SOHO Daily Meeting Minutes for Thursday 19 June 2003 ANNOUNCEMENTS ------------- * See note at end for the latest HGA information * A Major Flare Watch has been declared on AR10386. The campaign number is 6961. * GITT scans for the EOF and EAF are scheduled for Thursday 26 June at 9:30am. * Commanding times for next week: Monday - D66 until 14:45 UT then D27 starts at 15:30 UT. Tuesday - Commanding is good all day. Wednesday - Commanding is good all day. Thursday - Gap then D16 starts at 17:30. Friday - Gap from 18:15-19:10 UT. Saturday - Commanding is good all day. Sunday - D66 until 14:30 UT then D27. FOT REPORT ---------- Spacecraft Status: Nominal, HGA Position Monitoring Disabled, APME-B being used in place of APME-A Spacecraft Anomalies: None Accomplished Activities: HGA Test/maneuver, SWAN Planned Activities: Nominal HGA Table Upcoming Operations: None Ground Anomalies: 169/1413 Lost 7 minutes of unrecoverable TLM from 1413 to 1420, 6 minutes of recoverable TLM from 1613 to 1619, and 45 seconds of unrecoverable TLM at 1813 all due to a MPA problem with the predicts at D16. 169/1513 POCC timing problem while executing procedure to set ESR warning flag receivers on board the spacecraft. 169/0414 POCC timing problem caused by intermittent telemetry while executing the pre-pass limit set procedure. CDS limits were inhibited from 0414 until 1727; no other impacts. SOLAR STATUS ------------ 06/18 DOY 169 - 06/19 DOY 170 EIT daily On-Line Solar Status and observations: http://umbra.nascom.nasa.gov/eit/plan/log_form20030619.html LASCO daily On-Line Solar Status and observations: http://lasco-www.nrl.navy.mil/observations/Todays_obs.html Web Page for Planning: http://www.bbso.njit.edu/arm Magnetic Maps and Heliospheric Forecasts: http://www.lmsal.com/forecast/ INSTRUMENT STATUS ----------------- CDS: Nominal. JOP153, La Palma study, NIS spectral atlas on quiet sun. Tomorrow: JOP153, EIT shutterless support, La Palma study, GIS spectral atlas. UVCS: Nominal. Streamer study and synoptics. LASCO: Nominal. C2/C3 synoptics, JOP153, JOP159. EIT: Nominal. 195 CME watch and synoptics, JOP153, JOP159. MDI: Nominal. Full disk magnetograms and dopplergrams, JOP153, La Palma support. TRACE: Nominal. La Palma support, JOP153. AOB --- After a spacecraft offpoint maneuver late this morning confirmed that the high gain antenna (HGA) had in fact not moved more than a small amount (in comparison to the steps commanded) since the first offpoint on June 4, we decided to switch to the redundant HGA electronics. The FOT did so at approximately 19:30 UT, and we commanded an HGA motion about the spacecraft Z axis (i.e., east-west antenna motion) of roughly one degree. Less than one-fifth of that motion took place, as determined from automatic gain control readings at the ground station. We commanded another 131 steps, without any noticable antenna movement. The similarity of the behavior on both the A and B sides indicates the likelihood of a mechanical problem with the antenna drive motor or mechanisms. We held a teleconference with the manufacturer of the motor (Moog) and, following their recommendation, tried to command the antenna in high speed (100 Hz instead of 0.1 Hz) in both directions, without success. During the night we will increase the temperature of the motor. Tomorrow we will repeat the same back and forth movement hoping to unstick the HGA. If we are unable to drive the antenna any further back toward the center of its E-W range, we will probably lose high-rate (i.e., scientific) telemetry this weekend or early next week. The spacecraft will continue to maintain contact in low rate via the low-gain antenna. The HGA east-west angle is near the "sweet spot" that would allow maximum coverage of the +/- 25-degree range of the spacecraft orbit's major axis, with some data loss (perhaps one month out of three) if we roll the spacecraft by 180 degrees once every ~ three months. (The 3 db half-width of the antenna beam is about 7 degrees.) With the help of the NASA Flight Dynamics Facility, we are also exploring the feasibility of changing the orbit in order to optimize the coverage period of the HGA . Your team should be prepared to safe your instrument for an off-time of 4-6 weeks.