ACE Weekly 01/24/2012 - 01/30/2012

All ACE spacecraft subsystems are performing as expected.

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Orbit/Attitude:

	Type        Attitude
	Date        01/30/2012
	DOY         030 2012
	Thrusters   2R 4R+ 4R-
	Duration    17:31 min
	Start       19:52:38z
	Stop        20:10:09z
	HGAStart    -7.21deg
	HGAStop     +7.26deg
	SunStart     6.47deg
	SunStop      9.63deg
	SpinStart   5.0441rpm
	SpinStop    5.0492rpm
	Nutation     0.04deg
	Firing      89 pulses
	FuelUsed      0.2765lbs
	FuelRemain  123.9884lbs
	FinalSCMass 1358.248lbs

The spacecraft will drift to a sun angle of 1.6 degrees on Wednesday
02/08/2012.  This is below the originally proposed 2 degree sun angle.
The FOT recommends keeping the current attitude and not performing
another maneuver.  The sun sensor can read sun angles down to +/- 0.25
degrees and 1.6 degrees is expected to be more than enough to create a
sun pulse.  If the sun pulse does stop occurring, the ACE Science Center
can generate a pseudo sun pulse when processing the science data.  There
will be no nutation as the spacecraft drifts to 1.6 degrees.  The
current attitude will give a slightly better (0.5dB) RF signal during
the Solar Exclusion Zone transit (SEV<1.0degrees).  MOCR 387 has been
resubmitted for Mission Director approval.

The next attitude maneuver is scheduled for Tuesday 02/21/2012.

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OCRs:

DOY 026 (01/26/2012)  1909-1911z  CRIS-011
The Image Intensifier was powered on after being automatically
safeguarded
during the previous week's solar activity (DOY 023-07:46:38z).  This OCR
was
last executed on 12/15/2006.

DOY 027 (01/27/2012)  2112-2119z  SIS-044
During the most recent large SEP event (January 24, 2012), the Matrix
detector strips # 38 and 47 on M1B HV side became noisy. Strip # 47 had
its threshold already raised, but now the noise level is beyond the
threshold control. Strip # 38 did not have its threshold raised, so it
will be raised now at the expense of strip # 61 as there is a limit of
20 strips.

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Activities:

Data Capture:  100%  DOY 022-029 2012

During last week's solar activity, the ULEIS shutter autonomously
closed and reopened
	Sun Jan 22 2012, DOY 022 07:21:39z closed to 25%
	Tue Jan 24 2012, DOY 024 14:19:47z closed to 6%
	Tue Jan 24 2012, DOY 024 15:08:51z closed to 1%
	Wed Jan 25 2012, DOY 025 04:20:19z open   to 6%
	Thu Jan 26 2012, DOY 026 07:02:27z open   to 25%
	Thu Jan 26 2012, DOY 026 20:16:03z open   to 100%

There was no noticeable degradation (<0.2%) in the solar arrays from
last week's solar storm.  There have only been 4 days where the solar
arrays have noticeably degraded ~1% due to solar activity (07/15/2000,
11/09/2000, 11/06/2001 & 10/29/2003)

WS1 (18-meter antenna at White Sands) tracked ACE and forwarded data to
the MMOC on Friday 01/27/2012.  Unfortunately, the server at the MMOC
crashed.  The MMOC server has been improved and is now ready anytime WS1
is ready to test their equipment.

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Anomalies:

DOY 024 01/24/2012  S-ACE-0639  S12-0001  SWEPAM-E Overcount Alarm
The SWEPAM-Electron Overcount Alarm occasionally flags during solar
events.  When it flags continuously (2 or more times in a row), we note
it with an anomaly report and notify the instrument team.  This is only
the 4th solar storm when a continuous overcount alarm has occurred.  The
SWEPAM-Ion Overcount Alarm has never flagged throughout the mission.
IMPACT:  The instrument automatically reduces voltages when the
overcount alarm occurs.

Days when SWEPAM-E Overcount Alarm Flagged

	      Intermittent             Continuous
	1997  0                        0
	1998  1 (352)                  0
	1999  0                        0
	2000  0                        3 (196-197,314)
	2001  5 (268,309-310,327-328)  0
	2002  1 (111)                  0
	2003  3 (303,306-307)          2 (301-302)
	2004  1 (208)                  0
	2005  4 (017-018,020,135)      0
	2006  4 (341-343,347)          0
	2007  0                        0
	2008  0                        0
	2009  0                        0
	2010  0                        0
	2011  1 (217)                  0
	2012  5 (022-023,025,027,028)  1 (024)