ACE Weekly 12/10/04 - 12/16/04 All ACE spacecraft subsystems are performing nominally. ============================================================================ Orbit/Attitude: No maneuvers were executed this reporting period. The next attitude maneuver is scheduled for 12/20/04. The following data from SK-34 on 12/6/04 is provided by FDF -- Burn Start: 18:38:48 UTC -- Burn Stop: 18:39:45 UTC -- Delta-V = 0.3234 m/sec (Sunward) -- Burn Duration = 58.6172 sec (continuous firing) -- Fuel Usage = 0.22055 lbm (0.1000 kg) -- Final Fuel Mass per tank = 43.6106 lbm (times 4 tanks) -- Fuel remaining = 173.7444 lbm -- Thrusters: Bottom-deck Axials 3A and 4A -- Post-SK spin axis right ascension = 255.35 deg -- Post-SK spin axis declination = -17.53 deg -- Initial spin rate = 5.0244 rpm -- Final spin rate = 5.0129 rpm -- Spin rate change = -0.0115 rpm Real-time Doppler measurement of the line-of-sight delta-V component, which was expected to be -0.3213 m/sec, showed the burn to be just 0.55 percent cold. This represents a performance deviation of 1.8 millimeter/sec. ============================================================================ OCRs Executed: ULEIS 073 - 12/10/04 - CMD transmitted 13:06:33/verified 13:06:46 ULEIS uses a look-up table to determine the priority of incoming particle events. This table is held in non-volatile EEPROM storage, but must be copied into RAM in order to be used by the software. This OCR sends the command to copy this table from EEPROM into RAM. OCRs Planned: SWPX 037 - Will coordinate with instrument team after the holidays. The SWEPAM Ion gain is starting to “slip” due to instrument aging. Provisions are made in the instrument to adjust for this loss by increasing the CEM voltage level but the gain is not linear across the entire spectrum. These sensitivity measurements are intended to characterize this non-linear behavior to let the SWEPAM science team determine the optimal CEM voltage to continue operations with and to define compensation parameters for data processing. ============================================================================ Ongoing Activities: ROBOTT ACE transitioned to Lights Out Operations on 11/13/04. All nominal realtime operations are now being performed using ROBOTT, with the exceptions of maneuvers and special commanding. 20 DRs have been written for ROBOTT v0.9. The ROBOTT developers have uncovered and are fixing a year rollover problem. Since Week 1 starts on the first week with 4 days in the new year, it is possible to have Jan 1, 2 and 3 in the previous year's final week (52 or 53). The software currently deletes the previous year's schedule on Jan 2. A temporary patch is being developed and will be implemented before the end of the year. ============================================================================ Extra Activities: 12/10/04 2nd Quarter MOC Security Scan was performed. No vulnerabilities were found. 12/15 & 12/16 SSR housekeeping data downlinked. No new soft Single Bit Errors have occurred. ============================================================================ Anomalies: DOY 350 (12/15/04) ACE Anomaly G04-0155 MAD 26m (DSS-66) Duplicate CMD echo A command sent at 14:39:44 resulted in 2 command echoes separated by 0.1 seconds. A similar problem was previously attributed to a router duplicating commands sent to the spacecraft. DR#N102543 IMPACT: None. Duplicate commands ignored; CMDs not in bypass mode.