ACE Weekly 01/28/2015 - 02/04/2015

ACE spacecraft subsystems are performing as expected.  This weekly
report covers 8 days in order to include the maneuver.

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Orbit/Attitude:

	Type           Attitude
	Date          02/04/2015
	DOY            035 2015
	Thrusters      2R 4R+ 4R-
	Duration        7:54 min
	Start          15:49:53z
	Stop           15:57:47z
	ra,decStart   304.91,-11.11
	ra,decStop    311.85,-10.91
	ra,decExpect  312.67,-44347
	Deviation       0.84 deg (-10% short)
	HGAStart       -8.53 deg
	HGAStop        +8.84 deg
	SunStart       13.54 deg
	SunStop         7.93 deg
	SpinStart     4.9999 rpm
	SpinStop      5.0004 rpm
	Nutation        0.27 deg
	Firing         40 pulses
	FuelUsed        0.1275 lbm
	FuelRemain    101.2344 lbm
	FinalSCMass   1335.494 lbm

The maneuvers have been short of the target every ~3 months (last
occurrence in Nov 2014).  We believe that the nitrogen fills the
internal lines as the fuel in the external lines is slowly used.  When
the nitrogen reaches the thrusters, it is expelled and the reduced
pressure causes the fuel from the A tanks to backfill the B internal
lines.  The process repeats every ~3 months.

Equilibrium will eventually set in when the excess nitrogen from the B
tanks is expelled (matching the amount of nitrogen in the A tanks).
Analysis is ongoing to determine if and when to close the B latch
valves.

The next attitude maneuver will be next week, but the date is uncertain
due to upcoming DSCOVR launch and antenna availability.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 025-032 2015

Santiago (Near Earth Network) continues their ranging tests while ACE is
in the low downlink rate.  The data will be used in preparing for the
DSCOVR mission.  More tests are scheduled for the coming week.

  01/28/2015  DOY 028  1505-1616z
  01/29/2015  DOY 029  1501-1613z
  01/30/2015  DOY 030  1711-1811z


The SSMO scheduling team continues to work on the schedule for the
DSCOVR launch (expected 2/8/2015).  MAVEN will be doing "Deep Dip 1" and
has increased DSN coverage starting 2/10/2014.  The risk of data loss is
higher than usual for February.

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Anomalies:

DOY 034  02/03/2014  S-ACE-0622  G11-0049  ITOS processes not finishing
Starting Tuesday 02/03/2014 (DOY 034), some processes started with the
ITOS "system" directive were hung and not finishing.  Some processes
completed successfully (e.g. ace_create_s_dumplist, pass_summary, etc)
and others did not (ace_data_fwd, ace_clock_report, moving files).  The
WIND ITOS context was not impacted.  ITOS was restarted Wednesday  (DOY
035).  This problem last occurred on 10/24/2012 (DOY 298 2012).
IMPACT:  Empty clock report file sent to ASC on DOY 034 & 035; corrected
files was resent on 2/4/2015 (DOY 035).  No data forwarding to NOAA SWPC
for ~1 hour on 2/4/2015.  Other hung system processes had minimal
impact.