STEREO Weekly Meeting Minutes for 2017-04-18 (Week 16) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * Ahead is operating nominally on the main lobe of the high gain antenna. * Attempts to recover Behind have transitioned back to a monthly schedule. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 15 (Apr 10-16) * On day 102 (Apr 12), during the DSS-14 support for Ahead, turbo decoder lock was lost briefly at 2132z. This anomaly resulted in the loss of 44 frames of real-time telemetry and SSR data. * On day 103 (Apr 13), a Return-To-Service (RTS) engineering demo was conducted with DSS-25 with Ahead. The purpose was to validate X-band tracking performance after the completion of the depot level maintenance. Turbo decoder lost lock intermittently from 2249z through 2304z which was during the interval when Conscan was enabled. The MOC sent four commands successfully. As the tracking, telemetry, and command data from this support were non-committed, the SSR was not played back and no instrument commands were sent. * The average daily science data return for Ahead was 6.2 Gbits during this week. * On day 104 (Apr 14), during a 3.2 hour support for Behind with the 34m station DSS-26 using the 80 KW transmitter to minimize 70m contentions, 320 commands were transmitted during the support. No carrier was detected by the DSN station 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 105 (Apr 15), during a 4.5 hour support for Behind with DSS-14, 480 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 106 (Apr 16), during a 6.5 hour support with DSS-14, 700 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. * Recovery planning activities continue. There is a telecon to discuss recovery operations today (Apr 18) at 1:00 PM EDT. * The next recovery operations for Behind are scheduled for May 13-14 using the array uplink configuration. Week 16 (Apr 17-23) * Ahead has 9 passes during the week, and overall coverage is nominal. There are eight passes at 720 kbps, and one at 240 kbps. * There are no passes for Behind during the week. Week 17 (Apr 24-30) * The 98th momentum dump on Ahead is scheduled for Monday, Apr 24, with ignition at 16:00 UT. This will be the 17th momentum dump without gyros. * Ahead has 11 passes (picked up track 53 on Tuesday for 2 hours courtesy of Spitzer) during the week, and overall coverage is nominal. There are ten passes at 720 kbps, and one pass at 160 kbps. * There are no passes for Behind during the week. Week 18 (May 1-7) * Ahead has 8 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, and one at 160 kbps. * There are no passes for Behind during the week. Week 19 (May 8-14) * DSN stations will be unavailable for a large part of the day on Thursday, May 11 for an exercise in preparation for DSN "Follow the Sun" operations. STEREO Ahead has passes just before and just after this exercise, so no problems are anticipated. * The recovery attempt for Behind during the week will use the uplink array configuration on Saturday and Sunday, May 13-14, to officially validate the technique. The configuration uses stations 24, 25, and 26 at Goldstone for uplink, with the 80 kW transmitter on station 26, and the 70 meter station 14 for downlink. The first 1.9 hours will be used with STEREO Ahead for calibration. There will be no SSR playback or instrument commanding during these Ahead passes. After calibration, the stations will switch to Behind for 2.8 hours on Saturday, and 3.7 hours on Sunday, as well as station 14 for 3.4 hours with the Radio Science Receiver. A waiver has been requested for station 26 dipping below the 27.5 degree limit on Sunday. * Ahead has 9 tracks during the week and overall coverage is nominal. There are 8 passes at 720 kbps, and one at 160 kbps. Week 20 (May 15-21) * Ahead has 11 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, one at 360 kbps, one at 240 kbps, and two at 160 kbps. * There are no passes for Behind during the week. Week 21 (May 22-28) * The 99th momentum dump on Ahead is scheduled for Monday, May 22, with ignition at 14:00 UT. This will be the 18th momentum dump with using the gyros. The dump is being scheduled a week or so early due to track coverage limitations. * Ahead has 8 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, and one at 240 kbps. * There are no passes for Behind during the week. Week 22 (May 29-Jun 4) * Monday, May 29, is Memorial Day, which is a holiday at APL. * Ahead has 8 tracks during the week, and overall coverage is nominal. There are seven tracks at 720 kbps, and one at 160 kbps. * There are no tracks for Behind during the week. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 16: M Apr 17 (107) T Apr 18 (108) W Apr 19 (109) T Apr 20 (110) F Apr 21 (111) S Apr 22 (112) S Apr 23 (113) ------------------------------------------------------------------------------- Scheduled activities for Week 17: M Apr 24 (114) Ahead: Momentum dump, 16:00 UT T Apr 25 (115) W Apr 26 (116) T Apr 27 (117) F Apr 28 (118) S Apr 29 (119) S Apr 30 (120) ------------------------------------------------------------------------------- Scheduled activities for Week 18: M May 01 (121) T May 02 (122) W May 03 (123) T May 04 (124) F May 05 (125) S May 06 (126) S May 07 (127) ------------------------------------------------------------------------------- Scheduled activities for Week 19: M May 08 (128) T May 09 (129) W May 10 (130) T May 11 (131) DSN stations down for "Follow the Sun" exercise F May 12 (132) S May 13 (133) Behind: DSN uplink array recovery attempt S May 14 (134) Behind: DSN uplink array recovery attempt ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 15 (135) T May 16 (136) W May 17 (137) T May 18 (138) F May 19 (139) S May 20 (140) S May 21 (141) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 22 (142) Ahead: Momentum dump, 14:00 UT T May 23 (143) W May 24 (144) T May 25 (145) F May 26 (146) S May 27 (147) S May 28 (148) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 29 (149) Memorial Day T May 30 (150) W May 31 (151) T Jun 01 (152) F Jun 02 (153) S Jun 03 (154) S Jun 04 (155) ------------------------------------------------------------------------------- Upcoming events: Behind events are contingent on recovering the spacecraft. 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 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