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Mission Operations Days: 2001/258 to 2001/264
September 15, 2001 00:00:00 GMT to September 21, 2001 00:00:00 GMT

Terra Spacecraft and MODIS Instrument Status:

Terra (AM-1) is in Normal Ops Mode
MODIS is in Science Mode - A Side
Component State(s) Comment
Blackbody A On (290 K); B Off Nominal
Calibration Electronics A On; B Off Nominal
Control Processor A On; B Off Nominal
Nadir Door Unlatched, Open Nominal
Space View Door Unlatched, Open Nominal
Solar Diffuser Door Unlatched, Closed Nominal
FDDI Formatter A On; B Off Nominal
FDDI Port A On; B Off Nominal
FIFO Memory #1 & #2 On; #3 & #4 Off Nominal
Format Processor A On; B Off Nominal
Power Supplies #1 On; #2 Off Nominal
PV VIS FPA A On; B Off Nominal
PV NIR FPA A On; B Off Nominal
PV SMIR FPA A On; B Off Nominal
PV LWIR FPA A On; B Off Nominal
PC LWIR FPA A On; B Off Nominal
RC Outgas Heaters All Off (CS, IS, OS) Nominal
RC LWIR FPA Heater On (83 K) Nominal
RC SMIR FPA Heater Off Nominal
Scan Assembly A On; B Off Nominal
SDSM A Off; B Off Nominal
SRCA A Off; B Off Nominal
PS1 Survival Heater Enabled Nominal
PS2 Survival Heater Enabled Nominal
Timing Generator A Off; B On Nominal
Flight Software Rev BD + 2 set of patches
  • FR Error Counting and Statistics (2 patches)
  • FR Band 5 Gain Change (20 commands)
Inhibit Ids Set None Nominal
TMON 66 (SRCA A) Disabled Nominal
TMON 67 (SRCA B) Disabled Nominal
TMON 68 (FIFO) Enabled Nominal
TMON 69 (EPS Current) Disabled Nominal

This Week's Completed MODIS Activities:

Saturday, September 15, 2001


Sunday, September 16, 2001

2001/259 22:57:41 Real Time Ran proc MOD_ALARMS_CP_ST_06(‘ENABLE’) to clear error address flag.

Monday, September 17, 2001


Tuesday, September 18, 2001


Wednesday, September 19, 2001

2001/262 18:05:27 Real Time Ran proc MOD_ALARMS_CP_ST_06(‘ENABLE’) to clear error address flag.
2001/262 20:44:46 ATC OA16: SDSM SCREENED
2001/262 22:23:39 ATC OA15: SDSM OPEN

Thursday, September 20, 2001


Friday, September 21, 2001


This Week's Scheduled MODIS Activities Not Completed:


Upcoming MODIS Events:

Friday, September 21, 2001


Saturday, September 22, 2001


Sunday, September 23, 2001


Monday, September 24, 2001


Tuesday, September 25, 2001


Wednesday, September 26, 2001


Thursday, September 27, 2001


Friday, September 28, 2001



The next Lunar Calibration roll maneuver is scheduled for day 2001/280 (October 7, 2001) with data collection from 07:10:54 to 07:17:24. The roll angle will be -11.3321 degrees.

MODIS Anomalies:

Formatter Error Events:

The FR error counter (MOD_SS_CP_STATUS_08) has “rolled over” 4 times since the A-Side restart following the PS-2 Anomaly. This is a 16-bit signed counter, therefore it “rolls over” every 32,768 counts. At present (2001/264-19:43:00), the counter is 8,154, which means that 139,226 errors have been seen since the A-Side restart.

A cyclic, increasing rate of Formatter errors has been detected. The increase in Formatter error rates occur at the same times we see decreases in the MOD_TP_FR_A_ENGINE, MOD_TP_ME_NX_HTSINK, and MOD_TP_ME_CHAS_TOP temperatures. The current trend of these mnemonics is a gradual decrease in temperature.

During the recent SRCA activities, the rate of FR errors was significantly reduced. At the same time, the average temperatures of the three telemetry points listed above each rose approximately 1 degree C.

MS Excel spreadsheets are available for download from:

These files contains the times for each FR error count as well as the three temperatures (from day 240 on) mentioned above. This file will be periodically updated with the most recent telemetry sets available. In this file, you can see a graph of this cyclic, increasing error rate. If you have any special requests, please let us know.

The current sustained maximum of the FR error rate is around 500 errors per hour with shorter bursts that reach up to 900+ errors per hour. The minimum rate of FR errors is around 200 per hour. As of yet, no problems with the science data have been reported. If the error rate continues to increase, there is the possibility of brief interruptions in science data as the FR attempts to deal with the large amount of errors. At present we have no indication to what this threshold level for science data loss may be.

We are still in a "wait and see" mode right now. However, everyone should be encouraged to consider options (i.e. B-side) before we have no choices left.

General Instrument Comments:

MODIS is in Science Mode on the A-side with the SVD and NAD open, operating with the Formatter Resolution Flight Software Patches (FRFSP).

Note: SD/SDSM calibrations were planned to be reduced to once per two weeks. This plan has been revised; SD/SDSM calibrations will continue to be scheduled once each week until the end of November.

MODIS Telemetry Trends:

Trending has resumed with the instrument on the A-side. With the currently decreasing beta angle, the amount of focal plane heater margin is increasing. The intermediate stage cooler temperature is stable.

The increase in formatter error events is also being trended (as described above) to aid in any future operational decisions necessary to maintain the health of the instrument and its science data.

Non-MODIS Significant Events:


Limited Life Item Status:

SRCA 10W Lamp #1: 189.7 of 500 hours
SRCA 10W Lamp #2: 145.3 of 500 hours
SRCA 10W Lamp #3: 154.5 of 500 hours
SRCA 10W Lamp #4: 61.5 of 500 hours

SRCA 1W Lamp #1: 558.2 of 4000 hours
SRCA 1W Lamp #2: 276.3 of 4000 hours

Solar Diffuser Door: 1709 of 3022 Movements
Nadir Aperture Door: 532 of 1316 Movements
Space View Door: 437 of 1316 Movements