STEREO Weekly Meeting Minutes for 2011-05-31 (Week 22) ANNOUNCEMENTS ------------- * None. INSTRUMENT and SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 21 * On day 144 (May 24), during the DSS 55 support for Ahead, turbo decoder lock was lost briefly at 0457z. This resulted in the loss of 34 frames of instrument SSR data. See DR# N107355 for more information. * On day 144 (May 24), during the DSS 24 support for Ahead, turbo decoder lock was lost briefly at 1923z. This resulted in the loss of one frame of instrument SSR data. See DR# N107361 for more information. * On day 147 (May 27), during the DSS 26 support for Ahead, initial telemetry acquisition was delayed 103 minutes due to a power outage at Goldstone. After electrical power was restored, telemetry lock was established at 1703z. The SSR playback was stopped and SSR pointers were repositioned. All SSR data were recovered. See DR# G111614 for more information. * On day 143 (May 23), during the DSS 65 support for Behind, turbo decoder lock was lost intermittently beginning at 1743z, 1858z, and 1915z. This resulted in the loss of several minutes of instrument SSR data. See DR# N107359 and N107363 for more information. * On day 144 (May 24), during the DSS 55 support for Behind, turbo decoder lock was lost briefly at 1918z. This resulted in the loss of one frame of instrument SSR data. See DR# N107360 for more information. * On day 144, downlink for the BEHIND observatory was configured to 360 kbps, for a duration of three hours, for testing the turbo rate 1/4 decoding capability of the ESA New Norcia station in support of the future NASA/ESA ExoMars mission. No SSR data were played back, and the realtime data were not visible within the MOC. The result of the test is not yet known. However, the signal was very weak. A lower telemetry rate would have had a stronger signal, but STEREO cannot go to lower rates at turbo 1/4. The usual STEREO operation mode is Turbo 1/6. * The average daily SSR downlink volume was 5.9 gigabits for Ahead, and 5.5 gigabits for Behind. Week 22 * SECCHI-Ahead had a watchdog reset yesterday (May 30) at 03:41 UT. Recovery back to Ops mode was completed by 15:35 UT the same day. * Turbo lock was lost briefly during the station 54 pass for Ahead early this morning (May 31). * The 32nd momentum dump on Behind was carried out this morning (May 31), with ignition at 16:00 UT. * The 38th momentum dump on Ahead will be carried out tomorrow (Jun 1), with ignition at 14:30 UT. * The STE-D door on Behind functioned normally this morning. After the last momentum dump, the instrument appeared to be working correctly, but the instrument's telemetry did not indicate open. The housekeeping rate was increased to watch for any possible anomalies. This was also be done for the Ahead momentum dump tomorrow. * In preparation for switching to the 160 kbps downlink rate in late June, early July, the DSN time has been increased to 8 hours/day on both spacecraft. * Ahead has 720 kbps passes on Monday, May 30 (D14), Thursday, Jun 2 (D14 and D43), and Friday, Jun 3 (D63). There are 13 passes during the week, and overall coverage is nominal. * Behind has 720 kbsp passes on Tuesday, May 31 (D63), Wednesday, Jun 1 (D63), Thursday, Jun 2 (D63), Friday, Jun 3 (D63), Saturday, Jun 4 (D63), and Sunday, Jun 5 (D43). There are 10 passes during the week, and overall coverage is nominal. * The subreflector on station 14 is currently fixed at 45 degrees. This reduces the signal strength by 2 dB. Ahead is scheduled to use station 14 on Thursday. There should be enough signal strength, even with the 2 dB reduction. The problem should be fixed by Friday. Week 23 * The IONET switches at APL will be upgraded. The backup switch will be upgraded on Jun 6 between 13-16 UT, which is during a track. This should not have an effect. The primary switch will be upgraded on Jun 8 between the Ahead pass ending at 14:45 UT, and the Behind pass starting at 16:50 UT. * Ahead has 720 kbps passes on Monday, Jun 6 (D14), Wednesday, Jun 8 (D63), Thursday, Jun 9 (D63), Friday, Jun 10 (D14), and Sunday, Jun 12 (D43). There are 12 passes during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Monday, Jun 6 (D63), Tuesday, Jun 7 (D63), Friday, Jun 10 (D63), Saturday, Jun 11 (D63), and Sunday, Jun 12 (D43). There are 14 passes during the week, and overall coverage is nominal. Week 24 * There will be a 2 hour return-to-service track on station 34 for Ahead on Jun 14. There will be no SSR playback during this track. Uplink will be enabled. * There will be test of the 160 kbps downlink during the station 25 pass for Ahead on Wednesday, Jun 15. The prior pass will be a 70 meter station, and a long 70 meter pass follows the test, so no data will be lost. Since the in-situ teams are planning to drop their telemetry rates for 160 kbps, this can be tested during the Jun 15 pass, but this is not required. The telemetry rates will drop to 160 kbps on Jun 27 for Ahead, and Jul 13 for Behind. At the same time that the nominal telemetry rate drops to 160 kbps, the telemetry rate for the 70 meter stations will drop from 720 kbps to 480 kbps. * Ahead has 720 kbps passes on Monday, Jun 13 (D63), Tuesday, Jun 14 (D63 and D14), Wednesday, Jun 15 (D63), and Thursday, Jun 16 (D43). There are 12 passes during the week, and overall coverage is 4.2 hours above nominal. * Behind has 720 kbps passes on Monday, Jun 13, Tuesday, Jun 14, and Wednesday, Jun 15, all using station 63. There are 14 passes during the week, and overall coverage is 1.5 hours above nominal. Week 25 * Ahead has a 720 kbps pass on Friday, Jun 24, using station 43. There are 10 tracks during the week, and overall coverage is 2.1 hours above nominal. * Behind has a 720 kbps pass on Sunday, Jun 26, using station 63. There are 14 tracks during the week, and overall coverage is 8 hours above nominal. Week 26 * Ahead switches downlink rate to 160 kbps on 35 meter stations, and 480 kbps on 70 meter stations on day 178 (Jun 27), starting with the station 15 pass. 480 kbps is the lowest rate that Ahead is projected to use with 70 meter stations--Behind will drop to 360 kbps for periods near the far side. * Ahead has 480 kbps passes on Thursday, Jun 30 (D63), and Sunday, Jul 3 (D43). There are 10 passes during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Monday, Jun 27, Wednesday, Jun 29, Thursday, Jun 30, Friday, Jul 1, and Saturday, Jul 2, all using station 63. There are 12 passes during the week, and overall coverage is nominal. Week 27 * Monday, July 4 is a holiday. * Ahead has 480 kbps passes on Tuesday, Jul 5 (D63 and D14), Wednesday, Jul 6 (D63 and D14), Thursday, Jul 7 (D14), and Friday, Jul 8 (D63). There are 13 passes during the week, and overall coverage is nominal. * Behind has 720 kbps passes on Tuesday, Jul 5 (D63), Friday, Jul 8 (D43), and Sunday, Jul 10 (D63). There are 12 passes during the week, and overall coverage is nominal. Week 28 * Behind will switch to the 160 kbps rate for 35 meter stations, and 480 kbps for 70 meter stations, starting with the station 55 pass on Jul 13. * Both spacecraft will have an HGA calibration on Jul 13, with Ahead starting at 15:00 UT, and Behind starting at 16:00 UT. * Behind will have a momentum dump on Tuesday, Jul 12, starting at 19:30 UT. * Ahead will have the 39th momentum dump on Thursday, Jul 14, starting at 15:00 UT. * Ahead has 480 kbps passes on Tuesday, Jul 12, and Saturday, Jul 16, both using station 43. There are 10 passes during the week, and overall coverage is 3.6 hours above nominal. * Behind has 720 kbps passes on Tuesday, Jul 12 (D43 and D63), and 480 kbps passes on Thursday, Jul 14 (D43), Friday, Jul 15 (D43 and D63), and Sunday, Jul 17 (D43). There are 15 passes during the week, and overall coverage is 4.1 hours above nominal. Other * The SECCHI team is still discussing what special observations they would like to make of Comet Elenin during its close approach to STEREO Behind. The closest approach is about 0.05 AU around mid-day on Jul 31. This is also the approximate time that the comet first becomes visible in the HI2-B telescope if the spacecraft is rotated by about 135 degrees to the south. They are considering which days they would like to rotate the spacecraft, and for how many hours. For simplicity of operations, the MOC would prefer a single roll angle if possible, instead of customizing the roll angle for each date. A roll angle of 135 degrees would keep Comet Elenin within the HI2-B field-of-view through Aug 5, and would also allow the comet to be seen in HI1-B from Aug 6-12. After Aug 15, Comet Elenin will be visible in HI1-B without any rotation. At that point it will have receded to a distance of 0.27 AU. APL will look into what the system momentum will be during the period of interest, and whether roll operations are feasible. The other instrument teams are also interested in what rolls may be planned, how often and for how long, since it affects their own measurements. SECCHI will come up with a more definite plan for observing Comet Elenin, and present it at the next weekly telecon. COORDINATED OBSERVATIONS ------------------------ ------------------------------------------------------------------------------- Scheduled activities for Week 22: M May 30 (150) Memorial Day Ahead: 720 kbps downlink on station 14 T May 31 (151) Behind: 720 kbps downlink on station 63 Behind: Momentum dump, 16:00 UT W Jun 01 (152) Ahead: Momentum dump, 14:30 UT Behind: 720 kbps downlink on station 63 T Jun 02 (153) Ahead: 720 kbps downlink on stations 14 and 43 Behind: 720 kbps downlink on station 63 F Jun 03 (154) Ahead: 720 kbps downlink on station 63 Behind: 720 kbps downlink on station 63 S Jun 04 (155) Behind: 720 kbps downlink on station 63 S Jun 05 (156) Behind: 720 kbps downlink on station 43 Notes: * Changing to 8 hours/day of downlink on both spacecraft in preparation for switching to 160 kbps downlink rate in late June, early July. ------------------------------------------------------------------------------- Scheduled activities for Week 23: M Jun 06 (157) Ahead: 720 kbps downlink on station 14 Behind: 720 kbps downlink on station 63 T Jun 07 (158) Behind: 720 kbps downlink on station 63 W Jun 08 (159) Ahead: 720 kbps downlink on station 63 T Jun 09 (160) Ahead: 720 kbps downlink on station 63 F Jun 10 (161) Ahead: 720 kbps downlink on station 14 Behind: 720 kbps downlink on station 63 S Jun 11 (162) Behind: 720 kbps downlink on station 63 S Jun 12 (163) Ahead: 720 kbps downlink on station 43 Behind: 720 kbps downlink on station 43 ------------------------------------------------------------------------------- Scheduled activities for Week 24: M Jun 13 (164) Ahead: 720 kbps downlink on station 63 Behind: 720 kbps downlink on station 63 T Jun 14 (165) Ahead: 720 kbps downlink on stations 63 and 14 Behind: 720 kbps downlink on station 63 Ahead: Return-to-service track on station 34 W Jun 15 (166) Ahead: 720 kbps downlink on station 63 Ahead: Test of 160 kbps on station 25 Behind: 720 kbps downlink on station 63 T Jun 16 (167) Ahead: 720 kbps downlink on station 43 F Jun 17 (168) S Jun 18 (169) S Jun 19 (170) ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 20 (171) T Jun 21 (172) W Jun 22 (173) T Jun 23 (174) F Jun 24 (175) Ahead: 720 kbps downlink on station 43 S Jun 25 (176) S Jun 26 (177) Behind: 720 kbps downlink on station 63 ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 27 (178) Ahead: Switch downlink rate to 160 kbps, 480 kbps for 70 m Behind: 720 kbps downlink on station 63 T Jun 28 (179) W Jun 29 (180) Behind: 720 kbps downlink on station 63 T Jun 30 (181) Ahead: 480 kbps downlink on station 63 Behind: 720 kbps downlink on station 63 F Jul 01 (182) Behind: 720 kbps downlink on station 63 S Jul 02 (183) Behind: 720 kbps downlink on station 63 S Jul 03 (184) Ahead: 480 kbps downlink on station 43 ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jul 04 (185) Independence day T Jul 05 (186) Ahead: 480 kbps downlink on stations 63 and 14 Behind: 720 kbps downlink on station 63 W Jul 06 (187) Ahead: 480 kbps downlink on stations 63 and 14 T Jul 07 (188) Ahead: 480 kbps downlink on station 14 F Jul 08 (189) Ahead: 480 kbps downlink on station 63 Behind: 720 kbps downlink on station 43 S Jul 09 (190) S Jul 10 (191) Behind: 720 kbps downlink on station 63 ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 11 (192) T Jul 12 (193) Behind: Momentum dump, 19:30 UT Ahead: 480 kbps downlink on station 43 Behind: 720 kbps downlink on stations 43 and 63 W Jul 13 (194) Behind: Switch downlink rate to 160 kbps Behind: End use of 720 kbps on 70 m DSN subnet HGA calibration, Ahead: 15:00 UT, Behind: 16:00 UT T Jul 14 (195) Ahead: Momentum dump, 15:00 UT Behind: 480 kbps downlink on station 43 F Jul 15 (196) Behind: 480 kbps downlink on stations 43 and 63 S Jul 16 (197) Ahead: 480 kbps downlink on station 43 S Jul 17 (198) Behind: 480 kbps downlink on station 43 Notes: * Dawn expected to achieve orbit about Vesta around Jul 16. ------------------------------------------------------------------------------- Upcoming events: 2011: * Jul 31 Behind: Close approach by comet Elenin 2012: * Jan 11 Both: HGA calibration * Jul DAWN - Vesta departure * Jul 11 Both: HGA calibration * Nov 4 Behind: Switch downlink rate to 120 kbps * Nov 13 Total solar eclipse, south Pacific 2013: * May 3 Ahead: Switch downlink rate to 120 kbps * Dec 12 Ahead: Mercury transit 2014: * Jan 20 Behind: End use of 480 kbps on 70 m DSN subnet * Apr 21 Behind: Resume use of 480 kbps on 70 m DSN subnet * Apr 29 Behind: Mercury transit * Oct 15 Behind: End use of 480 kbps on 70 m DSN subnet 2015: * Feb DAWN - Ceres arrival * Jan 20 - Mar 28 (TBC) Behind: Spacecraft behind Sun * Mar 17 - Jul 14 (TBC) Ahead: Spacecraft behind Sun * Jul 2 Behind: Resume use of 480 kbps on 70 m DSN subnet * Aug 25 - Oct 19 (TBC) Behind: Spacecraft behind Sun * Sep 25 Behind: End use of 480 kbps on 70 m DSN subnet * Jul DAWN - End of nominal mission 2016: * Apr 3 Behind: Resume use of 480 kbps on 70 m DSN subnet 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