ACE Weekly 12/19/2012 - 12/27/2012

All ACE spacecraft subsystems are performing as expected.  Note, this
weekly report covers 12 days.  Reports are being generated to match the
maneuver schedule.

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Orbit/Attitude:

	Type        Attitude
	Date        12/27/2012
	DOY         362 2012
	Thrusters   2R 4R+ 4R-
	Duration    7:37 min
	Start       17:20:15z
	Stop        17:27:52z
	HGAStart    -9.03deg
	HGAStop     +9.02deg
	SunStart    14.29deg
	SunStop     18.00deg
	SpinStart   5.0770rpm
	SpinStop    5.0786rpm
	Nutation     0.08deg
	Firing      39 pulses
	FuelUsed      0.1264lbs
	FuelRemain  117.2372lbs
	FinalSCMass 1351.497lbs

The next attitude maneuver is scheduled for Thursday 01/03/2012.  The
next station keeping maneuver (SK-64) is scheduled for 01/15/2012.  This
will be 2 months from SK-63 instead of the usual 3 months, due to the
weekly attitude maneuvers.

There has been no noticeable increase in fuel usage due to attitude
maneuvers (~3.3kg/year).  Station keeping maneuvers had been using
~0.3kg/year, so a 50% increase does not significantly affect the annual
fuel budget (4.1kg/year).  (1 kg ~ 2.2 lbm)

Table showing annual fuel estimates with increased weekly maneuvers
(based on only 2 months of weekly attitude maneuvers).

                  Normal     w/ Weekly Attitude Maneuvers
                  ------    -----------------------------
Attitude          3.3kg      no noticeable increase
Station Keeping   0.3kg      +~50% -> 0.45kg
---------------------------------------------------------
Annual Budget     4.1kg      currently ~53.2kg remaining

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OCRs:

None

========================================================================
Activities:

Data Capture:  99.997%  DOY 351-358 2012
DOY 354 10:49:25-10:49:44  18 seconds lost over a 20 second period

When we fall behind in the science playback, we don't redump the
redumps.  This ends our recent streak of perfect data capture (7.4
months since 5/9/2012).

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Anomalies:

None

========================================================================
Average Sun Angles With Weekly Attitude Maneuvers

Dates         Avg Sun    Avg SEV   Sun-SEV (indicates extra s/c tilt)
-----------   -------    -------   ----------------------------------
10/18-10/23   11.0deg     5.1deg    5.9deg
10/23-10/28    9.3deg     3.3deg    6.0deg
10/28-11/06    7.3deg     2.0deg    5.3deg
11/06-11/13    8.4deg     3.8deg    4.6deg
11/13-11/20   10.3deg     6.3deg    4.0deg
11/20-11/27   12.7deg     8.6deg    4.1deg
11/27-12/04   14.9deg    10.1deg    4.8deg
12/04-12/11   16.0deg    10.9deg    5.1deg
12/11-12/18   16.8deg    11.3deg    5.5deg
12/18-12/27   16.5deg    10.7deg    5.8deg

The following is background information that will be included in each
weekly report.
The project has accepted the SWEPAM team proposal to keep the spacecraft
at larger sun angles with weekly attitude maneuvers.  The SWEPAM-Ion
instrument has a series of channel electron multipliers (CEMs) and
larger sun angles allows more responsive CEMs to measure the solar wind.
The maximum sun angle follows the Sun-Earth-Vehicle angle (SEV).  The
SEV angle is determined by the size/shape of the orbit around L1.  When
the spacecraft antenna is pointed directly towards earth, the
spacecraft's sun angle will be equal to the Sun-Earth-Vehicle angle.
With weekly maneuvers, the average sun angle can be kept 4-6deg more
than the SEV angle.  This results in the spacecraft antenna aspect angle
being kept between 5 and 9 degrees and never pointing directly back at
earth.  For reference, the SWEPAM team prefers sun angles above 13
degrees.  With the current size of the L1 orbit, the sun angle will be
above 13 degrees for ~45% of the time.