Performance Analysis of the SO/PHI Software Framework for On-board Data Reduction

The Polarimetric and Helioseismic Imager (PHI) is the first deep-space solar spectropolarimeter, on-board the Solar Orbiter (SO) space mission. It faces: stringent requirements on science data accuracy, a dynamic environment, and severe limitations on telemetry volume. SO/PHI overcomes these restrictions through on-board instrument calibration and science data reduction, using dedicated firmware in FPGAs. This contribution analyses the accuracy of a data processing pipeline by comparing the results obtained with SO/PHI hardware to a reference from a ground computer. The results show that for the analyzed pipeline the error introduced by the firmware implementation is well below the requirements of SO/PHI.Workframe: International Max Planck Research School (IMPRS) for Solar System Science. Solar Orbiter: ESA, NASA. Support grants: DLR 50 OT 1201, Spanish Research Agency ESP2016-77548-05, European FEDER. Data: NASA/SDO HMI science team

Autonomous on-board data processing and instrument calibration software for the Polarimetric and Helioseismic Imager on-board the Solar Orbiter mission

This is an open access article. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.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 Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.This work was carried out in the framework of the International Max Planck Research School for Solar System Science at the Max Planck Institute for Solar System Research. Solar Orbiter is a mission led by the European Space Agency with contribution from the National Aeronautics and Space Administration (NASA). The Polarimetric and Helioseismic Imager instrument is supported by the German Aerospace Center (DLR) under grant Nos. 50 OT 1201 and 50 OT 1901. The Spanish contribution has been partly funded by the Spanish Research Agency under projects under grant Nos. ESP2016-77548-C5 and RTI2018-096886-B-C5, partially including European FEDER funds. IAA-CSIC members acknowledge and funds from the Spanish Ministry of Science and Innovation “Centro de Excelencia Severo Ochoa” Program under grant No. SEV-2017-0709. The solar data used in the tests are the courtesy of NASA/SDO HMI science team. Parts of the work shown in this paper have been introduced at the SPIE Astronomical Telescopes + Instrumentation conference.42 EditorialPeer reviewe

High performance scientific computing on FPGA aboard the solar orbiter PHI instrument

SO/PHI (Solar Orbiter Polarimetric and Helioseismic Imager) is a filtergraph-based, solar magnetograph aimed at mapping the vector magnetic field and the line-of-sight (LOS) velocity of the solar photospheric plasma. It belongs to the scientific payload of the European Space Agency’s Solar Orbiter mission which will orbit the Sun at 0.28 astronomical units. The limited telemetry rate combined with the large amount of scientific information retrieved by the SO/PHI instrument demand a sophisticated on-board data reduction and scientific analysis through the study of the polarization state of a specific spectral line. The main aim is to perform the complicated algorithm needed to translate the polarization state of the light spectrum in terms of some specific solar parameters like the magnetic field vector and velocity. Technically speaking, the inference of the solar physical quantities through a spectropolarimetric study is based on the inversion of the Radiative Transfer Equation (RTE) and these tasks require the processing of a huge quantity of data in parallel. The RTE inverter is the core of the on-board scientific data analysis and, probably, one of the most innovative parts of the instrument. Due to the unavailability of qualified for space processors, DSPs, or GPGPUs that fulfil the stringent computational requirements with the limited room and power consumption allocated to the instrument, a specifically designed hardware device has been implemented in SO/PHI. This device is in charge of inverting the RTE aboard Solar Orbiter under narrow time and power constraints. The main aim of this thesis is to design, build, and test such a hardware device for SO/PHI. With that goal in mind, we propose two different high-performance computing architectures for carrying out the RTE inversion using FPGA devices embedded in the SO/PHI instrument. The first of these proposals is a distributed-memory MIMD multiprocessor architecture on a Virtex-5 FPGA that exploits the functional and data fine parallelism. It uses a pipelined execution based on a novel MIMD programming method. The processors within the architecture are simplified for saving resources but they are able of eliminating latency and exploiting the computing power that the FPGA provides. The synchronization and the communication network between processors have been simplified using this proposal. The second proposal consists of a SIMD multiprocessor architecture to reach high performance in floating point operations. This architecture on a Virtex-4 FPGA squeezes the FPGA resources in order to reach the time constraints. It is focused in exploiting the data parallelism using several processors working together and using different data streams. One of the most important contributions of this architecture is the ability of saving resources allocating operation cores in a shared operation block, which is accessed by every processor. Some details for extending the architecture to other problems are pointed out. A study of how the radiation induced errors affect each block of the architecture is detailed, and two fault mitigation strategies are described. We also present a novel software tool, which automates the entire design process and system settings from an input C-like pseudo-code. This tool uses advanced techniques of software pipelining and parallelizing scientific algorithms in multicore systems. A compiler within the tool makes it easier the use and programming of the proposed MIMD and SIMD architectures. As a byproduct of our development, a specific, novel Singular Value Decomposition (SVD) architecture within the SIMD architecture is proposed as well. SVD is one of the steps in the RTE inversion but can be of interest to other developments as is a fairly common mathematical tool. The achieved FPGA systems improve the time and power consumption of ground-based systems based on commercial CPUs. The final system is tested using synthetic and real data. It satisfies the scientific precision requirements and the engineering computing time and power consumption requirements.Tesis Univ. Granada. Programa Oficial de Doctorado en: Ciencias de la Computación y Tecnología informátic

Towards real-time inversions of SPRING Stokes observations

In this talk, we identify the spectropolarimetric observations to be taken by the SPRING network and the requirements for the inversion of the data. Different options to achieve this task in real time are examined, including parallel computing and GPU implementations

Real-time inversion of solar spectropolarimetric data at high spatial and temporal resolution: HPC and GPU implementations

Software and Cyberinfrastructure for Astronomy VII (2022), Montreal, Jul 17-22, 2022.--Proceedings of SPIE - The International Society for Optical Engineering vol. 12189 Article number 121890I.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. © COPYRIGHT SPIE.This work has been funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 824135 (SOLARNET). Financial support by the State Agency for Research of the Spanish Ministerio de Ciencia e Innovacion through grant RTI2018-096886-B-C5 (including FEDER funds) and through a Center of Excellence Severo Ochoa award to Instituto de Astrofisica de Andalucia (SEV-2017-0709) is gratefully acknowledged. The Swedish 1 m Solar Telescope is operated on the island of La Palma by the Institute for Solar Physics of Stockholm University in the Spanish Observatory del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The Institute for Solar Physics is supported by a grant for research infrastructures of national importance from the Swedish Research Council (registration No. 2017-00625). This research has made use of NASA's Astrophysics Data System.Peer reviewe

Image compression on reconfigurable FPGA for the SO/PHI space instrument

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. © 2018 SPIE.This work has been partially funded by the Spanish Ministerio de Economia y Competitividad, through Project No. ESP2016-77548-C5-1-R, including a percentage from European FEDER funds

The quick RTE inversion on FPGA for DKIST

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. © 2018 SPIE.This work has been partially funded by the Spanish Ministerio de Economia y Competitividad, through Project No. ESP2016-77548-C5-1-R, including a percentage from European FEDER funds

Autonomous on-board data processing and instrument calibration software for the SO/PHI

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. © 2018 SPIE.This work was carried out in the framework of the International Max Planck Research School (IMPRS) for Solar System Science at the Max Planck Institute for Solar System Research (MPS). Solar Orbiter is a mission lead by the European Space Agency (ESA) with significant contribution from National Aeronautics and Space Administration (NASA). The SO/PHI instrument is supported by the German Aerospace Center (DLR) through Grant 50 OT 1201. The Spanish contribution has been partly funded by the Spanish Research Agency under project ESP2016-77548-05, partially including European FEDER funds. The solar data used in the test are the courtesy of NASA/SDO HMI science team

Reconfigurable accelerator on FPGA for scientific computing: from a space-borne instrument to a high-performance computing data center: work-in-progress

We present a scientific computing accelerator on FPGA that uses hundreds of processors working in parallel organized in several SIMD cores. The accelerator is installed within an Ethernet network and acts as a high-performance computing server. A prototype is presented for processing solar images and achieves a great performance that can compete with a cluster. © 2019 Copyright is held by the owner/author(s). Publication rights licensed to ACM.This work has been partially funded by the Spanish Ministerio de Ciencia, Innovación y Universidades, through Projects No.ESP2016-77548-C5-1-R and RTI2018-096886-B-C51, including a percentage from European FEDER funds. Authors also acknowledge financial support from the State Agency for Research of the Spanish MCIU through the >Center of Excellence Severo Ochoa> award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709

Appropriateness of antiplatelet therapy for primary and secondary cardio- and cerebrovascular prevention in acutely hospitalized older people

Aims: Antiplatelet therapy is recommended for the secondary prevention of cardio- and cerebrovascular disease, but for primary prevention it is advised only in patients at very high risk. With this background, this study aims to assess the appropriateness of antiplatelet therapy in acutely hospitalized older people according to their risk profile. Methods: Data were obtained from the REPOSI register held in Italian and Spanish internal medicine and geriatric wards in 2012 and 2014. Hospitalized patients aged ≥65 assessable at discharge were selected. Appropriateness of the antiplatelet therapy was evaluated according to their primary or secondary cardiovascular prevention profiles. Results: Of 2535 enrolled patients, 2199 were assessable at discharge. Overall 959 (43.6%, 95% CI 41.5–45.7) were prescribed an antiplatelet drug, aspirin being the most frequently chosen. Among patients prescribed for primary prevention, just over half were inappropriately prescribed (52.1%), being mainly overprescribed (155/209 patients, 74.2%). On the other hand, there was also a high rate of inappropriate underprescription in the context of secondary prevention (222/726 patients, 30.6%, 95% CI 27.3–34.0%). Conclusions: This study carried out in acutely hospitalized older people shows a high degree of inappropriate prescription among patients prescribed with antiplatelets for primary prevention, mainly due to overprescription. Further, a large proportion of patients who had had overt cardio- or cerebrovascular disease were underprescribed, in spite of the established benefits of antiplatelet drugs in the context of secondary prevention