ACE Weekly 02/27/04 - 03/04/04 All ACE spacecraft subsystems are performing nominally as ACE has made its closest angular approach to the Sun. An attitude maneuver was successfully executed on 03/01/04. The next attitude maneuver is tentatively scheduled for 03/08/04. ============================================================================ Orbit Events: The current ACE transit began February 22 and ends March 15 (a span of 22.49 days). This transit will involve the closest angular approach to the Sun yet seen, i.e., 0.63 degree (deg) from solar center. (By comparison, the solar angular radius as seen from Earth at that epoch will be approx. 0.27 deg). The updated details and epochs (UTC) follow: 22 Feb 05:22 4.75 deg inbound 28 Feb 15:51 2.0 deg inbound 1 Mar 17:19 1.19 deg inbound 3 Mar 21:57 0.63 deg closest approach 6 Mar 13:40 1.19 deg outbound 8 Mar 17:55 2.0 deg outbound 15 Mar 16:14 4.75 deg outbound The 1.19 deg reference was included because that was the closest approach during the December transit. ACE will spend 4.85 days within the 1.19 deg zone. ===================================================================== OCRs Executed: None ===================================================================== Ongoing Activities: TAPS: - Release 4.2.1 was delivered on 02/27/04 and is currently being tested by the FOT. Some problems have been encountered and the developers have been notified. These problems could possibly delay transition from GTAS to TAPS. - The latest SUG was released for review on 02/26/04 and comments have been submitted. ---------------------------------------------------------------------------- Automation (ROBOTT): - Release 0.4 (HSM & OFFLINE) is operational on String 1. - OFFLINE: 3 DRs have been verified on String 3, with 2 remaining to be verified by the FOT. - HSM: 2 DRs have been fixed on String 3; both have been verified. A third DR may be a part of the next release but has yet to be verified. - COMMAND&CONTROL: 6 DRs for C&C have been fixed and have been verified on String 3, with 2 more DRs remaining to be verified by the FOT. Some minor changes have been made to Command & Control to improve performance. - RTMON: There have been some minor problems encountered while testing the real-time monitor and the real-time tasks. Most of the problems involved tasks not being performed either by CRON or the "Start Real Time" button. Testing will continue with real-time monitor failover/reboot process. A true string failover test will not happen until the real-time monitor is moved over to String 2. - Testing of the next release and verification of all DRs apart of the next release will be finished by 3/7. Any DRs that are not verified by Monday March 8th, those DRs will not be included in Release 0.5. ============================================================================ Extra Spacecraft Activities: SEZ Related: The FOT has been loading both C&DH A&B timetag bins with Contingency Last Resort Timer Poke commands in order to mitigate the possibility of not being able to command the spacecraft during this part of the SEV transit. This will keep the C&DH's from reconfiguring if by chance the FOT is unable to command the spacecraft for 96 hours. On Wednesday, 03/03/2004, Day 04063, we had a 26-m test pass with DSS46. ACE was at an estimated SEZ angle of 0.63 degrees. The pass was not successful. No telemetry was acquired at the high data rate (87648bps). On Thursday, 03/04/2004, Day 04064, we had a 26-m test pass with DSS16. ACE was at an estimated SEZ angle of 0.75 degrees. The pass was successful. All telemetry was downlinked fine, and there were no problems with commanding. The following are some of the values that were monitored through out the pass with DSS16. - The HGA angle and range of the spacecraft that FDF obtained earlier in the day were 3.74 degrees and 1393766.265 km. -- At 498bps: SNR = 0.97dB and 43.01dB DSN RCVR_AGC = -113.20dB -- At 7968bps: SNR = 0.97dB and 43.01dB DSN RCVR_AGC = -118.74dB S/C RCVR_A&B_AGC = -91.11dB & -105.00dB -- At 87648bps: SNR = 9.8dB DSN RCVR_AGC = -119.68dB S/C RCVR_A&B_AGC = -89.55dB & -104.29dB ===================================================================== Anomalies: DOY 04058 (02/27/04) ACE Anomaly G04-0016 - MAD 26m (DSS66) TCP Problems At 1200, DSS66 brought carrier up on-time. The station stated that they had good two-way lock on the spacecraft with nominal Receiver Signal Levels. However, the Telemetry Control Processor (TCP) #1 channel 1 was unable to obtain lock on the low data rate of 498 bps. All troubleshooting attempted by the FOT and TSS was unable to remedy the situation. FOT was able to schedule time with DSS24. IMPACT: No pass activities were accomplished at DSS66. All planned activities accomplished at DSS24. DR#M102336 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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 Email: gamiller@pop500.gsfc.nasa.gov ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~