Anomaly Investigations. The following anomalies have occurred since Launch : SDPSS DPC4 error

Transcription

1 User Workshop ESRIN 2005

2 Anomaly Investigations The following anomalies have occurred since Launch : SDPSS DPC4 error

3 Anomaly Investigations The following anomalies have occurred since Launch : SDPSS DPC4 error ENV-908 half OBT wrap around

4 Anomaly Investigations The following anomalies have occurred since Launch : SDPSS DPC4 error ENV-908 half OBT wrap around Unexpected SDPSS switch to pause mode

5 Trend charts optical bench Over the complete analysed period of 36 months, the optical bench temperatures are stable within 1 LSB of 0.4 K The mean is stable within 40 mk, achieved due to big thermal inertia and standard ON/OFF heaters switching The thermal control loop is working perfectly The offset between the 3 THSS sensors is low (+/- 200 mk) and constant over time, which means that any of the three thermistors could be used as backup in case of failure of one or two of them temperatureoptical Bench Temperature trends deg C deg C Orbital mean date Optical Bench Temperature trends THSS Orbital mean date E0095 mean E0096 mean E0097 mean R6082 mean Y1161 mean E0095 mean E0096 mean E0097 mean

6 Trend charts CCD temperatures deg C CCD 1,2,3,4,5 Temperatures trend Orbital min/max/mean date E4520 min E4520 max E4520 mean E4521 min E4521 max E4521 mean E4522 min E4522 max E4522 mean E4523 min E4523 max E4523 mean E4524 min E4524 max E4524 mean deg C CCD mean Temperatures trend date E4520 mean E4521 mean E4522 mean E4523 mean E4524 mean The amplitudes of the CCD temperatures are about 60 mk p-p and stable over the 36 months period analysed. The variation of the orbital mean is per CCD temperature is extremely stable (less than 1 mk) along the last 36 months All 5 CCDs behave very similar Thermal subsystem performance is stable and excellent

7 Trend charts peltier currents Min/Max temperatures are nearly constant and amplitudes within 200 ma p-p (Operational limit for spikes: 1.78 A) Maximum is stable (around 0.5 A) at and well below the monitoring limit of 1.6 A Orbital mean currents curves are stable within 5 ma (=1% of the value) No degradation of CCD thermal regulation loop AMP AMP MERIS Peltier current trends Orbital min/max Date MERIS Peltier current trends Orbital mean E0134 mean E0135 mean E0136 mean E0137 mean E0138 mean E0134 min E0134 max E0135 min E0135 max E0136 min E0136 max E0137 min E0137 max E0138 min E0138 max Date

8 Trend charts VEU temperature Internal T VEU orbital amplitude (=maxmin of E0190) always around 9K, = indication of good performance stability (offset & gain) of analogue electronics Strong correlation of mean, min, max and even standard deviation with the seasons is observed, which is explained by the seasonal variation of sun incidence angle on the +Y radiator (where the VEU is mounted on) Long term drift of mean temperatures by +0.5 K/year is not at all critical THSS sensors (E0080, 81, 82) behave very similar and any of them can be used as redundant sensor in case one of the three should fail. No significant degradation observed. deg C deg C VEU min/max Temperatures trend date VEU mean temperatures trend E0080 mean 25 E0081 mean 24.5 E0082 mean E0190 mean date E0080 min E0080 max E0081 min E0081 max E0082 min E0082 max E0190 min E0190 max

9 Trend charts ICU controlled heaters current Min always at zero, as expected Max seem to decrease => probability that all heaters are ON at the same time (which is the driving event for max) decreases, which is good for thermal stress on the ICU heaters switching board. Operational limit of 5 A is respected with a comfortable margin. Mean is stable (apart from a slight expected seasonal variation) No degradation observed AMP MERIS ICU controlled heaters current trend date E0120 min E0120 max E0120 mean E0120 std

10 Trend charts equipment pseudo power Watt Pseudo Power Equipment c Date Pseudo Power Equipment := DSU + SDPSS + VEU Decrease due to Voltage decrease Overall, boxes consumption is o.k. (< 60 W)

11 Life limited items - Diffusers MERIS Diffuser exposure to UV accumulated hours Diffuser Diffuser 1 Diffuser 2 Doped Diffuser accumulated minutes Diff 2 & doped Diff orbits since launch 0 Exposure is in line with the recommended calibration activities Calibration frequencies and corresponding commanding of number of frames parameter for the averaged frame in on ground calibration mcmd can be continued nominally Limitation for Diffuser 2 has been relaxed to 90 min => large margin

12 Diffuser ageing July 02 - May May % 0.00% -0.10% -0.20% -0.30% -0.40% -0.50% -0.60% cam 1 cam 2 cam 3 cam 4 cam 5 all -0.70% -0.80% -0.90% Degradation limited to 560nm band and lower

13 Instrument Degradation Mean Instrument degradation at orbit (mid August 2005) degaradation m1 m2 m3 m4 m5 all Meris Band Instrument throughput degradation < 3% at 412nm No degradation for wavelengths above 500 nm

14 Geolocation Northern Hemisphere Southern Hemisphere

15 Restituted Attitude Pitch Roll Yaw Delivered operationally as of 31 Jan 2005 based on AOCS-Estimator output Historical restituted attitude available as of 30 June 2005

16 Disparity analysis Landsat ETM+ band 3 MERIS band 7

17 MER_FS Geo-location Before After

18 Offset Control Loop OCL Has been switched to OFF on the 17 Dec 2004 OCL-ON OCL-OFF OCL-ON OCL-OFF Each point represents the blank value averaged on the entire orbit All the orbits selected are located outside the SAA area

19 Impact of OCL-OFF Along track modulation have been removed. Across track modulation due to calibration and degradation corrections

20 Conclusion The trends show a stable MERIS behaviour Slight degradations (e.g. in VEU temperature) are not critical Diffuser 2 exposure time has now a comfortable margin in the allocation MERIS is still (after more than 3 years) on nominal redundancy chains The ENVISAT system has now implemented an restituted attitude service We are still improving the data products on a daily basis.