ACE Weekly 12/18/2013 - 12/24/2013

All ACE spacecraft subsystems are performing as expected.

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Orbit/Attitude:

	Type         Attitude
	Date         12/23/2013
	DOY          357 2013
	Thrusters    2R 4R+ 4R-
	Duration     6:10 min
	Start        13:41:01z
	Stop         13:47:11z
	HGAStart     -9.05 deg
	HGAStop      +9.00 deg
	SunStart     14.76 deg
	SunStop      16.62 deg
	SpinStart    4.9774 rpm
	SpinStop     4.9786 rpm
	Nutation      0.07 deg
	Firing       31 pulses
	FuelUsed       0.1031 lbm
	FuelRemain   109.8504 lbm
	FinalSCMass  1344.111 lbm

The next attitude maneuver is scheduled for Tuesday 12/31/2013.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 349-356 2013

Friday 12/20/2013 - DSN declared the DSS-54 antenna "red" due to
excessive noise from one of the azimuth drive points.  DSS-54 is
tentatively scheduled to return to service on Friday 12/27/2013.

Monday 12/23/2013 - DSN decommissioned the DSS-27 antenna.

ACE acquired WS1 time for Thursday 12/26/2013 and Friday 12/27/2013 to
help relieve contention at DSN.  However, WS1 time is less available as
the new moon approaches (1/1/2014) and LRO's view overlaps with ACE.

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Anomalies:

DOY 358  12/24/2013  S-ACE-0672  G13-0015  ITOS event & other problems
After the transition to mmocops1p on 12/15/2013 (DOY 349), ITOS had
occasional problems (errors from unix directives, not saving Wind
attitude data, not forwarding Wind real-time data, command graph
errors).  The computer was rebooted on 12/24/2013.  After the reboot,
the ITOS event log was not being saved in the postgres database.  The
ITOS software was restarted and no problems have appeared since.
IMPACT:  The operations software (ITOS,MUS,etc) can occasionally be
troublesome.  Several problems have automatic recovery.  Restarting the
software and/or the computer can reduce the number of issues.  The ITOS
event log (cmd times, etc) for the first pass on DOY 358 was lost.


Update for S13-0001 Tank Temperature & Spin Rate Anomaly

The B1 Fuel Tank temperature increased on 9/19/2013 (18.4C to 19.5C) and
11/05/2013 (to 20.9C).  The temperature has continued to rise (to 21.5C)
with the rest of the spacecraft as we approach perihelion.  At 2053z
12/22/2013, the thermostat for the fuel tank heaters turned off.


Background Information - Propulsion Heaters

There are 7 propulsion system thermostats that range from 18 to 27C.
The following table provides the current used by each set of heaters and
the typical state before 12/22/2013.

Current Description                       State before 12/22/2013
------- --------------------------------  ------------------------------
0.11A   Top Deck Axial Thruster heaters   never on
0.11A   Top Deck Radial Thruster heaters  never on
0.11A   Btm Deck Axial Thruster heaters   on ~30minutes every 2-3 hrs
0.22A   Btm Deck Radial Thruster heaters  on ~30minutes every 2-3 hrs
0.23A   Internal Lines heaters            occasionally on 30 minutes
0.08A   External Lines heaters            occasionally off 30 minutes
0.38A   Tank heaters                      always on

(Internal line heaters rarely turn on during perihelion and turn on ~4
times/day during aphelion.)


Since Monday 12/23/2013, the tank heaters have been turning off every 2
hours for ~30 minutes.  This has caused the remainder of the propulsion
system thermostats/heaters (except for the top deck thruster heaters) to
turn on/off to compensate for the changes in temperature.  All of the
thermostats are functioning as expected, but several propulsion system
temperatures are fluctuating by ~5C as the system is not reaching a
steady state temperature.  This does not seem to be affecting any other
spacecraft temperatures (e.g. the instrument deck).