ACE Weekly 12/10/2008 - 12/16/2008

All ACE spacecraft subsystems are performing nominally.

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Orbit/Attitude:

	Type        Attitude       SK-49
	Date        12/10/2008     12/10/2008
	DOY         345 2008       345 2008
	Thrusters   2R 4R+ 4R-     1A 2A
	Duration    9:28 min       36.851 sec
	Start       15:49:53z      18:03:15z
	Stop        15:59:21z      18:03:53z
	HGAStart    -2.22deg       +7.40deg
	HGAStop     +7.40deg       +7.52deg
	SunStart     8.74deg        5.54deg
	SunStop      5.54deg        5.42deg
	Nutation     0.13deg        0.16deg
	Firing      48 pulses      Continuous
	FuelUsed      0.1617lbs      0.1345lbs
	FuelRemain  146.1408lbs    146.0064lbs
	FinalSCMass 1380.401lbs    1380.267lbs

The next attitude maneuver is scheduled for Friday 12/19/2008.

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OCRs:

DOY 351 (12/16/2008)  2040-2050z  SIS-042
M1B HV strip #17 was disabled due to a saturated leakage current that caused
oscillations in SIS RTSW data.  There are a total of 512 strips in the M1
and M2 detectors in the two SIS telescopes.  25 strips have been disabled
since launch (2 VLSI readout channels were not working at launch).

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Activities:

Data Capture:  100%  DOY 342-349 2008

There is a higher than normal risk of data loss from October 2008 through
February 2009.  If there are problems with the passes, it may not be
possible to acquire additional DSN time.  This higher-risk period has been
occurring every winter for the past couple of years.  For more information
refer to 10/14/2008 weekly.

The FDF timing coefficient file delivered on 12/1/2008 was missing the
1/1/2009 leap second.  This was corrected with the 12/15/2008 timing
coefficient file and no problems are expected.  Errors in the ACE Clock
Calibration would have an impact on the ACE Science Center's data
processing.

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Anomalies:

DOY 345  12/10/2008  S-ACE-0393  S08-0006  S3DPU_I limit violation
S3DPU current (S3DPU_I) briefly violated the red high limit (RH > 145mA).
The S3DPU Idle Counter (SSDIDLECTR) was at 33.
	2008-345:23:33:35 - 23:34:07.  148.176-149.744mA 
IMPACT:  The last brief S3DPU_I violation was 2007-316-21:59:36.  S3DPU_I is
higher when the instruments are processing more data as indicated by a low
SSDIDLECTR.

DOY 346  12/11/2008  S-ACE-0392  G08-0126  DSS-46 CMD/SLE Problems
DSS-46 was unable to maintain a bound state for SLE commanding at Beginning
Of Track (BOT).  The station rebooted and reloaded the equipment several
times before the problem was resolved.  DR#C106686
IMPACT:  Activities delayed 30 minutes.  The playback was completed on the
next day.

DOY 349  12/14/2008  S-ACE-0394  G08-0127  DSS-46 TCP Configuration
The TCP was not configured to send high-rate data to the ACE MOC (low
latency).  The FOT contacted the Ops Chief and relayed the information to
the station.  DR#C106699.  This same problem occurred on 10/15/2008
(AR#G08-0096 DR#C106579) and 10/30/2008 (AR#G08-0104 DR#C106604).  DSN is
reviewing the desktop/TCP configuration.  
IMPACT:  Manual intervention required.  Activities delayed 56 minutes.  The
playback was completed on the next day.

DOY 351  12/16/2008  S-ACE-0395  G08-0128  DSS-27 Red
DSS-27 was unavailable due to problems with the transmitter.  DSN
Maintenance released their time with DSS-46 and the pass was taken 2 hours
later.  One of the advantages of ACE automation is that passes can be easily
rescheduled.  In this particular case, manual intervention was required to
simply update the DSN schedule.
IMPACT:  There will only be 2 northern hemisphere ranging passes between the
maneuvers on DOY 345 and 354.  There will be 9 southern hemisphere ranging
passes.  This should be sufficient for orbit determination, but additional
northern hemisphere ranging passes would have helped.  Also, if the
additional time was not acquired, it would have taken 3 days to catch up on
the SSR playback.