ACE Weekly 09/21/2016 - 10/04/2016

All ACE spacecraft subsystems are performing as expected.

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Attitude/Orbit:

Type               Attitude               Spin Down
Date             09/22/2016              09/22/2016
DOY                266 2016                266 2016
Thrusters        2R 4R+ 4R-                 3R- 4R-
Duration      12:14 minutes              14 seconds (~13.70s)
Start             15:45:25z               17:12:20z
Stop              15:57:39z               17:12:34z
ra,decStart   175.72,-11.13           186.67,-13.64
ra,decStop    186.67,-13.64           186.68,-13.66
ra,decExpect  186.70,-13.98           186.67,-13.64
Deviation          0.10 deg (-0.9%)   
HGAStart          -8.44 deg               +6.74 deg
HGAStop           +6.74 deg               +6.71 deg
SunStart          11.98 deg               15.34 deg
SunStop           15.34 deg               15.32 deg
SpinStart        5.0904 rpm              5.0939 rpm
SpinStop         5.0939 rpm              4.9500 rpm
Nutation           0.17 deg                0.27 deg
Firing            63 pulses              Continuous
FuelUsed         0.1798 lbm              0.0422 lbm
FuelRemain       88.088 lbm              88.046 lbm
FinalSCMass    1322.347 lbm            1322.305 lbm

Type               Attitude			Attitude
Date             09/27/2016			10/03/2016
DOY                271 2016			277 2016
Thrusters        2R 4R+ 4R-			2R 4R+ 4R-
Duration      10:33 minutes			9:53 minutes
Start             16:02:44z			17:55:29z
Stop              16:13:17z			18:05:22z
ra,decStart   186.83,-13.61			197.48,-10.52
ra,decStop    197.38,-10.66			203.39,-17.43
ra,decExpect  198.53,-10.91			203.41,-17.68
Deviation          1.10 deg (-9.3%)		0.20 deg (-2.2%)
HGAStart          -4.75 deg			-1.43 deg
HGAStop           +7.88 deg			+8.75 deg
SunStart          12.04 deg			9.92 deg
SunStop           15.69 deg			18.76 deg
SpinStart        4.9499 rpm			4.9528 rpm
SpinStop         4.9530 rpm			4.9553 rpm
Nutation           0.16 deg			0.14 deg
Firing            53 pulses			49 pulses
FuelUsed         0.1710 lbm			0.1469 lbm
FuelRemain       87.875 lbm			87.728 lbm
FinalSCMass    1322.135 lbm			1321.988 lbm


The 9/22/2016 maneuvers had been moved from 9/20/2016 due to a DSN antenna anomaly, which caused ACE to lose its 9/20/2016 support (reference 09/14/2016 - 09/20/2016 ACE weekly).  

The 9/22/2016 spin down maneuver targeted 4.95 rpm.  Flight Dynamics' post-maneuver report estimated the maneuver had a performance error of 0%.  ACE had last performed a Spin Down maneuver on 5/14/2013.

The weekly Attitude Maneuver was executed on 9/27/2016.  Post-maneuver analysis estimated the attitude maneuver underperformed by ~9.3%.  Preliminary investigation found the maneuver had been planned using a spin rate of 4.5 rpm, instead of 4.95 rpm (reference SOAR S-ACE-99).  Root Cause and Corrective Analysis (RCCA) will be performed.  

Upcoming Maneuver Schedule:
- Attitude Maneuver:                    Tuesday, 10/11/2016
- Station Keeping (SK-82):              TBD

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OCRs:

None

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Activities:

Data Capture: 100%  2016 DOY 263 - 2016 DOY 276

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Anomalies:   

DOY 271  09/27/2016 SOAR S-ACE-99  Maneuver underperformed due to incorrect spin rate 
Weekly attitude maneuver performed on 9/27/2016.  Post-maneuver analysis estimated the maneuver underperformed by ~9.3%.  Preliminary FOT investigation found the maneuver was planned using a spin rate of 4.5 rpm, instead of 4.95 rpm.
IMPACT:  
Immediate - FOT confirmed post-maneuver attitude within constraints and would last until our next regularly scheduled maneuver day, 10/03/2016.  No immediate corrective action was necessary to address the underperformance.  NASA MD notified.  
Preventive - Root Cause and Corrective Analysis (RCCA) performed.  Automated Validation of GMAN User Inputs will be implemented (e.g. spin rate 4.9-5.1 rpm, delta between current and target attitudes, date verification and fuel mass change).