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The detector control unit of the fine guidance sensor instrument on-board the ARIEL mission: design status

ARIEL is an ESA mission whose scientific goal is to investigate exoplanetary atmospheres. The payload is composed by two instruments: AIRS (ARIEL IR Spectrometer) and FGS (Fine Guidance System). The FGS detection chain is composed by two HgCdTe detectors and by the cold Front End Electronics (SIDECAR), kept at cryogenic temperatures, interfacing with the F-DCU (FGS Detector Control Unit) boards that we will describe thoroughly in this paper. The F-DCU are situated in the warm side of the payload in a box called FCU (FGS Control Unit) and contribute to the FGS VIS/NIR imaging and NIR spectroscopy. The F-DCU performs several tasks: drives the detectors, processes science data and housekeeping telemetries, manages the commands exchange between the FGS/DPU (Data Processing Unit) and the SIDECARs and provides high quality voltages to the detectors. This paper reports the F-DCU status, describing its architecture, the operation and the activities, past and future necessary for its development

The instrument control unit of the ARIEL payload: design evolution following the unit and payload subsystems SRR (system requirements review)

ARIEL (Atmospheric Remote-sensing InfraRed Large-survey) is a medium-class mission of the European Space Agency, part of the Cosmic Vision program, whose launch is foreseen by early 2029. ARIEL aims to study the composition of exoplanet atmospheres, their formation and evolution. The ARIEL’s target will be a sample of about 1000 planets observed with one or more of the following methods: transit, eclipse and phase-curve spectroscopy, at both visible and infrared wavelengths simultaneously. The scientific payload is composed by a reflective telescope having a 1m-class elliptical primary mirror, built in solid Aluminium, and two focal-plane instruments: FGS and AIRS. FGS (Fine Guidance System)1 has the double purpose, as suggested by its name, of performing photometry (0.50-0.55 µm) and low resolution spectrometry over three bands (from 0.8 to 1.95 µm) and, simultaneously, to provide data to the spacecraft AOCS (Attitude and Orbit Control System) with a cadence of 10 Hz and contributing to reach a 0.02 arcsec pointing accuracy for bright targets. AIRS (ARIEL InfraRed Spectrometer) instrument will perform IR spectrometry in two wavelength ranges: between 1.95 and 3.9 µm (with a spectral resolution R > 100) and between 3.9 and 7.8 µm with a spectral resolution R > 30. This paper provides the status of the ICU (Instrument Control Unit), an electronic box whose purpose is to command and supply power to AIRS (as well as acquire science data from its two channels) and to command and control the TCU (Telescope Control Unit)

Preliminary surface charging analysis of Ariel payload dielectrics in early transfer orbit and L2-relevant space environment

Ariel [1] is the M4 mission of the ESA’s Cosmic Vision Program 2015-2025, whose aim is to characterize by lowresolution transit spectroscopy the atmospheres of over one thousand warm and hot exoplanets orbiting nearby stars. The operational orbit of the spacecraft is baselined as a large amplitude halo orbit around the Sun-Earth L2 Lagrangian point, as it offers the possibility of long uninterrupted observations in a fairly stable radiative and thermo-mechanical environment. A direct escape injection with a single passage through the Earth radiation belts and no eclipses is foreseen. The space environment around Earth and L2 presents significant design challenges to all spacecraft, including the effects of interactions with Sun radiation and charged particles owning to the surrounding plasma environment, potentially leading to dielectrics charging and unwanted electrostatic discharge (ESD) phenomena endangering the Payload operations and its data integrity. Here, we present some preliminary simulations and analyses about the Ariel Payload dielectrics and semiconductors charging along the transfer orbit from launch to L2 include

Enabling planetary science across light-years. Ariel Definition Study Report

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution

Active Common-Mode Filter for Photovoltaic Transformerless Inverters

In the recent years the research on photovoltaic converters has been focused on topologies that do not feature a line frequency transformer, in order to reduce costs and successfully increase the overall efficiency. The main problem in removing the galvanic isolation is that the parasitic capacitance present between the cell and the metal frame enclosing the panel (usually earth-connected) enables a common-mode current to be injected into the grid by the converter. This paper proposes an active common-mode filter able to compensate the high-frequency common-mode voltage variations at the output of the power converters, that represent the principal cause of ground leakage current. The advantage of this solution concerns the capability to operate with an arbitrary power factor. In this work it is applied in cascade to a converter with standard full-bridge topology driven by a three-level PWM strategy. Simulation and experimental results shows the feasibility of the proposed approach

Power Losses Analysis in Interleaved Flyback Based PV Grid Connected Micro-Inverters

This paper analyzes the power losses of photovoltaic micro-inverters based on flyback topology. A double secondary winding flyback converter topology was considered to inject alternating current into the grid. The purpose of this work is the identification and quantification of the different power losses present in a simple flyback topology and in the interleaved version with two different control strategies. The power losses comparison was carried out after designing a 250 W power converter using commercial, low cost components. Simulations in Matlab/Simulink environment highlighted the effectiveness of the interleaved architecture

DC-AC converter, in particular for providing power supply from a solar panel to a mains power supply

A DC-AC converter, in particular for providing electric energy from a solar panel to an electric network, comprising: an input section (10) for receiving a substantially direct voltage; an H-bridge (20) adapted to receive said substantially direct current through said input section (10) and designed to output a substantially alternating voltage, said H-bridge (20) being drivable at least in the following conditions: at least one operating condition, at which electric energy is supplied to said electric network (2); a first and a second recirculation condition, at which a current flows through at least part of said H-bridge (20), and no electric energy is supplied to said electric network (2). The converter (1) further comprises: an output section (40) to supply said substantially alternating current to said electric network (2); an uncoupling module (50) operatively interposed between said input section (10) and said H-bridge (20) and configured for uncoupling said input section (10) from said H-bridge (20) at said first and second recirculation conditions of said H-bridge (20)

DC-AC converter, in particular for providing power supply from a solar panel to a mains power supply

A DC-AC converter, in particular for providing electric energy from a solar panel to an electric network, comprising: an input section (10) for receiving a substantially direct voltage; an H-bridge (20) adapted to receive said substantially direct current through said input section (10) and designed to output a substantially alternating voltage, said H-bridge (20) being drivable at least in the following conditions: at least one operating condition, at which electric energy is supplied to said electric network (2); a first and a second recirculation condition, at which a current flows through at least part of said H-bridge (20), and no electric energy is supplied to said electric network (2). The converter (1) further comprises: an output section (40) to supply said substantially alternating current to said electric network (2); an uncoupling module (50) operatively interposed between said input section (10) and said H-bridge (20) and configured for uncoupling said input section (10) from said H-bridge (20) at said first and second recirculation conditions of said H-bridge (20)