ACE Weekly Report 03/21-27/02

All ACE spacecraft subsystems are performing nominally.  Attitude
maneuvers were successfully performed on 03/19/02 and 03/22/02.  The
next attitude maneuvers are scheduled for 03/28/02 and 04/04/02.

The Project has approved the FDF proposal to widen the HGA constraint.
The constraint will be increased in several steps, over the next four
months with the maximum constraint being reached by late June, when the
spacecraft will be at its maximum range.  The current HGA constraint is
4.5 degrees.  The first and largest step will be an increase to 5.5
degrees.  The approach used will be to allow the spacecraft to drift
until the new constraint would be violated.  An attitude maneuver would
then be executed using the 4.5 degree constraint as the target.  Once
the spacecraft has drifted to 5.5 degrees without negatively impacting
operations or NOAA, the HGA constraint used for maneuvers will be
changed to 5.5 degrees and the spacecraft would be allowed to drift to
the next step (yet to be determined).  The new HGA constraint will be
kept at 5.5 degrees for several weeks, to allow for analysis prior to
continuing with the next step.
Calculations were updated following the maneuver on 03/22/02 and the 4.5
constraint is scheduled to be violated on 03/28/02.  The spacecraft HGA
will have drifted to ~4.8 degrees prior to the maneuver execution.  NOAA
has been notified of the planned increase of the HGA constraint and will
analyze any impact to their data.  The FOT has developed several
procedures and scripts which will be used to recover from an anomaly
resulting from the increased HGA, if one were to occur.

FORMATS 2001.01D1 string 2 installation was completed March 25, 2002.
String 1 installation is slated for the week of April 1st.

2QFY02 GITT security scans completed.

Anomalies:
03/23/02  DOY 082 AR# G02-0032 MOC experienced severely degraded
telemetry throughout D27 support. There were also three telemetry
dropouts.  Numerous SSR dumps performed during following support to
capture affected SSR data.  The ACE NOPE has been notified and is
investigating (DR# G100928).