STEREO Weekly Meeting Minutes for 2016-08-09 (Week 32) 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 31 (Aug 1-7) * On day 214 (Aug 1), during the DSS-65 support for Ahead, turbo decoder lock was lost briefly at 1151z and again at 1236z. This anomaly resulted in the loss of 2 frames of SSR data. * On day 214 (Aug 1), the DSS-43 support for Ahead was deleted to assist Ground Based Radio Astronomy with a pulsar radio emission observation (PSR J1119-6127) after recent SGR-like (soft gamma repeater) X-ray and gamma-ray activity. As the track coverage on Monday was sufficient, this did not cause any negative impact to science data return. * On day 215 (Aug 2), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 1715z and again at 2044z. This anomaly resulted in the loss of 2 frames of SSR data. * On day 216 (Aug 3), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 1620z and again at 2043z. This anomaly resulted in the loss of 2 frames of SSR data. * On day 217 (Aug 4), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 1338z. This anomaly resulted in the loss of 1 frame of SSR data. * On day 218 (Aug 5), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 1718z, 2100z, 2230z, and again at 2236z. This anomaly resulted in the loss of 4 frames of SSR data. * On day 219 (Aug 6), during the DSS-25 support for Ahead, turbo decoder lock was lost briefly at 1829z. This anomaly resulted in the loss of 1 frame of SSR data. * The average daily science data return for Ahead was 5.9 Gbits during this week. * There are no tracks for Behind during the week. * Starting in July, attempts to contact Behind have been reduced to once monthly, alternating months between phased uplink array passes, and single-dish passes which have a wider beam. This will continue through June 2017, after which recovery attempts will be suspended until January 2020, when the nominal uplink rate returns to 125 bps. The next uplink array attempt will be Sep 17-18. * 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 32 (Aug 8-14) * The 90th momentum dump on Ahead is scheduled for 19:30 UT this afternoon (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. This is the first test with station 34. 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) * There will be an IONET router switch on Wednesday, Aug 17, between 14:15-15:00 UT, which is in between tracks. If the switch is unsuccessful, then the network will be restored to its present configuration before the next track. * 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. If the previous test with station 34 is successful, then this test may be changed to an attenuator test. * Behind will be at perihelion on Aug 25. * Ahead has 14 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, two at 360 kbps, and nine at 240 kbps. One of the Madrid passes was changed to a 70 meter pass. * Behind starts the week at an SPE angle of 14.3 degrees. There are no tracks for Behind during the week. Week 35 (Aug 29-Sep 4) * Ahead has 12 passes during the week, and overall coverage is nominal. There is one pass at 720 kbps, two at 360 kpbs, eight at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 14.1 degrees. There are no tracks for Behind during the week. Week 36 (Sep 5-11) * Monday, Sep 5, is Labor Day, which is a holiday at APL. * The 91st momentum dump on Ahead is scheduled for Thursday, Sep 8, with ignition at 19:30 UT. This momentum dump is scheduled about 8-9 days early because of DSN coverage limitations, particularly in regards to the launch of OSIRIS-REx whose first launch window starts later that day, with additional daily opportunities up until Sep 15. Launch contingency plans are still being worked. * Ahead has 11 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, four at 360 kbps, three at 240 kbps, and one at 160 kbps. * Behind starts the week at an SPE angle of 14.0 degrees. There are no tracks for Behind during the week. Week 37 (Sep 12-18) * Ahead has 8 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, one at 360 kbps, and three at 240 kbps. * Behind starts the week at an SPE angle of 13.8 degrees. * Uplink array attempts for Behind are scheduled for Sep 17, 18. Each attempt will begin with 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 Sep 17 for battery recovery, and a 5.3 hour pass on Sep 18 for carrier recovery. Station 14 will listen for the Behind carrier, using the Radio Science Receiver. Additional coverage from external sites is still being worked. Week 38 (Sep 19-25) * A 2.6 hour return-to-service track for station 63 with STEREO Ahead is scheduled for Saturday, Sep 24. There will be no SSR playback or instrument commanding during this track. * Ahead has 9 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, one at 360 kbps, one at 240 kbps, and three at 160 kbps. * Behind starts the week at an SPE angle of 13.7 degrees. There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) Behind: Perihelion F Aug 26 (239) S Aug 27 (240) S Aug 28 (241) ------------------------------------------------------------------------------- Scheduled activities for Week 35: M Aug 29 (242) T Aug 30 (243) W Aug 31 (244) T Sep 01 (245) F Sep 02 (246) S Sep 03 (247) S Sep 04 (248) ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 05 (249) Labor Day T Sep 06 (250) W Sep 07 (251) T Sep 08 (252) Ahead: Momentum dump, 19:30 UT F Sep 09 (253) S Sep 10 (254) S Sep 11 (255) ------------------------------------------------------------------------------- Scheduled activities for Week 37: M Sep 12 (256) T Sep 13 (257) W Sep 14 (258) T Sep 15 (259) F Sep 16 (260) S Sep 17 (261) Behind: Phased array recovery attempt S Sep 18 (262) Behind: Phased array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 38: M Sep 19 (263) T Sep 20 (264) W Sep 21 (265) T Sep 22 (266) F Sep 23 (267) S Sep 24 (268) Ahead: Return-to-service track with DSS-63 S Sep 25 (269) ------------------------------------------------------------------------------- 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