ACE Weekly 07/12/02 - 07/18/02

All ACE spacecraft subsystems are performing nominally. An attitude 
maneuvers was executed on 07/12/02. The next attitude maneuver is scheduled 
for 07/30/02.

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Ongoing Activity:
The engineering test to determine the new HGA constraint is continuing. The 
current constraint is 6.0 deg., with current tests reaching 6.5 
degrees.  The attitude maneuver on 7/12/02 targeted +6.5 deg.

The FOT has been monitoring the Signal Strength, the MFR AGC levels, and 
the Signal-to-Noise Ratios(SNR). The drop in RF levels from an HGA angle of 
0 deg to 6 deg has been approximately 3dB. There has been no loss of 
telemetry due to the increased HGA angles.  Once all analysis has been 
completed, the new HGA constraint will be determined.

The following HGA angles and range values are from FDF.
Man Date Pre Man   Post Man    Earth-ACE Range
03/28/02 -4.58 deg  +4.38         1408287 km
04/04/02 -4.35      +4.50         1414808
04/11/01 -5.09      +3.79         1428491
04/18/02 -5.16      +3.85         1440512
04/26/02 -5.77      +5.56         1455949
05/06/02 -5.72      +5.43         1493008
05/17/02 -5.81      +5.31         1527979
05/28/02 -4.34      +4.88         1550263
06/06/02 -2.38      +5.96         1576064
06/20/02 -6.57      -3.66         1590405
06/26/02 -6.43      +5.94         1592458
07/12/02 -6.5       +6.5

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Stationkeeping Maneuver Information from FDF

We have a stationkeeping maneuver (SK-26) scheduled for Tuesday, July 30, 
to be followed by an attitude reorientation.  The delta-V direction will
be Sunward, requiring the aft-end canted axials 3A and 4A.  Based on the 
latest OD, halo re-targeting results show a delta-V of 0.908 m/sec is 
needed.  Preliminary finite burn modeling predicts a burn duration of 162.7 
sec (2.7 min) and a fuel usage of 0.634 lbm (0.288 kg).  Also, we expect to 
see a spin rate drop of around 0.037 rpm from this burn (no spin correction 
maneuver will be necessary).

The required spin range is 4.90 to 5.10 rpm.  Since we're at right about 
5.0 at the moment, we'll end up at about 4.96 rpm, well within the 
tolerances by 0.06 rpm.

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TPOCC Release 5.2 Testing Status

Testing of TPOCC Release 5.2 on String 3 is completed.  No major problems 
were identified.

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Anomalies:

DOY 02198 (07/17/2002) - ACE Anomaly #G02-0086 No MFR Data from D27
Throughout the pass, no MFR data was populated in the monitor blocks from 
D27. MFR data is being used in the ongoing analysis of increasing the HGA 
angle out to 6.5 degrees. IMPACT: Degraded analysis of HGA angle.


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Glen A. Miller
Honeywell Technical Services Inc.

ACE Flight Operations Team
Goddard Space Flight Center
Bldg. 14, Rm. W10A
Mail Stop 428.2
Greenbelt, MD 20771

Office: 301-286-7071
Fax:    301-286-1729
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