The upcoming generation of 4-meter solar telescopes (such as DKIST and EST) and planned networks for synoptic solar observations (such as SPRING) will rely on full Stokes spectropolarimetric measurements to infer the properties of the solar atmosphere. They will produce a wealth of data whose analysis represents a formidable challenge. To solve this problem, we have pursued two approaches within the H2020 SOLARNET project: parallelization of a Milne-Eddington Stokes inversion code for use in mid-size servers and implementation in graphics processing units (GPUs). Here we present the results of those efforts. P-MILOS and G-MILOS are two Stokes inversion codes that can be used to produce maps of physical quantities in real time during the observations at the telescope, or to generate science-ready data from time series of spectropolarimetric measurements taken by both imaging and slit-based spectropolarimeters. These codes will open a new era in solar research.
KEYWORDS: Data processing, Calibration, Image processing, Space operations, Polarimetry, Demodulation, Polarization, Sensors, Magnetism, Imaging systems
A frequent problem arising for deep space missions is the discrepancy between the amount of data desired to be transmitted to the ground and the available telemetry bandwidth. A part of these data consists of scientific observations, being complemented by calibration data to help remove instrumental effects. We present our solution for this discrepancy, implemented for the Polarimetric and Helioseismic Imager on-board the Solar Orbiter mission, the first solar spectropolarimeter in deep space. We implemented an on-board data reduction system that processes calibration data, applies them to the raw science observables, and derives science-ready physical parameters. This process reduces the raw data for a single measurement from 24 images to five, thus reducing the amount of downlinked data, and in addition, renders the transmission of the calibration data unnecessary. Both these on-board actions are completed autonomously.
The Sunrise balloon-borne solar observatory carries a 1 m aperture optical telescope and provides us a unique platform to conduct continuous seeing-free observations at UV-visible-IR wavelengths from an altitude of higher than 35 km. For the next flight planned for 2022, the post-focus instrumentation is upgraded with new spectro- polarimeters for the near UV (SUSI) and the near-IR (SCIP), whereas the imaging spectro-polarimeter Tunable Magnetograph (TuMag) is capable of observing multiple spectral lines within the visible wavelength. A new spectro-polarimeter called the Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is under development for observing near-IR wavelength ranges of around 770 nm and 850 nm. These wavelength ranges contain many spectral lines sensitive to solar magnetic fields and SCIP will be able to obtain magnetic and velocity structures in the solar atmosphere with a sufficient height resolution by combining spectro-polarimetric data of these lines. Polarimetric measurements are conducted using a rotating waveplate as a modulator and polarizing beam splitters in front of the cameras. The spatial and spectral resolutions are 0.2" and 2 105, respectively, and a polarimetric sensitivity of 0.03 % (1σ) is achieved within a 10 s integration time. To detect minute polarization signals with good precision, we carefully designed the opto-mechanical system, polarization optics and modulation, and onboard data processing.
In this paper we present a novel FPGA implementation of the Consultative Committee for Space Data Systems Image Data Compression (CCSDS-IDC 122.0-B-1) for performing image compression aboard the Polarimetric Helioseismic Imager instrument of the ESA’s Solar Orbiter mission. This is a System-On-Chip solution based on a light multicore architecture combined with an efficient ad-hoc Bit Plane Encoder core. This hardware architecture performs an acceleration of ~30 times with respect to a software implementation running into space-qualified processors, like LEON3. The system stands out over other FPGA implementations because of the low resource usage, which does not use any external memory, and of its configurability.
In this contribution we present a multi-core system-on-chip, embedded on FPGA, for real-time data processing, to be used in the Daniel K. Inouye Solar Telescope (DKIST). Our system will provide “quick-look” magnetic field vector and line-of-sight velocity maps to help solar physicists to react to specific solar events or features during observations or to address specific phenomena while analyzing the data off line. The stand-alone device will be installed at the National Solar Observatory (NSO) Data Center. It will be integrated in the processing data pipeline through a software interface, and is competitive in computing speed to complex computer clusters.
KEYWORDS: Data processing, Image processing, Calibration, Image sensors, Digital imaging, Space operations, Field programmable gate arrays, Polarimetry, Sensors
The extension of on-board data processing capabilities is an attractive option to reduce telemetry for scientific instruments on deep space missions. The challenges that this presents, however, require a comprehensive software system, which operates on the limited resources a data processing unit in space allows. We implemented such a system for the Polarimetric and Helioseismic Imager (PHI) on-board the Solar Orbiter (SO) spacecraft. It ensures autonomous operation to handle long command-response times, easy changing of the processes after new lessons have been learned and meticulous book-keeping of all operations to ensure scientific accuracy. This contribution presents the requirements and main aspects of the software implementation, followed by an example of a task implemented in the software frame, and results from running it on SO/PHI. The presented example shows that the different parts of the software framework work well together, and that the system processes data as we expect. The flexibility of the framework makes it possible to use it as a baseline for future applications with similar needs and limitations as SO/PHI.
In this work we propose a multiprocessor architecture to reach high performance in floating point operations by using radiation tolerant FPGA devices, and under narrow time and power constraints. This architecture is used in the PHI instrument that carries out the scientific analysis aboard the ESA’s Solar Orbiter mission. The proposed architecture, in a SIMD flavor, is aimed to be an accelerator within the Data Processing Unit (it is composed by a main Leon processor and two FPGAs) for carrying out the RTE inversion on board the spacecraft using a relatively slow FPGA device – Xilinx XQR4VSX55–. The proposed architecture squeezes the FPGA resources in order to reach the computational requirements and improves the ground-based system performance based on commercial CPUs regarding time and power consumption. In this work we demonstrate the feasibility of using this FPGA devices embedded in the SO/PHI instrument. With that goal in mind, we perform tests to evaluate the scientific results and to measure the processing time and power consumption for carrying out the RTE inversion.
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