MIPAS In-Orbit Operation
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MIPAS In-Orbit Operation. Presented by P. Mosner/R. Geßner Astrium GmbH. Contents. Part1 (P. Mosner) : Switch-On and Data Acquisition Phase (SODAP): History MIPAS Anomalies (1) - Mechanisms Modifications to Operational Procedures. Part2 (R. Geßner) :

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MIPAS In-Orbit Operation

Presented by

P. Mosner/R. Geßner

Astrium GmbH


Contents

  • Part1 (P. Mosner) :

    • Switch-On and Data Acquisition Phase (SODAP): History

    • MIPAS Anomalies (1) - Mechanisms

    • Modifications to Operational Procedures

  • Part2 (R. Geßner) :

    • MIPAS SODAP and CAL/VAL Characterisations

    • Operational Aspects of Instrument Performance

    • MIPAS Anomalies (2) - Miscellaneous

    • Long-Term Observations

    • Summary



MIPAS Switch-On and Data Acqusition Phase (SODAP) - History

  • Locking of MIPAS coolers at L – 6 hours 28 February 2002

  • Launch01 March 2002 01:07 UTC

  • Principal MIPAS switch-on Sequence during SODAP

    • ICU switch-on 11-13 March 2002

    • -> OLB-B thermostat anomaly, was resolved later

    • Unlocking of ASU, ESU, INT 17 March 2002

    • Transition Standby -> Heater 18-19 March 2002

    • Cooler and CBB characterisation 20-23 March 2002

    • First MIPAS measurements 24 March 2002

    • Timing characterisations 24-26 March 2002

    • Handover to MPS 26 March 2002

    • SODAP -> CAL/VAL Phase handover begin April 2002


MIPAS Anomalies (1) - ESU stepsize limitation

  • A HEATER MCMD resulted in a transition to HTR/REF Mode

  • Explanation :

    • the Heater MCMD occurs at a time where the requested Heater Mode transition can cause a conflict with activities finalising the ongoing sweep

    • this occurs only if ESU step sizes larger than the instrument specification value are commanded, which was demonstrated by tests on EQM at Ottobrunn

  • Operational solution:

    • every Heater MCMD is preceded by an Elevation Wear Cycle (in this case the surveillance related to the failure is inhibited for a short period of time)

    • BUT: the conflict may occur for other type of commanding where such a solution is not possible


M1,M2

M5,M6

M3,M4

Slide 1 stop after init

Slide 1

End Stop

Slide 2 stop at neg. end

Neg. End

Slide 2

Positive Direction

Pos. End

LockPosition

Initialisation Marks

MIPAS Anomalies (1) - Interferometer initialisation

  • An IDU re-initialisation failed (after non-nominal switch-off)

  • Explanation :

    • After a non-nominal IDU switch-off it can occur that both IDU slides are outside the init marks (Slide 1 being at positive APS side, Slide 2 at negative APS side. If this is the case the failure occurs due to

    • The slide 2 stops than at the neg. end stop behind the lock position

    • The lock position rail insert presents a small step on the rail where a velocity error can occur


MIPAS Anomalies (1) - Interferometer initialisation

  • Operational solution:

    If the IDU isn’t initialised after the transition from Standby to Heater, it is required to perform 3 times the following initialisation steps after reaching Heater Mode:

    - initialise the IDU slides

    - move slide 1 to the negative rail end and slide 2 to the positive rail end


MIPAS Anomalies (1) - Cooler performance

  • MIPAS instrument was switched off due to cooler vibration failure

  • Failure Observations and Explanation :

    - The cooler accelerations increased extremely (acceleration increase from <3mg to 12 mg; 1st harmonic acceleration increased by 50 times)This was caused due to loss of proportionality between compressor/displacer B drive level and amplitudes/PPO outputs

    • The proportionality for compressor B failed due to a mis-adjustment of the phases and amplitudes for the 1., 2. and 3. harmonics by the VCS. All of these harmonics correction products are processed and corrected individually.

    • The probable reason was the ageing of the VCS setting due to the long “on-line” operation without a repeated learning cycle

  • Operational solution(still under discussion):

    • Every 2-4 weeks (TBC) perform 5 VCS re-learn cycles (in Heater Mode)

    • If the failure re-occurs stop and re-start cooling once per month


Modifications to Operational Procedures

  • Mode Transition Standby to Heater:

    • Special IDU initialisation to correct IDU init problems

  • Start Measurement:

    • Update PAW gain setting for Measurement (switch PAW table 1)

  • Stop Measurement (Trans. Measurement to Heater):

    • the Heater MCMD is preceded by an Elevation Wear Cycle to allow the higher elevation stepsize (as discussed before)

    • Update the PAW gain setting, if a LOS/CAL sequence follows (PAW table 2)

  • Non-Linearity Characterisation:

    • New procedure added

    • Change due to limitation from the non-availability of ARTEMIS

  • Update SPE filter set:

    • Procedure added



MIPAS Characterisation in SODAP and CALVAL

  • Timing Characterisation

    • Mode Transition Times

    • Duration of Operational Sequences

  • Temperature Characterisation

    • MIPAS Optics Module / Interferometer

    • Calibration Blackbody

  • MIPAS Anomalies: Complementary Failures


OFF

Functions

11.050 sec

11.052 sec

BB CAL

Nom.

MEAS

20.000 sec

20.035 sec

DS CAL

SEM

< 55 hrs

35.5 hrs

10.200 sec

10.203 sec

HEATER

STANDBY

LAUNCH

LOS CAL

11.050 sec

11.063 sec

20.000 sec

20.014 sec

MIPAS Timing Characterisation: Mode Transition Times

  • Correlation between MCMD TT and time stamp of Source Packet


MIPAS Timing Characterisation: Summary (1)

  • Mode Transitions :

    • Heater to Measurement:20.035 sec  5.9 ms

      - > higher than values on-ground due to shift of ZPD position to align forward and reverse sweeps; effect understood

    • Heater to LOS CAL:11.063 sec  0 ms(IOM: 10.066 sec)

      20.014 sec  8.2 ms

    • Meas. to SEM,DS,BB:11.052 sec  5.9 ms

      10.203 sec  3.9 ms


MIPAS Timing Characterisation: Summary (2)

  • Duration of activities:

    • Elevation Scan Sequence (ESS - 16 high resolution sweeps):

      71.202 sec  5.8 ms(design value: 71.200 sec)

    • ESS Sequence (5 ESS + Offset Calibration):

      387.610 sec  8.4 ms(design value: 387.600 sec)

    • INT turnaround time:

      0.450 sec  4.5 ms(design value: 0.450 sec)

    • Low Resolution Sweeps: 0.400 sec (0.4 sec)

    • Medium Resolution Sweeps: 2.002 sec (2.0 sec)

    • High Resolution Sweeps: 4.003 sec (4.0 sec)


Interferometer temp

MIO Baseplate temp

MIPAS Temperature Characterisation: Optics Module

  • MIO temperature increase in the mission:

    216 K (L+10 days) -> 221 K (L+25 days) -> 224 K (L+ 68 days)

  • MIO baseplate orbital temperature variation: 0.2 K p-p, but Interferometer remains very stable (hence also the Beamsplitter)


MIPAS Temp Characterisation: CBB Temperatures (1)

  • CBB temperature profile shows 3 effects:

    • Temperature increase by about 1.7 Kwhen MIPAS is switched into Measurement Mode - > ASU shutter opens and the CBB sees parts of the atmosphere via the side baffle

    • Temperature change by about 3 Kwhen CBB heater level is changed by one step (0.27 W)

    • Orbital oscillation by about 0.2 K


Orbital variation

MIPAS to

Measurement

CBB

HL= 6

CBB HL= 4

CBB HL= 5

MIPAS to

Measurement

MIPAS to

Heater Mode

MIPAS Temp Characterisation: CBB Temperatures (2)



Operational Aspects of Instrument Performance

  • Radiometric, spectral or ILS performance : no operational impacts so far

  • LOS pointing performance:

    • analogue gain setting needs to be increased for LOS Calibration (poor signals especially in Channel D2)

    • first LOS signal (crosscorrelation peak) in a series of star measurements still earlier than expected; no major impact since other measurements “rectify” the CC peak; nevertheless explanation required

  • Gain measurements reveal some deterioration of optical throughput in the range of a few percent;could be contaminants (ice) on the detectors

    -> similar effects observed on other ENVISAT instruments

    -> operational impact for MIPAS: may require Decontamination Heating

    -> however: risk of this kind of cooler operation needs to be traded against the performance degradation

    -> going back to STANDBY (Coolers OFF) may be sufficient



MIPAS Anomalies (2) - Complementary Failures days)

  • SPE related error messages

    • Occasional “SPE correctable memory fault” reporting (EDAC)

    • Occurrences of an “unexpected sample count” - no impact on GS detected so far (not all L0 data available)

    • Occurrences of “ICE AUX Data not included” (5-6 events per day - but relatively poor statistics) - results in a loss of the SP’s from the respective sweep

      -> seems to be SPE-ICE communication problem

      - not correlated to Orbit position nor Instrument activity

      - not observed during EQM testing initiated immediately in OTN

      -> not really understood -> to be observed


Required Long-term Observations (1) - MIPAS Mechanisms days)

  • ASU/ESU :

    • Lifetime limited aspects (ESU leadscrew rotations) - some margin

  • Interferometer:

    • Monitor the warning anomaly flags (history reporting at ESOC)- Slide Movement Force Warning (1N Force)- Differential Speed Warning (1.5%)

    • Monitor fringe count errors (via Measurement data analysis)

    • Lifetime limited items: Number of INT sweeps - depends very much on operational scenario - see updated MIPAS IOM; little margin

  • Cooler:

    • Monitor Cooler Vibrations (Compressor/Displacer acceleration and harmonics)

    • Monitor Temperature stability (stability flags)

    • Monitor warning anomaly flags (ICU anomaly counts)

    • Important: take cyclically RTT formats (twice per orbit)


Required Long-term Observations (2) - Others days)

  • Statistics on source packet losses :

    • evaluation of history entries required

  • Evaluation of life limited items :

    • depending on operational scenario - see previous page

  • Optical throughput :

    • needs to be observed together with NESR evaluations to decide whether detector warm-up is required


CONCLUSIONS days)

  • MIPAS functional and operational behaviour excellent

  • Characterisation data is as expected and very accurate

  • Operational measures for detected anomalies in place

  • Long-term observations required on mechanisms and on source packet losses

  • Documentation: MIPAS SODAP Report + CAL/VAL extension


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