Spicam: Spectroscopy for the investigation of the characteristics of the atmosphere of Mars

The SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) UV-IR dual spectrometer is dedicated to the study of the atmosphere of Mars. It is the first instrument to perform stellar occultations at Mars; its UV imaging spectrometer was designed primarily for atmospheric vertical profiling by stellar occultation. The IR spectrometer is dedicated to nadir measurements Of H₂O abundances simultaneously with UV ozone measurements, for a better understanding of the chemical coupling H ₂O-O₃. The principal SPICAM achievements are: the first vertical profile of density/ temperature of CO2 obtained from a planetary orbiter; numerous vertical profiles of ozone and cloud layers; the systematic measurement of total vertical ozone along-track on the dayside provides the first climatic map of ozone on Mars; the first simultaneous measurements of ozone and water vapour from an orbiter; the discovery of nightglow NO bands in UV; the discovery of auroral activity near the crustal remnant magnetic field; a thorough study of the ionosphereupper atmosphere through high-altitude aeronomical observations of O, H, CO, CO⁺, and CO₂; and the first measurement of H₂O and CO₂ ice albedo spectra (simultaneously with OMEGA and PFS). Other products of IR nadir observations are: surface albedo at various wavelengths; the intensity of O₂( ¹Δg) emission due to photo-dissociation of ozone; the equivalent widths of carbon dioxide and water ice (on the surface and in aerosol layers); and water vapour total column amount. All of these successes are the result of a highly versatile instrument, a highly capable spacecraft, and engineers and scientists dedicated to the design, building and testing of the instrument, integration on the spacecraft, and complex operations managed at ESTEC and ESOC.