ACE Weekly 09/03/04 - 09/09/04

All ACE spacecraft subsystems are performing nominally.  An attitude=20
maneuver was successfully executed on 09/03/04.  The next attitude maneuver=
=20
is scheduled for 09/10/04.

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Orbit Events:

The ACE transit of the Solar Exclusion Zone (SEZ) continues through=20
09/11/04.  The minimum Sun angular radius was 0.32 degrees (as seen from=20
Earth's center) on 08/30/04.  Features of this transit are given in the=20
following table.

8/18    4.96 deg inbound
8/25    2.13 deg inbound
8/29   0.61 deg inbound
8/30    0.32 deg  minimum SEZ angle this transit
8/31   0.41 deg outbound
9/05    2.30 deg outbound
9/11    4.78 deg outbound

Some preliminary data in regards to Signal-to-Noise Ratios (SNR) for=20
contacts with DSS-27 at
low (498 bps), medium (7968 bps) and high (87648 bps) downlink data rates:

         DOY   SEV angle   498     7968     87648
          ---     ----------    ----     ------    -------
         241   1.03-1.00=B0                         8.2
         242   0.67-0.64=B0                         4.1
         243   0.35-0.32=B0  15.0     7.5      -2.5 (no data at hi-rate)
         244   0.37-0.40=B0  17.8    13.0      2.8
         245   0.67-0.70=B0                         8.0
         246   1.05-1.08=B0                         9.5

 From the last transit, we found that DSS-27 could get good lock with=20
SNR=3D0dB (noise as big as signal).  Given this data and the data from the=
=20
last transit, it looks like the following is a good rule-of-thumb:

0.3=B0-0.5=B0       50-50 chance of getting hi-rate with 34m/D27
 >0.5=B0           likely to get hi-rate with 34m/D27

0.5=B0-0.8=B0       50-50 chance of getting hi-rate with 26m
 >0.8=B0           like to get hi-rate with 26m

We have been able to get acquire low and medium rate at any SEV angle=20
(Sun-Earth-Vehicle).

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OCRs Executed:

None

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Ongoing Activities:

TAPS:
- Installation of TAPS release 4.3 occurred on 07/20/04.  FOT testing of=20
this release is ongoing.
   -- Of the 6 DRs fixed in release 4.3, all have been verified.
   -- Two (2) new DRs have been opened to date.

----------------------------------------------------------------------------
Automation (ROBOTT):

- On 08/25/04, ROBOTT v0.8.1 was installed on String 1 (OCR GND-143).
   -- Operations is being conducted in the "auto" mode with the FOT closely=
=20
monitoring and noting any discrepancies.
- Testing of v0.8.1 by the FOT will continue on String 2.
   -- To date all DRs fixed in this release have been tested.  One (1) DR
has failed and eight (8) new DRs have been written against v0.8.1.
- ROBOTT v0.9 is in development and is tentatively scheduled for delivery=20
to Strings 2 & 3 in the coming week.

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Extra Spacecraft Activities:

None

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Anomalies:

DOY 04250 (09/06/04) ACE Anomaly G04-0103 - ROBOTT Failed To Run Script=20
FOT_RUN_ADS
The FOT configured C&C to run the script FOT_RUN_ADS before BOT=20
occurred.  After the procedure G_INITIAL_CONTACT was ran C&C failed to=20
execute the script FOT_RUN_ADS.  IMPACT:  FOT had to initiate a block=20
replay and execute the script FOT_RUN_ADS manually. DR CDSID# 00021051

DOY 04252 (09/08/04) ACE Anomaly G04-0088 (Appended) - ADS Failure
Received error when attempting to start ADS.  Killed processes on=20
workstation and rebooted the software.  IMPACT:  No impact to FDF.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Glen A. Miller
ACE Flight Operations Observatory Engineer
Honeywell Technology Solutions Inc.
Goddard Space Flight Center
Building 14, Room W10A
Mail Stop 428.2
Greenbelt, MD 20771

Office: 301-286-7071
Pager: 800-425-3174
Fax:    301-286-1729
gamiller@pop500.gsfc.nasa.gov
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~