STEREO Weekly Meeting Minutes for 2008-06-17 (Week 25) ANNOUNCEMENTS ------------- * None. INSTRUMENT AND SPACECRAFT STATUS -------------------------------- * All subsystems on both spacecraft are nominal, except that the Ahead spececraft is currently operating on IMU #2. DISCUSSION AND OPERATIONS CONSTRAINTS ------------------------------------- Week 24 * The station 26 transmitter developed a problem on day 163 (Jun 11) during the Behind pass. This resulted in a 14 minute SECCHI data gap. It was decided to not re-establish the uplink so as to avoid further gaps. Thus, no commanding or tracking data was available during most of the pass. * The average daily downlink was 7.1 gigabits on Ahead, and 7.5 gigabits on Behind. Week 25 * There will be a momentum dump on Ahead tomorrow (Jun 18) at 14:30 UT. * IMU and ST alignments will be uploaded to G&C RAM on both spacecraft tomorrow (Jun 18). Week 26 * A SECCHI stepped calibration roll is scheduled for Ahead on day 178 (Jun 26) at 08:55. This is the perihelion roll. Perihelion is actually at 21:55 UT on the following day. * A SECCHI stepped calibration roll is scheduled for Behind on day 177 (Jun 25) at 14:20 UT. This is a make-up for the previous calibration roll, which had some pointing problems. * The G&C team has taken steps to increase the probability of success during the upcoming calibration rolls. GT-enable will be maintained throughout the maneuver. GT-rate will be disabled. If the GT saturation validation parameter is invalid, then a slight step will be applied to bring it back into range. Week 27 * SECCHI GT-driven off-points on both spacecraft are scheduled for Monday, day 182 (Jun 30), at 16:15 for Ahead, and 12:15 for Behind. These off-points are used to flat field the EUVI telescope. The total amount of off-point will be no more than 2 arc minutes. Week 28 * The 8th hga calibrations are scheduled on both spacecraft on day 191 (Jul 9), at 14:00 UT for Ahead, and 17:00 UT for Behind. HGA roll scripts in case of star tracker loss will also be tested. These scripts will roll the spacecraft by +/- 0.5 and 1.0 degrees. Other * The next momentum dump on Behind is expected to occur sometime around day 198 (Jul 16). * APL is investigating the possibility of using telemetry rates of 240 and 120 kbps during the extended mission. The initial investigation seems to show that these rates are feasible, but they've never been tested. Once it's been determined that the spacecraft are capable of these rates, APL will work with DSN to plan how to test and use these rates. * On August 4th, the track durations will increase from 4 to 5 hours, in preparation for decreasing the telemetry rate to 480 kbps. It's expected that Ahead will need to drop to 480 kbps in the middle of August, and Behind during the first week in September. The 2 kbps uplink will be maintained. * There was some discussion about track schedules, and how changes to the schedule are distributed to the instrument teams. It was decided to maintain the present system for the time being. COORDINATED OBSERVATIONS ------------------------ ------------------------------------------------------------------------------- Scheduled activities for Week 25: M Jun 16 (168) T Jun 17 (169) W Jun 18 (170) Ahead: momentum dump 14:30 T Jun 19 (171) F Jun 20 (172) S Jun 21 (173) S Jun 22 (174) Notes: * Jun 20-30, SUMER observing ------------------------------------------------------------------------------- Scheduled activities for Week 26: M Jun 23 (175) T Jun 24 (176) W Jun 25 (177) Behind: SECCHI stepped calibration roll, 14:20 T Jun 26 (178) Ahead: SECCHI stepped calibration roll, 08:55 F Jun 27 (179) S Jun 28 (180) S Jun 29 (181) Notes: * Jun 20-30, SUMER observing ------------------------------------------------------------------------------- Scheduled activities for Week 27: M Jun 30 (182) SECCHI GT-driven off-point, Ahead 16:15, Behind 12:15 T Jul 01 (183) W Jul 02 (184) T Jul 03 (185) F Jul 04 (186) S Jul 05 (187) S Jul 06 (188) Notes: * Jun 20-30, SUMER observing ------------------------------------------------------------------------------- Scheduled activities for Week 28: M Jul 07 (189) T Jul 08 (190) W Jul 09 (191) HGA calibrations, Ahead: 14:00, Behind: 17:00 T Jul 10 (192) F Jul 11 (193) S Jul 12 (194) S Jul 13 (195) ------------------------------------------------------------------------------- Scheduled activities for Week 29: M Jul 14 (196) T Jul 15 (197) W Jul 16 (198) Behind: momentum dump (TBC) T Jul 17 (199) F Jul 18 (200) S Jul 19 (201) S Jul 20 (202) ------------------------------------------------------------------------------- Upcoming events: 2008: SECCHI Stepped calibration rolls Ahead: Sep 23, Dec 16 Behind: Aug 26, Dec 2 ICAL-001: Jun 30-Jul 3, Aug 4-8, Sep 1-5 * Jul 23,30 EIT shutterless * Aug 1 Total solar eclipse, 9:20-11:20 UT * Aug 4 Begin 5 hour daily DSN tracks * Aug 11 Ahead: Switch downlink rate to 480 kbps * Sep 8 Behind: Switch downlink rate to 480 kbps * Oct 6 Messenger - Mercury fly-by * Nov 1-Dec 15 SUMER campaign