M109456 for more information. * On day 188 (Jul 6), during the DSS-26 support for Ahead, turbo decoder lock was lost intermittently beginning at 2025z through 2045z. As 1447 frames of SSR data were not received, SSR pointers were repositioned and all SSR data were recovered. See DR# G117298 for more information. * On day 189 (Jul 7), during the DSS-25 support for Ahead, turbo decoder lock was lost intermittently between 1609z and 1640z. This anomaly resulted in the loss of 3 frames of SSR data. * On day 191 (Jul 9), during the DSS-45 support for Ahead, turbo decoder lock was lost intermittently beginning shortly after BOT at 2326z through 192-0004z due to the station sub-reflector declared red and fixed at a 30 degree angle. At 192-0005z, Conscan was enabled and the downlink signal level increased by approximately 2 dB and remained nominal for the remainder of the support. This anomaly resulted in the loss of 553 frames of real-time telemetry and SSR data. See DR# N110320 for more information. * The Ahead observatory operated nominally during this week. After over 2 years, the HGA feed assembly has returned to below the 85 deg C operational temperature limit with no adverse effects. In fact, it appears that the HGA is unchanged. * On day 186 (Jul 4), the Ahead observatory was at aphelion in its heliocentric orbit. * On day 188 (Jul 6), the 89th momentum dump was executed successfully at 1600z, which imparted an estimated delta V of 0.106 m/sec. This was the 8th momentum dump that did not use the IMU. After thruster operations completed, there was a 1.1 degree of roll angle error which was dampened out over the next 12 minutes. Fine pointing stabilized 2.1 minutes after completion of the momentum dump. * The average daily science data return for Ahead was 5.5 Gbits during this week. * To minimize the impact on DSN, GSFC has directed to reduce Behind recovery operations to monthly, alternating the nominal single station recovery configuration with the uplink array use. Recovery operations will be suspended in July 2017 and resume in January 2020 when the LGA uplink returns to 125 bps. * There was some discussion about the use of the Radio Science Receiver during the downlink recovery passes for Behind. A payment mechanism is required. A suitable DSN task plan has been identified, and is under review. Week 28 (Jul 11-17) * A MOC interface test with the new station 36 at Canberra is scheduled for tomorrow, Jul 13, for 1 hour starting at 14:00 UT. This will not involve the spacecraft. * Station 35 will conduct an engineering test of pointing to the Ahead spacecraft on Thursday, Jul 14, in support of the upcoming OSIRIS-REx mission. There will be no effect on operations. The spacecraft will remain in spaceweather mode. Several additional tests are scheduled for the upcoming weeks. * Ahead has 10 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, one at 360 kbps, four at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 15.1 degrees. * Uplink array attempts for Behind are scheduled for July 16, 17. The first 1.9 hours each day will use the Ahead spacecraft to calibrate the phasing between the stations. There will be no SSR playback or instrument commanding during these passes. Following the calibration, there will be a 3.3 hour pass for Behind on Jul 16 for battery recovery, and a 5.3 hour pass on Jul 17 for carrier recovery. The elevation will drop below 27.5 degrees for the last 48 minutes, so a waiver has been requested and granted. Station 14 will listen for the Behind carrier, using the Radio Science Receiver, along with the Allen Telescope Array. Week 29 (Jul 18-24) * The 35th SECCHI stepped calibration roll for Ahead is scheduled for Monday, Jul 18, starting at 13:00 UT. System momentum will be about 6 N-m-s. This is the aphelion roll, and the fourth without using the gyros. The roll was delayed until system momentum was compatible with a roll. * Station 35 will conduct the second engineering test of pointing to the Ahead spacecraft on Monday, Jul 18, in support of the upcoming OSIRIS-REx mission. There will be no effect on operations. The spacecraft will remain in spaceweather mode. * The first project interface test with the new station 36 at Canberra is scheduled for 3 hours on Wednesday, Jul 20. The new station is expected to be operational sometime later this year. The downlink rate will be 160 kbps, and there will be no SSR playback or instrument commanding during the pass. * Ahead has 12 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, three at 360 kbps, five at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 15.0 degrees. There are no tracks for Behind during the week. Week 30 (Jul 25-31) * Ahead has 11 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, two at 360 kbps, and seven at 240 kbps. One of the 70 meter passes was converted to a 34 meter pass to help out the Rosetta mission, which is nearing the end of their mission. * Behind starts the week at an SPE angle of 14.9 degrees. There are no tracks for Behind during the week. Week 31 (Aug 1-7) * Ahead has 12 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, two at 360 kbps, seven at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 14.7 degrees. There are no tracks for Behind during the week. Week 32 (Aug 8-14) * The 90th momentum dump on Ahead is scheduled for 19:30 UT on Tuesday, Aug 9. This will be the ninth momentum dump without using the gyros. * Station 34 will conduct the third engineering test of pointing to the Ahead spacecraft on Saturday, Aug 13, in support of the upcoming OSIRIS-REx mission. There will be no effect on operations. The spacecraft will remain in spaceweather mode. * Ahead has 13 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, four at 360 kpbs, six at 240 kbps, and one 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 33 (Aug 15-21) * Ahead has 15 passes during the week, and overall coverage is nominal. There is one pass at 720 kbps, five at 360 kbps, seven at 240 kbps, and two at 160 kbps. * Behind starts the week at an SPE angle of 14.4 deg. * The single station recovery tracks for the monthly recovery operations for Behind will be Aug 19-21 (Friday-Sunday). The 80 kW Station 26 transmitter will be used for the two battery recovery tracks on Friday and Saturday, and Station 14 will be used for the carrier recovery on Sunday. Week 34 (Aug 22-28) * Station 34 will conduct the fourth engineering test of pointing to the Ahead spacecraft on Monday, Aug 22, in support of the upcoming OSIRIS-REx mission. There will be no effect on operations. The spacecraft will remain in spaceweather mode. * Behind will be at perihelion on Aug 25 * Ahead has 14 passes during the week, and overall coverage is nominal. There are two passes at 720 kbps, two at 360 kbps, and ten at 240 kbps. * Behind starts the week at an SPE angle of 14.3 degrees. There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 27 (179) Ahead: Battery maintenance, 17:00 UT T Jun 28 (180) Ahead: Uplink frequency ramping test with ESA/ESOC W Jun 29 (181) T Jun 30 (182) F Jul 01 (183) S Jul 02 (184) S Jul 03 (185) ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 04 (186) Independence Day Ahead: Aphelion T Jul 05 (187) Juno arrival at Jupiter W Jul 06 (188) Ahead: Momentum dump, 16:00 UT T Jul 07 (189) F Jul 08 (190) S Jul 09 (191) S Jul 10 (192) ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 11 (193) T Jul 12 (194) W Jul 13 (195) MOC interface test with station 36, 14:00 UT T Jul 14 (196) Ahead: Station 35 pointing test for OSIRIS-REx F Jul 15 (197) S Jul 16 (198) Behind: Phased array recovery attempt S Jul 17 (199) Behind: Phased array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 29: M Jul 18 (200) Ahead: SECCHI stepped calibration roll, 13:00 UT Ahead: Station 35 pointing test for OSIRIS-REx T Jul 19 (201) W Jul 20 (202) Ahead: Project interface test with station 36 T Jul 21 (203) F Jul 22 (204) S Jul 23 (205) S Jul 24 (206) ------------------------------------------------------------------------------- Scheduled activities for Week 30: M Jul 25 (207) T Jul 26 (208) W Jul 27 (209) T Jul 28 (210) F Jul 29 (211) S Jul 30 (212) S Jul 31 (213) ------------------------------------------------------------------------------- Scheduled activities for Week 31: M Aug 01 (214) T Aug 02 (215) W Aug 03 (216) T Aug 04 (217) F Aug 05 (218) S Aug 06 (219) S Aug 07 (220) ------------------------------------------------------------------------------- Scheduled activities for Week 32: M Aug 08 (221) T Aug 09 (222) Ahead: Momentum dump, 19:30 UT W Aug 10 (223) T Aug 11 (224) F Aug 12 (225) S Aug 13 (226) Ahead: Station 34 pointing test for OSIRIS-REx S Aug 14 (227) ------------------------------------------------------------------------------- Scheduled activities for Week 33: M Aug 15 (228) T Aug 16 (229) W Aug 17 (230) T Aug 18 (231) F Aug 19 (232) S Aug 20 (233) S Aug 21 (234) Notes * Single station recovery attempts for Behind, Aug 19-21 ------------------------------------------------------------------------------- Scheduled activities for Week 34: M Aug 22 (235) Ahead: Station 34 pointing test for OSIRIS-REx T Aug 23 (236) W Aug 24 (237) T Aug 25 (238) F Aug 26 (239) S Aug 27 (240) S Aug 28 (241) ------------------------------------------------------------------------------- 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