STEREO Weekly Meeting Minutes for 2017-12-12 (Week 50) ANNOUNCEMENTS ------------- * The Dec 26 STEREO weekly planning meeting is canceled. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Behind has transitioned to a weekly schedule to attempt to recover the spacecraft. Passes are scheduled approximately every three days to keep within the 72 hour command loss timer. Typically, two of those days use a search pattern consisting of two diamonds, based on the estimated uncertainty in the ephemeris. The double diamond pattern is executed twice, once to send commands, and then again 40 minutes later to listen for the carrier. An additional pass uses the standard configuration. In some cases, the older "1 kHz" frequency acquisition sequence is used, with one day for battery recovery, and another for carrier recovery. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 49 (Dec 4-10) * On day 339 (Dec 5) the 41st SECCHI stepped calibration was executed at 0855z for perihelion in the Ahead orbit. This was the 10th SECCHI stepped calibration roll to be conducted without gyro use. * On day 339 during a 3.1 hour 4 kHz carrier recovery search pattern support for Behind with DSS-63, 320 commands were transmitted during the support for carrier recovery. No carrier was detected by either the DSN station or the radio science receiver team. All 7 points on the pattern were covered twice. Three commands must be received sequentially to power on the transmitter. * On day 340 (Dec 6), during the DSS-35 support, telemetry binds were dropped at 0532z on both Ahead and Behind command workstations due to a NASCOM network issue. This anomaly resulted in the loss of 3.4 hours of real-time telemetry, commanding, and monitor data. All SSR data was received. * On day 342 (Dec 8), the STEREO project received authorization to continue ESA cross support for 2018. * On day 343 (Dec 9), during the DSS-63 support for Ahead, initial acquisition of telemetry was 3 minutes late at 1533z due to a connection engine issue at the controlling complex. Later in the support, turbo decoder lock was lost intermittently between 1606z through 1607z. These anomalies resulted in the loss of 3 minutes of real-time telemetry and monitor data and 322 frames of SSR data. See DR #M110372 for more information. * On day 343, during a 3 hour 4 kHz carrier recovery support for Behind with DSS-63, 320 commands were transmitted during the support. No carrier was detected by either the DSN station or the radio science receiver team after attempting to power on the TWTA for 30 minutes. Transitioned to battery recovery operations for the remainder of the support which consists of repeatedly sweeping a 4 kHz uplink range and sending commands for IEM switched power and PDU 1553 interface bus off. * On day 344 (Dec 10), during the DSS-63 support for Ahead, turbo decoder lock was lost intermittently between 1200z through 1205z. This anomaly resulted in the loss of 169 frames of real-time telemetry and SSR data. * The average daily science data return for Ahead was 5.4 Gbits during this week. Week 50 (Dec 11-17) * Ahead has 17 tracks during the week, and overall coverage is now nominal. Two 70 meter passes for Behind have been reallocated to Ahead. There are three passes at 720 kbps, five at 360 kbps, one at 240 kbps, and eight at 160 kbps. Using the stations 25 & 26 to maintain data return on Ahead. * A single recovery attempt for Behind is scheduled for Thursday, Dec 14. Two recovery tracks were switched to Ahead to maintain data return. Week 51 (Dec 18-24) * Thursday, Dec 21st, the 105th momentum dump on Ahead is scheduled with ignition at 16:00 UT. This will be the 24th dump without using the gyros. * Ahead has 14 tracks during the week, and overall coverage is nominal. There are three passes at 720 kbps, two at 360 kbps, and nine at 160 kbps. * A Behind recovery attempt is scheduled for Saturday, Dec 23. The Saturday attempt will be a double diamond search pattern for carrier recovery. Two recovery tracks needed to be reallocated to Ahead. Week 52 (Dec 25-31) * Monday, Dec 25, is Christmas Day which is an APL holiday. * Tuesday Dec 26 STEREO weekly planning meeting is canceled. * Ahead has 13 tracks during the week, and overall coverage is nominal. There are five passes at 720 kbps, two at 360 kbps, two at 240 kbps, and four at 160 kbps. * Behind recovery attempts are scheduled for Monday, Dec 25 (battery search pattern), Wednesday, Dec 27 (carrier search pattern), and Saturday, Dec 30 (nominal 4kHz carrier recovery). Week 1 (Jan 1-7) * January 1 is the New Year holiday. * Ahead has 15 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, two at 360 kbps, five at 240 kbps, and one at 160 kbps. * There are four recovery attempts for Behind during the week. A 1 kHz frequency acquisition pass for battery recovery will be carried out Monday, Jan 1, with the subsequent carrier recovery pass on Tuesday, Jan 1. Search pattern attempts will be carried out on Friday, Jan 5, for battery recovery, and Sunday, Jan 6, for carrier recovery. Week 2 (Jan 8-14) * Ahead has 14 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, one at 360 kbps, three at 240 kbps, and three at 160 kbps. * Recovery attempts for Behind using the 1 kHz frequency acquisition sequence are scheduled on Tuesday, Jan 9 (battery) and Friday, Jan 12 (carrier). A search pattern for battery recovery is scheduled for Sunday, Jan 14. Week 3 (Jan 15-21) * Ahead has 16 tracks during the week, and overall coverage is nominal. There are six track at 720 kbps, eight at 240 kbps, one at 360 kbps and one at 160 kbps. * A carrier recovery search pattern track for Behind is scheduled for Tuesday, Jan 16. Recovery tracks using the 1 kHz frequency acquisition sequence are scheduled for Thursday, Jan 18 (battery), and Saturday, Jan 20 (carrier). * Jan 15 is Martin Luther King Jr. Day, a US government holiday. Week 4 (Jan 22-28) * On Wednesday Jan 24 Behind would resume 125 bps uplink on LGA assuming nominal operations. * Ahead has 13 tracks during the week, and overall coverage in nominal. There are seven tracks at 720 kbps, two at 360 kbps, and four at 240 kbps. * Weekly recovery operations for Behind continue. A battery recovery search pattern track is scheduled for Tuesday, Jan 23, and the corresponding carrier recovery search pattern track will be on Friday, Jan 26. On Sunday, Jan 28 a battery recovery 1 kHz sweep sequence is scheduled. Other * The SECCHI HI team has requested an off-point maneuver for stray light calibration. This involves moving by up to 1 degree in the Y direction. This will be the first time this maneuver will be performed without using the gyros. The MOC expects to be able to perform this maneuver possibly later this month. They are currently testing it on the hardware simulator with approximately 12 minute duration steps. The guide telescope will be disabled. The SECCHI team also has to make changes to their procedures, and will discuss a time for scheduling the maneuver once the MOC is ready. * From the radiometric data analysis of the STEREO BEHIND recovery track on Dec 1st, day 335, with DSS-65, GSFC noted some unusual RF results. During this support, the MOC received 4 possible carrier lock indications, which based on signal levels, did not appear to be an actual signal. The DSN RSR team is investigating. * There is a leap second at the start of 2018. However, STEREO does not have any tracks that bridge Dec 31 and Jan 1 and would be directly impacted. * STEREO switched over to DSN's Follow the Sun Operations on Nov. 6. DSN would like to know if there have been any issues. Misson Ops has two or three they will send in to be forwarded to the Follow the Sun Operations Manager. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 50: M Dec 11 (345) T Dec 12 (346) W Dec 13 (347) T Dec 14 (348) Behind: Recovery track, DSN 63 F Dec 15 (349) S Dec 16 (350) S Dec 17 (351) ------------------------------------------------------------------------------- Scheduled activities for Week 51: M Dec 18 (352) T Dec 19 (353) W Dec 20 (354) T Dec 21 (355) Ahead: Momentum dump, 16:00 UT F Dec 22 (356) S Dec 23 (357) Behind: Recovery track, DSN 14 (search pattern, carrier) S Dec 24 (358) ------------------------------------------------------------------------------- Scheduled activities for Week 52: M Dec 25 (359) Christmas Behind: Recovery track, DSN 63 (search pattern, battery) T Dec 26 (360) W Dec 27 (361) Behind: Recovery track, DSN 63 (search pattern, carrier) T Dec 28 (362) F Dec 29 (363) Behind: Recovery track, DSN 14 S Dec 30 (364) S Dec 31 (365) ------------------------------------------------------------------------------- Scheduled activities for Week 01: M Jan 01 (001) New Year Behind: Recovery track, DSN 14 (1 kHz, battery) T Jan 02 (002) Behind: Recovery track, DSN 63 (1 kHz, carrier) W Jan 03 (003) T Jan 04 (004) F Jan 05 (005) Behind: Recovery track, DSN 63 (search pattern, battery) S Jan 06 (006) S Jan 07 (007) Behind: Recovery track, DSN 14 (search pattern, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 02: M Jan 08 (008) T Jan 09 (009) Behind: Recovery track, DSN 63 (1 kHz, battery) W Jan 10 (010) T Jan 11 (011) F Jan 12 (012) Behind: Recovery track, DSN 63 (1 kHz, carrier) S Jan 13 (013) S Jan 14 (014) Behind: Recovery track, DSN 14 (search pattern, battery) ------------------------------------------------------------------------------- Scheduled activities for Week 03: M Jan 15 (015) T Jan 16 (016) Behind: Recovery track, DSN 63 (search pattern, battery) W Jan 17 (017) T Jan 18 (018) Behind: Recovery track, DSN 14 (1 kHz, battery) F Jan 19 (019) S Jan 20 (020) Behind: Recovery track, DSN 63 (1 kHz, carrier) S Jan 21 (021) ------------------------------------------------------------------------------- Scheduled activities for Week 04: M Jan 22 (022) T Jan 23 (023) Behind: Recovery track (search pattern, battery) W Jan 24 (024) T Jan 25 (025) F Jan 26 (026) Behind: Recovery track (search pattern, carrier) S Jan 27 (027) S Jan 28 (028) Behind: Recovery track (1 kHz, battery) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 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 2022: 2023: * May 5 Behind: Mercury transit * Jul 17 Behind: Closest approach to Earth * Aug 13 Ahead: Closest approach to Earth 2024: 2025: * Apr 7 Ahead: Mercury transit 2026: 2027: * Feb 1 Behind: Mercury transit 2028: 2029: * Jun 30 Ahead: Mercury transit