Analyse statistique et physique d'images hyperspectrales planétaires: objectifs, objets et méthodes

Icy and mineral surfaces of the Solar System scientific interest The surfaces of evolved planets and satellites are « boundary layers » Their physical, chemical and structural properties characterize the nature and the evolution of these processes marked by numerous internal or external geophysical processes dark materials produced by irradiation of SO 2 ice by magnetospheric particles lava flows resulting from the upwelling of asthenospheric magma volatile deposits condensed from the atmosphere after eruption and transport of volcanic gases

Remote sensing of planetary surfaces by NIR imaging spectroscopy concepts Principal characteristics of the imaging spectrometer OMEGA (Mars Express) The imaging spectrometers measure the spectrum of the solar light or of the thermal radiation respectively reflected or emitted by a planetary surface for an array of discretized pixels distributed throughout the scene

Remote sensing of planetary surfaces by NIR imaging spectroscopy The bidirectional reflectance The bidirectional reflectance of a medium is defined as the radiance emerging in a given direction from the surface illuminated by a collimated irradiance per unit incident irradiance. x y z O Flux F e i e I (0, e, e ) incidence angle emission angle azimuth

Remote sensing of planetary surfaces by NIR imaging spectroscopy nature of retrieved scientific information An imaging spectrometer samples the bidirectional reflectance (BRDF) of the observed surface both in the :

Spatial complexity at all scales 1 cm

Remote sensing of planetary surfaces by NIR imaging spectroscopy physics of spectral signal formation specular reflection coherent effects multiple scattering between particles absorption Shadow hiding effets diffuse multiple scattering atmospheric absorption atmospheric scattering and diffuse illumination

The analysis of hyperspectral data a possible methodological scheme Segmenting the scene into spatial units Mapping of their physical, chemical and structural properties

Détection automatique composants - classification spectroscopique CO2 glace H2O glace CO2+H2O minéraux « wavanglet »

Réduction de dimensionnalité et classification statistique « MNF+PPI »

Modélisation - caractérisation physique « spectribase + SYSPIMS »

OMEGA : instrument is still operating well with almost no aging OMEGA/Mars Express 3200 séquences dobservation contenant des volatiles (40% des images) Collection du LPG (images prétraitées et calibrées) :

25 hour-orbit: the spacecraft is circling the planet roughly once per martian sol (day) Periapsis altitude of the orbit : 106 kilometers Periapsis is near 75 degrees south latitude in the South Pole region of Mars. This summer, the CRISM team will continue planning for the next round of spacecraft checkouts and instrument calibrations which begin when the aerobraking phase ends in September and refining the software it will use to operate the instrument and collect data. The mission primary science phase, set to last two years, starts in early November. CRISM/MRO