STEREO Weekly Meeting Minutes for 2016-07-19 (Week 29) 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 28 (Jul 11-17) * On day 195 (Jul 13), an interface test was successfully conducted with the new 34m BWG station at the Canberra complex, DSS36. The MOC successfully bound to the station from all three command and control workstations for Ahead, as well as all three for Behind, and sent 5 no-op commands from each. Monitor data were successfully received and processed by the MOC. The spacecraft was not involved in these preliminary tests. * On day 197 (Jul 15), during the DSS-24 support, command bind was lost at 1840z due to a transmitter issue. The MOC rebound the command link at 1855z. Later in the support, turbo decoder lock was lost at 2043z, and again at 2245z. This anomaly resulted in the loss of 2 frames of SSR data. See DR# G117309 for more information. * On day 198 (Jul 16), the Ahead observatory was used to phase calibrate the 8th uplink array, using DSS-24, 25, and 26 for 1.9 hours, to support the array use for STEREO Behind battery recovery. An approximate 12.5 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 199 (Jul 17), the Ahead observatory was used again to phase calibrate the 9th uplink array, using DSS-24 and 26 for 1.9 hours, to support the array use for STEREO Behind transmitter carrier recovery. As the transmitter for DSS25 was declared red, the station was not used for uplink array. With the single 20 kW and 80 kW transmitters, an approximate 8.6 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. See DR# G117314 for more information. * The average daily science data return for Ahead was 5.9 Gbits during this week. * On day 198 (Jul 16), the 8th 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 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. At 1937z, the DSS-25 transmitter tripped due to a high voltage arc and remained off-line for the remainder of the support. This anomaly resulted in reducing the uplink gain to 9 dB, as compared to a single 34m station, for the remaining 31 frequency segments. 324 commands covering 36 frequency segments were sent for battery state of charge recovery. See DR# G117312 for more information. * On day 199 (Jul 17), the 9th uplink array for STEREO Behind recovery was conducted using DSS-24 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. As the transmitter for DSS-25 was declared red, the configuration consisted of two 34m stations at the Goldstone complex, using the 80 kW and one 20 kW transmitters incorporating the frequency segmented acquisition sequence with the MOC sending commands for transmitter carrier recovery. At 1919z, the command state did not transition to operational as expected resulting in the loss of commanding one frequency segment. At 1959z, DSS-26 80 kW transmitter tripped off due to fast antenna reflective power. The station was able to bring the transmitter back online at 2030z; however, the uplink power was lowered to 41 kW in order to keep additional interlocks from occurring. This anomaly resulted in the loss of commanding for 3 frequency segments. With DSS-24 uplinking at 20 kW and DSS-26 uplinking at 41 kW in a two station uplink array, the uplink array gain was reduced to 5.6 dB over a single 34m station. This would be equivalent to a 70m uplink at 20 kW. The Allen Telescope Array and the DSN 70m station, DSS-14, monitored the downlink. JPL Radio Science also configured radio science receivers to aid in the signal detection. 628 commands covering 32 frequency segments were sent. There were 2 occurrences where the DSS14 declared lock, but correlating these lock times with the signal levels and high carrier residuals seem to indicate these may be false locks. JPL Radio Science also reported there were no indications of a spacecraft signal present in real-time, but a further in-depth look at the open loop data is being conducted. See DR# G117315, G117316, and G117317 for more information. * Station 35 conducted an engineering test of pointing to the Ahead spacecraft on Thursday, Jul 14, in support of the upcoming OSIRIS-REx mission. This test was for a contingency search pattern. The spacecraft was used only as a radio source, and there was no effect on operations. The test was successful, and the backup test for station 35 on Jul 18 was cancelled. Week 29 (Jul 18-24) * The 35th SECCHI stepped calibration roll for Ahead was carried out yesterday (Jul 18), starting at 13:00 UT. Preliminary indications are that the roll is nominal. Some steps look noisier than others, but this is to be expected without the IMU. * Yesterday, during the station 26 support for Ahead, the station lost power at 19:29 UT. Pointers were later repositioned, and all data were recovered. * The first project interface test with the new station 36 at Canberra is scheduled for 1.6 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. Week 35 (Aug 29-Sep 4) * Ahead has 13 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 29: M Jul 18 (200) Ahead: SECCHI stepped calibration roll, 13:00 UT 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) 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) ------------------------------------------------------------------------------- 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