ACE Weekly 04/23/04 - 04/29/04 All ACE spacecraft subsystems are performing nominally. An attitude maneuver was successfully executed on 04/27/04. The next attitude maneuver is scheduled for 05/12/04. ============================================================================ Orbit Events: From Craig Roberts (FDF): The next ACE transit of the old Solar Exclusion Zone (SEZ) will run from 05/19/04 to 06/14/04. For the first time ever, ACE will transit the solar disk on 06/01/04. On that date, the Sun's angular radius is 0.2629 degree (as seen from Earth's center). The solar transit will last nearly 21 hours (again, as seen from Earth's center). The main features of this transit are given in the following table (times are UTC). 5/19 01:42 4.75 deg inbound 5/27 07:45 2.0 deg inbound 5/30 23:39 0.63 deg inbound 6/01 01:18 0.2629 deg (kissing solar disk inbound) 6/01 10:46 0.197 deg (radius of closest approach to solar center) 6/01 22:14 0.2629 deg (kissing solar disk outbound) 6/02 23:28 0.63 deg outbound 6/06 11:15 2.0 deg outbound 6/14 07:18 4.75 deg outbound The 0.63 deg epochs are included because that radius represents the closest approach during our last transit in February/March. ACE will spend almost exactly 3 days within this zone. ===================================================================== OCRs Executed: 04/23/04 - OCR SEP-107 was successfully completed with Mark Popecki monitoring. SEPICA was returned to its nominal configuration after two weeks in engineering mode. 04/28-29/04 - OCRs SWX-30 and SWM-31 were successfully executed with Jim Raines directing the High Voltage ramp up on both SWICS and SWIMS. Both instruments are back to their nominal configuration. ===================================================================== Ongoing Activities: TAPS: - Transition from GTAS to TAPS occurred on 03/18/04. All trending activities are being accomplished using TAPS. No problems have been noted to date. - Installation of TAPS release 4.3 is tentatively scheduled for the first week of July 2004. All open DRs will be fixed in this release. ---------------------------------------------------------------------------- Automation (ROBOTT): - Release 0.6 installed on String 2 on 04/09/04. FOT testing is almost completed. -- 24 DRs have passed verification. 6 additional DRs have been opened as a result of FOT Testing. -- 1 DR (color allocation) still needs some work. There are no color issues if C&C is brought up by CRON or the Start Real-Time button. If C&C is brought up with the individual button, there still maybe some color issues, but these do not occur every day. - Installation of Release 0.6 to String 1 is tentatively planned for the week of May 10th. The date is highly dependent on the FOT's testing progress. - SUG development is ongoing. Tentative release date is the end of May. A DRAFT version may be available prior to that. - FOT training on ROBOTT is to begin the week of May 3rd. ============================================================================ Extra Spacecraft Activities: - The S3DPU Anti-Reset Patch activity with Mark Popecki (SEPICA) and Jim Raines/Scott Lasley (SWICS/SWIMS) was successfully completed on 04/29/04. To date there have been no problems reported with the new patch. All three instruments (SEPICA/SWICS/SWIMS) are back in their nominal configuration. ===================================================================== Anomalies: DOY 04115 (04/24/2004) ACE Anomaly G04-0029 - MAD 26m (DSS-66)- Dropped Blocks The FOT reported intermittent VC2 errors throughout the DSS-66 pass. The Ops Chief confirmed seeing the dropped blocks from SPC-60. IMPACT: Degraded data during pass. All data subsequently recovered postpass via CDR files. DR# N102100. DOY 04115 (04/24/2004) ACE Anomaly G04-0030 - MAD 26m (DSS-66)- Incorrect Modulation Index Post pass analysis discovered a discrepancy with the command modulation index on day 04115 with station D-66. The nominal carrier suppression value is 1.60 dB (0.86 radians), however, on this day the value was 8.39 dB. IMPACT: Throughout the pass, during periods of commanding, the AGC levels would drop. This was an indication of a possible problem with the command modulation index. However, no commands were lost due to the problem. DR# N102105 DOY 04119 (04/28/2004) ACE Anomaly G04-0031 - GDS 26m (DSS-16) - Drive OFF Early At 18:58:00, FOT instructed DSS-16 to bring carrier down and end track at 19:10. At 19:00:00, DSS-16 turned drive OFF (10 minutes early). At 19:01:53, DSS-16 reacquired and put telemetry to line. IMPACT: None. All pass activities had already been completed. Data lost during that time was subsequently retrieved via the on-board recorder. DR# G104341 DOY 04120 (04/29/2004) ACE Anomaly G04-0032 - GDS 34m (DSS-27) - Extraneous Command Echo During the execution of the procedure G_END_DAY, it was found that there was a discrepancy between the number of commands sent by the FOT and the number of command echoes received from DSS-27. Our ground system reported 1 test block sent, 1 test echo received, 76 commands sent and 77 command echoes received. Querying DSS-27, they reported their command system logged 77 commands and 77 echoes. IMPACT: None. DR#G104347 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Glen A. Miller ACE Flight Operations Observatory Engineer Honeywell Technology Solutions Inc. Goddard Space Flight Center Building 14, Room W10A Mail Stop 428.2 Greenbelt, MD 20771 Office: 301-286-7071 Pager: 800-425-3174 Fax: 301-286-1729 gamiller@pop500.gsfc.nasa.gov ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~