CE Weekly 07/18/03 - 07/24/03
All ACE spacecraft subsystems are performing nominally. No maneuvers were
executed this week. The next attitude maneuver is scheduled for 07/25/03.
============================================================================
Orbit Events:
According to Craig Roberts (FDF), the ACE orbit is in fine shape. Based on
current indications, he expects we'll get at least a good four month coast
from the June 23rd point. That would put the next stationkeeping burn in
latter October. It's possible we could even go longer into November,
depending on how upcoming attitude burn perturbations play out.
The next SEV transit will occur during the 09/01/03 - 09/23/03 time frame.
Expected minimum SEV angle will be 1.76 degrees.
The essential timeline based on a 30-min step scan for this 22 day, 8.5
hour event is:
- SEZ entry (4.75 deg inbound) on Sept. 1 at 0100Z
- Minimum Sun-Earth-ACE angle = 1.760 deg on Sept. 12 at 0800Z
- SEZ exit (4.75 deg outbound) on Sept. 23 at 0930Z
============================================================================
OCRs Executed:
NONE
============================================================================
Ongoing Activities:
TAPS:
Trending, Analysis and Plotting System (TAPS) development continues with
emphasis being placed on fixing the DRs attributed to the current release.
Testing is progressing on both TAPS#1 and TAPS#2. The next release is
projected to occur in the next two weeks.
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Automation (ROBOTT):
FOT testing of ROBOTT Release 0.1 is ongoing. CRON testing on String 2 is
progressing, although some minor problems have occurred. The Automation
Team is performing testing on the Command & Control system. The first
release to the FOT is still TBD.
============================================================================
Anomalies:
DOY 03200 (7/19/2003) - ACE Anomaly G03-0061 - GDS 26m (DSS-66) Incorrect
Predicts
The FOT noticed high RCVR_A_VCO and RCVR_B_VCO values, in addition to
RCVR_A_LOCK and RCVR_B_LOCK out of lock. DSS-66 notified us that they were
having trouble acquiring 2 way and would have to perform it manually. At
12:51:40, DSS-66 notified us that we had a "go for command". Receiver AGCs
and VCOs were stable and nominal. At 13:17:20, DSS-66 informed the FOT
that they had incorrect predicts and asked to reacquire the S/C using the
correct predicts. At 13:18:40, DSS-66 gave the "go for command". The FOT
sent a NO_OP verifying command capability. IMPACT: Delayed pass
activities. All telemetry was acquired. DR# M101745
DOY 03201 (7/20/2003) - ACE Anomaly G03-0062 - Ground System - Network Dropout
There was a dropout within the network which affected command capability
for approximately 45 seconds. At the time the dropout occurred a command
was being sent to the S/C. The command did not get transmitted to the S/C
and the ground system acted accordingly when verification was not received
by the S/C. The command was retransmitted and verification was eventually
received. IMPACT: FAILCMDTFRM_CT incremented from 64 to 65.
DOY 03204 (7/23/2003) - ACE Anomaly G03-0065 - GDS 26m (DSS-66) TCP Problems
At 14:05:55, DSS-66 put telemetry online (BOT @ 14:10:00) but it dropped
out at 14:09:22. At 14:11, DSS-66 reported their receivers were in lock,
but TCP-1 wasn't able to find the data. At 14:14, DSS-66 stated that data
was present on channel 2 and switched to the channel but still no data. At
14:19, TCP-1 was rebooted but still no data. DSS-66 said that after the
reboot of TCP-1, the desktop displayed a value of 87648 for the bit
rate. DSS-66 decided to reload the desktop with the correct bit
rate. Reloading the desktop didn't correct the problem, so at 14:27 DSS-66
switched to TCP-2. At 14:30:10, telemetry was back online. At 14:33, the
FOT confirmed the "go for command". A /no_op command was sent at 14:35 to
confirm a good command link. At 14:36:02, the no_op was verified. At
14:37:15, during G_INITIAL_CONTACT, the command was sent to transition the
S/C to high rate. However, DSS-66 encountered the same problem with TCP-2
at 87648 bps as they did with TCP-1 at 498 bps. At 14:42:22, after the
switch from TCP-2 back to TCP-1 (87648 bit rate), telemetry
resumed. IMPACT: Delayed pass activities. All telemetry was
acquired. DR# M101753
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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
Email: gamiller@pop500.gsfc.nasa.gov
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~