ACE Weekly 01/23/2013 - 01/29/2013

All ACE spacecraft subsystems are performing as expected.

========================================================================
Orbit/Attitude:

	Type        Attitude
	Date        01/29/2013
	DOY         029 2013
	Thrusters   2R 4R+ 4R-
	Duration    5:15 min
	Start       15:40:32z
	Stop        15:45:47z
	HGAStart    -8.87deg
	HGAStop     +8.98deg
	SunStart    10.37deg
	SunStop     9.47deg
	SpinStart   5.0734rpm
	SpinStop    5.0745rpm
	Nutation     0.06deg
	Firing      27 pulses
	FuelUsed      0.0907lbm
	FuelRemain  116.6396lbm
	FinalSCMass 1350.900lbm

The next attitude maneuver is scheduled for Tuesday 02/05/2013.

========================================================================
OCRs:

None

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

Data Capture:  100%  DOY 020-027 2013

The SWEPAM-Electron current has slowly increased over the life of the
mission.  At launch, the maximum current used was ~0.1035Amps.  This
past week, the maximum current used had reached 0.1105Amps.  The FOT had
set an alarm for this value.  With a maximum current of 0.1105Amps, the
instrument is slowly approaching the onboard shut-off value of
0.1137Amps.  The SWEPAM instrument team was notified and they are
reviewing an increase to the onboard shut-off value.  Note, the
instrument current usage cycles from 0.099Amps to 0.1105Amps over a ~1
minute cycle.

========================================================================
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
12/27-01/03   16.0deg     9.1deg    6.9deg
01/03-01/08   15.2deg     7.2deg    8.0deg
01/08-01/15   13.8deg     6.0deg    7.8deg
01/15-01/22   12.3deg     4.0deg    8.3deg
01/22-01/29   10.6deg     2.4deg    8.2deg

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.