MODIS IOT Aqua Weekly Report

Mission Operations Days: 2002/215 to 2002/221
August 3rd, 2002 00:00:00 GMT to August 10th, 2002 00:00:00 GMT

At 20:23 GMT on July 29th, 2002 (2002/210), the Aqua spacecraft autonomously entered Safe Mode. This caused the instruments to transition to Safe Mode as well. MODIS' doors (SVD and NAD) closed and all the subsystems were powered off except the power supply, control processor, and timing generator. The instrument survival heaters remained enabled.

Transitioning back to Science Mode for MODIS began on August 5th, 2002 (2002/217).

See Non-MODIS significant events and completed activities sections below for details.

Aqua Spacecraft and MODIS Instrument Status:

This Week's Completed MODIS Activities:

None

None

2002/217 21:04:25-21:05:59 Real-Time MOD_STBY_PM_TXTN('B') Transition MODIS from Safe Mode to Standby Mode on Side B
2002/217 21:07:28-21:07:56 Real-Time MOD_MEM_PM_DUMP('MOTOR_POS_WHEN_HIT',12,0,0,1,1) Dump NAD and SVD Trigger Step Counts from the previous Safe Mode Transition
2002/217 22:20:21-22:22:44 Real-Time MOD_SVD_TO_OPEN Move the SVD to its Open Position (from Closed)
2002/217 22:23:05-22:25:33 Real-Time MOD_NAD_TO_OPEN Move the NAD to its Open Position (from Closed)
2002/217 22:42:37-22:43:21 Real-Time MOD_MEM_PM_DUMP('MOTOR_POS_WHEN_HIT',12,0,0,1,1) Dump NAD and SVD Trigger Step Counts from their recent Openings

2002/218 14:50:45-14:52:43 Real-Time MOD_SCI_PM_TXTN('B') Transition MODIS from Standby Mode to Science Mode on Side B
2002/218 14:53:00-14:53:30 Real-Time CDH_FMU_TAXI('MODIS','B','ENAB') Enables the MODIS Taxi Port
2002/218 14:55:04-14:55:26 Real-Time MOD_FR_MODE('NIGHT') Sets the MODIS Formatter to Night Rate
2002/218 19:42:35-19:43:28 Real-Time MOD_BB_ON('B','B') Turns on the MODIS Black Body
2002/218 19:43:50-19:44:21 Real-Time MOD_SET_BB_TEMP(1733) Sets the Black Body Heater Temperature to 285 K.

None

None

2002/221 21:32:40-21:45:51 MCL OA16: SD/SDSM Screened, SDSM at Sun - B Side
2002/221 22:23:59-22:24:15 MCL SRCA Setup Activity
2002/221 22:24:29-22:58:42 MCL OA19: SRCA Full Radiometric - B Side
2002/221 23:11:33-23:24:44 MCL OA15: SD/SDSM Open, SDSM at SD - B Side

This Week's Scheduled MODIS Activities Not Completed:

None

Upcoming MODIS Events:

Remaining Calibrations for August: weekly SD/SDSM, SRCA Full Spatial, SRCA Full Spectral, Black Body, PC ECAL, and PV ECAL.

Maneuvers:

There will not be a lunar calibration roll maneuver on Aqua in August. The required roll angle would have exceeded the limit of -20 degrees.

The Deep Space Calibration pitch maneuver(s) have been indefinitely suspended pending mission review.

MODIS Anomalies:

The FOT reported receiving a Taxi 2 Error at 2002/219 05:38:02. This error indicates that there was a momentary communication problem between MODIS and the FMU. A possible missing science data packet may have resulted.

EDOS has notified us of two time jumps in Aqua MODIS data packets. They are:

A bit flip in the coarse time of the Time Code field (03eb instead of 03e3). There was no Reed-Solomon (RS) correction, so the error is believed to have occurred on the spacecraft/instrument.

A MODIS packet had two bytes missing in the coarse time of the Time Code field resulting in an invalid time. The two fine time bytes were shifted into the coarse time field. The packet length was only 640 bytes instead of 642 bytes. There was no RS correction and the CADU first header pointer had the correct value accounting for the two fewer bytes so the error is believed to have occurred on the spacecraft/instrument.

There were no FR or CP events around either of these two time jumps.

General Instrument Comments:

The Aqua MODIS instrument was transitioned to Standby Mode on 2002/217 at 21:05 GMT (August 5th, 2002). The Space View Door was opened at 22:22 GMT and the Nadir Door was opened at 22:25 GMT. The Aqua MODIS instrument was transitioned to Science Mode at 14:52 GMT on August 6th, 2002 (2002/218). The formatter rate was set to NIGHT and will remained in that state until the MODIS Master Command Load (MCL) began at 00:00 GMT on August 7th, 2002 (2002/291). The normal DAY/NIGHT transitions resumed at that point. On 2002/220 (August 8th, 2002) the Aqua MODIS Black Body (B Side) was successfully turned on and set to its nominal operational temperature of 285 K. The Heater duty cycle was previously, and remained set, at the 1/3 level. The Aqua MODIS CFPAs reach their operational temperature of 83K at 2002/219 23:15 GMT. The CFPAs began their cooling when the SVD was opened on 2002/217.

The SVD and NAD are Open, the survival heaters are enabled, and the Black Body is heated to 285 K.

MODIS Telemetry Trends:

The FM1 MODIS instrument telemetry is trending nominally.

Non-MODIS Significant Events:

At 20:23 GMT on July 29th, 2002 (2002/210), the Aqua spacecraft autonomously entered Safe Mode. This caused the instruments to transition to Safe Mode as well. MODIS' doors (SVD and NAD) closed and all the subsystems were powered off except the power supply, control processor, and timing generator. The instrument survival heaters remained enabled.

The anomaly was caused by a low output from one of the Earth Sensors for several seconds while the spacecraft was near the South Pole. The Earth Sensor output is computed by one of two algorithms. One algorithm is apparently flawed, and was being used at the time of the anomaly. A patch was created to force the sensor to choose the properly functioning algorithm for nearly all attitude possibilities. The patch was tested and loaded on 2002/217 around 15:00 GMT. After 5 hours of successful operation with the patch in place, the "go" was given for the instruments to begin their recovery operations.

Limited Life Item Status:

SRCA 10W Lamp #1: 203.7 of 500 hours
SRCA 10W Lamp #2: 177.9 of 500 hours
SRCA 10W Lamp #3: 180.7 of 500 hours
SRCA 10W Lamp #4: 57.7 of 500 hours

SRCA 1W Lamp #1: 500.3 of 5000 hours
SRCA 1W Lamp #2: 269.8 of 5000 hours

Solar Diffuser Door: 1782 of 3022 Movements
Nadir Aperture Door: 1051 of 1316 Movements
Space View Door: 630 of 1316 Movements

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Last Update: Tuesday, 03-Dec-2002 13:09:00 EST