For ESA’s EnVision Mission to Venus, a consortium of three spectrometers from across Europe has been formed to collaborate not only on the management and science aspects, but also on the technical implementation. One important technical goal of the VenSpec suite is to implement a clean, simple and robust interface to the spacecraft and to provide an abstraction layer between the channels and the spacecraft. This is achieved by implementing the Central Control Unit (CCU), which provides a harmonized power and data interface to the spacecraft and allows the channels to design for a simple tailored internal interface to the CCU. The CCU consists of two electrical subsystems, the Data Handling Unit (CCU DHU), developed by the Max Planck Institute for Solar System Research (MPS) in Göttingen and the Institute of Computer and Network Engineering (IDA) in Braunschweig and the Power Supply Unit (CCU PSU), developed by the Instituto de Astrofísica de Andalucía (IAA-CSIC) in Granada, the system responsibility being at the DLR Institute of Planetary Research (DLR-PF) in Berlin. Within this framework, an extended electrical architecture trade-off was performed in 2023 to optimize the system, guaranteeing the requested functionality and complying to requirements from all sides. As a result of the trade-off. a single power and data interface were found to be the most suitable and robust solution considering performance, reliability, Fault Detection Isolation and Recovery (FDIR) and Electromagnetic Compatibility (EMC) considerations as well as the complexity of the associated verification campaign. This paper demonstrates the options that were suggested by the different parties and justifies the final architecture, which has been chosen to achieve the best solution for the VenSpec suite.
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.
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.
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