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The goal of the OMEGA instrument (planned to fly the Mars'96 Orbiter) is to monitor the past and present evolution of Mars through visible and infrared spectral mapping of its surface. The spectral range (0.5 to 5.1 micrometers) includes signatures of major and minor components of both the surface and the atmosphere of Mars. The spectral and spatial resolutions required and the high signal to noise ratio lead to a three channel instrument: (1) A visible spectrometer (whiskbroom type) with a bidimensional silicon array (288 by 384 elements 23 by 23 micrometers) and a refractive telescope illuminating a holographic grating. (2) A two-channel infrared spectrometer (pushbroom type) based on linear InSb array (128 elements). A reflective telescope and a scanning device give the imaging capability. The IR detectors, cooled at 77 K were developed in France by the Societe Anonyme de Telecommunication (SAT) for this instrument with adapted geometry and specific two band filters. A specific electronic was developed for this instrument, especially one digital electronics based on a transputer associated to a digital signal processor in order to obtain a high efficiency, error free, data compression. After its space qualification, the instrument was fully calibrated at the Institut d'Astrophysique Spatiale (IAS) Orsay.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.