The Venus infrared atmospheric gases linker instrument concept for solar occultation studies of Venus atmosphere composition and structure onboard the Venus Orbiter Mission of the Indian Space Research Organization
Résumé
In this paper, we describe the concept of the Venus InfraRed Atmospheric Linker (VIRAL) spectrometer for investigation of the composition and structure of the planetary atmosphere at the top and above the cloud layer of Venus onboard the Venus Orbiter Mission announced by the Indian Space Research Organization (ISRO). VIRAL includes two channels, an infrared echelle spectrometer channel and an ultra-high resolution heterodyne interferometer channel. Here, we present the concept of the echelle channel only. The instrument is designed to perform solar occultation, providing an optimal photon yield combined with a superior spectral resolving power that exceeds 20,000. VIRAL echelle spectrometer will cover the wavelength range from 2.3 to 4.3 μm, and achieve high vertical resolution (with a footprint of about 1 km at the limb) to allow the detailed altitude profiling of the Venusian upper atmosphere with its composition and structure. We present the instrument concept, its preliminary optical design and science objectives of the experiment.