Venus Analogue Emissivity Measurements in the Lab and in the Field Using a Venus Emissivity Mapper Emulator: VEMu2.0

Kurzfassung

Three major missions to Venus are scheduled for launch in the early 2030’s that will unlock the secrets of our still surprisingly mysterious neighbor. On the VERITAS mission [1], the Venus Emissivity Mapper (VEM) [2] will provide measurements of the surface minerology in unprecedented detail. Venus’s atmosphere is composed mainly of CO2 with clouds of H2SO4, making direct observations of the surface challenging. VEM peers through the clouds by exploiting six narrow windows of higher transmissivity in the near-infrared (NIR) spectral range between 0.86 and 1.18 μm. Due to the 460 °C surface temperatures on Venus, emissivity measurements on the nightside of the planet can be observed through these windows and mineralogical information can be deduced from emissivity maps of the surface. This will allow VEM to distinguish basaltic from more silicic rocks and contribute to detection of past and present volcanism. In preparation for the VERITAS mission, extensive efforts are being made to understand the measurement capabilities and limitations of the VEM instrument. As part of these efforts, a VEM emulator, VEMulator2.0 [3,4], has been developed to provide training for scientists on evaluating emissivity data in complex scenarios using reflectance and emission measurements in the field as well as in the controlled environment of the Planetary Spectroscopy Laboratory (PSL) [5] at the DLR, Berlin. This paper describes the setup and calibration of VEMu2.0 as well as a calibration check and spatially resolved emission measurements performed at PSL. Finally, measurements carried out as part of the 2023 VERITAS field campaign [6] to study the radar and spectral characteristics of unvegetated volcanic surfaces in Iceland will be discussed.