Metis On-Board SW overview

OBSW overview Summary Metis OBSW structure Operative Modes Acquisition Schemes On-board data processing chains MPPU & CPC UV Detector Visible Detector

OBSW main tasks METIS functionalities are realized trough the OBSW exploiting the HW resources. MPPU & CPC Handle TM/TC communication with Solar Orbiter Manage and control METIS detectors Manage and control METIS IOM mechanisms Manage thermal control of METIS Monitor METIS status and handle FDIR Execute scientific operational sequences Perform scientific data processing and compression UV Detector Visible Detector

On Board Software Structure METIS OBSW consists of two executable, both running on the MPPU CPU board, plus a set of HW procudures. Main OBSW modules The Boot Loader Software executable stored on the PROM memory loads the Instrument Management Software executable from MRAM (non volatile memory) to RAM memory starts its execution In case no SW image could be loaded in RAM, it enters the Software Maintenance Mode permitting SW patching and SW Images configuration. The Instrument Management Software executable stored in MRAM memory loaded in RAM memory and started by the Boot-loader implements all the instrument management functionalities necessary for the mission HW implemented Software (part of) Data processing OBSW Executables Page 4

Metis Operative Modes MODE Description OFF Metis unpowered POWER UP entered whenever power is fed BOOT Check and load the SW image SW Maintenance / Boot SW Maintenance dedicated to perform SW images patch and configuration, and memory management. SAFE/STAND-BY idle mode where METIS keeps its basic survival functionalities, delivers basic HK telemetry and waits for operations. It is also a SAFE mode where the instrument will fall as a consequence of FDIR intervention. SETUP AND CONFIGURATION intended for configuration of all operative parameters, diagnostics and preparation of observations. DIAGNOSTIC intended as troubleshooting mode OPERATIONAL normal mode of operations. Observation sessions takes place as driven by telecommands coming from the platform.

Metis Nominal Operations Power Applied

Metis Nominal Operations Power Applied Successful Boot

Metis Nominal Operations Power Applied Successful Boot Instrument in SAFE Mode

Metis Nominal Operations Power Applied Successful Boot Instrument in SAFE Mode Transition to SETUP Subsystems power on Instrument common configuration

Metis Nominal Operations Power Applied Successful Boot Instrument in SAFE Mode Transition to SETUP Subsystems power on Instrument common configuration Transition to OPS Configure Acquisition Configure PMP Configure Compression START ACQUISITION

Metis Acquisition Schemes The VL and UV channels can be operated in different modes, depending mainly by: Different on board processing Different sub-system operations VLDA Polarised Acquisition Polarised Brightness - pB The different operations provide 6 nominal acquisition schemes, 3 for the VL and 3 for the UV channel. Actually 3 more schemes exists: VL-Temporal Noise UV-Temporal Noise UV Photon Counting – Test Mode but these modes are not used in Nominal operations and are not described here. Total Brightness - tB Fixed Polarisation UVDA Photon Counting Photon List Accumulation Analog

VLDA Processing: Polarised Acquisition CME monitoring Spacecraft light curve Sun Disk Monitoring data compression VLDA Read Re-ordering C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization 1 3 2 4 5 8 Log Matrix exposure frames corrected frames Every single frame will be Readout, Reordered.

VLDA Processing: Polarised Acquisition CME monitoring Spacecraft light curve Sun Disk Monitoring data compression VLDA Read Re-ordering C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization 1 3 2 4 5 8 Log Matrix exposure frames corrected frames A Cosmic Ray Scrub will be applied to remove cosmic rays from METIS images; The algorithm compares pixels having the same coordinates belonging to 2 images sequentially acquired in the same configuration. If the pixels show very different signals, the pixel having the maximum value is replaced by the pixel with the minimum value. The pixels that have been modified are recorded into a Log Matrix.

VLDA Processing: Polarised Acquisition CME monitoring Spacecraft light curve Sun Disk Monitoring data compression VLDA Read Re-ordering C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization 1 3 2 4 5 8 Log Matrix exposure frames corrected frames The CME detection algorithm operates on the VL frames. The implemented algorithm computes the running difference of consecutive images and looks for abrupt changes caused by possible arising of transient bright events. METIS field of view is split in 8 sectors, the signal resulting by averaging the pixels belonging to each sector is then monitored looking for abrupt changes caused by possible arising of transient bright events. The temporal series of the computed values is then sent to ground as a light curve. The same algorithm is used to monitor if the Sun disk is entering into the Metis FOV.

VLDA Processing: Polarised Acquisition CME monitoring Spacecraft light curve Sun Disk Monitoring data compression VLDA Read Re-ordering C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization 1 3 2 4 5 8 Log Matrix exposure frames corrected frames For VLDA measurements, every image is obtained by averaging in memory several frames acquired with the polarimeter in the same condition and using the same Detector Integration Time (DIT). s1 S s2 … sNDIT Detector Integration Time (DIT) 1 ÷ 600 s NDIT within 1 ÷ 64 NDIT

VLDA Processing: Polarised Acquisition CME monitoring Spacecraft light curve Sun Disk Monitoring data compression VLDA Read Re-ordering C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization 1 3 2 4 5 8 Log Matrix exposure frames corrected frames Each VL image provides a data quality hint supplying the pixels spatial variance and the average signal computed on a proper sub-array of the final (i.e. after co-adding) raw image. The info are gathered in the data header. Noise computation areas

VLDA Processing: Polarised Acquisition CME monitoring Spacecraft light curve Sun Disk Monitoring data compression VLDA Read Re-ordering C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization 1 3 2 4 5 8 Log Matrix exposure frames corrected frames Finally an algorithm based on CCSDS-123, optimized for solar corona images, is applied to maximize the scientific return. Main characteristics: lossless and lossy compression in one single package; Re-mapping to produce a ‘radial’ image to exploit the geometry of solar corona enhancing compression Radial binning Uniform and radially variably binning possible Prediction on previous images Area 1 Area 2 Area 3 Area 4

Polarized Brightness Total Brightness

VLDA Processing: Fixed Polarization (FLUCTS) Read Re-ordering Pre-filter … Up to 64 images Spacecraft data compression Radialization Masking Binning Compression TM Packetization In this acquisition scheme the VL detector acquires continuously the commanded frames with a given detector integration time. This acquisition scheme has been created in order to perform acquisitions at high rate. A minimum detector integration time of 1s can be set and a maximum number of 64 frames can be acquired. At 1s detector integration time and for 64 frames, the total acquisition time is of about 11 minutes, including processing time. Every single frame will be Readout, Reordered. A possible pre-filter can be applied to each incoming frame in order to reduce the number of pixels to be stored on board. The pre-filter function can apply a uniform 2x2 binning or a radial masking. All frames are acquired by keeping the polarisation angle at the same fixed position. Eventually, the individual frames are compressed and delivered to ground.

VLDA Processing: Fixed Polarization (FLUCTS) DIT ≥ 1s Max expected duration < 11 minutes

UVDA Photon Counting Unit The main tasks of the Photon Counting Unit : Offset correction: the pixels values as acquired from the UVDA are corrected by subtracting an offset which depends on the x,y coordinates. Through a proper system of delays, the system will generate 3x3 pixel windows that sweep dynamically the whole matrix at the pace of the pixel clock (12 MHz). The processing system will perform the following tasks on each 3x3 window:   1 3 2 4 5 8 checking, according to appropriate discrimination, for the presence of a charge distribution representing a photon event; computing the centroid coordinates; computing the amplitude of the event, i.e. the integrated signal on the 3x3 window. Photon List Spacecraft Photon Counting Unit UVDA Offset Correction Photon Detection Photon List Generation TM Packetization Photons Matrix Accumulation Matrix Compression TM Packetization

Photon Counting: Photon list - Accumulation The list of events are then handled differently for the 2 sub-cases: Photon Counting – Photon List: No processing on the list of events, the data stream is packetized and sent to the S/C Photon Counting – Accumulation: An 1k x 1k event matrix is built. The pixel of coordinates (x,y) contains the number of events registered for that position on the detector. An energy vector is also produced reporting the distribution energy of the set of the detected events. Photon List Spacecraft Photon Counting Unit UVDA Offset Correction Photon Detection Photon List Generation TM Packetization Photons Matrix Accumulation Matrix Compression TM Packetization

UVDA – Analog Mode Spacecraft Log Matrix Every single frame is Readout. A first average is computed by the Pre-sum module. A Cosmic Ray Scrub is applied to remove cosmic rays from METIS images; it provides also the Log Matrix of the pixels that have been modified The final exposure is obtained by averaging in memory several acquisitions having the same Detector Integration Time (DIT). As for the VL case, also the UV channel provides a data quality hint supplying the pixels spatial variance and the average signal computed on a proper sub-array of the final (i.e. after co-adding) raw image coded in the data header. Finally a customized compression algorithm is applied to maximize the scientific return. data compression Spacecraft UVDA Read PreSum C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization Analog Mode acquisition Corrected acquisitions exposure 1 3 2 4 5 8 frames Log Matrix

Photon List Generation CME monitoring Spacecraft Polarised Acquisition scheme Sun Disk Monitoring light curve Read Re-ordering C.Rays & SEP Co-adding Statistics data compression Radialization Masking Binning Compression TM Packetization VLDA frame corrected frame 1 3 2 4 5 8 exposure Read Re-ordering Pre-filter VL-FP Acquisition scheme … data compression Read PreSum C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization Analog Mode UVDA 1 3 2 4 5 8 Photon List frame acquisition exposure Photon Counting Mode Offset Correction Photon Detection Photon List Generation TM Packetization Photon Counting Unit Photons Matrix Accumulation Matrix Compression TM Packetization

Photon List Generation CME monitoring Spacecraft Polarised Acquisition scheme Sun Disk Monitoring light curve Read Re-ordering C.Rays & SEP Co-adding Statistics data compression Radialization Masking Binning Compression TM Packetization VLDA frame corrected frame 1 3 2 4 5 8 exposure Read Re-ordering Pre-filter VL-FP Acquisition scheme … data compression Read PreSum C.Rays & SEP Co-adding Statistics Radialization Masking Binning Compression TM Packetization Analog Mode UVDA 1 3 2 4 5 8 Photon List frame acquisition exposure Photon Counting Mode Offset Correction Photon Detection Photon List Generation TM Packetization Photon Counting Unit Photons Matrix Accumulation Matrix Compression TM Packetization

Metis On-Board SW overview