VenSpec-H: an Infrared Spectrometer to Study Venus' Activity

IntroductionThe VenSpec-H instrument [1] is part of the EnVision M5 mission payload, which has been selected by ESA in June 2021 for launch in 2031. EnVision is a medium-class mission to determine the nature and current state of geological activity on Venus, and its relationship with the atmosphere, to understand how Venus and Earth could have evolved so differently. VenSpec-H will target different molecular species in nadir viewing geometry, as to better characterize the surface-atmosphere interaction. Scientific ObjectivesVenSpec-H is part of the VenSpec suite, including also an IR mapper and a UV spectrometer. The science objectives of this suite is to search for temporal variations in surface temperatures and tropospheric concentrations of gases indicative of volcanic eruptions; and study surface-atmosphere interactions and weathering by mapping surface emissivity and tropospheric gas abundances.To contribute to this investigation, VenSpec-H is designed to H2O and HDO contents in the first scale height of Venus atmosphere and to probe H2O, HDO, CO, OCS, SO2 in the 30 to 40km altitude range on the nightside of Venus and above the cloud top on the dayside. Instrument DesignVenSpec-H is a nadir pointing, high-resolution (R~8000) infrared spectrometer that will perform observations in different spectral windows between 1 and 2.5 microns.This instrument has direct heritage from NOMAD-LNO [2, 3] that is currently onboard ExoMars Trace Gas Orbiter, although a series of modifications have been introduced to address the specific scientific objectives of the EnVision mission. Studies were performed to optimize the instrument design, as well as to choose four spectral windows with sufficient SNR, to achieve the instruments scientific objectives [4]. AcknowledgementsThis work has been performed with the support of the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination by the ESA Prodex Office. References1. Helbert, J., et al., Proc. SPIE 11128, Infrared Remote Sensing and Instrumentation XXVII, 1112804 (2019)2. Neefs, E., et al., Appl Opt 54(28), 8494-520 (2015)3. Vandaele, A.C., et al., Space Science Reviews 214(5) (2018)4. Robert, S., et al., EnVision Conference, Paris, France, 12-14 Feb. (2020)