UARS Weekly Status Report

26 June 1998




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                UARS WEEKLY STATUS REPORT - 26 JUNE 1998

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

SOLSTICE continues to operate normally, collecting solar data on all 
available orbital tracking periods and stellar calibration observations, 
whenever possible.  

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

SUSIM has successfully gathered its normal solar, offset, and occultation
scan data this past week without apparent problems.

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

PEM/AXIS was active from June 18 through June 19 and became active again
on June 22.  It is currently generating energy deposition from inverted X-ray 
spectra for each of its 16 look directions. 

GSFC has proposed an OBC operation plan for the activation of PEM boom 
instruments during the daylight portions of every orbit.  This OBC operation 
plan is accepted by PEM.  PEM has proposed a series of test procedures for 
activation and is waiting response from GSFC.  PEM is also waiting for GSFC
scheduling and implementation of the OBC plan and its operation test procedures.

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

HALOE was powered on June 20, 1998.  All engineering parameters are nominal
and the science data products continue to be of excellent quality.

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

Nothing received.

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

HRDI is currently off.  Next scheduled turn-on is July 3rd.

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

Nothing received.

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

Routine processing of instrument Daily Activity Plans continues 
with no other problems.  The MPG continues to assist the Project 
Scientist with the scheduling of instrument operations.

An orbit-adjust maneuver for the UARS spacecraft is being planned 
for 12 August 1998.  In preparation for the thruster firing on 
12 August, small thruster "burns" for calibration are being 
planned for 28 July 1998.

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

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

REPORTING PERIOD

This report covers 12 June 1998 (Orbit 36903, GMT Day 164) through 19 June 
1998 (Orbit 37006, GMT Day 170).


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
        PEM       169/0120     36978       AXIS on
        PEM       170/2305     37006       AXIS off

The beta angle reached a minimum angle of 0.0 degrees on 15 June 1998 (DOY 
166).  The beta angle is now increasing toward a maximum angle of 33.8 
degrees on 30 June 1998 (DOY 181).

A Forward-to-Reverse Yaw Around maneuver (number 69) was successfully 
executed in Orbit 36941 at 13:56:57 UTC on 15 June 1998.  The SSPP 
Instruments (ACRIM, SOLSTICE, and SUSIM) were enabled.  Due to the SA 
position at 269 degrees, the effective night length of the spacecraft after 
the maneuver was 48 minutes.  Post maneuver analysis of data indicate that 
during the Yaw Around, the end-of-night load bus voltage was 23.8 volts and 
the average depths of discharge (DODs) on Batteries 2 and 3 were 
approximately 23.5 and 23.0 percent respectively.

Two Rmanually generatedS stellar offset experiments requested by SOLSTICE 
operations were performed on GMT days 167 and 169.


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 25.0 V end-of-night (EON) load bus voltage. 
Battery temperatures are stable with a temperature delta between Battery 2 
and Battery 3 of 1.1 degrees C.  Additional battery performance data for 
each battery on 13 June 1998 and 19 June 1998 are provided in Appendix D.

The clock error ranged from -12.3 to -3.4 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.

%     ALERTS            =     none
%     OUT-OF-LIMITS     =     08

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

%     FOT     01
%     HRDI    05
%     PEM     02

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

%     FOT     01

One (1) Anomaly Report remained OPEN at the end of this report period (see 
Appendix E).

TRANSPONDER FREQUENCIES:
     Transponder A:  98/146  -  2287.496748
     Transponder B:  98/147  -  2287.499000



GROUND SYSTEM OPERATION

No (0) operational support problem(s) 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 98/162 show the observatory data loss to be 
20 hours, 44 minutes, 05.940 seconds (an increase of 11.424 seconds since 
last report period).  This is a 0.0351 percent data loss which equals a 
99.9649 percent data capture for the mission.

The increase of 11.424 seconds occurred on Day 167 and resulted from the 
downlink Data Rate Change (DRC) not being covered by tape recorder data.

Command Management System (CMS) preparations to accommodate the upcoming 
Flight Software/PMON uplink were implemented.  This included verifying that 
all CMS resident Relative Time Sequences (RTSs) are identical to the RTSs 
in the flight software image, modifying CMS database files to reflect 
planned changes in the size of the stored command loads as well as the size 
allocation of individual RTSs, and testing of the aforementioned 
modifications.

Testing the command side of the I/P Net remains on hold.  Testing will 
begin when MSOCC provides a command loop interface from the POCC through 
the I/P Net to the UARS Simulator.


OTHER SIGNIFICANT EVENTS

Continued the upgrade to the OBC Power Monitor (PMON) flight software.  
Ground System testing continued this week.  Documentation of the System 
table definitions was completed.  New ASCII system table files were 
generated.  Extensive testing of the Ground Software was conducted on 17 
June 1998.  The ATSC programmer was present and the discrepancy related to 
the DUMPCMD directive default values was demonstrated.  This was thought to 
be related to database version which was ruled out following tests with the 
baseline, current operational, and revised (reduced ATC) versions.


Work continues on the UARS orbit adjust planning re-scheduled for 12 August 
1998.  An orbit adjust procedure using B/D thrusters for translation and 
altitude control has been completed and is in review.  A second orbit 
adjust procedure using B/D thrusters for translation and A/C thrusters for 
altitude control has also been prepared and is in review.  The decision as 
to which procedure is to be used will be made in early July and is 
dependent on the latch valve refill tests scheduled by the propulsion 
branch.

FOT continues to support CNMOS in their efforts to make necessary software 
changes (MSOCC, CMS, DCF, etc.) to support the year 2000 rollover.

Monitoring of the magnetic field model performance continues.

FOT continues to improve a Power Profile for UARS based on the current 
status of the Modular Power System.

FOT continues to support the new UARS ground system re-engineering effort.


MEETINGS

A meeting was held on 15 July 1998 with NASA and contractor personnel to 
discuss the Propulsion Module Line Fill Test - Latch Valve drive circuits, 
Remote Interface Unit (RIU), and the UARS simulator.  A RIU from the Hubble 
program will be available.  Jackson and Tull personnel will build the drive 
circuit and cabling based on schematics from the UARS spacecraft supplied 
by the UARS FOT.  Allied personnel will operate the UARS Test and Training 
Simulator (UTTS) for the test.  Arrangements have been made with the 
Building 3 Facility Operations Manager (FOM) and ATSC Manager for a hallway 
location to perform the test in Building 3 near the UTTS.  The test is 
planned for late July 1998.

No UARS Battery telecon was held this week.  The next telecon has not been 
scheduled.



FUTURE SIGNIFICANT EVENTS

The next UARS Yaw Around Maneuver is currently scheduled for 15 July 1998.

The UARS orbit altitude is dropping slowly and a drag makeup orbit adjust 
is targeted for 12 August 1998.


PERSONNEL CHANGES

None


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 19 June 1998

ORBIT      AOS         NO.    SUBSYS      REASON
-----      ---         ---    ------      -------  
36909     164/1114   98-196   OBC       Clk Adj fr 20.6 to 0.00 msec/day
36945     166/2117   98-197   HRDI      HTR Cycle from 175 to 25 amp mins
36953     167/1002   98-198   HRDI      HTR Cycle from 25 to 100 amp mins
36970     168/1318   98-199   HRDI      HTR Cycle from 100 to 75 amp mins
36978     169/0120   98-200   PEM AXIS  Power ON
36987     169/1507   98-201   HRDI      HTR Cycle 75 to 100 amp mins
36988     169/1656   98-202   HRDI      HTR Cycle 100 to 125 amp mins
37006     170/2305   98-203   PEM/AXIS  Power OFF




_______________________________________________________________

                               APPENDIX B
                  OUT-OF-LIMITS & ALERTS OCCURRENCES
                      Week ending 19 June 1998

MNEMONIC      STATE      DESCRIPTION                       ORBITS
---------     -----      ------------                      ------
WIEUTEMP       Y-LO     WINDII EU Temperature         CONTINUOUS     
QTSISAIF       Y-HI     SSPP Baseplate by SISA I/F    36909-17,23-60,81-                                                    
                                                      84,89,93,96-8,701-2
HRPSEQBIMON    Y-HI     PSE Quiet Bus Cur. Monitor    36938,43-4,52,67,                          
                                                      81,82
SOSTMPRNTRN    Y-LO     Temperature Entrance          36932-47
ACTEMPANA2     Y-LO     Temp ACR 2                    36939-47
HRIFESURVTEMP  Y-HI     IFE Surv Temp                 36959, 72-74,83
NBRECBI        Y-HI     NBTR B Current                36981-3,96
SOSTMPRBLFT    Y-LO     Temperature Bot_Left_Front    36943-44


The following ALERT occurrences were detected:

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



                               APPENDIX C
                 CLOCK & SOLAR ARRAY RATE CORRECTIONS
                      Week ending 19 June 1998

                      CLOCK DRIFT RATE ADJUSTMENTS

     ORBIT              TIME                 CLOCK RATE CHANGE
     -----              ----                 -----------------
     36909     164/11:17 (13 Jun 98)     from 20.6 to 00.0 msec/day


_______________________________________________________________

                               APPENDIX D
                    UARS BATTERY PERFORMANCE DATA
                      Week ending 19 June 1998

     13 Jun 1998 - GMT Day 164 Beta = 10.2 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/-4.62   +0.0/ +0.0   18.2   0.000      0.0
2   +44.8/ -11.2  +6.11/+3.87  +30.4/-13.6   25.8   1.020     21.3
3   +56.0/  -5.6  +4.83/+2.92  +29.2/-14.4   25.8   1.018     20.6

     19 Jun 1998 - GMT Day 170 Beta = 11.6 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   18.2   0.000      0.0
2   +28.0/ -11.2  +5.79/+4.51  +31.2/-14.8   25.0   1.025     22.2
3   +84.0/  -5.6  +4.51/+3.55  +30.0/-15.2   25.0   1.022     21.6


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



                               APPENDIX E
                         UARS ANOMALY REPORTS
                      Week ending 19 June 1998


                    NEW ANOMALY REPORTS GENERATED
  AR NO.   SUBSYS    ORBIT      TIME       TTR     PROBLEM/DATA LOSS
  ------   ------    -----      ----       ---     -----------------
98-030     FOT     36910    164/1250Z     N/A     TAC #6 Crashed


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


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


                       OPEN ANOMALY REPORTS
  AR NO.   SUBSYS    ORBIT      TIME       TTR      PROBLEM/DATA LOSS
  ------   ------    -----      ----       ---      -----------------
98-024     FOT     36997     163/00:02  19991     LATE ACQ., NO RF
98-030     FOT     36910     164/12:50            TAC 6 CRASH
98-031     FOT     36930     165/19:55            TAC 6 CRASH
98-032     FOT     37973     168/16:51            TAC 4 CRASH


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