This paper, “Land-surface processes and interactions mission," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.
This paper, “ALADIN: an atmospheric laser Doppler wind lidar instrument for wind velocity measurements from space," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.
AEROSPATIALE presents the main results of the feasibility study under ESA contract on a coherent 2μm lidar instrument capable of measuring water vapour and wind velocity in the planetary boundary layer. The selected instrument configuration and the associated performance are provided, and the main critical subsystems identified (laser configuration, coherent receiver chain architecture, frequency locking and offsetting architecture. The second phase of this study is dedicated to breadboard the most critical elements of such an instrument in order to technologically consolidate its feasibility.
The European Space Agency (ESA) is defining candidate missions for Earth Observation. In the class of the Earth Explorer missions, dedicated to research and pre-operational demonstration, the Land Surface Processes and Interactions Mission (LSPIM) will acquire the accurate quantitative measurements needed to improve our understanding of the nature and evolution of biosphere-atmosphere interactions and to contribute significantly to a solution of the scaling problems for energy, water and carbon fluxes at the Earth’s surface. The mission is intended to provide detailed observations of the surface of the Earth and to collect data related to ecosystem processes and radiation balance. It is also intended to address a range of issues important for environmental monitoring, renewable resources assessment and climate models. The mission involves a dedicated maneuvering satellite which provides multi-directional observations for systematic measurement of Land Surface BRDF (BiDirectional Reflectance Distribution Function) of selected sites on Earth. The satellite carries an optical payload : PRISM (Processes Research by an Imaging Space Mission), a multispectral imager providing reasonably high spatial resolution images (50 m over 50 km swath) in the whole optical spectral domain (from 450 nm to 2.35 μm with a resolution close to 10 nm, and two thermal bands from 8.1 to 9.1 μm). This paper presents the results of the Phase A study awarded by ESA, led by ALCATEL Space Industries and concerning the design of LSPIM.
ALCATEL-SPACE has been involved for years in the development of highest performance space optical payload for Earth observation, notably in the domain of multi/super/hyperspectral observation, through the successful development of VEGETATION (for CNES) and MERIS (for ESA). The paper will analyse how the lessons of the development of MERIS are key benefits for the definition of the next generation hyperspectral payload of the ESA SPECTRA mission. It will highlight the areas where a direct heritage is applicable, such as the calibration strategy, and domains where technology progresses allow major evolutions, such as for instance in the definition of the payload's data processing architecture. SPECTRA (Surface Processes and Ecosystem Changes Through Response Analysis) is one of the three candidate missions in the ESA Earth Core Explorer program of research oriented missions that is currently under phase A study. Its scientific objective is to describe, understand and model the role of terrestrial vegetation in the global carbon cycle and its response to climate variability under the increasing pressure of human activity.
The European Space Agency (ESA) is defining candidate missions for Earth Observation. In the class of the Earth Explorer missions, dedicated to research and pre-operational demonstration, the Land Surface Processes and Interactions Mission (LSPIM) will acquire the accurate quantitative measurements needed to improve our understanding of the nature and evolution of biosphere-atmosphere interactions and to contribute significantly to a solution of the scaling problems for energy, water and carbon fluxes at the Earth's surface. The mission is intended to provide detailed observations of the surface of the Earth and to collect data related to ecosystem processes and radiation balance. It is also intended to address a range of issues important for environmental monitoring, renewable resources assessment and climate models. The mission involves a dedicated maneuvering satellite which provides multi-directional observations for systematic measurement of Land Surface BRDF (Bi-Directional Reflectance Distribution Function) of selected sites on Earth. The satellite carries an optical payload: PRISM (Processes Research by an Imaging Space Mission), a multispectral imager providing reasonably high spatial resolution images (50 m over 50 km swath) in the whole optical spectral domain (from 450 nm to 2.35 micrometer with a resolution close to 10 nm, and two thermal bands from 8.1 to 9.1 micrometer). This paper presents the results of the Phase A study awarded by ESA, led by ALCATEL Space Industries and concerning the design of LSPIM.
For the post 2000 time frame, the ESA has defined candidate missions for Earth Observation. In the class of the Earth Explorer missions, dedicated to research and demonstration missions, the Land-Surface Processes and Interactions Missions involves a dedicated satellite carrying a single optical payload named PRISM. PRISM is a push broom multispectral imager providing high spatial resolution images in the whole optical spectral domain. It provides an access on any site on Earth within at maximum 3 days. In addition, the mission will be able to provide multi- directional observations by combining instrument depointing capabilities and satellite maneuvering. The instrument radiometric performance reach a high level of accuracy by involving on-board calibration capabilities. This paper presents the results of one of the two pre-feasibility studies awarded by ESA, led by AEROSPATIALE and concerning the PRISM payload.
AEROSPATIALE, prime contractor, presents the main results related to the activities performed in order to demonstrate the feasibility of a coherent 2 micrometers lidar instrument capable of measuring water vapor and wind velocity in the planetary boundary layer, and to determine the main subsystem critical items: selected instrument configuration and associated performances, 2 micrometers laser configuration with phase conjugation, coherent receiver chain architecture, and frequency locking and offsetting architecture. The second phase of this study will be dedicated to breadboard the most critical elements of the instrument at 2 micrometers in order to technologically consolidate the feasibility of such an instrument.
For the post 2000 time frame, the European Space Agency (ESA) has defined candidate missions for Earth observation. In the class of the Earth Explorer missions, dedicated to research and demonstration missions, the land-surface processes and interactions mission (LSPIM) involves a dedicated satellite carrying a single optical payload named PRISM (processes research by an imaging space mission). PRISM is a push broom multispectral imager providing high spatial resolution images (50 m over 50 km swath) in the whole optical spectral domain (from 450 nm to 2.3 micrometer with a resolution close to 10 nm, and three bands from 8 to 12.3 micrometer). It provides an access on any site on Earth within at maximum 3 days. In addition, the mission will be able to provide multi-directional observations by combining instrument depointing capabilities and satellite maneuvering. The instrument radiometric performance reaches a high level of accuracy by involving on-board calibration capabilities. This paper presents the results of one of the two pre-feasibility studies awarded by ESA, led by AEROSPATIALE and concerning the PRISM payload.
AEROSPATIALE, prime contractor, presents the main results related to the activities performed in order to demonstrate the feasibility of a coherent 2 micrometer lidar instrument capable of measuring water vapor and wind velocity in the planetary boundary layer, and to determine the main subsystem critical items: (1) selected instrument configuration and associated performances, (2) 2 micrometer laser configuration with phase conjugation, (3) coherent receiver chain architecture, (4) frequency locking and offsetting architecture. The second phase of this study will be dedicated to breadboard the most critical elements of the instrument at 2 micrometers in order to technologically consolidate the feasibility of such an instrument.
AEROSPATIALE, leading a European team, has just conducted a successful study, under ESA contract, to demonstrate the feasibility of a spaceborne Doppler wind lidar instrument meeting the scientific requirements of wind velocity measurements from space with high spatial resolution. A first parametric investigation, based upon the initial set of mission requirements, and supported by dedicated models and detailed trade-off studies, took account of capabilities of most promising signal processing algorithms and calibration/validation constraints: it yielded a large conically scanned instrument deemed technologically risky. A risk analysis was then carried out to propose a less challenging instrument meeting most key mission requirements. The fixed line-of-sight concept with return signal accumulation appeared as most attractive. A second set of requirements agreed upon by scientific users was therefore issued, with relaxed constraints mainly on horizontal resolution, keeping roughly the same level of wind velocity measurement accuracy. A second instrument and subsystem trade-off was then performed to eventually produce an attractive instrument concept based upon a pair of small diameter telescopes each one associated to one scanning mirror rotating stepwise around the telescope axis, which drastically reduces the detection bandwidth. Following the main contract, studies of accommodation on the International Space Station have been performed, confirming the interest of such an instrument for wind measurements from space.
AEROSPATIALE, leading a European team, has just conducted a successful study, under ESA contract, to demonstrate the feasibility of a spaceborne Doppler wind lidar instrument meeting the scientific requirements of wind velocity measurements from space with high spatial resolution. A first parametric investigation, based upon the initial set of mission requirements, and supported by dedicated models and detailed trade-off studies, took account of capabilities of the most promising signal processing algorithms and calibration/validation constrains: it yielded a large conically scanned instrument deemed technologically risky. A risk analysis was then carried out to propose a less challenging instrument meeting most key mission requirements. The fixed line-of-sight concept with return signal accumulation appeared as most attractive. A second set of requirements agreed upon by scientific users was therefore issued, with relaxed constraints mainly on horizontal resolution, keeping roughly the same level of wind velocity measurement accuracy. A second instrument and subsystem trade- off was then performed to eventually produce an attractive instrument concept based upon a pair of small diameter telescopes each one associated to one scanning mirror rotating stepwise around the telescope axis, which drastically reduces the detection bandwidth. Following the main contract, studies of accommodation on the International Space Station have been performed, confirming the interest of such an instrument for wind measurements from space.
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