STEREO Weekly Meeting Minutes for 2014-07-08 (Week 28) ANNOUNCEMENTS ------------- * See the discussion below about solar conjunction operation testing during week 28. * A new phone number will be assigned to this telecon. As soon as this number is known, it will be distributed to all team members. * EA mode will no longer be used on the spacecraft. After the spacecraft come out from conjunction, this will free up an additional 100 Mbits of SSR space for the instruments. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 27 (Jun 30-Jul 6) * On day 185 (Jul 4), the DSS-55 support for Ahead was cancelled due to antenna being declared red. No other stations were available for tracking. On the next support later that day at 1430z, SSR pointers were repositioned to prevent SSR data loss. See DR #M108128 for more information. * On day 186 (Jul 5), during the DSS-55 support for Ahead, turbo decoder lock was lost at 1059z. This anomaly resulted in the loss of one frame of SSR data. * On day 182 (Jul 1), IMPACT unsuccessfully loaded a flight software patch to LET on Ahead to reduce telemetry generation in preparation for HGA side lobe operations. The same patch is believed to have been uploaded to Behind successfully yesterday (Jul 7). The IMPACT team is planning a telecon to discuss the anomaly. * On day 187 (Jul 6), final preparations for testing the solar conjunction configuration on the Ahead observatory were conducted. The PLASTIC and IMPACT instrument suites ramped down the necessary high voltages and the SECCHI COR1 and 2 covers were closed. A flight software patch was loaded to the IMPACT IDPU in preparations for the reduced data rates on HGA side lobes. The remaining science data on the SSR was played back. The necessary S/C bus telemetry configurations for side lobe operations were loaded to C&DH RAM and verified consisting of MOps macro release 1.1.22. 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 1830z, the SECCHI instrument at 1835z, and the SWAVES instrument at 1840z. Reduced gyro operations are continuing and G&C control gains were adjusted for lack of SECCHI GT input. The S/C was configured for the first side lobe use on the HGA for the next track on day 188. In between DSN tracks, the spacecraft was configured for the solar conjunction side lobe emergency communication data rates, 633 bps downlink and 125 bps uplink, broadcasting S/C bus telemetry. The Ahead HGA feed temperature is continuing to track according to predictions, currently at 108 degrees C. * Three issues have so far been identified with the solar conjunction testing, two of which were already known. It was known that ranging lock would be intermittent on the side lobes, and flight dynamics is looking into whether Doppler data can be used instead. Another known problem is that the partitions were not reassigned for testing, because the instrument partition sizes weren't known, so the G&C telemetry will start overwriting. * The unanticipated issue encountered with the solar conjunction testing is that the star tracker did not come completely up after the reset. This has happened twice before on each spacecraft, for varying durations, and has also been seen on other missions with this model star tracker. The fault protection rules powered on the IMU to take over from the star tracker, which later successfully promoted to full operational mode in a little under an hour. The IMU is still on, since no commands will be sent to the spacecraft for the next three days. The IMU is a consumable resource, and should not be on during the entire out-of-contact period, so an autonomy rule is needed to power off the IMU once the star tracker is online. There will be a chance to test this new autonomy rule during the corresponding Behind testing in late September, early October. * Conjunction testing is on schedule so far. The earliest opportunity to start turning on the instruments is projected for Friday, starting at 05:30 UT. * On day 181 (Jun 30), during the DSS-14 support for Behind, telemetry lock was lost intermittent at BOT at 1840z due to a sub reflector anomaly. To increase the downlink received power, the downlink rate was changed to 360 kbps and SSR pointers were repositioned. This anomaly resulted in the SECCHI partition 19 to fill beginning at 182-0657z for 19 minutes. See DR #G115182 for more information. * It was reported that the gap in SECCHI-Behind data is much larger than the 19 minutes described above, closer to 13 hours. The SECCHI team had requested that pointers be moved to avoid losing calibration data taken during the momentum dump, and this may have led to a much larger data gap prior to the dump. * On day 186 (Jul 5), during the DSS-54 support for Behind, turbo decoder lock was lost intermittently between 0853z through 1208z. This anomaly resulted in the loss of 10 frames of SSR data. * On day 183 (Jul 2), the 64th momentum dump was executed successfully on Behind at 2000z, which imparted a delta V of 0.081 m/sec. * The average daily SSR playback volume during the week was 5.4 gigabits for Ahead, and 48.8 gigabits for Behind. Week 28 (Jul 7-13) * The 69th momentum dump on Ahead was conducted successfully yesterday 9 UT while the HGA is on the first side lobe. The momentum was adjusted to a lower setting than usual, 8 N-m-s, as will be done during solar conjuction. * After the momentum dump, the Ahead spacecraft was commanded into a reset at 09:45 UT. It was then at a data rate of 633 bps downlink, and 125 bps upload, and came up on the HGA second side lobe. No more commands will be sent up to the spacecraft for the next three days to simulate the situation during conjunction. * Tomorrow, Jul 9, at 02:45 UT (late tonight EDT), a time-tagged command will start the Ahead spacecraft rolling. It will then cycle through the antennas, starting with the -Z LGA 7 hours later at 09:45 UT. After 12 hours it will switch to the +Z LGA at 21:45 UT. The telemetry rate at this point will be 12 bps downlink, 28 bps uplink. The DSN will attempt lock on this signal on Thursday morning, Jul 10. * On Thursday, Jul 10, at 09:45 UT, the Ahead spacecraft will autonomously reset after not having received any commands for 3 days. It will continue to rotate. There will be a one hour support with station 55 to observe this. After the reset, the spacecraft will be back on the HGA antenna. Only the carrier will be visible--the station will not be able to lock on. * A time-tagged command will put the Ahead spacecraft back into three-axis stabilized mode on the 2nd side lobe at 19:45 UT, prior to the second DSN support on Thursday, Jul 10. This will be followed by a test of the 1 degree HGA off-point configuration. The telemetry rate on the 70 meter station will be 360 kbps downlink, and 2 kbps uplink. * Ahead spacecraft recovery will start immediately after the 1 degree HGA off-point test. The SSR will be played back, and nominal SSR playback will be carried out after that. There is a 4 hour track, and a 9.6 hour track after that. * If all goes well, instruments should be able to start powering on during the station 63 pass on Friday, Jul 11, starting at 05:30 UT. Before the end of the track, the HGA will be returned back to nominal pointing for passes starting Saturday, Jul 12. There are three supports on Saturday, for a total of about 12 hours, and three supports on Sunday, also for about 12 hours. * Behind will reach perihelion tomorrow, Jul 9. System momentum will be high, and the SECCHI stepped calibration roll will be delayed by one week. * Overall, Ahead has 13 passes during the week, with ten 70 meter passes, and three 34 meter passes. * Behind has 8 passes during the week, and overall coverage is nominal. No 70 meter passes are scheduled during the week. All passes are at 160 kbps. * The current HGA feed temperatures are 72 degrees on Ahead, at an SLE angle of 15.1 degrees while on the second side lobe, and 108 degrees on Behind at an SLE angle of 8.5 degrees. Week 29 (Jul 14-20) * On Sunday, Jul 15, is the 29th SECCHI Step Calibration on Behind at 0435z for perihelion. System momentum will be 3 N-m-s. * On Sunday, Jul 15, the 20th HGA calibration on Behind will be carried out at 13:00 UT, during the station 63 pass. The SPE angle is 8.8 degrees, which is safe for carrying out the calibration. * A 2 hour Project Interface Test (PIT) will be carried out between the Ahead spacecraft and the new 34 meter station D35 at Canberra. There will be no instrument commanding or SSR playback during this pass. This test will be mostly a connectivity test. * Ahead has 13 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Thursday, Jul 17 (D43 at 720 kbps), Friday, Jul 18 (D63), Saturday, Jul 19 (D43 at 720 kbps), and Sunday, Jul 20 (D14 at 720 kbps). The following passes will be carried out at 160 kbps: Tuesday, Jul 15 (D55), Wednesday, Jul 16 (D65), Thursday, Jul 17 (D55), Saturday, Jul 19 (D55 and D15), and Sunday, Jul 20 (D65). ESA Malargue passes are scheduled for Monday and Tuesday, Jul 14-15. * Behind has 10 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Jul 14 (D63), Tuesday, Jul 15 (D63 at 720 kbps), Friday, Jul 18 (D63 at 720 kbps), and Saturday, Jul 19 (D14). The following passes will be carried out at 160 kbps: Wednesday, Jul 16 (D55), Thursday, Jul 17 (D45 and D54), Friday, Jul 18 (D45), Saturday, Jul 19 (D25) and Sunday, Jul 20 (D55). Week 30 (Jul 21-27) * On Thursday, Jul 24, a 3 hour project interface test (PIT) with the new 34 meter station D35 at Canberra will be carried out with Behind. There will be no instrument commanding or SSR playback during this pass. * On Sunday, Jul 27, a return-to-service pass with station 26 will be carried out. There will be no instrument commanding or SSR playback during this pass. * Ahead has 10 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Tuesday, Jul 22 (D63 at 720 kbps), Wednesday, Jul 23 (D14), Friday, Jul 25 (D14 at 720 kbps), Saturday, Jul 26 (D43), and Sunday, Jul 27 (D14 at 720 kbps). The following passes will be carried out at 160 kbps: Monday, Jul 21 (D54), Thursday, Jul 24 (D55), Saturday, Jul 26 (D54), and Sunday, Jul 27 (D55). * Behind has 12 passes during the week, and overall coverage is nominal. 70 meter passes are scheduled for Monday, Jul 21 (D43 at 720 kbps and D63), Tuesday, Jul 22 (D14 at 720 kbps), Wednesday, Jul 23 (D14 at 720 kbps), Friday, Jul 25 (D63), and Saturday, Jul 26 (D14 at 720 kbps). The following passes will be carried out at 160 kbps: Thursday, Jul 24 (D54), Friday, Jul 25 (D24), Saturday, Jul 26 (D55), and Sunday, Jul 27 (D54). Week 31 (Jul 28-Aug 3) * The HGA angle on Ahead is expected to reach the soft stop on July 28. After this, the telemetry signal will start to drift off the center of the main lobe, and the achievable telemetry rate will start to drop. During week 32, the maximum telemetry rate will still be 720 kbps. This drops to 480 kbps in week 33, and 360 kbps in week 34, after which the spacecraft will switch to side lobe 1. There are two 34 meter supports during week 32 which will be at 96 kbps, on Aug 6 and 9. After that, only 70 meter supports will be used. * C&DH flight software version 3.2.4 will be written EEPROM copy 1 on Ahead on Jul 29. * The 65th momentum dump on Behind will be carried out on Jul 28, with ignition at 19:45 UT. This is earlier than usual due to schedule constraints. * A 3 hour Project Interface Test (PIT) will be carried out on Behind with station 35 on Jul 30. * The RF margin using the 70 meter stations has been reevaluated, and it has been determined that the 720 kbps rate can be used routinely when on the main lobe. From this point on, this rate will be used for all Behind passes until the HGA soft stop limit is reached. * Ahead has 10 passes during the week, and overall coverage is nominal. There is one pass at 720 kbps, one pass at 480 kbps, one pass at 240 kbps, six passes at 160 kbps, and one pass at 120 kbps. * Behind has 10 passes during the week, and overall coverage is nominal. There are five passes at 720 kbps, and five passes at 120 kbps. Week 32 (Aug 4-10) * The 70th momentum dump on Ahead will be carried out on Aug 4, with ignition at 18:00 UT. * Ahead has 10 passes during the week, and overall coverage is nominal. There are seven passes at 720 kbps, one pass at 240 kbps, and two passes at 96 kbps, on Aug 6 and 9. * Behind has 9 passes during the week, and overall coverage is nominal. There are four passes at 720 kbps, three passes at 240 kbps, one pass at 160 kbps, and one pass at 120 kbps. Other * During side lobe 1 operations, the spacecraft will switch weekly between modes emphasizing either SWAVES or IMPACT. There's only one mode of operation for side lobe 2. * The MOC needs to know what additional ApID(s) will be sent down in realtime when in the SWAVES-emphasis mode on side lobe 1. * The SSR space available for the instruments will be split up approximately as 40% for SWAVES, 30% for IMPACT, and 30% for PLASTIC. * The MOC will try to avoid turning off the instruments on Ahead if possible. They will have to make sure that the DFDs for the new instrument rates are properly balanced. This will be especially challenging for the second side lobe. COORDINATED OBSERVATIONS ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 07 (188) Ahead: Momentum dump using first side lobe, 09:00 UT Ahead: Command s/c reset, 09:45 UT, up on second side lobe T Jul 08 (189) W Jul 09 (190) Ahead: Start spacecraft rotation via time-tagged command Behind: Perihelion T Jul 10 (191) Ahead: Autonomous reset, 09:45 UT Ahead: Stop rotating, 19:45 UT, recover back to HGA +1 degree F Jul 11 (192) Instrument SSR partitioning and real-time telemetry rates due S Jul 12 (193) Ahead: Back to nominal HGA pointing. Power on instruments. S Jul 13 (194) Ahead: Continue instrument recovery Notes: * Solar conjunction operations test on Ahead, Jul 6-12. All science instruments will be off during this test. Instrument power on may start as soon as Friday, Jul 11. ------------------------------------------------------------------------------- Scheduled activities for Week 29: M Jul 14 (195) T Jul 15 (196) Behind: SECCHI stepped calibration roll, 04:35 UT Behind: HGA calibration, 13:00 UT W Jul 16 (197) T Jul 17 (198) Ahead: Project interface test with new 34 meter station D35 F Jul 18 (199) S Jul 19 (200) S Jul 20 (201) Notes: * Continuation of instrument power on activities through the week, as needed. ------------------------------------------------------------------------------- Scheduled activities for Week 30: M Jul 21 (202) T Jul 22 (203) W Jul 23 (204) T Jul 24 (205) Behind: Project interface test with new 34 meter station D35 F Jul 25 (206) S Jul 26 (207) S Jul 27 (208) Behind: Return-to-service test with D26 ------------------------------------------------------------------------------- Scheduled activities for Week 31: M Jul 28 (209) Behind: Momentum dump, 19:45 UT T Jul 29 (210) W Jul 30 (211) Behind: Project interface test with new 34 meter station D35 T Jul 31 (212) F Aug 01 (213) S Aug 02 (214) S Aug 03 (215) Notes: * Ahead is expected to reach the soft stop on the HGA angle on July 28. The telemetry rate will slowly drop after this. ------------------------------------------------------------------------------- Scheduled activities for Week 32: M Aug 04 (216) Ahead: Momentum dump, 18:00 UT T Aug 05 (217) W Aug 06 (218) T Aug 07 (219) F Aug 08 (220) S Aug 09 (221) S Aug 10 (222) ------------------------------------------------------------------------------- Upcoming events: 2014: * Aug Ahead: HGA on main lobe, offpoint 1 degree (TBC) * Aug 14 Ahead: Solar Conjunction Readiness Review * Aug 20 Ahead: Instrument power down * Aug 23 Ahead: HGA on 1st side lobe * Sep 07-Nov 15 Behind: Passage of Comet Siding Spring through HI2-B * Sep 18 Behind: MOps Readiness for S/C Testing Review * Sep 29-Oct 6 Behind: Test of solar conjunction operations * Sep 21 MAVEN arrival at Mars * Oct 17 Behind: Comet Siding Spring encounter with Mars * Oct 20 Ahead: Instrument power on * Oct 23 Behind: Solar Conjunction Readiness Review * Nov 10 Ahead: HGA on 2nd side lobe * Nov 19 Behind: HGA hits soft stop * Dec 1 Behind: HGA on 1st side lobe 2015: * Jan 6 Behind: HGA on 2nd side lobe * 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 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 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