ACE Weekly Report:  06-21-00

All ACE spacecraft subsystems are performing nominally. An
Attitude maneuver was successfully executed on 06-16-00.  The next
attitude maneuvers are scheduled for 06-23-00 and 06-30-00.  A
stationkeeping maneuver is also scheduled for 06-30-00.


On 06-15-00 ACE had a DSN 26m Automation test with Station D16.  A backup
station (D66) was configured with the legacy equipment, in the event of any
problems with D16.  Station 66 put its telemetry in record, while D16 had
theirs on line to the MOC.  The test was a partial success.  The next DSN 26m
Automation test is scheduled for June 25, 2000.


     Successes:

     1.  ACE successfully performed all nominal daily commanding
activities.

     2.  FDF verified the receipt of good ranging data.

     3.  FOT generated two LZP products, one using the data from the 26m
automated test and one using data from Station 66's legacy system.  Scientists
verified the products were identical with the exception of two frames.

	

     Discrepancies:

     1. FOT experienced several critical S/C parameters flag followed by a 3
second telemetry dropout.  Once telemetry returned all S/C parameters were
nominal.  Analysis offline of the raw data files shows the frame just prior to
the telemetry dropout contained fill data (numerous 'ffff' words).  The CDR
file from D16 was analyzed and contained the corrupted frame and three second
dropout.  The CDR file from D66 was also analyzed and did not have the
corrupted frame nor the three second dropout.

     2. ACE captures a Raw Observation Clock file during each support.  This
file is then used to perform Clock calibration prior to the next support.  The
Data from the 26M automated system corrupted the Raw Observation Clock file.
The end result caused the S/C GMT time to be two days in the future.  This
problem was caught prior to the next day's support and a workaround was
performed to alleviate the corruption.

     3. AOS was delayed ~5 minutes.


On 6-19-00 ACE suffered ~3 minute data loss due to problems with
Station 66's receiver.
The remainder of the support completed without any further problems. 
All SSR data successfully captured  (DR# L04443). 

================================================

Jacqueline Maldonado Snell
Honeywell Technology Solutions Incorporated (HTSI)
Goddard Space Flight Center
Bldg. 3 Rm N135C, Code 428.2
Greenbelt, MD 20771
Phone: (301) 286-7072
Fax:   (301) 286-0218
E-mail:   Jacqueline.Snell.1@gsfc.nasa.gov