STEREO Weekly Meeting Minutes for 2014-04-22 (Week 17) ANNOUNCEMENTS ------------- * The HGA feed temperatures on both spacecraft have now exceeded their nominal operational limits, due to the decreasing SPE angle between the Sun and Earth. See below for details. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 16 (Apr 14-20) * On day 105 (Apr 15), during the DSS-63 support for Ahead, turbo decoder lock was lost briefly at 0626z. This anomaly resulted in the loss of three frames of SSR data. * On day 107 (Apr 17), during the DSS-55 support for Ahead, turbo decoder lock was lost briefly at 1228z. This anomaly resulted in the loss of five frames of SSR data. * On day 110 (Apr 20), during the DSS-55 support for Ahead, turbo decoder lock was lost intermittently between 1040z and 1447z. This anomaly resulted in the loss of eight frames of SSR data. * Between DOYs 103 and 105 (Apr 13-15) the spacecraft occasionally dropped fine-pointing lock. This happened six times. This was due to the reaction wheels operating at low speeds and reduced gyro operations during this time period. * On day 103 (Apr 13), the HGA feed on Ahead exceeded its operational temperature limit of 85 C. While the HGA feed is an all metal waveguide design, the temperature will increase as the SPE angle decreases. Detailed thermal analysis is underway and off pointing the HGA will be necessary to prevent damage on both observatories. Options to mitigate the impact to science and the space weather broadcast are actively being investigated. * Ahead is closer to the Sun than Behind, and thus the temperature limit was reached at a larger SPE angle. In the short term, the SPE angle for Behind will be leveling, and then increasing for a while. However, Ahead's SPE angle will continue to decrease linearly. * It is currently anticipated that damage will occur to the HGA feed when the temperature reaches 180 C. However, the sensor will saturate at 136 C, and the temperature will need to be kept below this level. There are currently no autonomy rules tied to the HGA feed temperature, but the MOC is looking into the possibility of adding one. * On day 109 (Apr 19), during the DSS-63 support for Behind, no commanding or ranging was conducted due to the transmitter being declared red. See DR #M107909 for more information. * 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 angle decreases. Detailed thermal analysis is underway and off pointing the HGA will be necessary to prevent damage on both observatories. Options to mitigate the impact to science and the space weather broadcast are actively being investigated. * The average daily SSR playback volume during the week was 4.9 gigabits for Ahead, and 5.3 gigabits for Behind. Week 17 (Apr 21-27) * Ahead has 12 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. * MOps macro 1.1.20 will be loaded onto both spacecraft during the week, to assist in downloading the attitude history data. * 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 kbps), 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) * MOps macro 1.1.20 will be loaded onto EEPROM on both spacecraft on May 18. * Ahead has 11 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, May 12 (D14 at 720 kbps), 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. Week 21 (May 19-25) * The 30th SECCHI stepped calibration roll on Ahead is scheduled for May 20, starting at 14:45 UT. The system momentum is expected to be 1 N-m-s. * Ahead has 10 passes during the week, and overall coverage is nominal. 70 meter passes, all using station 14 at 720 kbps, are scheduled for Tuesday, May 20, Friday, May 23, and Sunday, May 25. The following passes will be carried out at 160 kbps: Wednesday, May 21 (D55), and Saturday, May 24 (D65). The following station 26 passes will be carried out at 240 kbps: Monday, May 19, and Thursday, May 22. * Behind has 11 passes during the week, and overall coverage is nominal. 70 meter passes, all at 720 kbps, are scheduled for Monday, May 19 (D63), Wednesday, May 21 (D14), and Friday, May 23 (D63). The following passes will be carried out at 160 kbps: Tuesday, May 20 (D24), Thursday, May 22 (D54), Friday, May 23 (D24), and Saturday, May 24 (D55, D15). The station 26 pass on Sunday, May 25, will be carried out at 240 kbps. Week 22 (May 26-Jun 1) * Ahead has 12 passes during the week, and overall coverage is nominal. 70 meter passes, all at 720 kbps, are scheduled for Monday, May 26 (D14), Friday, May 30 (D63), and Saturday, May 31 (D63). The following passes will be carried out at 160 kbps: Tuesday, May 27 (D55), Friday, May 30 (D26), and Sunday, Jun 1 (D25). The station 26 pass on Wednesday, May 28, will be carried out at 240 kbps. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- 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) ------------------------------------------------------------------------------- Scheduled activities for Week 21: M May 19 (139) T May 20 (140) Ahead: SECCHI stepped calibration roll, 14:45 UT W May 21 (141) T May 22 (142) F May 23 (143) S May 24 (144) S May 25 (145) ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 26 (146) T May 27 (147) W May 28 (148) T May 29 (149) F May 30 (150) S May 31 (151) S Jun 01 (152) ------------------------------------------------------------------------------- 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