ACE Weekly 03/20/2012 - 03/26/2012

All ACE spacecraft subsystems are performing as expected.

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Orbit/Attitude:

No maneuvers were completed this week.  The next attitude maneuver is
scheduled for Wednesday 03/28/2012.

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OCRs:

None

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Activities:

Data Capture:  100%  DOY 078-085 2012

Ranging tests were performed with WS1 on Tuesday 3/20/2012 (DOY 080) and
Wednesday 3/21/2012 (DOY 081).  WS1 was able to receive its own range
tones, but the range signal was weak.  More range testing will be
needed, but will wait until the LRO viewperiod ends earlier in the day.
FDF is working with WS1 to analyze the range data.  FDF is also looking
at the minimum level of range data needed to support ACE if WS1 ranging
doesn't work.  The FDF minimum data analysis is expected at the end of
April 2012.

Since LRO is the prime mission on WS1, it is expected that there will be
at least 1 week every 4 weeks where the LRO viewperiod prevents WS1 from
tracking ACE.  This will occur around each new moon.  The extent that
ACE time will be split between DSN and WS1 has not yet been decided.  A
presentation will be provided to SSMO management when WS1 testing and
development are complete.

The next Solar Exclusion Zone transit (SEZ) will be the first week of
May.  The minimum Sun-Earth-Vehicle angle (SEV) will be 0.67 degrees.
The angle is larger than the Nov 2011 transit (0.42 deg) and the Feb
2012 sun crossing (0.16 deg).  For the past 2 months, the radio solar
flux has been extremely low (<120 sfu), except for the first 2 weeks of
March (Region 1429; 120-150 sfu).  For the May 2012 transit, with the
increased SEV angle and the relatively quiet sun, no problems are
expected.  But if the radio solar flux jumps above ~200 sfu, then there
may be data loss.


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Anomalies:

None