ACE Weekly 04/22/2009 - 04/28/2009

All ACE spacecraft subsystems are performing nominally.

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Orbit/Attitude:

No maneuvers were completed this week.  The next attitude maneuver is
scheduled for Friday 05/01/2009.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 109-116 2009

The ASC address for receiving real-time data changed on April 14.  The
request for updating the GSFC fanout continues to work through the
NISN/Nascom system.  ASC (ACE Science Center) has not received real-time
data since April 14.

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Anomalies:

DOY 111  04/21/2009  S-ACE-0431  G09-0026  DSS-46 Transmitter Failures
DSS-46 transmitter failure (TXR1 S20K) at Beginning Of Track ("body
coolant indication").  The station switched to backup transmitter (TXR2
S2K) within 10 minutes.  In the last hour of the pass, the transmitter
(TXR S2K) tripped off ("Klystron drive power high fault").  The problem
was resolved within 40 minutes.  DR#C106879 and C106880
IMPACT:  Spacecraft bin dumps were being performed during the final
transmitter failure.  TPOCC did not successfully write the dump file;
the procedure did not complete and the rest of the state-of-health
checks were not performed.  Final state-of-health checks were performed
on the following pass.

DOY 113  04/23/2009  S-ACE-0432  G09-0027  DSS-27 Red
DSN has declared DSS-27 red for 2 weeks (DOY 113-128).  9 out of 15 ACE
passes during this time were scheduled with DSS-27.  The SSMO scheduling
team has done a wonderful job of rescheduling passes.  DR#G109389
IMPACT:  There were no passes on DOY 113 or DOY 116.  Passes have been
moved to avoid SSR Failovers (SSR capacity 43 hours).  Data capture
continues to be 100%.

Background Information.  ACE playback is initiated via ground command
(as opposed to spacecraft load).  This gives ACE considerable
flexibility in moving automated passes.  The ACE Mission Director was
the driving force behind this design.

DOY 114  04/24/2009  S-ACE-0433  G09-0028  DSS-24 Power Outage
Goldstone power outage caused tracking to stop with DSS-24 (1657z).
Telemetry and Commanding restored after 1 hour (1756z) but with only 25
minutes left in the pass.  DR#G109390
IMPACT:  SSR redumps and final state-of-health checks were performed on
the following pass.

DOY 115  04/25/2009  S-ACE-0434  G09-0029  DSS-46 CMD/SLE Problems
DSS-46 was unable to process SLE commands at Beginning Of Track (BOT).
The Ops Chief notified the FOT (Saturday).  Rebooting the TCP resolved
the problem.  The last DSS-46 CMD/SLE problem occurred on 02/19/2009.
DR#C106892
IMPACT:  Activities delayed 20 minutes.