ACE Weekly 06/03/2015 - 06/09/2015

All ACE spacecraft subsystems are performing as expected.

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Orbit/Attitude:

Type 		Attitude
Date 		06/09/2015
DOY 		160 2015
Thrusters 	2R 4R+ 4R-
Duration 	5:19 minutes
Start 		15:49:35z
Stop 		15:54:54z
ra,decStart 	76.73,38.91
ra,decStop 	82.91,39.73
ra,decExpect 	83.23,39.70
Deviation 	0.24 deg (-4.7%)
HGAStart 	-10.48 deg
HGAStop 	+10.99 deg
SunStart 	16.07 deg
SunStop 	17.55 deg
SpinStart 	5.0129 rpm
SpinStop 	5.0141 rpm
Nutation 	0.07 deg
Firing 		27 pulses
FuelUsed 	0.0893 lbm
FuelRemain 	97.8835 lbm
FinalSCMass 	1332.144 lbm

The next attitude maneuver is scheduled for Tuesday, 06/16/2015.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 151-158 2015

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Anomalies:

Update from last week's (5/27/2015 - 6/02/2015) reporting period:

DOY 148 05/28/15 S-ACE-0704 Data Gaps during SSR Playback (DR# N109954)

During the DSS-24 contact on DOY-148 (BOT=0000 UT, EOT=0230 UT),
multiple instances of data gaps were identified during the SSR
playback of ACE data.

Consecutive data gaps in playback data with a duration as long as
4.4 min and as low as 2 seconds were observed during the contact
(overall data gaps play back start: 147/16:01:56 (UT) and data gaps
End time: 147/21:54:16 (UT)).

Inspection of the ITOS event log indicates that (real-time) multiple
occurrences of frame sequence errors (and skipped frames) were recorded
during the 148:00:02:40.9 (UT) through 148:02:16:05.494 (UT) real time
contact time frame.

The ACE FOT has also confirmed that the data gaps are only present in
the playback data (vc4) and not real time frames (vc1). Furthermore,
the data gaps identified in the IDR data is consistent with the data
gaps observed via inspection of the SLE files.

The root cause of the anomaly is unknown at this time but DR# N109954
has been documented and the issue is under investigation.

IMPACT:
The net (playback) data captured for DOY 147 corresponds to 96.686%
(that is, a data loss of 3.314% or 47.717 minutes).

With the goal of confirming that the DOY 147/148 SLE file playback
data gaps matched the results identified with the IDR data, the FOT
retrieved the IDR files from DSN on 6/5/2015, and using the M-MOC tools
confirmed that the data gaps are equivalent for the two data products
(i.e., the % of gaps and the actual times of the gaps matched exactly).