User Workshop ESRIN 2005

Anomaly Investigations

The following anomalies have occurred since Launch : • SDPSS DPC4 error

Anomaly Investigations

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

Anomaly Investigations

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

Trend charts optical bench temperature

• 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 thermistorscould be used as backup in case of failure of one or two of them

Optical Bench Temperature trendsOrbital mean

19.2

19.4

19.6

19.8

20

20.2

20.4

20.6

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06date

deg

C

E0095mean

E0096mean

E0097mean

R6082mean

Y1161mean

Optical Bench Temperature trendsTHSS Orbital mean

19.519.55

19.619.65

19.719.75

19.819.85

19.919.95

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06date

deg

C

E0095mean

E0096mean

E0097mean

Trend charts CCD temperaturesCCD mean Temperatures trend

-22.501

-22.500

-22.499

-22.498

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06

date

deg

C

E4520 mean

E4521 mean

E4522 mean

E4523 mean

E4524 mean

CCD 1,2,3,4,5 Temperatures trendOrbital min/max/mean

-22.6

-22.55

-22.5

-22.45

-22.4

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06date

deg

C

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

• 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

Trend charts peltier currentsMERIS Peltier current trends

Orbital min/max

00.10.20.30.40.50.6

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06

Date

AM

P

E0134 min

E0134 max

E0135 min

E0135 max

E0136 min

E0136 max

E0137 min

E0137 max

E0138 min

E0138 max

MERIS Peltier current trendsOrbital mean

0.4

0.42

0.44

0.46

0.48

0.5

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06Date

AM

P

E0134 mean

E0135 mean

E0136 meanE0137 mean

E0138 mean

• 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

Trend charts VEU temperature

• Internal T VEU orbital amplitude (=max-min 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.

VEU mean temperatures trend

2222.5

2323.5

2424.5

2525.5

2626.5

27

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06

date

deg

C

E0080 meanE0081 meanE0082 meanE0190 mean

VEU min/max Temperatures trend

15

1719

2123

25

2729

31

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06

date

deg

C

E0080 min

E0080 max

E0081 min

E0081 max

E0082 min

E0082 max

E0190 min

E0190 max

Trend charts ICU controlled heaters current

MERIS ICU controlled heaters current trend

0

0.5

1

1.5

2

2.5

3

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06

date

AM

P

E0120 minE0120 maxE0120 meanE0120 std

• 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

Trend charts equipment pseudo power

Pseudo Power Equipment

5556575859606162636465

01.03.02 01.03.03 01.03.04 01.03.05 01.03.06Date

Wat

t

c

• Pseudo Power Equipment := DSU + SDPSS + VEU• Decrease due to Voltage decrease • Overall, boxes consumption is o.k. (< 60 W)

Life limited items - Diffusers

• 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 calibrationmcmd can be continued nominally

• Limitation for Diffuser 2 has been relaxed to 90 min => large margin

MERIS Diffuser exposure to UV

0

1

2

3

4

0 5000 10000 15000 20000 25000orbits since launch

accu

mul

ated

hou

rsD

iffus

er 1

0

15

30

45

60

accu

mul

ated

min

utes

Diff

2 &

dop

ed D

iff

Diffuser 1Diffuser 2Doped Diffuser

Diffuser ageing

July 02 - May 2005

-0.90%

-0.80%

-0.70%

-0.60%

-0.50%

-0.40%

-0.30%

-0.20%

-0.10%

0.00%

0.10%

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

cam 1cam 2cam 3cam 4cam 5all

July 02 – May05

• Degradation limited to 560nm band and lower

• Instrument throughput degradation < 3% at 412nm

• No degradation for wavelengths above 500 nm

Mean Instrument degradation at orbit 18000 (mid August 2005)

0.97

0.975

0.98

0.985

0.99

0.995

1

1.005

0 2 4 6 8 10 12 14 16

Meris Band

dega

rada

tion

m1m2m3m4m5all

Instrument Degradation

Geolocation

Northern Hemisphere Southern Hemisphere

Restituted Attitude

Roll YawPitch

• Delivered operationally as of 31 Jan 2005 based on AOCS-Estimator output• Historical restituted attitude available as of 30 June 2005

Disparity analysis

Landsat ETM+ band 3MERIS band 7

MER_FS Geo-location

Before After

Offset Control Loop

OCL Has been switched to OFF on the 17 Dec 2004

Each point represents the blank value averaged on the entire orbit

All the orbits selected are located outside the SAA area

OCL-ON

OCL-OFF

OCL-ON

OCL-OFF

Impact of OCL-OFF

•Along track modulation have been removed.•Across track modulation due to calibration and degradation corrections

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.