UARS Weekly Status Report

17 August 2001




********************************************************************

                UARS WEEKLY STATUS REPORT - 17 AUG 2001

********************************************************************

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

With the exception of a brief off period last night (01229) due to TMON
response, SOLSTICE continues to operate normally, taking 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.

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

SUSIM was turned off on Aug. 8 and back on Aug. 11.  On Aug. 17, SUSIM
was unexpectedly turned off as were other instruments due to the TMON.
Otherwise, SUSIM has completed its daily solar scans this past week
during periods of predicted UARS telemetry.

With the impending end of UARS operations, we display a summary of
downloads at SUSIM's ftp site.

---

SUMMARY OF SUSIM DATA DOWNLOADS
8/11/01

Since April 2000, there have been a total 2666 downloads of SUSIM data
from 258 unique downloaders.  These DO NOT include those just visiting
the SUSIM WWW site, but rather, those actually downloading SUSIM data
from SUSIM's ftp site.  Many individuals make repeat visits to get
CURRENT DATA.  The downloaders include individuals from the following
institutions and countries.

NASA CENTERS (4)

Ames Research Center
Goddard Space Flight Center
Jet Propulsion Laboratory
Marshall Space Flight Center

US UNIVERSITIES and EDUCATIONAL INSTITUTIONS (20)

Applied Physics Laboratory, Johns Hopkins University
California State University, Northridge
Florida Institute of Technology
New Mexico Institute of Mining and Technology
Rochester Institute of Technology
Southwestern University
State of Indiana, Department of Education
State University of New York, Stony Brook
University at Albany, State University of New York
University of Arizona
University of California, Berkeley
University of Colorado
University of Florida
University of Maryland
University of Michigan
University of North Dakota
University of Southern California
University of Texas
University of Vermont
University of Washington


US CORPORATIONS (8)

Harris, Inc.
Kodak
Lockheed Missles and Space
Microsoft
Motorola Inc.
Robotic Systems Technology, Inc.
Science Systems and Applications, Inc
Southwest Research Institute


US GOVERNMENT RESEARCH LABORATORIES (8)

Air Force Phillips Laboratory
Aeronomy Laboratory, National Oceanic & Atmospheric Administration
Arnold Engineering Development Center, U.S. Air Force
High Altitude Observatory, National Center for Atmospheric Research
Los Alamos National Laboratory
National Optical Astronomy Observatory
Naval Research Laboratory
Space Environment Center, National Oceanic & Atmospheric Administration


INTERNATIONAL ORGANIZATION (.int)

European Space Agency


FOREIGN COUNTRIES (24)

Argentina (ar)
Australia (au)
Austria (at)
Bulgaria (bg)
Canada (ca)
China (cn)
Croatia (hr)
Finland (fi)
France (fr)
Germany (de)
Hungary (hu)
Japan (jp)
India (in)
Italy (it)
The Netherlands (nl)
New Zealand (nz)
Norway (no)
Peru (pu)
Poland (po)
Spain (es)
Russia (ru)
Slovakia (sk)
Switzerland (ch)
United Kingdom (uk)

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

***** ALL PEM COMMUNICATION SHOULD NOW BE THROUGH THE PEM2K:: NODE *****

     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).  Currently, PEM has requested GSFC assistance with compiling for
the DEC Alpha since the GSFC executables run on the Alpha and SwRI's compiled
versions do not.

    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.

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

HALOE continues to provide outstanding scientific measurements in all 
science channels.  HALOE was powered off at beginning-of-day today as 
scheduled.  All engineering parameters are within nominal operating region.

Results of gain and bore sight calibration tests conducted during the last 
positive and negative beta cycles indicate no change in instrument 
performance.  HALOE data has been certified through the end of June 2001. 

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

Nothing received.

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

HRDI continues to function normally, making wind measurements during
the sunlit parts of orbits nearly every day, and measuring nighttime winds
when power is available.

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

Nothing received.

***********
MPG
***********
 
On 16 August 2001 the MPG participated in the UARS 
Technical Team Meeting.  This series of meetings 
is being held to monitor and coordinate activities
associated with the anticipated close down of science
data collection by UARS instruments.
 
As far as daily operations are concerned, the processing of 
instrument Daily Activity Plans continues with no problems.

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

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

                           REPORTING PERIOD

This report covers 04 August 2001 (Orbit 54106, GMT Day 216) through 10 August 
2001 (Orbit 54222, GMT Day 222).

                          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           216/0953     54112     AXIS Off
         HALOE         216/2333     54120     Power Off
         ACRIM         219/2335     54165     Power Off
         SUSIM         219/2335     54165     Power Off
         SOLSTICE      219/2335     54165     Power Off
         HRDI          222/0213     54197     PB (INST) OFF

A Forward-to-Reverse Yaw Around maneuver (number 101) was successfully executed 
in Orbit 54176 beginning 220/16:29:57 and completing at 220/17:07:07 on 08 
August 2001.  The SOLSTICE instrument was in day only and all other instruments 
were in their off or standby mode (including HRDI and PEM).  Due to the SA 
position at 269 degrees, the effective night length of the spacecraft after the 
maneuver was approximately 56.4 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 22.9 and 23.0 percent respectively.  The next (reverse-to-
forward) YAW is scheduled for 11 September 2001 (DOY 254).

The beta angle ranged between the angles of 19.9 degrees to 5.8 degrees for 
this report period.  The beta angle is now increasing towards a maximum angle 
of 46 degrees on 25 August 2001 (DOY 237).

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 1.2 to 1.3 degrees C.  Additional battery performance data for each 
battery on 03 August 2001 and 10 August 2001 are provided in Appendix D..

The clock error ranged from Ð10.5 to 11.5 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            =  15


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

¥     FOT            =  08


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

TRANSPONDER FREQUENCIES:
· Transponder A:  00/316  - 2287.496493
· Transponder B:  01/119  - 2287.499116


                        GROUND SYSTEM OPERATION

Eight (8) 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 01/221 show the observatory data loss to be 303 hours, 00 
minutes, 09.248 seconds. This shows a loss of 04 minutes and 20.992 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 increase of 04 minutes and 20.992 seconds occurred over two (2) days:
· 2 minutes and 2.000 seconds on Day 219 due to a Late AOS TTR# 14170
· 2 minutes and 18.992 seconds on Day 221 due to a Late AOS TTR# 14170

                      OTHER SIGNIFICANT EVENTS

                      UARS SATELLITE OPERATIONS

UARS FOT and technical team conducted a series of thruster firings this week in 
order to prime the propulsion system should any deboost activities take place.  
The A-C attitude thrusters were fired on Tuesday 07 August 2001 over the course 
of four passes.  All of the tests went very well.  The A-C attitude thrusters 
were fired for pulse widths of 40,100 and 280 msec. For each pulse width both a 
positive and negative torque command was given for all three axes (giving a 
total of six commands for each pulse width).  The FOT also executed this set of 
six commands twice for each pulse width in order to verify that the same 
response was seen for multiple data sets.  

All responses were nominal with the exception of the negative roll and positive 
yaw firings. On these firings a disturbance was seen in two axes instead of 
just one. This lead the team to believe the C3 attitude thruster was under 
performing.  Upon further investigation the C3 thruster appears to be operating 
near 50% of its expected performance.  Regardless of this finding, UARS still 
has more than enough control of all three axes in order to perform an orbit 
adjust. 

On Wednesday, 08 August 2001 the FOT executed a 4.5 second burn using the B-D 
translation thrusters. This burn caused 4 yaw attitude thruster firings to 
occur after the termination of the translation burn in order to maintain 
attitude error limits. This sequence is exactly what was desired and expected.  
From both the realtime plots and data analysis it appears that the B-D 
translation thrusters performed exactly like they did the last time they were 
used in 1994.  

Finally, on 09 August 2001, the B-D translation thrusters were fired again.  
This burn was longer in duration than the previous dayÕs and lasted 
approximately 13.5 seconds. The primary objective was to verify that the flight 
software would properly swap translation with attitude thrusters as needed 
during the same ACS cycle. This happened five times and executed exactly as it 
was designed.

After the three tests this week the FOT feels confident that the propulsion 
system is working properly.  Longer burns will be necessary to provide 
calibration data to FDF, however the hardware is ready to support any 
activities that will be required.  The FOT would also like to thank all those 
who helped make this happen in such a short period of time.
      
                              MEETINGS

The UARS FOT attended a Command Authorization Meeting (CAM) on 06 August 2001 
for the upcoming Attitude and Translation Test Burns.
The UARS FOT attended a Go-NoGo Meeting on 07 August 2001 for the Attitude 
Thruster Test.
The UARS FOT attended a Script Review on 07 August 2001 for Translation 
Thruster Test.
The UARS FOT attended a Go-NoGo Meeting for the Translation Thruster Test on 08 
August 2001.
The UARS FOT attended a Go-NoGo Meeting for the Orbit Adjust on 09 August 2001.


                       FUTURE SIGNIFICANT EVENTS

The next UARS Yaw slew is scheduled for 11 September 2001 (DOY 254).  This 
maneuver will be a Reverse to Forward Flight maneuver (Southern 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 10 August 2001

ORBIT     AOS          NO.      SUBSYS      REASON
-----     ---          ---      ------      ------
54112     216/0953     01-488    PEM/AXIS   AXIS 1,2 POWER OFF
54116     216/1716     01-487    NBTR       NOOPS
54120     216/2333     01-489    HALOE      Power OFF
54143     218/1314     01-490    OBC/CLK    Clk Adj 0.0 to -20.6 msec/day
54148     218/2019     01-491    NBTR       NBTR PBK / RTS-58
54159     219/1314     01-492    PM         ATTITUDE THRUSTER BURN                
54159     219/1357     01-492    PM         THRUSTER BURN CONT
54160     219/1456     01-492    PM         THRUSTER BURN CONT
54160     219/1537     01-492    PM         THRUSTER BURN COMPLETE
54160     219/1537     01-493    OBC        Clk Adj -20.6 to 0.0 msec/day
54165     219/2335     01-495    ACRIM      Power OFF
54165     219/2335     01-496    SUSIM      Power OFF
54165     219/2335     01-494    SOLSTICE   DAY ONLY
54175     220/1537     01-497    MACS       BEGIN YAW
54175     220/1537     01-498    MACS       GENASCII TABLE 37
54175     220/1537     01-499    MACS       GENASCII TABLE 58
54176     220/1734     01-500    ACS/TAM    TAM ALIGNMENT
54176     220/1734     01-497    MACS       YAW COMPLETE
54178     220/1924     01-501    PM         ENGINEERING BURN
54189     221/1511     01-502    PM         ENGINEERING BURN
54197     222/0213     01-503    HRDI       PB (INST) OFF
_______________________________________________________________________________

                            APPENDIX B
               OUT-OF-LIMITS & ALERTS OCCURRENCES
                    Week ending 10 August 2001

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 10 August 2001

                     CLOCK DRIFT RATE ADJUSTMENTS

ORBIT     TIME         CLOCK RATE CHANGE
-----     -----        -----------------
54143     218/1223     Clk Adj 0.0 to -20.6 msec/day
54160     219/1603     Clk Adj -20.6 to 0.0 msec/day
_______________________________________________________________________________

                            APPENDIX D
                   UARS BATTERY PERFORMANCE DATA
                     Week ending 10 August 2001

     03 August 2001 - GMT Day 215 Beta = 54.1 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      12.0      0.000      0.0
2    +16.8/-78.4     +6.11/+4.51   +29.2/-14.4    24.2      1.030      21.4
3    +22.4/-50.4     +5.15/+3.87   +28.8/-14.4    24.2      1.020      21.1


     10 August 2001 - GMT Day 222 Beta = 5.8 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      12.0       0.000      0.0
2    +16.8/-67.2     +5.15/+3.87   +28.8/-12.8    25.4       1.040     20.5
3    +22.4/-56.0     +4.19/+2.92   +28.0/-12.8    25.4       1.030     20.5


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

___________________________________________________________________________

                                 APPENDIX E
                      UARS ANOMALY REPORTS
                    Week ending 03 August 2001

                  NEW ANOMALY REPORTS GENERATED
AR NO.     SUBSYS     ORBIT     TIME        TTR       PROBLEM/DATA LOSS
------     ------     -----     ----        ---       -----------------
01-046     FOT        54108     216/0436    14170     Generic Late Acquisition
01-047     FOT        54116     216/1636    23990     Equipment prob. @ W/S
01-046     FOT        54151     219/0016    14170     Generic Late Acquisition
01-046     FOT        54194     221/2108    14170     Generic Late Acquisition
01-046     FOT        54208     222/2028    14170     Generic Late Acquisition
01-046     FOT        54209     222/2211    14170     Generic Late Acquisition
01-048     FOT        54209     222/2211    N/A       Ephemeris Load Rejected
01-046     FOT        54210     222/2351    14170     Generic Late Acquisition


                ANOMALY CLOSURE INFORMATION RECEIVED
AR NO.     SUBSYS     ORBIT     TIME        TTR       PROBLEM/DATA LOSS
------     ------     -----     ----        ---       -----------------
01-047     FOT        54116     216/1636    23990     Equipment prob. @ W/S
01-048     FOT        54209     222/2211    N/A       Ephemeris Load Rejected


               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
------     ------     -----     ----         ---       -----------------
01-045     FOT     see list     August 01    14170     Generic Late Acquisition


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