UARS Weekly Status Report

05 January 2001




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                UARS WEEKLY STATUS REPORT - 05 JAN 2001

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***********
SOLSTICE
***********

In support of this week's yaw maneuver, SOLSTICE operated in day only mode
as we were turned off and on each orbit to conserve power. This lasted for
two days during which we performed our normal solar observations but
gathered no stellar observations. The remainder of the week SOLSTICE
collected solar data on all available orbital tracking periods and stellar
calibration observations whenever possible. We continue to gather enough
data to meet all the SOLSTICE science objectives during this period of
reduced tape recorder operations.

Preliminary analysis of data following the operations anomaly in December
(reported in weekly report on 12/15/00) shows some degradation in the
SOLSTICE detectors. The instrument's gradual degradation is routinely
calibrated using data from the stellar observations. This one day step in
degradation will be included as part of this analysis as we have done in
the past for similar "one day hits". Two of the three SOLSTICE detectors
showed little degradation due to the exposure and have recovered nicely.
The mid-uv channel (170-315nm) showed the largest degradation of
approximately 40%. This degradation essentially decreases the lifetime of
the detector but we do not expect it to prematurely stop working.

We are planning a few special observations of Mercury to be carried out
starting next week when availabilities are favorable (Jan 8 - Jan 12)

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SUSIM
***********

SUSIM performed daily solar scans of the sun during periods of
predicted UARS telemetry.

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ACRIM
***********

Nothing received.

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PEM
***********

     AXIS 1 was activated on December 25 and deactivated on December 28.  The 
PEM zenith spectrometers are activate in daylight mode.

     At the present time, PEM energy deposition from its spectrometers is not 
being generated.  Recent data configuration changes have affected PEM software 
causing multiple failures.  These failures are being reviewed by the PEM team.
In order to correct for new telemetry requirements, PEM will need to update 
processing code with a patch delivery.  The delivery patch may include changes 
which would allow the PEM software to execute on a DEC Alpha machine.  GSFC is
helping PEM with some DEC Alpha particulars which have caused PEM level 3
code to fail on DEC Alpha machines (software below level 3 executes on the
DEC Alpha).

   The PEM team is working on replacing the PEM:: machine with a DEC Alpha 
machine to be called PEM2K::. Initial tests of telemetry transfers through 
PEM2K:: have been successful; however, unexplained missing transfers have 
occurred to PEM2K::.  PEM Telemetry is runing in duplicate streams through 
PEM:: and PEM2K::. We find that there are occasional files which transfer 
from the CDHF to PEM::, but are missing from PEM2K::.

    Updated HEPS calibration parameters have been finalized and are ready for 
delivery.  Updated MEPS quality calibration files have been finalized and are 
ready for delivery.  Level 3 software errors, discovered by Dr. Dean Pesnell, 
have been fixed; his suggestions have been incorporated with in the PEM 
production code.  Both updated HEPS and MEPS calibration data, along with the 
Level 3 code changes, will influence the in-situ energy deposition predictions,
so new versions of PEM energy deposition Level 3 files will be generated.

*Beginning of power orbit day (PEM activation): array current >5 amps, array 
     voltage >53.5 volts, and battery current >2.0 amps.  
 End of power orbit day (PEM deactivation): time in power orbit day >4 minutes,
     array current <9 amps, and battery currents <0.2 amps.
 Power orbit day variation: ~39-40 min at yaw to ~50-51 min at maximum beta.

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HALOE 
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Nothing received.

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MLS
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Nothing received.

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HRDI
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Nothing received.

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WINDII
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Nothing received.

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MPG
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The MPG participated in the Monthly Status Review meeting for
UARS, held on 3 January 2001.

Daily processing of instrument Daily Activity Plans continues
with no problems. Instrument operations schedule is now complete
to 9 February 2001.

***********
CDHF
***********

Nothing received.
                  
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FOT
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                         REPORTING PERIOD

This report covers 23 December 2000 (Orbit 50746, GMT Day 358) through 
29 December 2000 (Orbit 50850, GMT Day 364).

                       SPACECRAFT OPERATION

The observatory is now in Forward Flight (Southern Hemisphere viewing) 
and is performing nominally under two-battery operations.  The 
instrument operational changes were:


                INSTRUMENT OPERATIONAL CHANGES


     Instrument     Time       Orbit     Comment
 PEM          359/2339     50775     DAY ONLY     
 AXIS         359/2339     50775     AXIS 1 ON     
 PEM          360/1140     50783     DAY ONLY FIX     
 HALOE        361/2342     50805     POWER OFF          
 PEM          364/2345     50850     AXIS 1 OFF     


The beta angle ranged between the angles of 25.5 degrees to 05.3 degrees 
for this report period.  The beta angle is now decreasing towards a 
minimum angle of 2 degrees on 31 December 2000 (DOY 366).

Spacecraft battery 1, 2, and 3 performance monitoring continues.  
Battery 1 remains OFF the charge relay.  Battery 2 and Battery 3 are 
currently maintaining greater than 23.8 V end-of-night (EON) load bus 
voltage.  Battery temperatures are stable with a temperature delta 
between Battery 2 and Battery 3 of 0.6 and 0.6 degrees C respectively.  
Additional battery performance data for each battery on 22 December 2000 
and 28 December 2000 are provided in Appendix D.

The clock error ranged from Ð10.9 to 10.5 msec during this report 
period.  Clock rate adjustments are listed in Appendix C.

All instrument and subsystem engineers were advised on the initial 
excursion of ALERTS or Out-Of-Limits conditions detected by the FOT for 
this report.  A summary is listed below and the details of ALERT and 
Out-Of-Limits occurrences are listed in Appendix B.

¥     OUT-OF-LIMITS  =  00
¥     ALERTS         =  00

The following real-time command sheets were executed for the listed 
operational element(s) during this report period (see Appendix A).

¥     FOT           =  11
¥     PEM           =  03
¥     AXIS          =  01
¥     HALOE         =  01

UARS Anomaly Reports initiated during this report period are listed in 
Appendix E and summarized below.

¥     FOT             =  02

Four (4) Anomaly Report remained OPEN at the end of this report period 
(see Appendix E).

TRANSPONDER FREQUENCIES:
· Transponder A:  00/315  -  2287.496493
· Transponder B:  00/314  - 2287.498584
 
 
                      GROUND SYSTEM OPERATION
 
 Two (2) operational support problems occurred this period.  Anomaly 
Reports are included in Appendix E.
 
 The data loss calculations supplied by Data Capture Facility (DCF) from 
mission start through UTC Day 00/363 show the observatory data loss to 
be 300 hours, 01 minutes, 48.968 seconds. This shows an overall increase 
of 24.080 seconds since the last report period This is a 0.39 percent 
data loss, which equals a 99.61 percent data capture for the mission.
 
 The decrease of 24.080 seconds occurred over one (1) day:
 
· 24.080 seconds on Day 363 due to a Late AOS


                    OTHER SIGNIFICANT EVENTS

                    UARS SATELLITE OPERATIONS

This week UARS successfully flew through the solar eclipse on 25 
December 2000.  The EOD SOC dropped 0.5 percent for one orbit and 
immediately recovered on the next orbit.

The FOT and FSW group uplinked a one word patch to eliminate fixed point 
overflow messages being received in the status buffer.  The uplink was 
successful and no overflow messages have been received since the patch 
was made.

The FOT also generated the yaw plan and corresponding command sheets for 
the upcoming yaw on 31 December 2000.  All preparations have been made 
and the load was built on 29 December 2000.

The performance of the TAMs continues to be monitored and analyzed on a 
daily basis.  Further testing of the TAMs on both the simulator and 
onboard will continue next week.  The FOT is trying to get the TAMs 
ready before the next high beta period which will begin around 16 
January 2000.


                           MEETINGS

The FOT attended a Year End Review Meeting on 27 December 2000.


                 FUTURE SIGNIFICANT EVENTS


The next UARS Yaw slew is scheduled for December 31, 2000 (DOY 366).  
This maneuver will be a Forward to Reverse Flight maneuver (Northern 
Hemisphere viewing).


Attachments:  Appendix A,  Real-time Commands Sheets
              Appendix B,  Out-Of-Limits & ALERT Occurrences
              Appendix C,  Clock & Solar Array Rate Corrections
              Appendix D,  UARS Battery Performance Data
              Appendix E,  UARS Anomaly Reports

                      APPENDIX A
                 REAL-TIME COMMAND SHEETS
                Week ending 29 December 2000

ORBIT     AOS          NO.      SUBSYS     REASON
-----     ---          ---      ------     ------
50750    358/0659     00-748    NBTR      NOOPS D-358
50757    358/1818     00-750    NBTR      NOOPS D-359
50764    359/0619     00-750    NBTR      NOOPS D-359
50769    359/1319     00-750    NBTR      NOOPS D-359
50772    359/1820     00-751    NBTR      NOOPS D-360
50775    359/2339     00-752    PEM       ZEPS/HEPS TO DAY ONLY
50775    359/2339     00-753    AXIS      AXIS 1 ON
50780    360/0701     00-751    NBTR      NOOPS D-360
50783    360/1140     00-754    PEM       TO DAY ONLY FIX
50787    360/1822     00-755    NBTR      NOOPS D-361
50794    361/0623     00-755    NBTR      NOOPS D-361
50805    361/2342     00-757    HALOE     POWER OFF
50811    362/0818     00-756    NBTR      PLAYBACK
50832    363/1906     00-758    OBC       UFLTR TLM PATCH
50845    364/1547     00-759    OBC/ACS   Mag. Model time update
50850    364/2345     00-760    PEM       AXIS 1 OFF
_______________________________________________________________________
                         
                      APPENDIX B
             OUT-OF-LIMITS & ALERTS OCCURRENCES
               Week ending 29 December 2000

The following Out-Of-Limits occurrences were detected:

MNEMONIC     STATE        DESCRIPTION     ORBITS
--------     -----        -----------     ------
             -None this report period


The following ALERT occurrences were detected:

MNEMONIC     DESCRIPTION                 ORBITS
--------     -----------                 ------
             -None this report period

________________________________________________________________________

                       APPENDIX C
           CLOCK & SOLAR ARRAY RATE CORRECTIONS
              Week ending 29 December 2000

              CLOCK DRIFT RATE ADJUSTMENTS

ORBIT     TIME                 CLOCK RATE CHANGE
-----     -----                -----------------
          -None this report period


____________________________________________________________________

                          APPENDIX D
                UARS BATTERY PERFORMANCE DATA
                 Week ending 29 December 2000


     22 Dec 2000 - GMT Day 357 Beta = 27.6 deg, SA Pos = 269 deg

     DIFF V (mV)    TEMP (C)      CURR (amp)   EON V  AVE C/D   AVE
BAT  MAX/MIN        MAX/MIN       MAX/MIN      MIN    RATIO     DOD(%)
---  -----------    --------      ----------   -----  -------   ------
1   +728.0/+728.0   -3.05/-4.31   +0.0/+0.0    14.2   0.000     0.0
2   +39.2/-28.0     +5.79/+4.83   +30.4/-14.4  24.5   1.040     21.3
3   +22.4/-112.0    +5.15/+3.87   +29.6/-15.2  24.5   1.040     21.0


     28 Dec 2000 - GMT Day 363 Beta = 10.7 deg, SA Pos = 269 deg

     DIFF V (mV)    TEMP (C)      CURR (amp)    EON V   AVE C/D  AVE
BAT  MAX/MIN        MAX/MIN       MAX/MIN       MIN     RATIO   DOD(%)
---  -----------    --------      ----------     -----  ------  ------
1    +728.0/+728.0  -3.68/-4.94   +0.0/+0.0     14.2    0.000   0.0
2    +11.2/-22.4    +4.51/+3.87   +29.6/-13.2   26.2    1.020   19.9
3    +22.4/-22.4    +3.23/+2.60   +28.8/-12.8   26.1    1.020   19.3


     V/T LEVEL CHANGES
ORB#           TIME             LVL FR-TO
-----          ----             ----------
no changes     V/T 5

_______________________________________________________________________

                                  APPENDIX E
                     UARS ANOMALY REPORTS
                 Week ending 29 December 2000

                 NEW ANOMALY REPORTS GENERATED
AR NO.   SUBSYS    ORBIT     TIME       TTR     PROBLEM/DATA LOSS
------   ------    -----     ----       ---     -----------------
00-057     FOT     50778     360/0439   14170   Generic Late cquisition
00-057     FOT     50827     363/1003   14170   Generic Late Acquisition


             ANOMALY CLOSURE INFORMATION RECEIVED
AR NO.   SUBSYS     ORBIT     TIME     TTR     PROBLEM/DATA LOSS
------   ------     -----     ----     ---     -----------------


              ANOMALY INVESTIGATION REPORTS GENERATED
AR NO.   SUBSYS     ORBIT     TIME     TTR     PROBLEM/DATA LOSS
------   ------     -----     ----     ---     -----------------
         -None this report period


                     OPEN ANOMALY REPORTS
AR NO.   SUBSYS     ORBIT     TIME      TTR     PROBLEM/DATA LOSS
------   ------     -----     ----      ---     -----------------
00-053   FOT        50168     319/1113  23157   Late Acquisition
00-054   FOT        50280     326/2147  23187   RESET PTP /2:39 32K
00-056   FOT        50584     347/0502  23302   Premature LOS.
00-057   FOT        see list  Dec 00    14170   Generic late Acquisition

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