STEREO Weekly Meeting Minutes for 2014-04-15 (Week 16) ANNOUNCEMENTS ------------- * The HGA feed on Behind has exceeded its operational temperature limit due to the low Sun-spacecraft-Earth angle. Mitigation strategies are being discussed. See below for details. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 15 (Apr 7-13) * On day 097 (Apr 7), a Return-To-Service (RTS) engineering demo on Ahead was conducted with DSS-63. The purpose was to validate X-band tracking performance after the completion of the depot level maintenance (DLM) and re-grouting activities. All test objectives were met successfully. Tracking, telemetry, and command data from this support was non-committed. * On day 099 (Apr 9), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 0929z. This anomaly resulted in the loss of two frames of SSR data. * On day 100 (Apr 10), due to an organized cyber-attack on JHU/APL, as a precautionary measure, external access to the STEREO MOC was locked down for incoming traffic earlier than the planned date on day 104. Access is still available using APL supplied VPN access or from a static IP address. Note that the STEREO MOC networks were not affected by the cyber-attack. * On day 103 (Apr 13), during the DSS-65 support for Ahead, turbo decoder lock was lost intermittently between 1006z and 1033z, and a full drop in lock between 1033z and 1039z. This anomaly resulted in the loss of 1840 frames of SSR data. See DR #N109535 for more information. * On day 100 (Apr 10), during the DSS-25 support, turbo decoder lock was lost briefly at 2029z. This anomaly resulted in the loss of three frames of SSR data. * The HGA feed on Behind has exceeded its operational temperature limit. While the HGA feed is an all metal waveguide design, the temperature will increase as the SPE (Sun-Probe-Earth) angle decreases. Detailed thermal analysis is underway and off pointing the HGA will most likely be necessary on both observatories. The details are still being worked out. This situation has not been previously modeled, since it was beyond the original design period for the mission. The current SPE angle is about 7 degrees for Behind, and 12 degrees for Ahead. However, Ahead's orbit takes it closer to the Sun, and its temperature is expected to eventually exceed that of Behind. Any antenna off-pointing strategy is expected to impact more the space weather beacon data than the science data return, but this is not yet certain. * The average daily SSR playback volume during the week was 4.5 gigabits for Ahead, and 4.4 gigabits for Behind. Week 16 (Apr 14-20) * Ahead has 13 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Apr 14 (D63 at 720 kbps), Tuesday, Apr 15 (D63, D14 at 720 kbps), Wednesday, Apr 16 (D63), and Friday, Apr 18 (D43). The following passes will be carried out at 160 kbps: Thursday, Apr 17 (D55, D24), Friday, Apr 18 (D24), Saturday, Apr 19 (D15), and Sunday, Apr 20 (D55). * Behind has 10 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for every day of the week except Friday, and all of the passes are carried out at 720 kbps except Sunday. The following passes will be carried out at 160 kbps: Thursday, Apr 17 (D25), Friday, Apr 18 (D55), Saturday, Apr 19 (D34), and Sunday, Apr 20 (D25). Week 17 (Apr 21-27) * Ahead has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Apr 21 (D63 at 720 kbps), Tuesday, Apr 22 (D63), Wednesday, Apr 23 (D14), Thursday, Apr 24 (D43), and Friday, Apr 25 (D43 at 720 kbps). The following passes will be carried out at 160 kbps: Thursday, Apr 24 (D55), Friday, Apr 25 (D55), Saturday, Apr 26 (D54, D25), and Sunday, Apr 27 (D54, D25). * Behind has 13 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Apr 21 (D63 at 720 kbps), Wednesday, Apr 23 (D43), and Sunday, Apr 27 (D43 at 720 kbps). The following passes will be carried out at 160 kbps: Wednesday, Apr 23 (D54), Thursday, Apr 24 (D54), Friday, Apr 25 (D55), Saturday, Apr 26 (D55, D15), and Sunday, Apr 27 (D55). The station 26 pass on Friday, Apr 25, will be carried out at 240 kbps. Week 18 (Apr 28-May 4) * The 67th momentum dump on Ahead is scheduled for Wednesday, Apr 30, with ignition at 15:00 UT. * Mercury will transit the disk as seen from Behind on Tuesday, Apr 29, from approximately 1:49-06:08 UT. SECCHI observations will cover a longer time to include the COR1 telescope. * Ahead has 12 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Apr 29 (D14 at 720 kbsp, D43), Wednesday, Apr 30 (D43), Thursday, May 1 (D43 at 720 kbsp), and Sunday, May 4 (D63, D14, both at 720 kbps). The following passes will be carried out at 160 kbps: Monday, Apr 28 (D54), Wednesday, Apr 30 (D55), and Friday, May 2 (D24). The station 26 pass on Saturday, May 3, will be carried out at 240 kbps. * Behind has 13 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Apr 28 (D63 at 720), Wednesday, Apr 30 (D43, D14, both at 720 kbps), and Thursday, May 1 (D43 at 720 kbps). The following passes will be carried out at 160 kbps: Thursday, May 1 (D55, D24), Friday, May 2 (D55), Saturday, May 3 (D55, D25), and Sunday, May 4 (D55). The following station 26 passes will be carried out at 240 kbps: Tuesday, Apr 29, Friday, May 2, and Sunday, May 4. Week 19 (May 5-11) * The 62nd momentum dump on Behind is scheduled for Tuesday, May 6, with ignition at 23:30 UT. * Ahead has 8 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, May 6 (D63 at 720 kbps), and Saturday, May 10 (D43, D14 at 720 kbps). The following passes will be carried out at 160 kbps: Thursday, May 8 (D25), and Sunday, May 4 (D55). The station 26 pass on Friday, May 9, will be carried out at 240 kbps. * Behind has 10 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, May 5 (D63 at 720 kbps), and Friday, May 9 (D43 at 720 kbps). The following passes will be carried out at 160 kbps: Tuesday, May 6 (D25), Thursday, May 8 (D55, D24), and Saturday, May 10 (D55, D25). The station 26 pass on Sunday, May 11, will be carried out at 240 kbps. Week 20 (May 12-18) * Ahead has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, May 12 (D14), Thursday, May 15 (D63 at 720 kbps), and Friday, May 16 (D43). The following passes will be carried out at 160 kbps: Tuesday, May 13 (D26), Wednesday, May 14 (D55), Thursday, May 15 (D25), and Saturday, May 17 (D55). The following station 26 passes will be carried out at 240 kbps: Wednesday, May 14, Friday, May 16, and Sunday, May 18. * Behind has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, May 12 (D14 at 720 kbps), Friday, May 16 (D63), and Saturday, May 17 (D43). The following passes will be carried out at 160 kbps: Tuesday, May 13 (D54), Wednesday, May 14 (D54), Thursday, May 15 (D55, D25), Friday, May 16 (D25), Saturday, May 17 (D65), and Sunday, May 18 (D54). The station 26 pass on Saturday, May 17, will be carried out at 240 kbps. Other * Planning is continuing for the STEREO conjunction. Configuration testing will be carried out in September. The HGA temperature issue will be a factor in the conjunction planning. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 16: M Apr 14 (104) Ahead: COR2 long-exposure campaign T Apr 15 (105) Ahead: COR2 long-exposure campaign W Apr 16 (106) Ahead: COR2 long-exposure campaign T Apr 17 (107) F Apr 18 (108) S Apr 19 (109) S Apr 20 (110) ------------------------------------------------------------------------------- Scheduled activities for Week 17: M Apr 21 (111) T Apr 22 (112) W Apr 23 (113) T Apr 24 (114) F Apr 25 (115) S Apr 26 (116) S Apr 27 (117) ------------------------------------------------------------------------------- Scheduled activities for Week 18: M Apr 28 (118) T Apr 29 (119) Behind: Mercury transit W Apr 30 (120) Ahead: Momentum dump, 15:00 UT T May 01 (121) F May 02 (122) S May 03 (123) S May 04 (124) ------------------------------------------------------------------------------- Scheduled activities for Week 19: M May 05 (125) T May 06 (126) Behind: Momentum dump, 23:30 UT W May 07 (127) T May 08 (128) F May 09 (129) S May 10 (130) S May 11 (131) ------------------------------------------------------------------------------- Scheduled activities for Week 20: M May 12 (132) T May 13 (133) W May 14 (134) T May 15 (135) F May 16 (136) S May 17 (137) S May 18 (138) ------------------------------------------------------------------------------- Upcoming events: 2014: * Sep 07-Nov 15 Behind: Passage of Comet Siding Spring through HI2-B * Sep 21 MAVEN arrival at Mars * Oct 17 Behind: Comet Siding Spring encounter with Mars 2015: * Jan 14 - Mar 19 (TBC) Behind: Spacecraft behind Sun * Mar DAWN - Ceres arrival * Feb 11 - Jul 08 (TBC) Ahead: Spacecraft behind Sun * Aug 25 - Oct 19 (TBC) Behind: Possible interference from Sun * Jul DAWN - End of nominal mission 2016: * Jul 5 Juno arrival at Jupiter 2017: * Jul 11 Ahead: Switch downlink rate to 160 kbps * Jul 22 Behind: Switch downlink rate to 160 kbps 2018: * Mar 5 Ahead: Mercury transit