UARS Weekly Status Report

19 April 2002




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                UARS WEEKLY STATUS REPORT - 19 APR 2002

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

SOLSTICE continues under day only operations due to low power
conditions. We are performing default solar observations during this
time.

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

Nothing received.

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

Nothing received.

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

PEM continues to receive NMC data files from NOAA.  No problems have
been encountered.

PEM support of the UARS Traceability Mission for the TIMED mission has
been organized with the GVUI team.  Predicted TIMED-UARS conjunctions from
the high geographic latitudes were compared with the expected magnetic position
and the PEM climatology.  Positional and anticipated precipitation flux 
information showed that the expected electron precipitation as a function of 
magnetic activity had the highest probably of a successful conjunction on
April 19.  Continued monitoring has shown changes in conjunction times.  For
conjunctions within 300 km, there are now 4 times shown:

Contact #    Date    Day  Time   Geo Lat   ILAT   MLT   Hemisphere
                                  (deg)   (deg)   (hr)
    1      April 18  108  21:30   56.87   54.43   2.96  North
    2      April 18  108  22:18  -56.89   66.06   6.07  South
    3      April 23  113  14:56   56.98   53.09   2.77  North
    4      April 23  113  15:44  -56.98   48.03   2.24  South

Contact times have remained about the same as from the last update; however, 
the time offsets and interspacing of spacecraft have changed a bit which has
caused the last contact on April 18 to no longer meet the requirement above.  
Of coarse, what is important is that PEM passes through the aurora at the 
same time GUVI is imaging at the same location, and this does not necessarily 
mean that UARS and TIMED are in conjunction.

*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.

***********
HALOE 
***********

Nothing received.

***********
MLS
***********

Nothing received.

***********
HRDI
***********

Nothing received.

***********
WINDII
***********

Nothing received.

***********
MPG
***********

The MPG continues to serve as the point-of-contact
for UARS instrument operations to support re-engineering
of the UARS Mission Operations Concept to develop 
capabilities for the Science Traceability Mission.
 
Daily processing of instrument Daily Activity Plans 
continues with no problems.

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

Nothing received.
                  
***********
FOT
***********

                           REPORTING PERIOD

This report covers 06 April 2002 (Orbit 57784, GMT Day 096) through 12
April 2002 (Orbit 57889, GMT Day 102).

                         SPACECRAFT OPERATION

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


                    INSTRUMENT OPERATIONAL CHANGES


       Instrument    Time          Orbit     Comment
       HALOE        100/1859      57856     Power OFF (YAW)
       PEM          101/1858      57871     Power OFF
       SUSIM        101/1858      57871     Power OFF



The  beta  angle  ranged between the angles of 32.82 degrees  to  7.14
degrees  for  this  report period.  The beta angle is  now  decreasing
towards a minimum angle of 0 degrees on 13 April 2002 (DOY 103).
   
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 0.68 to 0.95 degrees C.  Additional
battery  performance data for each battery on 05  April  2002  and  12
April 2002 are provided in Appendix D.

The  clock  error  ranged from -10.1 to 14.3 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            =    03
    HALOE          =    01
    PEM AXIS       =    02
    SUSIM          =    01

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

    FOT            =    0

Three  (3)  Anomaly Reports remained OPEN at the end  of  this  report
period (see Appendix E).

TRANSPONDER FREQUENCIES:
    Transponder A:  01/333  - 2287.496855
    Transponder B:  02/043  - 2287.498879


                        GROUND SYSTEM OPERATION


Zero  (0) operational support problems occurred this period.   Anomaly
Reports are included in Appendix E.

The  data  loss  calculations are no longer  being  supplied  by  Data
Capture Facility (DCF).


                       OTHER SIGNIFICANT EVENTS

                       UARS SATELLITE OPERATIONS


All  FOT  efforts  are currently being directed to  the  readiness  of
Eclipse for the upcoming yaw maneuver on 13 April 2002.  All converted
CECIL  procedures are being re-executed against the simulator for  all
instrument  turn  ons, as well as all of the POCC resident  microloads
involved in the turn ons.  The yaw script and yaw command sheets  have
been  modified to reflect Eclipse command syntax.  The stored  command
load has been checked and the FOT is ready for the yaw.

                               MEETINGS

The FOT attended a UARS YAW Maneuver CAM on Thursday, April 11, 2002.


                       FUTURE SIGNIFICANT EVENTS


The next UARS Yaw slew is scheduled for 13 April 2002 (DOY 103).  This
maneuver  will  be  a  Reverse to Forward  Flight  maneuver  (Southern
Hemisphere viewing).


Attachments:    Appendix A, Real-time Command 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 12 April 2002

ORBIT   AOS        NO.      SUBSYS      REASON
-----   ---        ---      ------      ------
57853   100/1404   02-119   OBC/CLK     CLK ADJ FR 0.0 TO -20.6 MSEC/DAY
57856   100/1859   02-120   HALOE       POWER OFF (YAW)
57869   101/1402   02-121   PEM         CALIBRATION
57871   101/1858   02-122   PEM         POWER OFF
57871   101/1858   02-123   SUSIM       POWER OFF
57875   102/0118   02-124   OBC/CLK     CLK ADJ FR -20.6 TO 0.0 MSEC/DAY
57880   102/0956   02-125   OBC/CLK     CLK ADJ FR 0.0 TO 20.6 MSEC/DAY
                                   
                                   
                                   
                              APPENDIX B
                  OUT-OF-LIMITS & ALERTS OCCURRENCES
                       Week ending 12 April 2002

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 12 April 2002

                     CLOCK DRIFT RATE ADJUSTMENTS

ORBIT          TIME                   CLOCK RATE CHANGE
-----          -----                  -----------------
57853          100/1407               CLK ADJ FR 0.0 TO -20.6 MSEC/DAY
57875          102/0128               CLK ADJ FR -20.6 TO 0.0 MSEC/DAY
57880          102/1000               CLK ADJ FR 0.0 TO 20.6 MSEC/DAY


                              APPENDIX D
                     UARS BATTERY PERFORMANCE DATA
                       Week ending 12 April 2002


  05 April 2002 - GMT Day 095 Beta = 34.23 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  -3.16/-4.38  +0.0/ +0.0    9.6     0.000     0.0
2  + 11.2/- 16.8  +4.48/+3.82  +26.8/-13.2  26.4     1.040    18.9
3  + 11.2/- 22.4  +3.82/+2.85  +25.6/-12.8  26.4     1.030    18.5


  12 April 2002 - GMT Day 102 Beta = 7.14 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 -3.16/-4.38  +0.0/ +0.0     0.0    0.000     0.0
2  + 11.2/+134.0 +4.50/+3.87  +27.8/-15.8   25.0    1.010    20.6
3  + 22.4/- 22.4 +3.55/+2.60  +26.7/-15.8   25.0    1.010    20.3

      V/T LEVEL CHANGES
ORB#          TIME       LVL FR-TO
-----         ----       ---------
-no changes    V/T 5
   
                              APPENDIX E
                         UARS ANOMALY REPORTS
                       Week ending 12 April 2002

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


                ANOMALY CLOSURE INFORMATION RECEIVED
AR NO.    SUBSYS    ORBIT     TIME      TTR       PROBLEM/DATA LOSS
------    ------    -----     ----      ---       -----------------
-None this report period.


                  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
------    ------    -----     ----      ---       -----------------
02-004    SOLSTICE  56883     036/0050  N/A       Solstice in Wrong Mode
02-023    FOT       57767     094/2027  24285     Early LOS on OMNI Pass
02-024    FOT       57783     095/2209  24285     SOLSTICE INOPS in Day