Observability of small scale atmospheric spatial variability by the VenSpec-U instrument onboard EnVision

Kurzfassung

The VenSpec-U instrument[1] onboard the future ESA EnVision mission, will be one of the three spectrometers of the VenSpec suite, that will study Venus’ surface and atmosphere. VenSpec-U will focus on the upper part of the atmosphere and will perform UV observations of the cloud top. It will measure the backscattered sunlight on the dayside of Venus, from which radiance factor spectra will be derived by taking the incoming solar spectral irradiance into account. The scientific objectives of VenSpec-U will regard both the chemical composition and the dynamical properties of the atmosphere. Four main elements to investigate can be derived from these science goals. The firsts are the abundance of sulphured species, including especially SO2 and SO. These species will be identified separately thanks to the “High Resolution” (HR) channel of the instrument, that will have a spectral resolution of 0.3 nm to cover the 205-235 nm wavelength range corresponding to the common absorption band of SO2 and SO. The third objective is to monitor the unidentified UV absorber and its spectral characteristics. To that end, the “Low Resolution” (LR) channel of the instrument will operate from 190 nm to 380 nm, with a spectral resolution of 2-5 nm. Finally, VenSpec-U will investigate the small scale spatial variability of the cloud-top, by performing observations with a pushbroom observation strategy that allows the acquisition of images, at spatial samplings ranging from 3 to 24 km.