EOMODEL: A MODEL LIBRARY FOR EARTH OBSERVATION END-TO-END SIMULATORS

The development of end-to-end mission performance simulators for Earth Observation missions has been progressively increasing in the last years, with ESA carrying out several activities to promote reuse among end-to-end simulators and reducing the re-engineering process taking place when evolving the simulators beyond the feasibility studies. Two of these activities are the ARCHEO-E2E study and the recently started EOMODEL/BIBLOS activity. During the ARCHEO-E2E study, an extensive review of Earth Observation missions and their instruments allowed deriving a Reference Architecture for end-to-end mission performance simulators. The use of this Reference Architecture for the development of new simulators has the potential of reducing the reengineering process associated to the evolution of the simulator throughout the different mission phases. Moreover, the identification of common elements for different types of instruments also enables reuse of the architectural elements across several mission simulators. The final task performed in the ARCHEO-E2E activity was the definition of a roadmap to reach an operational Reference Architecture, including the identification of priorities in implementing generic building blocks and improvements to the existing simulation framework and model repository. The EOMODEL activity builds upon the ARCHEO-E2E project to consolidate its results and implement a selection of some of the modules identified therein. Thus, the objectives of EOMODEL/BIBLOS are the following:  To identify all the generic models that would need to be implemented as part of an Earth Observation library to be used for the development of mission performance end-to-end simulators.  To perform the detailed definition, development and validation of a subset of these models, giving priority to those needed to simulate representative satellite images (i.e. Geometry, Scene and Instrument modules).  To develop a website (BIBLOS) to make the implemented models available to the space community. This presents the EOMODEL/BIBLOS activity, and in particular the Earth Observation library roadmap and the rationale for the selection of a subset of modules, the models selected for implementation and the type of missions they are applicable to, and the functionality of the library’s website. The EOMODEL/BIBLOS activity is carried out under ESA contract by GMV Poland with consultancy from the Warsaw Military University of Technology. INTRODUCTION The EOMODEL/BIBLOS activity is a follow-up of the ARCHEO-E2E project [1], which identified a reference architecture that could be used for developing End-to-end simulators (E2ES) for Earth Observation (EO) missions, as well as the modules and building blocks that compose the proposed Reference Architecture. The ARCHEO-E2E study focused on the four main types of instruments for Earth Observation. There are 4 main types of instruments: Passive Opticals, Active Microwaves, Passive Microwaves and Active Opticals, [2]. The simulation chain of any E2ES for EO missions can be divided into six high-level Modules: Geometry, Scene Generator, Instrument, Level-1 Processing, Level-2 Retrieval and Performance Evaluation. Although the data flows between these high-level modules and even their order of execution could vary depending on the type of mission and instrument at which they are applied to, Fig. 1 shows the typical generic data flow that is considered as the Reference Architecture. Fig. 1. Generic data flow at the highest level of the Reference Architecture The high-level modules are:  Geometry Module. In charge of simulating the spacecraft orbit and attitude, as well as the generation of the observation geometry of each instrument.  Scene Generator Module. In charge of simulating the scene to be observed (terrain, ocean or atmosphere) and all environmental effects (radiative transfer models, atmosphere simulation, illumination conditions...) to be considered for the correct generation of the stimuli to be entered to the instrument model.  Instrument Module. In charge of simulating the sensor behaviour, having different outputs depending on the type of instrument.  Level-1 Processing Module. In charge of the generation of level-1 products, from level-1a to level-1c.  Level-2 Retrieval Module. In charge of performing the retrieval of the geophysical parameters that are the objective of the mission/instrument. Depending on the mission and on its definition of the products, this module would generate level-2 data or products at a higher level of processing.  Performance Evaluation Module. In charge of performing the needed analysis of the simulator outputs to evaluate the performances of the mission. It could be run at different points of the simulation chain. Each of these high-level modules is composed by Building Blocks (BBs). A Building Block is a unit of software that performs a certain functionality. Geometry Module Scene Generator Module Stimuli Geometry data Orbit & AOCS Configuration Instrument Module Raw Data Instrument Configuration