PLATO (PLAnetary Transits and Oscillations of stars) is the ESA’s third medium-class mission (M3), adopted in 2017 under the Cosmic Vision 2015-2025 program after selection in 2014. Set for launch in 2026 from French Guiana’s Kourou, its primary goal is to discover and provide an initial bulk characterization of diverse exoplanets, including rocky ones, orbiting bright solar-type stars. Operating from a halo orbit around L2, 1.5 million km from Earth, PLATO’s Payload consists of 26 telescopes (24 normal, 2 fast) capturing images every 25 seconds and 2.5 seconds, respectively. These work in tandem with the AOCS (S/C Attitude and Orbit Control System). Each camera comprises four CCDs, yielding 20.3 MP images—81.4 MP per normal camera and 2.11 gigapixels overall. The onboard P/L Data Processing System (DPS) handles this huge data volume, employing Normal and Fast DPUs along with a single ICU. The ICU manages data compression, overseeing the P/L through a SpaceWire network. This paper provides a comprehensive overview of the Instrument Control Unit’s (ICU) status following the rigorous performance test conducted on the Engineering Model (EM) and its evolution during the development phases of the Engineering Qualification Model (EQM) and Proto-Flight Model (PFM). The content delineates the outcomes derived from the extensive performance test executed on the Engineering Model (EM), detailing the meticulous activities undertaken during the Assembly, Integration, and Verification (AIT/AIV) processes of the EQM. Additionally, it explains the status of the Proto-Flight Model (PFM), offering insights into its development path.
Ariel 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. It has been selected by ESA in March 2018 and adopted in November 2020 to be flown, then, in 2029. It is the first survey mission dedicated to measuring the chemical composition and thermal structures of the atmospheres of hundreds of transiting exoplanets, in order to enable planetary science far beyond the boundaries of the Solar System. The Payload (P/L) is based on a cold section (PLM – Payload Module) working at cryogenic temperatures and a warm section, located within the Spacecraft (S/C) Service Vehicle Module (SVM) and hosting five warm units operated at ambient temperature (253-313 K). The P/L and its electrical, electronic and data handling architecture has been designed and optimized to perform transit spectroscopy from space during primary and secondary planetary eclipses in order to achieve a large set of unbiased observations to shed light and fully understand the nature of exoplanets atmospheres, retrieving information about planets interior and determining the key factors affecting the formation and evolution of planetary systems.
Ariel (Atmospheric Remote Sensing Infrared Exoplanet Large Survey) [1] [2] is the fourth Mission (M4) of the ESA’s Cosmic Vision Program 2015-2025, selected in March 2018 and officially adopted in November 2020 by the Agency, whose aim is to characterize the atmospheres of hundreds of diverse exoplanets orbiting nearby different types of stars and to identify the key factors affecting the formation and evolution of planetary systems. The Mission will have a nominal duration of four years and a possible extension of two years at least. Its launch is presently scheduled for mid 2029 from the French Guiana Space Centre in Kourou on board an Ariane 6.2 launcher in a dual launch configuration with Comet Interceptor. The baseline operational orbit of the Ariel is a large amplitude halo orbit around the second Lagrangian (L2) virtual point located along the line joining the Sun and the Earth-Moon system at about 1.5 million km (~236 RE) from the Earth in the anti-Sun direction. Ariel’s halo orbit is designed to be an eclipse-free orbit as it offers the possibility of long uninterrupted observations in a fairly stable environment (thermal, radiation, etc.). An injection trajectory is foreseen with a single passage through the Van Allen radiation belts (LEO, MEO and GEO near-Earth environments). This is approximated by a worst-case half orbit, prior the injection and transfer to L2, with a duration of 10.5 hours, a perigee of 300 km (LEO), an apogee of 64000 km (GEO and beyond), and an inclination close to 0 degrees. During both the injection trajectory and the final orbit around L2, Ariel will encounter and interact mainly with the Sun radiation and the space plasma environment. In L2 the Ariel spacecraft will spend most of its time in the direct solar wind and the Earth’s magnetosheath with passages through the magnetotail. These three environments, along with LEO and GEO, can lead to the build-up of a net electric charge on the spacecraft and payload conductive and dielectric surfaces leading to the risk of Electro Static Discharges (ESD), potentially endangering the whole Payload integrity and telecommunications to Ground.
KEYWORDS: Data modeling, Image compression, Data processing, Data compression, Cameras, Satellites, Data acquisition, Algorithm development, Satellite communications, Performance modeling
PLAnetary Transits and Oscillations of stars (PLATO) is a medium-class mission selected by ESA in the framework of the Cosmic Vision programme. The PLATO Instrument Control Unit (ICU) is responsible for the management of the scientific payload, the communication with the satellite on board computer, the acquisition of housekeeping and scientific data from the 26 PLATO cameras and their processing before the downloading to the satellite mass memory unit. The data produced by the cameras cannot be transmitted directly to ground as soon as they are acquired but an onboard pre-processing and compression is needed. While the pre-processing stage is in charge of the camera's Data Processing Units (DPUs), the compression is executed on board ICU. Due to the highly demanding science requirements, the compression must be rigorously lossless. In this paper we will review the overall ICU onboard data processing chain, from the DPUs to the satellite mass memory, presenting the compression strategies implemented in the ICU application software architecture, and the results of the performance test run on the ICU Engineering Model.
The PLATO mission, part of ESA’s Cosmic Vision program, is expected to be launched by 2026 and will focus on discovering exoplanets from gas giants down to small rocky planets. Equipped with telescopes and cameras, including 24 normal and 2 fast cameras, it mainly aims to find Earth-sized planets in the habitable zone of Sun-type stars. The Data Processing System, comprising DPUs and the ICU, manages payload operations, with an On-Board Control Procedures (OBCP) engine enhancing autonomy and flexibility. Written in OCL, OBCPs are independent procedures loaded into the ICU memory, enabling late-stage modifications and regular re-execution, reducing repetitive uploads and conserving bandwidth. In this paper, we present a brief overview of the OCL (On-Board Command) language and its features, as well as the capabilities and benefits of having OBCPs. We also describe the OBCP flight software environment and the OBCP engine implemented in the ASW, along with the features and capabilities of the OBCP for the PLATO mission.
This study focuses on the radiation performance of a system composed of a room-temperature C-band Phased Array Feed (PAF) illuminating the 64-m diameter Sardinia Radio Telescope (SRT) main reflector from its primary focus (f/D=0.328). The PAF, a square array with 8x8 dual-polarized antennas, is the first version of a prototype designed for radio astronomy applications in the framework of an R&D (Research and Development) project of the Italian National Institute for Astrophysics (INAF). To guarantee high sensitivity and low noise temperature, the PAF elements have been designed for an optimum coupling with the SRT main reflector by trading off between maximizing the illumination efficiency and minimizing the spillover. In this paper, first, we present the results of the electromagnetic simulation of the PAF element radiation patterns in the Far Field (FF) region, both by assuming no interaction with the reflector and by taking into account the reflection from the SRT main reflector primary focus; second, we present the performance of the beamformed patterns obtained by applying two different beamforming methods; finally, we assess the aperture blockage effect due to the SRT sub-reflector. Results are shown at three frequencies within the operative band of the C-band PAF, i.e. at 4.5, 5.5 and 6.0 GHz.
KEYWORDS: Data processing, Technetium, Diagnostics, Control systems, Automation, Data communications, Thulium, Telecommunications, Design, Virtual reality
This paper presents a methodology to automate and accelerate the PLATO Payload (P/L) Boot Software (BSW) testing procedures by presenting a set of pre-programmed TCL scripts with different verification targets, satisfying the BSW requirements. These scripts are conceived in order to run an autonomous regression testing while verifying the BSW core functionalities, and in case of an additional BSW verification is needed, a set of scripts will be available for obtaining an automatic quick health-statement. The present method was proven by carrying out the pre-programmed functional and performance tests on the different PLATO’s BSW versions installed on the ICU development models. The tests performed on these models have proven their effectiveness during the BSW testing process, since the testing time has been greatly reduced and the test results can be archived to maintain a useful record that contemporaneously with the dedicated TCL scripts may assist in future verification of the flight BSW version.
The SKA LOW telescope is an interferometer composed of 512 stations. Each station consists of 256 electronically steered antennas. The Low Frequency Aperture Array is the portion of the SKA-LOW telescope including the antennas and the related electronics. The LFAA signal processing chain amplifies, transports and combines the signals from the antennas composing each station into a coherent beam. Beamforming is performed in the frequency domain, with stringent requirements on bandpass flatness, linearity in a RFI contaminated spectral region, and allowed signal degradation. We adopted an architecture including a highly optimized oversampled polyphase filterbank for channelization, and a distributed network beamformer. The system has been validated as part of the Aperture Array Verification System, a single station operating at the SKA site in Western Australia.
In order to validate the design of the Low Frequency Aperture Array (LFAA) for the Square Kilometer Array-Low telescope (SKA-Low), a complete model has been developed. The model includes 1) a sky simulator, producing a realistic sky signal with predefined spectrum and correlation properties, plus correlated and uncorrelated Radio Frequency Interference (RFI) signals; 2) a nonlinear model of the analog receiver chain; 3) a close representation of the digital signal processing algorithms for channelization, calibration and beamforming. The model describes correctly all the aspects of the LFAA station beamformer, generating the expected signal for up to 256 antennas and reproduces the processing required to combine them into a station signal. It is an useful tool to analyze variants of the proposed signal processing algorithms or to highlight possible problems. The resulting simulated output can be used to analyse the beamforming performance and as an input for a correlator simulation model in a telescope end-to-end simulation.
KEYWORDS: Prototyping, Analog electronics, Signal processing, Electronic filtering, Digital filtering, Data conversion, Software development, Field programmable gate arrays, Polarization, Antennas
A novel version of digital hardware Italian Tile Processing Module (ITPM) 1.6 has been released for the Low-Frequency Aperture Array (LFAA) component of the Square Kilometre Array (SKA). This back-end includes two plugged-in main blocks, as an analog device , the Pre-ADU board, and an Analog to Digital Unit (ADU), a 6U board containing sixteen dual-inputs Analog to Digital Converters and two Field Programmable Gate Array (FPGA) devices, capable of digitizing and processing 32 RF input signals (50-650 MHz). We present the main features of the upgrade of the board compared to previous versions: there are new and high performance components improving processing capability, mechanical changes matching the design of the housing sub-rack and finally a general reduction of the overall power consumption. The ITPM ADU 1.6 version, now in engineering phase together with its sub-rack system, is currently the last prototype before the design of the industrial line for mass production, necessary for the LFAA deployment. Results of system performances will be presented.
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