ACE Weekly 10/12/2007 - 10/16/2007

All ACE spacecraft subsystems are performing nominally.

Note:  ACE Weekly Reports will now cover Wednesday to Tuesday (instead of
the previous Friday to Thursday).

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Orbit/Attitude:

No maneuvers were performed.  The next attitude maneuver is scheduled for
Monday, 10/29/2007.

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OCRs:

None

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Activities:

Space Link Extension (SLE) Testing status
DSN continues to troubleshoot 26m SLE problems.  The following tests have
been scheduled for testing both DSN and the ACE MOC SLE upgrade (v3.1)
	Day  Date   DOY  Station
	Wed  10/17  290  DSS-54
	Thu  10/18  291  DSS-34
	Mon  10/22  295  DSS-66
	Wed  10/24  297  DSS-46
	Thu  10/25  298  DSS-34
	Mon  10/29  302  DSS-46
	Thu  11/01  305  DSS-66 with DSS-27
	Thu  11/01  305  DSS-27
	Mon  11/05  309  DSS-24


Multi-Mission Ops Center (MMOC)
The ACE team has started working with the ITOS developers to replace the
TPOCC mission software with ITOS.

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Anomalies:

DOY 286  10/13/2007  S-ACE-0234  G07-0087  DSS-66  S-Band Exciter
Problems with DSS-66 S-Band Exciter (uplink) affected CMD, RNG and TLM.  The
downlink is affected since in the spacecraft is in coherent mode (Downlink
frequency based on uplink.  Ratio of frequencies = Uplink/Downlink =
240/221).  When problems like this have occurred in the past, the FOT has
requested that the ground station increase the RF loop bandwidth to improve
downlink data capture.  However, this was a un-staffed weekend shift.
DR#M104463
IMPACT:  Several command failures due to bit-flips in the command sequence.
All command failures were rejected by the spacecraft.  Daily commanding
sequence was not completed.  The final spacecraft configuration was not
nominal but had no impact.  340 seconds of playback data lost, intermittent
between DOY 285 2222z to DOY 286 1246z.

Note:  340 seconds corresponds to 0.39% daily loss which is reported for
data capture metrics.  In terms of complete major frames (128 second cycle),
the daily data loss corresponds to 9.5%.

DOY 286  10/13/2007  S-ACE-0235  G07-0088  ROBOTT/C&C Froze
ROBOTT automation software froze during the intermittent telemetry and
command failures.
IMPACT:  The ROBOTT software did not notify the FOT that the daily
commanding sequence was not completed and that the final spacecraft
configuration was not nominal.

DOY 287  10/14/2007  S-ACE-0236  G07-0089  DSS-27 Antenna Stop
Ground antenna went to brake causing loss of telemetry and two way lock with
spacecraft at 18 minutes before End Of Track.  Uplink re-established at 2.5
minutes before End Of Track.  SSR playback properly terminated before End Of
Track.  DR#G108100
IMPACT:  If the uplink was not re-established, the SSR playback would have
been continuing as the spacecraft changed data rates.  This causes the SSR
to be stuck in playback mode.  Although this has happened in the past and
contingencies are in place to automatically reconfigure the SSR at the
beginning of the next support, it is preferable to terminate the SSR
playback properly before End Of Track.