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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~