ACE Weekly 03/26/2008 - 04/01/2008

All ACE spacecraft subsystems are performing nominally.

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Orbit/Attitude:

	Type        Attitude
	Date        03/26/2008
	DOY         086 2008
	Thrusters   2R 4R+ 4R-
	Duration    14:40 min
	Start       15:08:00z
	Stop        15:22:40z
	HGAStart    -6.30deg
	HGAStop     +7.00deg
	SunStart     6.75deg
	SunStop     11.32deg
	Nutation     0.39deg
	Firing      75 pulses
	FuelUsed      0.2401lbs
	FuelRemain  150.8236lbs
	FinalSCMass 1385.083lbs

The next attitude maneuver is scheduled for Wednesday 04/16/2008.

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OCRs:

None

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Activities:

None

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Anomalies:

DOY 086  03/26/2008  S-ACE-0294  G08-0034  DSS-66/Network Error/SLE Abort
After a brief network error at 17:11:59, the ACE MOC SLE software issued a
"Protocol Abort" and the ACE MOC automatically attempted to rebind.  The
Bind attempts were not successful.  When the ACE MOC issues a Protocol
Abort, the station must set the TCP Production Status to "halt" and then
back to "operate".  The ACE MOC was finally able to bind at 17:29:58.
DR#M104724  This problem last occurred on 01/11/2008 (AR#G08-0005).
IMPACT:  Commanding delayed 18 minutes

DOY 090  03/30/2008  S-ACE-0295  G08-0035  Excessive Network Loss
Network data loss was 1.1% for most of the pass with DSS-27 (2111-2302z).
DR#N104779
IMPACT:  All data available on CDR.  CDR verified before the beginning of
the next pass.


Background Information
During a pass, it is not possible to determine whether data gaps will be
available at DSN's CDR Facility.  Therefore, after a playback is done, all
data gaps are redumped as time permits.  If the pass has excessive data loss
and is staffed, the CDR files are checked to determine if they contain the
missing data.  If the pass is not staffed, redumps are continued on the next
support until certain constraints are met.
DSN has discussed of changing the network connection from UDP to TCP
(guaranteed delivery).  This would simplify ACE operations.  There is a
concern that TCP would add a delay to data delivery.  For ACE operations, it
is better to have guaranteed delivery even if the data delay is 5-10
seconds.  Note, other missions may have different priorities.

Furthermore, downloading the CDR ultimately results in a doubling of the ACE
network usage (once for the pass and once for verifying the data is on the
CDR).  Guaranteed delivery would reduce the need to download CDR files.