STEREO Weekly Meeting Minutes for 2018-07-31 (Week 31) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Behind has transitioned to a monthly schedule to attempt to recover the spacecraft. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 30 (Jul 23-29) * On day 205 (Jul 24), during the DSS-34 support for Ahead, turbo decoder lock was lost briefly at 0259z and 0500z. This anomaly resulted in the loss of 10 frames of real-time telemetry and SSR data. * On day 205 (Jul 24), the 111th momentum dump for Ahead was executed successfully at 2030z, which imparted an estimated delta V of 0.080 m/sec. This was the 30th momentum dump that did not use the IMU. After thruster operations completed, there was a 0.45 degree of roll angle error. Fine pointing was not stabilized until 13.8 hours after completion of the momentum dump. Post momentum dump, the wheel speed avoidance algorithm set a target of zero rad/sec for reaction wheel #4 which resulted in two lengthy periods of intermittent fine-pointing lock and associated x-axis errors (205-2035z/206-1023z; 206-1739z/2034z). While the algorithm is supposed to keep all reaction wheels away from zero and outside +/-30.79 rad/sec, it is not known at this time why wheel 4 was allowed to operate so close to zero for so long. At 206-2034z, wheel 4 autonomously moved away from zero and eventually settled at ~ -82 rad/sec when all four wheels re-distributed momentum. This G&C issue is being investigated. * The SECCHI team reports that the problems with loss of fine pointing had the following effects on their data. They had two false CME event detections from the COR2 instrument. COR1 was mostly unusable during this period, and HI saw smearing from the rll error. * The average daily science data return for Ahead was 6.4 Gbits during this week. Week 31 (Jul 30-Aug 5) * Ahead has 12 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 360 kbps, and three at 240 kbps. * There are no recovery passes for Behind during the week. Week 32 (Aug 6-12) * There will be a telemetry assessment review on Friday, Aug 10, between 9-12 EDT. Webex invitations have gone out. * Parker Solar Probe is currently scheduled for launch of Saturday, Aug 11. STEREO will start looking into launch contingencies this afternoon (Jul 31). There are three launch contingencies to negotiate. * Ahead has ten tracks during the week, and overall coverage is nominal. There are four tracks at 720 kbps, three at 360 kbps, two at 240 kbps, and one at 160 kbps. * There are no recovery passes for Behind during the week. Week 33 (Aug 13-19) * The 44th SECCHI stepped calibration roll is scheduled for Tuesday August 14th at 05:55 UT and taking 4.5 hours. This will be the midpoint roll. System momentum will be 1 N-m-s. * Ahead has ten tracks during the week, and overall coverage is nominal. There are five tracks at 720 kbps, two at 360 kbps, two at 240 kbps, and one at 160 kbps. * Recovery tracks for Behind using the double diamond search pattern are scheduled for Monday, Aug 13 (battery), Tuesday, Aug 14 and Wednesday, Aug 15 (both carrier). Week 34 (Aug 20-26) * The project interface test originally scheduled for Thursday, Aug 19, has been cancelled. * Ahead has 14 tracks during the week, and overall coverage is nominal. There are six tracks at 720 kbps, three at 360 kbps, four at 240 kbps, and one at 160 kbps. * There are no recovery passes for Behind during the week. Week 35 (Aug 27-Sep 2) * The 112th momentum dump on Ahead is scheduled for Wednesday, Aug 29, with ignition at 14:30 UT. This will be the 31st dump without using the gyros. * Ahead has 12 tracks during the week, and overall coverage is currently short 4.7 hours between Monday and Tuesday. There are six tracks at 720 kbps, one at 360 kbps, two at 240 kbps, and three at 160 kbps. A request for ESA time to relieve the shortage has been submitted; however, ESA reports that STEREO has used up its allocation. * There are no recovery passes for Behind during the week. Week 36 (Sep 3-9) * Monday, Sep 3, is Labor Day, which is an APL holiday. * The DSN network will be down for maintenance between 11-14 UT on Wednesday, Sep 5. This will have no effect on STEREO operations. * Ahead has 11 tracks during the week, and overall coverage is currently short almost 8 hours between Thursday and Saturday. There are six tracks at 720 kbps, two at 360 kbps, and three at 240 kbps. A request for ESA time to relieve the shortage has been submitted; however, ESA reports that STEREO has used up its allocation. * There are no recovery passes for Behind during the week. Other: * A question came up about continuing to search for STEREO Behind. The impact of searching once per month is considered to be minimal on both the DSN and the MOC, and the plan is to continue to attempt to recover Behind. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 31: M Jul 30 (211) T Jul 31 (212) W Aug 01 (213) T Aug 02 (214) F Aug 03 (215) S Aug 04 (216) S Aug 05 (217) ------------------------------------------------------------------------------- Scheduled activities for Week 32: M Aug 06 (218) T Aug 07 (219) W Aug 08 (220) T Aug 09 (221) F Aug 10 (222) S Aug 11 (223) S Aug 12 (224) ------------------------------------------------------------------------------- Scheduled activities for Week 33: M Aug 13 (225) Behind: Recovery track, DSN 14 (search, battery) T Aug 14 (226) Ahead: SECCHI stepped calibration roll, 5:55 UT Behind: Recovery track, DSN 14 (search, carrier) W Aug 15 (227) Behind: Recovery track, DSN 14 (search, carrier) T Aug 16 (228) F Aug 17 (229) S Aug 18 (230) S Aug 19 (231) ------------------------------------------------------------------------------- Scheduled activities for Week 34: M Aug 20 (232) T Aug 21 (233) W Aug 22 (234) T Aug 23 (235) F Aug 24 (236) S Aug 25 (237) S Aug 26 (238) ------------------------------------------------------------------------------- Scheduled activities for Week 35: M Aug 27 (239) T Aug 28 (240) W Aug 29 (241) Ahead: Momentum dump, 14:30 UT T Aug 30 (242) F Aug 31 (243) S Sep 01 (244) S Sep 02 (245) ------------------------------------------------------------------------------- Scheduled activities for Week 36: M Sep 03 (246) Labor Day T Sep 04 (247) W Sep 05 (248) T Sep 06 (249) F Sep 07 (250) S Sep 08 (251) S Sep 09 (252) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 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