Cryogenic reflectance spectroscopy under high vacuum conditions for outer planets exploration

Kurzfassung

Recently selected Venus missions, such as NASA's VERITAS, ESA's EnVision, and DAVINCI, are all equipped with instruments that focus on the 1 μm region in their payloads. Specifically, VERITAS and EnVision utilize the Venus Emissivity Mapper (VEM) as a multi-spectral imaging system. VEM is designed to provide global mapping of Venus's surface in all available spectral windows. Meanwhile, DAVINCI has a descent imager that obtains images of the surface around 1 μm. To support these missions, the Planetary Spectroscopy Laboratory (PSL) at DLR has a Venus spectroscopy setup consisting of a Bruker VERTEX 80V FTIR spectrometers with an attached vacuum chamber equipped with an induction heating system. PSL can measure emissivity spectra of Venus analogues at temperatures up to 1000K in the spectral range from 0.8 to 1.2 μm. Additionally, PSL has two hemispherical reflectance units available that can be mounted in the internal chamber of the Bruker VERTEX 80V spectrometer. PSL has already measured the emissivity of over 300 rock samples at Venus surface temperatures for calibration and verification efforts for VEM on VERITAS and the VenSpec-M channel on the EnVision mission. Hemispherical reflectance measurements are also taken for each sample. These data will be used for the basic and enhanced calibration datasets for the missions as well as all other Venus missions carrying similar instrumentation. Coordination and cross-calibration of the missions' instruments are crucial. Team members from VERITAS, EnVision, and DAVINCI are collaborating to establish a good cross-calibration between the missions. The data obtained by these missions will provide unique insights into the coupled surface-atmosphere system of Venus.