ACE Weekly 12/19/2007 - 12/25/2007

All ACE spacecraft subsystems are performing nominally.

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

No maneuvers were completed this week.  The next attitude maneuver is
scheduled for Friday 12/28/2007.  Station-Keeping #46 has been tentatively
scheduled for Thursday 01/17/2008.

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

None

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

34m HEF S-Band Transmitter
DSN has requested additional ACE test passes to verify fixes implemented
with the new S-Band 250W transmitters at DSS-45 and DSS-65.  The following
tests have been scheduled.

	Date       DOY  Station   Test
	Fri 12/28  362  DSS-45    S-Band XMTR, SLE and range data


The risk of data loss has again increased for the December-January time
frame.  If there are problems with the passes, it may not be possible to
acquire additional DSN time.  The following discusses some of the issues
involved.

* In the winter months, our viewperiods from antennas in the northern
hemisphere are shorter.  Since 4 of the 6 antennas are in the northern
hemisphere (Madrid, Spain & Goldstone, California), our overall available
time is reduced.
* SOHO has a 60-day continuous campaign from 12/03/2008 through 02/03/2008.
* Ulysses Nutation Season continues until February 2008.
* DSN has implemented a maintenance schedule where every antenna is
unavailable during daylight hours one day each week.  This has the biggest
impact on L1 missions, reducing available antenna time by 14% (1/7).
* DSS-45 and DSS-65 will eventually be available after the S-Band
transmitter installation is complete.  However, these antennas are already
utilized by other missions.

During December-January last year, there were several late-night
reschedulings, 3 SSR failovers due to lost passes, and a cumulative 4.2
hours of science data lost.  



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

DOY 355  12/21/2007  S-ACE-0257  G07-0109  DSS-46 Commanding Delayed
DSS-46 TCP1 CMD STAT read "waiting for start ack".  After several reboots
and TCP swaps, TCP1 CMD STAT went to "waiting for data".  DR#C106064
IMPACT:  Activities delayed 1 hour 40 minutes.  Additional DSN time was not
available.  It would take until 12/24/2007 (DOY 358) for SSR playback to be
caught up and back on schedule.


DOY 358  12/24/2007  S-ACE-0258  G07-0110  DSS-27 Antenna Stop
Antenna stopped tracking unexpectedly (1532z).  Station returned to track
within 11 minutes (1543z) and uplink established at 1546z.  DR#G108252
IMPACT:  SSR playback had not yet caught up.  Since automation does not
redump the redumps, this resulted in 1.9 hours of cumulative data loss (DOY
357 1805-2026z).