The TRISHNA program marks a step further in the fruitful cooperation built between CNES and ISRO since many years, through a new Earth observation mission dedicated to the improvement of water cycle understanding and water resource management. Thanks to its unprecedented high spatial resolution in the thermal infrared domain, together with a high revisit frequency, TRISHNA mission will significantly contribute to the detection of ecosystem stress and to the optimization of water use in agriculture in a context of global climate change. The TRISHNA payload is composed of two principal instruments: the VNIR-SWIR imager provided by ISRO, and the TIR (Thermal InfraRed) imager. CNES is responsible for the TIR instrument development with Airbus Defence and Space as a prime contractor. The targeted launch date for TRISHNA satellite is 2025, being then positioned as a precursor of the LSTM Copernicus mission from ESA. This paper presents a status of the TIR instrument development, currently in phase C after a successful Preliminary Design Review in 2021. The equipment development status is detailed, and the progress of validation activities at Airbus level is addressed, focusing on the tests at detection laboratory with a full detection chain including a Development Model (DM) detector, and the preparation of the extensive test campaign to be done on an Engineering Model (EM) of an equipped cryostat (including EM detector, filters, and cryocoolers). An overview of the instrument predicted radiometric, spectral and geometric performances is also presented, as well as some measured elementary performances already available on FM optics.
The x-ray integral field unit (X-IFU) instrument is the high-resolution x-ray spectrometer of the ESA Athena x-ray observatory. X-IFU will deliver spectra from 0.2 to 12 keV with a spectral resolution of 2.5 eV up to 7 keV from 5" pixels, with a hexagonal field of view of 5' equivalent diameter. The main sensor array and its associated detection chain is one of the major sub-systems of the X-IFU instrument, and is the main contributor to X-IFU’s performance. CNES (the French Space Agency) is leading the development of X-IFU; additional major partners are NASA-GFSC, SRON, VTT, APC, NIST, and IRAP. This paper updates the B-phase definition of the X-IFU detection chain. The readout is based on time-division multiplexing (TDM). The different sub-components of the detection chain (the main sensor array, the cold electronics stages, and the warm electronics) require global design optimization in order to achieve the best performance. The detection chain’s sensitivity to the EMI/EMC environment requires detailed analysis and implementation of dedicated design solutions. This paper focuses on these aspects while providing an update to the detection-chain design description.
We present a test platform for the Athena X-IFU detection chain, shared between IRAP and CNES. This test bench, housed in a commercial two-stage ADR cryostat provided by Entropy GmbH, will serve as the first demonstration of the representative end-to-end readout chain for the X-IFU, using prototypes of the future flight electronics and currently available subsystems. The focal plane array (FPA), placed at the 50 mK cold stage of the ADR, includes a 1024-pixel array of transition-edge sensor (TES) microcalorimeter spectrometers provided by NASA/GSFC, superconducting amplifiers (SQUIDs) from VTT, as well as superconducting readout electronics for frequency domain multiplexing (FDM), provided by SRON. The detection chain then continues with the prototype room temperature electronics for the X-IFU: the Warm Front-End Electronics (WFEE, provided by APC) and the Digital Readout Electronics (DRE, provided by IRAP). The test bench yields critical feedback on current subsystem designs and electronic interfaces, and in the future will also be used for refining the X-IFU calibration plan as well as laboratory astrophysics experiments relevant to future X-IFU science. In this presentation, we describe the characterization of the cryostat, various design trades for the FPA and readout chain, and recent results from our current setup.
CNES (French Space Agency) is in charge of the development of the X-IFU instrument for Athena. The main sensor array detection chain sub-system of the X-IFU instrument is one of the major sub-subsystem of the instrument, as the main contributor to the performance. This sub-system involves major partners of the X-IFU instrument, e.g GFSC, SRON, VTT, APC, and IRAP. The purpose of this paper is to present the baseline of the definition of the X-IFU detection chain in the frame at end of phase A/beginning of phase B. The readout is based on Time Domain Multiplexing (TDM). There are strong design issues which couple the different sub-components of the detection chain (the main sensor array, the cold electronics stages, and the warm electronics). The detection chain environment (thermal, mechanical and EMI/EMC environment) also requires a transverse analysis. This paper focuses on those aspects while providing design description of the sub-components of the detection chain.
CNES (French Space Agency) is developing a microsatellite to monitor and characterize CO2 surface fluxes, that is, the exchanges between sources (natural or anthropogenic) and sinks (atmosphere, ocean, land and vegetation). A better assessment of carbon fluxes is necessary to improve our understanding of the mechanisms governing the exchanges between sources and sinks, their seasonal variability, and their evolution in response to climate change. Values of CO2 concentrations need to be measured with high precision, of the order of 1 ppm (to be compared with the CO2 concentration of 400 ppm) to be able to estimate gradients which amounts to a few ppm.
The instrument on board MicroCarb is an infrared passive spectrometer operating in four wavelengths using an echelle grating (dispersive element) to achieve spectral dispersion. The spectral bands cover vissible end Short Wave infrared domain, from 764 μm to 2,075 μm.
The selected detector is the NGP (new Generation Panchromatic) manufactured by Sofradir, supplied with a specific AntiReflection coating in order to optimize both sensitivity and stray light.
The high accuracy level of the mission requires a high performance detector, operating at low incident flux, and whose imperfections will be very well known, in order to be corrected. The detector non-linearity is the main performance that has to be calibrated in order to allow the overall scientific objectives. CNES has developed a specific test bench in order to assess this performance.
This paper describes in detail
- The test bench constitution
- The test bench calibration
- The first detector measurements
The X-ray Integral Field Unit (X-IFU) is the high resolution X-ray spectrometer of the ESA Athena X-ray observatory. Over a field of view of 5’ equivalent diameter, it will deliver X-ray spectra from 0.2 to 12 keV with a spectral resolution of 2.5 eV up to 7 keV on ∼ 5” pixels. The X-IFU is based on a large format array of super-conducting molybdenum-gold Transition Edge Sensors cooled at ∼ 90 mK, each coupled with an absorber made of gold and bismuth with a pitch of 249 μm. A cryogenic anti-coincidence detector located underneath the prime TES array enables the non X-ray background to be reduced. A bath temperature of ∼ 50 mK is obtained by a series of mechanical coolers combining 15K Pulse Tubes, 4K and 2K Joule-Thomson coolers which pre-cool a sub Kelvin cooler made of a 3He sorption cooler coupled with an Adiabatic Demagnetization Refrigerator. Frequency domain multiplexing enables to read out 40 pixels in one single channel. A photon interacting with an absorber leads to a current pulse, amplified by the readout electronics and whose shape is reconstructed on board to recover its energy with high accuracy. The defocusing capability offered by the Athena movable mirror assembly enables the X-IFU to observe the brightest X-ray sources of the sky (up to Crab-like intensities) by spreading the telescope point spread function over hundreds of pixels. Thus the X-IFU delivers low pile-up, high throughput (< 50%), and typically 10 eV spectral resolution at 1 Crab intensities, i.e. a factor of 10 or more better than Silicon based X-ray detectors. In this paper, the current X-IFU baseline is presented, together with an assessment of its anticipated performance in terms of spectral resolution, background, and count rate capability. The X-IFU baseline configuration will be subject to a preliminary requirement review that is scheduled at the end of 2018.
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