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Summary on MAG splinter

Summary on MAG splinter. Enkelejda Qamili. Swarm 6 th Data Quality Workshop 26 th – 29 th September 2016, Edinburgh, UK. Overview. ASM-VFM residuals : root cause investigation in-orbit tests on-ground tests dB_sun correction model ASM/VFM inter-comparison analysis ASM-V data

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Summary on MAG splinter

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  1. Summary on MAG splinter EnkelejdaQamili Swarm 6th Data Quality Workshop 26th – 29th September 2016, Edinburgh, UK

  2. Overview • ASM-VFM residuals : root cause investigation • in-orbit tests • on-ground tests • dB_sun correction model • ASM/VFM inter-comparison analysis • ASM-V data • Features detected on magnetic data • Timeline of upcoming changes in the processor and data release

  3. ASM-VFM residuals : root cause investigation: 1 The Disturbance field is believed to be the consequence of local heating by the Sun near the VFM sensor, and a likely mechanism is thermo-electric current generation. An in-orbit Residual test campaign consisting in the activation of heaters near the VFM sensor was performed from 30/05 to 03/06. The aim of the tests was to create temperature gradients near the VFM sensor. After the activation of such heaters, some effects have been seen (OB Interface heater) but such effect can not explain the ASM-VFM scalar residuals we have. Recommendation on a further heater test (with different temperature settings and duration) that could improve the investigation are welcome

  4. ASM-VFM residuals : root cause investigation: 2 • ESA has invited Airbus to propose thermal tests for root cause investigation of the observed ASM-VFM magnetic residual and the STR Inter-Boresight-Angle variation • ASM- VFM • Thermal gradient across the OB Boom bracket • Thermal gradient between the OB Thermal Cover legs • Measure potential thermo-electric current on a piece of outer OB MLI • STR IBA correction model • Thermo-elastic stability of Optical Bench with STR cameras replaced by Titanium mass dummie

  5. ASM-VFM residuals : improvement of the current correction model Updated scaling :

  6. ASM-VFM residuals - Impact on magnetic data product • It was pointed out that: • All the rest of the systematics not covered by dB_sun are propagated to the VFM • L1b processor have modified VFM original parameters dBVFM BEARTH BVFM dBL1b BL1b There is no yet a clear physical explanation / evidence why they should change. But in-flight data consistently shows stability in the co-estimation approach.

  7. ASM/VFM inter-comparison analysis

  8. ASM/VFM inter-comparison analysis The anomaly detected during the manoeuvre have been model Where does this anomaly come from ?

  9. On the ASM vector mode data • The ASM vector mode works well • ASM-V data have been used to make useful comparison with the nominal VFM data and assess the so-called dB_Sun perturbation • They could also be used to investigate boom distortion and mechanical stability • They could even be used for field modelling • But the vector components of the ASM vector mode data should be used with caution during Field Aligned Current and Plasma Bubble events (ASM scalar data are not affected) • Issues affecting the data are now all well known • We now plan to produce a new version of the ASM-V data • GFZ validation efforts. Some features still to be further analysed.

  10. Features on Magnetic data By analyzing the Magnetic data using different techniques, some features (not yet explained) have been detected

  11. Operational processor: future improvements Fix of the Leap second issue ORBATT Implementation of the STR IBA Temperature Correction Model Increase STR frequency from 1 Hz to 2Hz Improvement re-sampling of STR data MAGNET dB_Thrust to be included in dB_Others instead of in dB_AOCS Improvement of interpolation of ASM measurements to UTC-exact second TIMELINE: - MAG_LR reprocessed by Jan 2017 - Full mission data reprocessed by July 2017.

  12. Conclusions • ASM-VFM scalar residuals • Further work on the improvement of the dB_sun correction model • In order to de-correlate the VFM Teu and the Beta angles, maybe we can investigate the possibility of an eventual test using the VFM Electronic Unit heater. • Further work on adjustment of the VFM pre-flight calibration parameter. • The root cause of the ASM-VFM residuals not yet identified : • on-ground testing with equipment/spares from development phase • New in orbit heater test: industries and users will be invited to comment the test before its implementation.

  13. Conclusions • What happens during the manoeuvre … • we don’t know whether the anomaly is caused by something happening inside or outside the instrument/s • Maybe the ASM-ASM differences are mapped to the VFM during the calibration processing step. • More analysis has to be done on the pre-flight characterisation of the ASM after the changes on the bracket and cabling were changed before launch. Maybe a small y-oriented effect has not been fully captured. • We could involve Leti team and see if it is possible to perform such test • Improvements of the processor coming soon. Check web-site for news. • ASM-V data … • IPGP/LETI will deliver an updated version of the ASM vector data that will be available for the users • Further investigations will continue

  14. Thank you

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