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.
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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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~