NIR reflectance hyperspectral microscopy for planetary science: Application to the MicrOmega instrument

Hyperspectral microscopy, by its capability to characterize in situ the composition of samples at their grain size scale and the coupling between the different phases, complements efficiently the remote sensing hyperspectral imagers. Objectives, rationale and limits of hyperspectral microscopy in the planetary science field are summarized in this paper. A new concept of NIR reflectance hyperspectral microscope, MicrOmega is presented and results obtained both with a representative breadboard and a first version of the MicrOmega instrument, recently integrated on the Phobos Grunt lander, are discussed. Results show that we are now able to build instruments capable of analyzing samples at the grain scale, typically a few tens of microns per pixel, within volume, weight, power and time budgets compatible with typical rover's constraints. We demonstrate the ability of such instruments to characterize samples, identify their major and minor constituents, some non-detectable from orbit, and their spatial coupling. Instruments based on the MicrOmega concept have been selected as part of the Hayabusa-2 Mascot Lander that will study in situ a C-class asteroid, as well as of the ExoMars rover that would characterize Mars potential past and present habitability. In both cases, these in situ analyses should provide essential data to improve our understanding of the history of the object explored. (C) 2012 Elsevier Ltd. All rights reserved.