MODIS IOT Terra Weekly Report

Mission Operations Days: 2001/272 to 2001/278
September 28, 2001 20:00:00 GMT to October 5, 2001 20:00:00 GMT

Terra Spacecraft and MODIS Instrument Status:

This Week's Completed MODIS Activities:

2001/272 22:45:01 Real-time Memory dump of formatter error event addresses
2001/272 22:46:27 Real-time Memory dump of formatter error event counts

None

None

2001/275 18:51:00-18:51:24 FOT performs S/C drag make-up maneuver

2001/276 09:22:10 ATC OA-16: SD/SDSM Screened
2001/276 11:01:04 ATC OA-15: SD/SDSM Open

None

None

This Week's Scheduled MODIS Activities Not Completed:

None

Upcoming MODIS Events:

None

None

280/05:15:00 - 05:49:00 Real-time FOT sets IRU to high rate (lower spacecraft attitude precision)
280/06:36:57 ATC Moved Formatter to Day Rate ahead by 03:23 to ensure 50/50 day/night data collection
280/07:10:46 ATC Set formatter to Day Rate
280/07:10:48 ATC Set SCIABNORM flag to ABNORM
280/07:10:50 ATC Set PV DCR computation to OFF
280/07:10:52 ATC Set PC DCR computation to OFF
280/07:10:54 ATC Set Sector Rotation to -3072
280/07:17:24 ATC Set Sector Rotation to zero
280/07:17:26 ATC Set PC DCR computation to ON
280/07:17:28 ATC Set PV DCR computation to ON
280/07:17:30 ATC Set SCIABNORM flag to NORM
280/07:17:32 ATC Set formatter to Night Rate
280/07:33:09 ATC Moved Formatter to Night Rate later by 03:23 to ensure 50/50 day/night data collection
280/05:15:00 - 05:49:00 Real-time FOT sets IRU to low rate (greater spacecraft attitude precision)

None

None

283/21:01:28 ATC OA-15: SD/SDSM Open
283/21:52:52 - 22:26:25 ATC OA-19: SRCA Full Radiometric
283/22:40:21 ATC OA-16: SD/SDSM Screened

284/06:05:30 - 06:57:09 ATC OA-22: SRCA Full Spectral Part 1 of 4
284/08:00:56 - 08:35:41 ATC OA-22: SRCA Full Spectral Part 2 of 4
284/09:22:58 - 10:14:14 ATC OA-22: SRCA Full Spectral Part 3 of 4
284/11:17:00 - 11:54:58 ATC OA-22: SRCA Full Spectral Part 4 of 4
284/15:15:35 - 15:18:06 ATC OA-27: PV Ecal
284/15:18:35 - 15:23:06 ATC OA-28: PC Ecal

None

Maneuvers:

A drag make-up maneuver was performed on October 3rd, 2001. The next drag make-up maneuver may occur in as soon as two weeks.

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 -11.3408 degrees.

MODIS Anomalies:

Formatter Error Events:

The FR error counter (MOD_SS_CP_STATUS_08) has “rolled over” 16 times since the A-Side restart following the PS-2 Anomaly, and 14 times since the latest string of errors started on August 15. This is a 16-bit signed counter, therefore it “rolls over” every 32,768 counts.

Overall, the error rate is increasing. Short term rate decreases are still observed during calibration activities such as this past week's SD calibrations. During the upcoming week, several calibrations are planned and the rate of error events will be monitored during this time to see the effect they have on the rate.

The IOT is currently tracking the dates and times the CP_STATUS_08 counter has “rolled” to monitor changes in the error rate. A brief MS Excel spreadsheet called, AM1_FR_error_rollovers_100901.xls is available for download from:

ftp://www.mcst.ssai.biz/pub/permanent/IOT/am1/analysis/FR_events/

This files contains the date and time for each FR error count rollover as well as the error count at the start of each day (~00:00:00 GMT).

The current rate of FR errors is approximately 32,000 a day. 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 and no configuration changes are planned until science data is affected.

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:

Current temperature trends are being compared to the spacecraft orbit beta angle which will be changing direction about November 1st. It is hoped that the change in beta angle will cause instrument warming which will decrease the rate of formatter error events. However, an increase in temperature may also mean a decrease in focal plane heater margin.

Non-MODIS Significant Events:

None

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: 1721 of 3022 Movements
Nadir Aperture Door: 532 of 1316 Movements
Space View Door: 437 of 1316 Movements

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Last Update: Wednesday, 26-Feb-2003 15:13:39 EST