STEREO Weekly Meeting Minutes for 2014-09-30 (Week 40) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. Ahead is operating on the first side lobe of the HGA to prevent overheating of the feed assembly. Behind is currently in solar conjunction testing. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 39 (Sep 22-28) * On day 267 (Sep 24), on the Ahead spacecraft, the SECCHI instrument team tested the second side lobe real-time data rate of 1005 bps. * The average daily science data return for Ahead, while operating on the first side lobe on the HGA, was 0.071 Gbits during this week. * On day 271 (Sep 28), during the DSS-14 support for Behind, for the first side lobe test track at the start of the Behind solar conjunction spacecraft testing, initial telemetry lock was 14 minutes late due to telemetry mis-configurations at the station. This anomaly resulted in the loss of 2.7 hours of spacecraft SSR data only. * On day 270 (Sep 27), final preparations for testing the solar conjunction configuration on the Behind observatory were conducted. The IMPACT instrument suite ramped down the necessary high voltages and the SECCHI COR1 and 2 covers were closed. The remaining science data on the SSR was played back. The necessary spacecraft bus telemetry configurations for side lobe operations were loaded to C&DH RAM and verified. In accordance with the solar conjunction entry procedure, a final snapshot of the analog diagnostic data in the data summary table was dumped. The PLASTIC and IMPACT instrument suites were powered down at 1800z and the SECCHI instrument at 1805z. The SWAVES instrument remained on as it will for the actual solar conjunction. Reduced gyro operations are continuing and G&C control gains were adjusted for lack of SECCHI guide telescope input. The timetag commands for the 67th momentum dump with ignition at 271-1630z were loaded and verified. * On day 271 (Sep 28), solar conjunction spacecraft testing on Behind continued with operations on the first side lobe and simulated entry into solar conjunction on the Behind observatory. At AOS of the 1530z support with DSS-14, the downlink was acquired on the first HGA side lobe at the 10 kbps downlink rate with 2.2 dB margin. Due to the low elevation and low ranging margin on BEHIND side lobes, ranging lock could not be obtained. As periodic momentum dumps will be necessary during side lobe operations, the 67th momentum dump executed with ignition at 1630z successfully with the system momentum target set low for rotating during solar conjunction. To simulate solar conjunction entry and test the modified safing mode on orbit, the Behind observatory was reset at 1730z. The SSR was not emptied before resetting due to the low downlink rate and as a result 6.4 hours of SWAVES SSR data was lost from 1110z through 1735z and 2.7 hours of spacecraft housekeeping data was lost as well. The DSN reacquired the downlink on the second side lobe at the 633 bps downlink rate using a second DSN receiver channel at 1752z as expected. The spacecraft autonomously recovered into C&DH standby mode nominally, with the exception of the star tracker, which promoted to AAD mode 12 minutes late. As designed, with the lack of star tracker data, IMU-A was powered on by the fault protection system to ensure stable G&C performance and remained on for 2.2 hours. This was the 3rd occurrence since launch of the Behind star tracker not promoting to AAD mode after it was reset. The Behind HGA feed temperature cooled to 61.2 deg C on the second HGA side lobe. * The average daily SSR playback volume for Behind was 2.9 Gbits during this week. * The current HGA feed horn temperatures are 108 C on Ahead, at an antenna angle of 9.0 degrees, and 61.2 C on Behind, at an antenna angle of 15.3 degrees. Week 40 (Sep 29-Oct 5) * A momentum dump on Ahead will be carried out on Tuesday, Sep 30, with ignition at 22:00 UT. The commands for the momentum dump were loaded during the previous pass. * Solar conjunction testing on Behind is continuing during the week. The earlier testing on Ahead concentrated on the process of going into solar conjunction. These tests will concentrate on the process of coming out. The recorder is also reconfigured during these tests, which was not done during the Ahead testing. * During the first pass on Monday, Sep 29, the MOC watched the spacecraft rotate. At 05:30 UT a macro put the spacecraft into 3-axis stabilized mode. * The signal levels from Behind look good. At the time of the telecon, Behind is up on the 34-meter station 25, and the signal has 2 dB of margin at 633 bps on the second side lobe at a 20 degree elevation. * On Tuesday, Sep 30, the 48 hour fault protection rule will trigger at 17:30 UT, switching to the -Z LGA. This will occur during the station 25 pass. * On Wednesday, Oct 1, Behind the soft command load timer will trigger at 5:30 UT, switching to the +Z LGA, and start the spacecraft slowly rotating. Station 14 will acquire the signal at 15:30, at 12 bps, and will watch the spacecraft rotate. This will provide an opportunity to calibrate the LGA on a 70 meter station. At 17:50, the 3 day hard command loss timer will trigger, resetting the spacecraft, and setting it back to 3 axis stabilized on the second side lobe. It will then be commanded to a 1 degree offset at 120 kbps, and spacecraft will be reconfigured back to operational mode. * On Thursday, Oct 2, the spacecraft will come up at a 1 degree offset, and will be commanded back to the center of the main lobe. Instrument power on is expected to begin during the station 36 support starting at 15:35 UT, with actual instrument commanding starting no earlier than 16:35 UT. An ESA New Norcia support is also available later in the day, as well as another DSN support and an ESA New Norcia support on Friday. The remainder of the passes during the week will be using 70 meter stations. There are at least two passes each day from Thursday to Monday. The current round-trip light travel time is 32 minutes. * The MOC will keep the instrument teams informed of the testing status throughout the week. * Ahead has 9 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has 14 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, one pass at 160 kbps, six passes at 120 kbps, three passes at 0.633 kbps, and one pass at 0.012 kbps. ESA passes have been scheduled for Thursday and Friday, Oct 2-3. Week 41 (Oct 6-12) * PLASTIC is expected to be reconfiguring their instrument on Monday and Tuesday, Oct 6-7. * Ahead has seven passes during the week, all at 10 kbps on the first side lobe, in SWAVES prime mode. * Behind has 13 passes during the week, and overall coverage is nominal. There are six passes at 720 kbps, one pass at 160 kbps, and six passes at 120 kbps. An ESA New Norcia pass is scheduled for Thursday, Oct 9. Week 42 (Oct 13-19) * A Project Interface Test (PIT) with station 35 is scheduled for the Behind spacecraft on Monday, Oct 13. There will be no SSR playback or instrument commanding during this pass. * The 30th SECCHI step-calibration roll for Behind is on Tuesday, Oct 14 (orbit mid-point) starting at 12:00 UT. System momentum is expected to be 1 N-m-s. This will be the last step-calibration roll on Behind before the start of side-lobe operations. * Ahead has nine passes during the week; eight are regular DSN passes at 10 kbps. There will also be an additional ESA pass with New Norcia on Thursday, Oct 17, for spacecraft health and safety. There will be no science coming down on this track and, because it is only 1.3 hours long, probably not enough time to send commands. All commanding is on the first side lobe, in IMPACT prime mode. * Behind has 12 passes during the week, and overall coverage is nominal. There are three passes at 720 kbps, three passes at 160 kbps, and six passes at 120 kbps. Week 43 (Oct 20-26) * The solar conjunction readiness review for both spacecraft is scheduled for Thursday, Oct 23, from 8:30-1:00 EDT. * Saturday, Oct 25, is the eighth anniversary of the launch of STEREO. * Ahead has 7 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. * Behind has 13 passes during the week, and overall coverage is nominal. There are three passes at 160 kbps, and ten passes at 120 kbps. Three of the passes are with the ESA New Norcia station. * Increased use of ESA stations is expected as the STEREO spacecraft move into contention with other missions. Week 44 (Oct 27-Nov 2) * Daily savings time in the U.S. ends on Sunday, Nov 2. * The 68th momentum dump on Behind will be carried out on Tuesday, Oct 28, with ignition at 22:00 UT. The commands will be loaded on the previous pass. * Ahead has 7 passes during the week, all at 10 kbps on the first side lobe, in IMPACT-prime mode. * Behind has 12 passes during the week, and overall coverage is nominal. Two passes are at 720 kbps, two at 160 kbps, and eight at 120 kbps. Four of the passes are with the ESA Malargue and New Norcia stations. Week 45 (Nov 3-9) * The long duration ephemeris for Behind will be loaded onto RAM on Tuesday, Nov 4. * Ahead will be shifted to the second side lobe at the end of the track on Sunday, Nov 9. * Ahead has 7 passes during the week, all at 10 kbps on the first side lobe, in SWAVES-prime mode. * Behind has 13 passes during the week, and overall coverage is short 13 hours between Monday-Thursday, Nov 3-6, and on Sunday, Nov 9. There is one pass at 720 kbps, two passes at 160 kbps, and ten passes at 120 kbps. Five of the passes are with ESA stations. Other * A comment was made that alarm messages about star tracker resets on Behind are being broadcast. This refers to the reset that occured on Sunday, and can't be cleared without disturbing the hard command loss timer countdown. * The use of DSN 34 meter stations to bring down space weather beacon data at 633 bps is being considered. This would have a significant impact on DSN costs. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 40: M Sep 29 (272) Behind: Solar conjunction testing continues Behind: Timed command to 3-axis stabilized, 5:30 UT T Sep 30 (273) Behind: Switch to -Z LGA, 17:30 UT Ahead: Momentum dump, 22:00 UT W Oct 01 (274) Behind: Switch to +Z LGA and start rotating, 5:30 UT Hard command loss timer, 17:50, switch to 3 axis stab. Switch from 2nd side lobe to 1 degree offset, 120 kbps T Oct 02 (275) Behind: Command back to 0 degree offset on main lobe. Recover spacecraft, start powering instruments back on. F Oct 03 (276) Behind: Continue recovery as needed S Oct 04 (277) S Oct 05 (278) Notes: * Test of solar conjunction operations on Behind, Sep 27-Oct 3 * Ahead operating on first side lobe, in IMPACT-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 41: M Oct 06 (279) T Oct 07 (280) W Oct 08 (281) T Oct 09 (282) F Oct 10 (283) S Oct 11 (284) S Oct 12 (285) Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 42: M Oct 13 (286) Behind: PIT test with station 35 T Oct 14 (287) Behind: SECCHI stepped calibration roll, 12:00 UT W Oct 15 (288) T Oct 16 (289) F Oct 17 (290) Behind: Comet Siding Spring encounter with Mars S Oct 18 (291) S Oct 19 (292) Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 43: M Oct 20 (293) T Oct 21 (294) W Oct 22 (295) T Oct 23 (296) Both: Solar Conjunction Readiness Review F Oct 24 (297) S Oct 25 (298) 8th anniversary of STEREO launch S Oct 26 (299) Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 44: M Oct 27 (300) T Oct 28 (301) Behind: Momentum dump, 22 UT W Oct 29 (302) T Oct 30 (303) F Oct 31 (304) S Nov 01 (305) S Nov 02 (306) End of daily savings time in U.S. Notes: * Ahead operating on first side lobe, in IMPACT-prime mode. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Scheduled activities for Week 45: M Nov 03 (307) T Nov 04 (308) W Nov 05 (309) T Nov 06 (310) F Nov 07 (311) S Nov 08 (312) S Nov 09 (313) Notes: * Ahead operating on first side lobe, in SWAVES-prime mode. * HGA on Ahead will be switched to second side lobe at the end of the track on Sunday, Nov 9. * Passage of Comet Siding Spring through HI2 on Behind, Sep 07-Nov 15 ------------------------------------------------------------------------------- Upcoming events: 2014: * Sep 07-Nov 15 Behind: Passage of Comet Siding Spring through HI2-B * Nov 10 Ahead: HGA on 2nd side lobe * Nov 17 Ahead: Test with 34 meter at 633 bps * Nov 19 Behind: HGA hits soft stop * Nov 28 Behind: SSR reconfiguration * Dec 1 Behind: HGA on 1st side lobe * Dec 8 Behind: Test with 34 meter at 633 bps, both side lobes 2015: * Jan 6 Behind: HGA on 2nd side lobe * Jan 12 Behind: Test with 34 meter at 633 bps * Jan 20 Behind: Instrument power down * Jan 22 - Mar 23 Behind: Spacecraft behind Sun * Mar DAWN - Ceres arrival * Mar 22 Ahead: Instrument power down * Mar 23 - Apr 06 Behind: S/C SSR Playback at 3 kbps * Mar 24 - Jul 07 Ahead: Spacecraft behind Sun * Mar 30 Behind: Instrument power on * Apr 25 Behind: HGA on 1st side lobe * Jul DAWN - End of nominal mission * Jul 8 Behind: HGA on 2nd side lobe * Jul 7-28 Ahead: S/C SSR Playback at 3 kbps * Jul 14 Ahead: Instrument power on * Sep 24 Ahead: HGA on 1st side lobe * Nov 20 Behind: HGA on 1st side lobe * Dec 29 Ahead: HGA on main lobe, offpoint 1 degree Ahead: SSR playback and reconfiguration, S/C checkout * Dec 31 Ahead: Instrument recommissioning 2016: * Jan 2 Behind: HGA on main lobe Behind: SSR playback and reconfiguration, S/C checkout * Jan 5 Behind: Instrument recommissioning * Jan 27 Both: HGA calibration * Feb 19 Ahead: HGA on main lobe * Mar 16 Both: Post Solar Conjunction Assessment Review * 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