ACE Weekly 06/28/02 - 07/04/02

All ACE spacecraft subsystems are performing nominally. No attitude 
maneuvers were executed this week. The next attitude maneuver is 
tentatively scheduled for 07/12/02.

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Ongoing Activity:
The engineering test to determine the new HGA constraint is continuing. The 
current constraint (as of 6/3/02) is 6.0 deg, with current tests reaching 
6.5 degrees.  The attitude maneuver on 7/12/02 is expected to target +6.5 deg.

The spacecraft is near its peak earth-spacecraft range of 1592458 km.  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 (expected)

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ACE Lissajous Orbit Status from FDF:
The ACE Lissajous orbit crossed into the old 4.75 deg Solar Exclusion
Zone(SEZ) on June 18th and will emerge early on July 4th after an
approximately 14-day transit.
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Anomalies:

DOY 02180 (06/29/2002) - ACE Anomaly #G02-0078  DSN - No MFR Data in 
Monitor Blocks
Throughout the pass, no MFR data was populated within the Monitor blocks
from DSN.  This is a known problem and is currently under investigation.
IMPACT: MFR data is being used in the ongoing analysis of increasing the 
HGA angle out to 6.5 degrees.  DR# G101321

DOY 02182 (07/01/2002) - ACE Anomaly #G02-0079  TPOCC - Cmd Echo Cnt Ceased
At 1645 the MOC noted that the number of command echo blocks received 
(mnemonic command_echo_bk) ceased incrementing after reaching a value of 3, 
though verification of all commands *was* being received. IMPACT: None 
noted. All procedures completed without any problems.

DOY 02182 (07/01/2002) - ACE Anomaly #G02-0080  DSN - SCP Failed
At 18:08:15, Telemetry ceased flowing into the MOC.  The station tried 
swapping SCPs to no avail.  IMPACT:  No telemetry or commanding available 
after 18:45:40. All end of day activities canceled.  DR #G101327

DOY 02183 (07/02/2002) - ACE Anomaly #G02-0081  DSN - Second Station 
Interference
At 1345, the MOC observed a second telemetry stream entering the ground 
system. Shortly thereafter the MOC's attempts to command the S/C were 
unsuccessful. The OPS Chief's investigation discovered that station 24 had 
come online with *no* briefing or communication of any kind with the 
MOC.  Station 24 was operating under an old schedule that had been changed 
the day before. This accounted for the second telemetry stream and the RF 
interference which prevented the MOC from commanding the S/C. IMPACT: The 
uplink from station 24 prevented commanding to the S/C for approximately 
1.5 hours.  This delayed receipt of science data at the ASC by 
approximately 24 hours.  DR #G101338