ACE Weekly 01/30/2013 - 02/05/2013

All ACE spacecraft subsystems are performing as expected.

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Orbit/Attitude:

	Type        Attitude
	Date        02/05/2013
	DOY         036 2013
	Thrusters   2R 4R+ 4R-
	Duration    5:15 min
	Start       18:07:07z
	Stop        18:12:28z
	HGAStart    -8.74deg
	HGAStop     +8.89deg
	SunStart     9.77deg
	SunStop      7.70deg
	SpinStart   5.0744rpm
	SpinStop    5.0756rpm
	Nutation     0.06deg
	Firing      27 pulses
	FuelUsed      0.0907lbm
	FuelRemain  116.5488lbm
	FinalSCMass 1350.809lbm

The next attitude maneuver is scheduled for Tuesday 02/12/2013.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 020-027 2013

The WS1 antenna (18-meter; part of the Near Earth Network) was used for
the pass on Wednesday 1/30 and on Friday 2/1.  These are the 3rd and 4th
operational passes with WS1.  ACE will use WS1 whenever DSN time is
limited and WS1 time is available.  The LRO mission is the prime user of
WS1.  We expect to use WS1 a couple of times each month.

With the spacecraft antenna angle pushed to 8-9 degrees, the WS1 EbN0
has been between 2 and 2.5dB.  During the Wednesday pass, the EbN0
dropped to ~1.3dB for ~10 minutes and a little bit of data was missed
(<1%).  The data was captured through redumps, but this provides a small
indication of where WS1 might not be able to process ACE high-rate data.

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Anomalies:

None

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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
01/29-02/05    9.1deg     3.2deg    5.9deg

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 4-8deg 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.