ACE Weekly 10/15/2008 - 10/21/2008

All ACE spacecraft subsystems are performing nominally.

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Orbit/Attitude:

No maneuvers were performed this week.  The next attitude maneuver is
scheduled for Friday 10/31/2008.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 286-293 2008

The risk of data loss has again increased for the October-February time
frame.  Several missions are competing for the same antenna time (daylight
hours).  If there are problems with the passes, it may not be possible to
acquire additional DSN time.  For more information refer to 10/14/2008
weekly.

New requirements on FDF ephemeris generation will need to be negotiated.
DSN implemented SPSv1.2 on 10/9/2008.  The new SPS requires a 26-week
scheduling grade ephemeris for viewperiod generation.  This will be in
addition to the 12-week predict grade ephemeris that is currently delivered.
(See AR#G08-0099 below)

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Anomalies:

DOY 289  10/15/2008  S-ACE-0360  G08-0095  DSS-46 SLE Bind Broken
At Beginning Of Track (BOT), the first command (TIME_BIN_LOAD) was not
transmitted to the spacecraft and FCLTU Bind was broken.  The ACE MOC SLE
software successfully rebinded, but the bind was broken for each subsequent
command retransmission.  The FOT requested that DSS-46 switch the uplink
system from Operate to Halt and back to Operate.  The first command was
successful transmitted after 10 minutes.  DR#C106578 attributes the problem
to DSS-46 TCP time.
IMPACT:  Manual intervention required.  Activities delayed 10 minutes.

DOY 289  10/15/2008  S-ACE-0361  G08-0096  DSS-46 TCP configuration
ACE is commanded from low-rate (498bps) to high-rate (87648bps) at the
beginning of every support.  This requires the station operator to manually
reconfigure the TCP (Telemetry Control Processor).  A brief misconfiguration
was quickly corrected by the station operator.  DR#C106579
IMPACT:  Minimal.  3 minute telemetry outage.

DOY 290  10/16/2008  S-ACE-0362  G08-0097  DSS-27 Transmitter Problems
DSS-27 transmitter calibration problems resulted in a lost interface to the
LMP (Link Monitor Processor).  An operator travelled to the antenna to
perform the resets.  DR#G108901
IMPACT:  Activities delayed 8 minutes.

DOY 294  10/20/2008  S-ACE-0364  G08-0099  New DSN/SPS/FDF requirements
This anomaly report is to document that DSN SPSv1.2 was implemented before
new requirements on FDF ephemeris generation were negotiated.
IMPACT:  Viewperiod generation will be based on the ephemeris created on
07/09/2008.  Even though there have been 8 attitude maneuvers, 1 spin
maneuver and 1 station keeping maneuver since July, there is only a few
seconds difference in viewperiods.  All of this is more of a problem with
Earth orbiters as opposed to L1 missions.

DOY 294  10/20/2008  S-ACE-0365  G08-0100  FDF Viewperiod Masks for D45/D65
FDF provides their own viewperiod generation that is used by the FOT and
scheduling team.  FDF recently added DSS-45 and DSS-65, however, the RISE
and SET times differ significantly from DSN's viewperiod files.  FDF has
been asked to verify with DSN that they are using the correct horizon masks.
IMPACT:  ACE has only scheduled one pass every ~2 months since the S-Band
transmitters went operational; DSS-45 and DSS-65 are already heavily used.
Fixing this problem, however, will avoid out-of-view problems when the
antennas are scheduled.