Developed by ADS under CNES responsibility in partnership with Eumetsat, IASI-NG payload on board of METOP-SG satellite will deliver data for operational meteorology, climate monitoring, and atmospheric chemistry in the next decades. In order to improve by a factor two compared to IASI the spectral resolution and radiometric error, the instrument is designed around a Mertz compensated interferometer, whose good spectral performances have been checked at subassembly level in 2020. The PFM is now fully integrated and will go through functional tests, performance tests at ambient and in TVAC through 2022. The aim of this paper is to give an overview on these activities.
Developed by Airbus Defense and Space under CNES overall responsibility in partnership with Eumetsat, the Infrared Atmospheric Sounding Interferometer New Generation (IASI-NG) is a key payload element of the second generation of European meteorological polar-orbit satellites (METOP-SG). It will continue and improve the IASI mission in the next decades (2020-2040) in the field of operational meteorology, climate monitoring, and characterization of atmospheric composition related to climate, atmospheric chemistry and environment. The main challenge is the performance improvement by a factor two compared to IASI with regard to spectral resolution and radiometric error. The measurement technique is based on wide field Fourier Transform Spectrometer (operating in the 3.5 - 15.5 μm spectral range) with an innovative Mertz compensated interferometer to manage the so-called self-apodisation effect and the associated spectral resolution degradation. End 2019, IASI-NG instrument Critical Design Review has been successful and since nearly all the sub-units of the PFM instrument have been fully characterized and delivered to ADS. Interferometer principle has been partially validated on a Bread Board Model and Interferometer EQM and PFM have completed qualification and performance test. The aim of this paper is first to present the performance budget of the instrument after CDR, based on sub-units consolidation (sub-unit CDR) or measurement (sub-assemblies PFM measurement). We will then focus on the overall instrument development status and the different upcoming milestones until the delivery.
This paper presents a global approach of POWER (Polarization and Directionalily of the Earths Reflectance) program: from instrument design . pre-flight and in-fligh1 calibrations till the first inflight results The POLDER sensor bas been developed by the Centre National d'Etudes Spatiales, the French space agency. It is part of the payload of the Advanced Earth Observation Satellite (ADEOS) developed by NASDA and launched m August 1996. POLDER had been acquiring data till the lost of ADEOS in June 1997.
This paper presents a global approach of the POLDER 2 mission: from instrument design, pre-flight and inflight calibrations till the first in-flight results. The POLDER 2 sensor has been developed by the Centre National d'Etudes Spatiales, the French space agency. It is part of the payload of the ADEOS II satellite developed by JAXA and launched in December 2002. POLDER 2 collected global data from April 2003, end of ADEOS II system check out phase, till the loss of the satellite on October 2003 due to a failure of the satellite power supply system.
The POLDER 2 sensor is designed to collect global and repetitive observations of the solar radiation reflected by the Earth-Atmosphere system for climate research. The sensor is a wide field-of-view (2400 Km swath), low resolution (6x7 Km² at nadir) multi-spectral imaging radiometer / polarimeter. The instrument concept is based on a telecentric optics, a rotating wheel carrying 15 spectral filters and polarizers, and a bidimensionnal CCD detector array. The multidisciplinary scientific objectives of POLDER 2 lead to severe radiometric and geometrical requirements, as well as a very accurate calibration of the sensor. These requirements are achieved through a stable instrument design, exhaustive pre-flight and original in-flight calibrations.
A derived model of POLDER 2 instrument will be flown on the payload of the CNES PARASOL micro satellite, the launch of which is planned end 2004. The PARASOL mission is part of the “Aqua train” i.e. the formation flying of 3 satellites following EOS-PM, so called “Aqua”.
Measuring the concentration of greenhouse gases from space is a current challenge. This measurement is achieved via a precise analysis of the signature of chemical gaseous species (CO2, CH4, CO, etc.) in the spectrum of the reflected sunlight. First at all, two families of spectrometers have been studied for the MicroCarb mission. The first family is based on the phenomena of interference between two radiation waves (Michelson Interferometer). The second family is based on the use of dispersive optical components. The second family has been selected for the forthcoming studies in the MicroCarb project. These instruments must have high radiometric and spectral resolutions, in narrow spectral bands, in order to discriminate between absorption lines from various atmospheric chemical species, and to quantify their concentration. This is the case, for example, for the instrument onboard the OCO-2 satellite (NASA/JPL).
Our analysis has led us to define a new instrumental concept, based on a dispersive grating spectrometer, with the aim of providing the same accuracy level as the OCO-2, but with a more compact design for accommodation on the Myriade Evolution microsatellite class. This compact design approach will allow us to offer a moderate-cost solution to fulfil mission objectives. Two other studies based on dispersive grating are in progress by CNES prime contractors (ASTRIUM and THALES ALENIA SPACE).
A summary of the main specifications of this design will be described, in particular the approach with the so-called “merit function”. After a description of such a space instrument, which uses a specific grating component, a preliminary assessment of performances will be presented, including the theoretical calculations and formula. A breadboard implementation of this specific grating has allowed us to show the practicality of this concept and its capabilities. Some results of this breadboard will be described. In addition, an instrument simulator is being developed to validate the performances of this concept. A grating component prototype has been built, and the specifications, together with the expected performances, will be described, in particular the polarisation ratio. Some elements about detectors will be also given regarding their suitability for the mission. This preliminary design is encouraging and shows that such a spectrometer may be compatible with a microsatellite platform (low mass, low power and compact design). Some prospects of improvements will also be considered.
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