ACE Weekly 11/26/2008 - 12/02/2008

All ACE spacecraft subsystems are performing nominally.

============================================================================
Orbit/Attitude:

No maneuvers were completed this week.  The next attitude maneuver is
scheduled for Wednesday 12/03/2008.

===========================================================================
OCRs:

None

============================================================================
Activities:

Data Capture:  100%  DOY 328-335 2008

There is a higher than normal risk of data loss from October 2008 through
February 2009.  If there are problems with the passes, it may not be
possible to acquire additional DSN time.  This higher-risk period has been
occurring every winter for the past couple of years.  For more information
refer to 10/14/2008 weekly.

============================================================================
Anomalies:

DOY 329  11/24/2008  S-ACE-0384  G08-0117  AC2WS1 Operating System Version
When the AC2WS1 hard drive failed (10/31/2008 G08-0104), the software
restore was not finished.  The operating software (e.g. /bin) was an earlier
version.  AC2WS1 is on the backup string; it took 2 weeks to discover and 1
week to troubleshoot.  The System Administrators had been called to another
mission before the restore had been completed.
IMPACT:  The TPOCC software did not work with this version of the operating
software.  However, no MOC failovers were required during this time.

DOY 331  11/26/2008  S-ACE-0385  G08-0118  No Lock on Receiver B
When DSS-46 established the uplink at BOT, the spacecraft RCVR B did not
lock on the uplink.  This occurs 1-3 times a year.  Since RCVR A is
transmitting, DSN sweeps the uplink to lock on RCVR A.  During this sweep,
RCVR B also locks on the uplink automatically.  There is no problem with the
spacecraft, but the FOT tracks these occurrences with anomaly reports for
trending purposes.  This last occurred on 12/09/2007 (AR#G07-0102)
IMPACT:  Minimal.  C&DH B timers were reset on the next day (DOY 332).

DOY 333  11/28/2008  S-ACE-0386  G08-0119  DSS-46 CMD/SLE Problems
DSS-46 was unable to configure for SLE commanding at Beginning Of Track
(BOT).  The station rebooted and reloaded the equipment several times.  The
problem was resolved when the station stopped and then re-established the
uplink using link 2.  DR#C106658
IMPACT:  Activities delayed 1 hour 40 minutes.  SSR playback completed on
the following pass.  Note, FOT intervention not required since the ACE MOC
SLE software automatically attempts to reconnect once a minute.

DOY 335  11/30/2008  S-ACE-0387  G08-0120  DSS-46 CMD/SLE Problems
DSS-46 was unable to configure for SLE commanding at Beginning Of Track
(BOT).  The station rebooted and reloaded the equipment several times.  The
problem was resolved when the station rebooted MCP (Monitor Control
Processor).  DR#C106666
IMPACT:  Activities delayed 40 minutes.  The SSR playback was completed on
the following pass.

DOY 336  12/01/2008  S-ACE-0388  G08-0121  Incorrect Nutation Calculation
The nutation provided in the maneuver summaries (starting 09/20/2007) is
calculated using an FOT tool called mansum.  The calculation incorrectly
included a factor of 2.  If the nutation was reported as 0.24 degrees, it
was actually 0.12 degrees.  MOCR 1383 will correct this problem.
IMPACT:  Actual nutation is smaller than reported by a factor of 2.

DOY 336  12/01/2008  S-ACE-0389  G08-0122  DSN Tracking Data To FDF
FDF did not receive tracking data from 11/19/2008 through 11/30/2008 while
JPL was using a backup track server (trk4).  A query script on the backup
server did not use the correct entry in the SCAP table (Security Content
Automation Protocol).  The query script was updated on 12/1/2008.  The SCAP
tables had been updated 09/15/2008.  The WIND mission tracking data was also
affected.
IMPACT:  JPL will retransmit the lost tracking data to FDF.  FDF was still
able to perform ACE orbit determination (OD) on 11/21/2008.  The problem was
resolved before the next scheduled ACE OD on 12/02/2008.