STEREO Weekly Meeting Minutes for 2017-11-21 (Week 47) ANNOUNCEMENTS ------------- * None 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. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 46 (Nov 13-19) * On day 317 (Nov 13), during the DSS-25 support for Ahead, a DSN demonstration test was conducted to validate SLE telemetry server operations and data delivery with TT&C software V1.4. As this was a test track, there was no SSR playback or instrument commanding. In the MOC, real-time telemetry and monitor data services were nominal and four commands were successfully received by the Ahead observatory. The DSN began using this software on Ahead on a regular basis yesterday (Nov 20). * On day 321 (Nov 17), during the DSS-34 support for Ahead, turbo decoder lock was lost intermittently between 0839z and 0844z and briefly at 0917z. This anomaly resulted in the loss of 4236 frames of real-time and SSR data. See DR #C113040 for more information. * On day 321 (Nov 17), during the DSS-84 support for Ahead, the transmitter tripped off-line at 2123z and remained unavailable for the remainder of the track. This anomaly resulted in the loss of 2.4 hours of commanding and tracking data and several seconds of SSR data loss during the transition from two-way to one-way communications. * On day 319 (Nov 15), the 104th momentum dump on Ahead was executed successfully at 1600z, which imparted an estimated delta V of 0.098 m/sec. This was the 23rd momentum dump that did not use the IMU. After thruster operations complete, there was a 0.39 degree of roll angle error which was dampened out over the next 14.6 minutes. Fine pointing stabilized 2.2 minutes after completion of the momentum dump. * On day 320 (Nov 16), the PLASTIC SSR science partition (#17) on Ahead reached 95% full and began recording only housekeeping data at 1509z for 14 minutes due to insufficient track time. * The average daily science data return for Ahead was 4.8 Gbits during this week. * On day 317 (Nov 13), during a 2.6 hour 4 kHz carrier recovery support for Behind with DSS-63, 260 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 320 (Nov 16), during a 3 hour 4 kHz battery recovery search pattern support for Behind with DSS-63, 320 commands were transmitted during the support. All 7 points on the pattern were covered twice. * On day 322 (Nov 18) during a 3 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. Week 47 (Nov 20-26) * Thursday, Nov 23, is Thanksgiving. Both Thursday and Friday, Nov 23-24, are holidays at APL. * Ahead has 17 tracks during the week, and overall coverage is nominal. There are six tracks at 360 kbps, one track at 240 kbps, and ten at 160 kbps. The data margins have been reanalyzed, and it was determined that two of the newer stations, DSN-35 and DSN-36 at Canberra, can have their nominal rates increased to 240 kbps, with a boost to 360 kbps when the entire pass is at high elevation. Two ESA tracks are used during the week. * Double diamond search patterns for Behind recovery are scheduled for Tuesday, Nov 21 (battery) and Wednesday, Nov 22 (carrier). Another recovery track is scheduled for Saturday, Nov 25. Week 48 (Nov 27-Dec 3) * Commercial power will be turned off in the MOC between 17:45 and 23:30 UT on Tuesday, Nov 18, to perform maintenance on a substation breaker. Power will be supplied by a portable generator during this work, and there should be no effect on operations. * Ahead reaches perihelion on Dec 3. * Ahead has 15 tracks during the week, and overall coverage is now nominal. There is one track at 720 kbps, three at 360 kbps, three at 240 kbps, and eight at 160 kbps. The previous data shortage was eliminated by bumping up several passes to 360 kpbs, adding two ESA supports, and moving a 70 meter pass from Behind to Ahead. * Only two recovery tracks scheduled for Behind Tuesday, Nov 28 (battery search pattern) and Friday, Dec 1 (carrier search pattern). The previously scheduled pass on Sunday was moved to Ahead. Week 49 (Dec 4-10) * On Tuesday (Day 338), Dec 5, The 41st SECCHI stepped calibration roll is scheduled starting at 08:55 UT for perihelion in the Ahead orbit. System momentum will be about 1 N-m-s. This will be the perihelion roll, and will be the 10th roll without gyros. * Ahead has 15 tracks during the week, and overall coverage is nominal. There are three tracks at 720 kbps, three at 360 kbps, one at 240 kbps, and eight at 160 kbps. * A double diamond carrier search pattern for Behind is scheduled for Tuesday, Dec 5. An additional recovery track is scheduled for Saturday, Dec 9. A 70 meter pass on Wednesday has been moved to Ahead to maintain science data return. 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 track 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. There are three passes at 720 kbps, one at 360 kbps, one at 240 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, Christmas Day which is an APL holiday. * Ahead has 14 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 five 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) * 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. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 47: M Nov 20 (324) T Nov 21 (325) Behind: Recovery track, DSN 63 (search pattern, battery) W Nov 22 (326) Behind: Recovery track, DSN 14 (search pattern, carrier) T Nov 23 (327) Thanksgiving F Nov 24 (328) APL holiday S Nov 25 (329) Behind: Recovery track, DSN 14 S Nov 26 (330) ------------------------------------------------------------------------------- Scheduled activities for Week 48: M Nov 27 (331) T Nov 28 (332) Behind: Recovery track, DSN 63 (search pattern, battery) W Nov 29 (333) T Nov 30 (334) F Dec 01 (335) Behind: Recovery track, DSN 63 (search pattern, carrier) S Dec 02 (336) S Dec 03 (337) Ahead: Perihelion ------------------------------------------------------------------------------- Scheduled activities for Week 49: M Dec 04 (338) T Dec 05 (339) Ahead: SECCHI stepped calibration roll, 08:55 UT Behind: Recovery track, DSN 63 (search pattern, carrier) W Dec 06 (340) T Dec 07 (341) F Dec 08 (342) S Dec 09 (343) Behind: Recovery track, DSN 63 S Dec 10 (344) ------------------------------------------------------------------------------- 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 63 (search pattern, 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