UARS Weekly Status Report

2 October 1998





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                UARS WEEKLY STATUS REPORT - 02 Oct 1998

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

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

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

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

SUSIM successfully gathered its normal solar, offset, and occulation
data during this past week without apparent problems.

We have asked that the version 7 SUSIM production software be promoted.
Reprocessing to the new version (V20) will soon begin.

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

     PEM was not active

     PEM is now conducting tests of the OBC activation.  PEM activation
occurs during daylight only, when there is adequate power generated from 
the UARS solar array.  Currently, testing is half-way completed, and the 
PEM magnetometer and medium energy spectrometers can activate under OBC 
control.  Tests are now being conducted on the high energy particle 
spectrometers.  Initial tests of these units show failure to enable high
voltage power.  The PEM team is investigating this result.

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

HALOE is presently off due to the yaw and is scheduled to power on
beginning of day October 3. When HALOE was on it was operating within its
nominal operating range. All science channels continue to provide excellent
science data.

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

MLS is scheduled to begin operations on Oct 6 and operate though Oct 10. The
MLS team will operate the instrument in a mode for diagnosing the reoccurance
of slips in the antenna scan mechanism, and to attempt to find a method of
operating the instrument which minimizes the impact of these slips on
scientific data.

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

HRDI started operating in the daytime-only mode on September 30th.  We are
currently evaluating operations in this new configuration.

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

WINDII is currently off, and is planned to be activated
Oct. 5-11, 1998. 

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

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

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

The CDHF attended a meeting involving possible impacts resulting
from the scheduled chilled water outage on the weekend of October 10-11.  
Current plans do not include an interruption in service at the CDHF 
during this time period.

The CDHF processed current day data through level 3 for all active
instruments. Additionally, CDHF personnel reprocessed: (R)= Requested
   (C) = Complete, (F)= Failed  (L) = Days remaining to reprocess.           
             60 days HAL (4.80) PROD (L1)    (1873R-1560C-23F=290L)
             24 days HAL (4.80) PROD (L3)    (1873R-882C=991L)
             85 days SOL (4.62) PROD (L2-L3) (2349R-1686C=663L)
              1 days SEN (5.00) PROD (L0)    (1R-1C=0L)              
  
The CDHF is scheduling the installation of IDL software version 5.1. This
installation will satisfy Y2K requirements and is also recommended by RSI as
a possible solution to a current PRINT routine problem reported by SOLSTICE.

The CDHF maintains a matrix of installation status on all patches/upgrades 
required on the current UARS VMS cluster operating systems for Y2K compliance.

CDHF pending software upgrades: SUSIM v7.0, IDL 5.1, OpenIngres
                  
***********
FOT
***********

REPORTING PERIOD

This report covers 19 September 1998 (Orbit 38370, GMT Day 262) through 25 
September 1998 (Orbit 38474, GMT Day 268).


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       262/0708     38374     ZEPS Off
        PEM       262/0943     38376     AXIS On
        PEM       266/2129     38443     AXIS Off
       WINDII     267/0401     38447     Off
       HALOE      267/0921     38450     On
      SOLSTICE    267/1102     38451     On
       ACRIM      267/1102     38451     On
       SUSIM      267/1950     38457     On

The beta angle ranged between 41.5 degrees to 17.1 degrees for this report 
period.  The beta angle is now decreasing toward a minimum angle of -2.0 
degrees for the yaw on 29 September 1998 (DOY 272).

The new power monitor (PMON) flight software was successfully uplinked 
during orbits 38446, 38447, 38448, and 38449 (267/02:21, 267/04:01, 
267/05:46, and 267/06:38 UTC).  PMON control of heaters began during orbit 
28450 (267/07:34 UTC).  The upgraded version of PMON includes enhanced 
capabilities for Rday-onlyS heater control, used to minimize spacecraft 
power loading during the solar array eclipse period (approximately half of 
each orbit).  The enhanced PMON software also includes the capability to 
support Rday-onlyS operation of instruments, in which they will be power 
cycled on when the solar array has excess power, and turned off during 
array eclipse periods.  PMON currently can support three instruments for 
this mode of operation: PEM, HRDI, and SOLSTICE.

Following the first orbit of the PMON software uplink, a low load bus 
voltage condition (23.2 V) resulted in automatic power shedding via the 
telemetry monitor (TMON) flight software.  The SSPP instruments (SOLSTICE, 
ACRIM, and SUSIM), as well as the HALOE and WINDII instruments, were 
powered off as part of this load shedding.  The low bus voltage resulted 
from the long duration of the first contact during solar array Rnight.S  
Pre-uplink simulations also showed low bus voltage for this contact (23.4 
V), but not low enough to RtripS TMON and result in the load shedding which 
actually occurred.  However, such fluctuations in bus voltage can result 
from minor orbital changes in other spacecraft loads, and therefore are 
tremendously difficult, if not impossible, to predict with certainty.  
Regardless, the TMON response was proper under the circumstances, and the 
SSPP and HALOE instruments were restored to full operation as soon as 
possible (WINDII was scheduled to be turned off the following day, so it 
was left powered off).

Examination of PMON telemetry following the uplink showed it working as 
planned, with one exception.  The WINDII heater load was not being properly 
controlled, due to a power switching unit (PSU) command conflict.  PSU 
documentation indicates that PSU commands must be separated by at least one 
second, and the PMON command responses were designed accordingly.  However, 
post-uplink examination of telemetry showed that the WINDII heater commands 
(which followed other PSU commands from PMON by one second) did not 
function.  The FOT determined that one second separation of PSU commands 
was probably not adequate, so the PMON command responses were modified to 
ensure at least two seconds between each PSU command.  These changes were 
uplinked on orbit 38473 (268/21:30 UTC), and all PMON PSU commands have 
functioned properly since that time.

Two manually generated SSPP stellar offset experiments were performed on 
GMT days 265 and 267 at the request of SOLSTICE operations.

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 1.0 to 1.3 degrees C.  Additional battery performance data 
for each battery on 18 September 1998 and 25 September 1998 are provided in 
Appendix D.

The clock error ranged from 10.2 to -11.7 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          =     00
%     OUT-OF-LIMITS   =     03

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

%     FOT       06
%     ACRIM     01
%     HALOE     01
%     PEM       03
%     SOLSTICE  01
%     SUSIM     01
%     WINDII    01

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

%     FOT       04

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

TRANSPONDER FREQUENCIES:
     Transponder A:  98/210  -  2287.496941
     Transponder B:  98/211  -  2287.499161


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 98/267 show the observatory data loss to be 
21 hours, 06 minutes, 52.340 seconds (an increase of 11.200 seconds since 
last report period).  This is a 0.0344 percent data loss which equals a 
99.9656 percent data capture for the mission.

The increase of 11.200 seconds occurred over two days:
7 0.256 seconds on Day 266 due insufficient overlap, and 
7 10.944 seconds on Day 267 due to insufficient overlap.

The FOT created and configured a new CMS Spacecraft Characteristics and 
Parameters file to accommodate the operational change to a reduced size ATC 
memory.  As of the PMON/Flight Software uplink on 24 September, the size of 
the stored command memory is now 768 commands (as compared to the previous 
size of 1024 commands).  In addition, the FOT created several new Relative 
Time Sequences(s) (RTSs) which were also necessary to facilitate proper 
PMON commanding with the new flight software.

A final dry run simulation of the new Power Monitor Software was completed 
on 23 September 1998.

The operational packs, software and database version following the PMON 
software update are:

       PACK #     GND S/W VER     DATBASE VER     COMMENT
       PE51          10.12          FOT 069         Prime
       PE03          10.12          FOT 069         Backup


OTHER SIGNIFICANT EVENTS

UARS SATELLITE OPERATIONS

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

Investigation into possible impacts of the Leonid meteorite shower in 
November 1998 continues.  FDF has supplied Leonid flux angles to both UARS 
Fixed Head Star Trackers (FHST).

YEAR 2000 OPERABILITY SUPPORT

UARS Test and Training Simulator (UTTS) - No change.

User Planning System (UPS) - The FOT coordinated with the UPS development 
team lead to discuss the FOTUs and the CMS test teamUs TDRS contact needs 
for Year 2K testing.  Several options for getting a Year 2K TDRS contact 
data to the CMS system were discussed.  These options will be pursued early 
next week.

Multi Satellite Operations Control Center (MSOCC) - Per an action item from 
last weekUs POCC/AP Year 2K status meeting, the FOT researched several 
questions given to them by the POCC/AP test team.  The FOT is in the 
process of generating a memorandum containing answers to the test teamUs 
questions.

At the request of the POCC test team, the FOT attempted to generate a 
sample Year 2K ATC load which included nothing but NOOP commands.  The 
purpose of the sample load was to enable the POCC/AP test team to perform 
load acceptance testing on the AP.  Unfortunately, the FOT and CMS test 
team was unable to successfully generate such a load.  Both the FOT and the 
CMS test team are currently investigating the reason that the back-up CMS 
is failing during the load generation process involving a Year 2K load.

Command Management System (CMS) - The FOT met with CMS software development 
team representative Tony Yan to discuss possible Year 2K related problems 
with the CMS software.  Specifically, Year 2K testing found that the CMS 
does not correctly sort the AOT and LOT of targets in the SSPP Orbital 
Events file when the view period of the target crosses the 1999-to-2000 
year boundary.  However, this particular problem does not present an 
operational concern as the only SSPP target that is viewed during that 
portion of the day is the Sun, and the Sun is not actually in view of UARS 
during the 1999/2000 cross-over.

Flight Dynamics Facility (FDF) - A partial coordinated data set was 
received at the end of this week but no testing has been attempted.

OBC PMON FLIGHT SOFTWARE UPDATE

Flight Software - Complete.

Ground Support Software - Complete.

Verification Testing - Complete.

Uplink - Successfully completed on 24 September 1998.

IP NETWORK TESTING

Space Network (SN) - No change.

Testing with the NCC 98 system to support routine flight operations is 
being planned.

Deep Space Network (DSN) and Ground Spaceflight Tracking and Data Network 
(GSTDN) - Commanding with the JSC simulator (destination code problem) is 
being investigated.

UARS PROPULSION MODULE B/D THRUSTER LINE FILL

The B/D thruster refill effort continues.  The Eaton Latch Valve test 
report is still being reviewed by the UARS FOT.

UARS RE-ENGINEERING - TELEMETRY PROCESSING

Flight operations is providing support to the re-engineering effort to 
process the UARS telemetry on the TOMS/EP control center computer system.  
The software performance continues to be evaluated.

UARS COMMAND RE-HOST PHASE 1 DEMONSTRATION

A phase 1 feasibility demonstration of the Lockheed Martin SCS-21 control 
center system was successfully conducted on 22 September 1998.  The NCC-98 
system was not available for the demonstration.  Future development is 
waiting Rgo aheadS approval.


MEETINGS

The FOT attended a meeting on 24 September 1998 concerning the User 
Planning System (UPS) Y2K release and plans for verification testing.

The next battery telecon is scheduled for 20 October 1998 at 1:00 pm.


FUTURE SIGNIFICANT EVENTS

The next UARS Yaw Around Maneuver is scheduled for scheduled for 29 
September 1998.

The United States Naval Observatory (USNO) issued  a Time Service 
announcement advising that the International Earth Rotation Service (IERS) 
will retard UTC time by 1.0 second at the end of December 1998. This means 
the addition of one leap second as the last second of 1998.

The next annular solar eclipse will occur on 16 February 1999 over the 
Indian Ocean, Australia and the South Pacific Ocean.


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 25 September 1998

ORBIT        AOS         NO.      SUBSYS         REASON
-----        ---         ---      ------         -------  
38374     262/0708     98-351     PEM      ZEPS OFF
38376     262/0943     98-352     PEM      AXIS ON
38402     264/0409     98-353     OBC      Clk Adj fr 0.00 to 20.6 msec/day
38426     265/1755     98-354     OBC      Clk Adj fr 20.6 to 0.00 msec/day
38443     266/2129     98-355     PEM      Power Off AXIS
38447     267/0401     98-356     WINDII   Power OFF
38448     267/0546     98-357     OBC      Clear TMONS
38446     267/0221     98-358     OBC      Load PMON Ver. 63
38450     267/0921     98-359     HALOE    Power ON
38451     267/1102     98-360     SOLSTICE Power ON
38451     267/1102     98-361     ACRIM    Power ON
38457     267/1950     98-362     SUSIM    Power ON
38473     268/2130     98-363     OBC      RTS Loads
38473     268/2130     98-364     OBC      GENASCII - RTS

_______________________________________________________________

                               APPENDIX B
                  OUT-OF-LIMITS & ALERTS OCCURRENCES
                      Week ending 25 September 1998

MNEMONIC      STATE        DESCRIPTION                       ORBITS
---------     -----        ------------                      ------
HRPSEQBIMON   Y-HI     PSE Quiet Bus Current Mon     38434,35,41,65,70
NBRECBI       Y-HI     NBTR-B Current                38434,35,70
QTSISAIF      Y-HI     SSPP Baseplate by SISA I/F    38446
OBSVLBEON     R-LO     Load Bus Volts at EON         38447-49
OBSBATVEON2   Y-LO     Battery 2 voltage at EON      38447-49
OBSBATVEON3   Y-LO     Battery 3 voltage at EON      38447-49
OBSSOC2       R-LO     Battery 2 Current SOC         38448-9
OBSSOC3       R-LO     Battery 3 Current SOC         38448-9
WIPBVOLTAGE   Y-LO     Pulse Bus Voltage             38434,35
WIQBVOLTAGE   Y-LO     Quiet Bus Voltage             38441
WIFWTEMP      Y-LO     Filter Wheel Temp             38457-465,473
WIISUTEMP     R-LO     ISU Temp                      38453-73


The following ALERT occurrences were detected:

MNEMONIC              DESCRIPTION                            ORBITS
---------             ------------                           ------
WIISUTEMPRL     ISU Temp Red Low                     38455-8
WIFWTEMPRL      Filter Temp Red Low                  38456-7
WIISUTEMPRL     WINDII ISU Temperature               38459-473
WIFWTEMPRL      WINDII FW Temperature                38460,61,63


_______________________________________________________________

                               APPENDIX C
                 CLOCK & SOLAR ARRAY RATE CORRECTIONS
                      Week ending 25 September 1998


                      CLOCK DRIFT RATE ADJUSTMENTS

     ORBIT              TIME                 CLOCK RATE CHANGE
     -----              ----                 -----------------
     38402     264/04:15 (21 Sept 98)     from 00.0 to 20.6 msec/day
     38426     265/17:55 (22 Sept 98)     from 20.6 to 00.0 msec/day


_______________________________________________________________

                               APPENDIX D
                    UARS BATTERY PERFORMANCE DATA
                      Week ending 25 September 1998


     18 Sept 1998 - GMT Day 261 Beta = 41.5 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 -3.30/-2.73   +0.0/ +0.0   18.1     0.000     0.0
2   +67.2/ 0.0   +5.71/+6.44  +28.8/-16.0   24.6     1.022    22.5
3   +33.6/-22.4  +4.77/+5.47  +28.4/-16.8   24.6     1.023    22.1


     25 Sept 1998 - GMT Day 268 Beta = 17.1 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   18.1    0.000     0.0
2   +50.4/0.0      +6.76/+5.15 +31.6/-16.0   24.2    1.023    22.8
3   +33.6/-44.8    +5.47/+3.87 +30.4/-16.4   24.2    1.021    22.2


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



                               APPENDIX E
                         UARS ANOMALY REPORTS
                      Week ending 25 September 1998


                        NEW ANOMALY REPORTS GENERATED
  AR NO.  SUBSYS   ORBIT      TIME       TTR    PROBLEM/DATA LOSS
  ------  ------   -----      ----       ---    -----------------
98-061    FOT     38385     263/0030    20202   AP-7 Crashed
98-057    FOT     38413     264/2123    14170   Generic Late Acquisition
98-062    TMON    38447     267/0401    N/A     TMONs NR-1 & NR-2 TRIPPED
98-063    FOT     38456     267/1840    N/A     ATC Load Errors


                     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
  ------   ------   -----    ----        ---      -----------------
98-057     FOT     Sept 98   See list   14170   GENERIC LATE ACQ
98-061     FOT     38385     263/00:30  20202   AP CRASH
98-062     FOT     38447     266/04:01          TMON 1 & 2 TRIP
98-063     FOT     38456     267/18:43          ATC LOAD ERRORS