SUNRISE III is the third flight of the international stratospheric balloon project Sunrise. The SUNRISE III carries a 1-meter aperture Gregorian telescope and provides a unique platform to perform seeing-free observations at UV-Visible-IR wavelengths. It is designed in the framework of NASA's long-duration balloon program to be launched at ESRANGE, Sweden, and to fly to Canada at float altitudes of 35 – 37 km. For the third flight, the post-focal instrumentation was extensively upgraded to enhance spectro-polarimetric capability; SUSI for 309 – 417 nm, TuMag for 525 nm and 517 nm, and SCIP for 765 – 855 nm. The gondola was also renewed to achieve stable pointing to a target on the solar surface. The team led by NAOJ provided SCIP through international collaboration with the Spanish and German teams. SUNRISE III was launched in July 2022 but was terminated because of a hardware problem. The telescope and instruments were successfully recovered and will be flown again in June 2024.
The ESA mission Solar Orbiter was successfully launched in February 2020. The Photospheric and Helioseismic Imager (PHI) provides measurements of the photospheric solar magnetic field and line of sight velocities at high solar latitudes with high polarimetric accuracy. The required pointing precision is achieved by an image stabilisation system (ISS) that compensates for spacecraft jitter. The ISS consists of a high-speed correlation tracker camera (CTC) and a fast steerable tip-tilt mirror operated in closed loop. We will present the results of the calibration measurements and performance tests from ground measurements, during commissioning and science phase. In addition, the correlation tracker was used to directly measure the pointing stability of the satellite.
We propose a wavefront error compensation system based on a spatial light modulator (SLM) and on the phase diversity technique for both wavefront sensing and wavefront correction. The phase diversity technique has been successfully used in balloon borne instruments (IMaX and TuMag) and in space-borne instruments (SO/PHI) to determine the wavefront error of the system of solar spectropolarimeters. The method usually requires either two cameras observing the same scene with a known phase difference (typically a defocus), or a mechanism that introduces a phase diversity plate within the optical path. Processing the focused and defocused images with the phase diversity algorithm yield the point spread functions of the instrument, allowing scientific images to be restored a posteriori. Here, we demonstrate that liquid crystal-based SLMs can successfully be used to introduce a phase shift instead of a physical mechanism. SLMs can provide different levels of defocusing as well as other wavefront aberrations. Their flexibility enables different procedures for a dynamic wavefront retrieval system. Moreover, the approach allows direct acquisition of corrected images since SLMs can also be used for wavefront compensation. They also reduce system complexity, as no mechanism and only a single camera are required, and they help eliminate non-common optical path effects. The compactness and low power requirements of SLMs can be of great advantage for small platforms with onboard optical instrumentation. We present preliminary results using the IMaX optical layout as the baseline for our demonstrator for a solar spectropolarimeter space instrument.
The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) has been developed for the third flight of the Sunrise balloon-borne stratospheric solar observatory. The aim of the SCIP is to reveal the evolution of three-dimensional magnetic fields in the solar photosphere and chromosphere using spectropolarimetric measurements with a polarimetric precision of 0.03% (1σ). Multiple lines in the 770 and 850 nm wavelength bands are simultaneously observed with two 2 k × 2 k CMOS cameras at a frame rate of 31.25 Hz. Stokes profiles are calculated onboard by accumulating the images modulated by a polarization modulation unit, and then compression processes are applied to the two-dimensional maps of the Stokes profiles. This onboard data processing effectively reduces the data rate. SCIP electronics can handle large data formats at high speed. Before the implementation into the flight SCIP electronics, a performance verification of the onboard data processing was performed with synthetic SCIP data that were produced with a numerical simulation modeling the solar atmospheres. Finally, we verified that the high-speed onboard data processing was realized on ground with the flight hardware using images illuminated by natural sunlight or an LED light.
The ESA/NASA Solar Orbiter space mission has been successfully launched in February 2020. Onboard is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a High Resolution Telescope (HRT) and the Full Disc Telescope (FDT). The instrument is designed to infer the photospheric magnetic field and line-of-sight velocity through differential imaging of the polarised light emitted by the Sun. It calculates the full Stokes vector at 6 wavelength positions at the Fe I 617.3nm absorption line. Due to telemetry constraints, the instrument nominally processes these Stokes profiles onboard, however when telemetry is available, the raw images are downlinked and reduced on ground. Here the architecture of the on-ground pipeline for HRT is presented, which also offers additional corrections not currently available on board the instrument. The pipeline can reduce raw images to the full Stokes vector with a polarimetric sensitivity of 10−3 · Ic or better.
SUNRISE III mission is a one-meter aperture telescope onboard a balloon within NASA Long Duration Balloon Program. Three post-focus instruments are used for studying the Sun’s dynamics and magnetism, among which the Tunable Magnetograph (TuMag) is a tunable imaging spectropolarimeter. TuMag is a diffraction-limited imager, a high sensitivity polarimeter (< 10-3 ), and a high-resolution spectrometer ( ~ 65 mÅ). It will be able to study solar magnetic fields at high spatial resolution (~100 km on the solar surface). It will make images of the solar surface magnetic field after measuring the state of polarization of light within three selected spectral lines: the Fe I lines at 525.02 nm and 525.06 nm, and the Mg I b2 line at 517.27 nm. It will be sensitive to the solar vector magnetic fields and line-of-sight velocities, in the photospheric and chromospheric layers. TuMag will be the first solar magnetograph onboard an aerospace platform with the capability of tuning the solar line to be observed. In this paper the TuMag end-to-end tests carried out during the verification phase are described. These tests are performed to characterize and calibrate the instrument. Specifically, they determine the polarimetric and spectroscopic performances of the instrument as well as the image quality. The availability of a singular facility, an ISO6 clean room with a coelostat on the building roof, allowed the use of solar light during the verification campaign. This was key to a complete instrument verification due to the unique spectroscopic and polarimetric characteristics of solar light.
The High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager (SO/PHI) on-board the Solar Orbiter mission (SO) provides near diffraction limited observations of the solar surface. The HRT Refocus Mechanism (HRM) allows for acquiring calibration data in flight which are used in post processing on ground to estimate the image quality of SO/PHI-HRT data products and its dependence on the SO-Sun distance. Our aim is to characterise the wavefront aberrations in the optical path of SO/PHI-HRT and consequently the image quality in the focal plane of the telescope. We use calibration data taken during the Near Earth Commissionning Phase (NECP) and the second Remote Sensing Check-out Window (RSCW2) of Solar Orbiter’s Cruise Phase (CP). In particular, we apply a Phase Diversity (PD) analysis to estimate the low-order wavefront aberrations. The restoration with the retrieved Point Spread Function (PSF) from the PD analysis increases the RMS contrast of the solar granulation in the visible continuum from 4 % to 10−11%.
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.
KEYWORDS: Image storage, Image filtering, Image processing, Control systems, Sensors, Image sensors, Data storage, Data processing, Field programmable gate arrays, Data acquisition
Present scientific space instruments generate a high amount of raw data while deep-space missions only have a very limited telemetry rate. Because the computation of the scientific relevant parameters is usually accompanied with the reduction of the data, the processing is desired to be carried out already on-board. To accomplish this, the following paper presents a flexible image processing framework which makes use of a heterogeneous data processing module consisting of a space-grade General Purpose Processor (GPP) as well as two dynamically reconfigurable Field-Programmable Gate Arrays used for hardware acceleration. The flexibility and capabilities of the presented framework are proven by means of three exemplary processing tasks of the Polarimetric and Helioseismic Imager (PHI) on-board Solar Orbiter.
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.
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 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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.