The Venus Emissivity Mapper Emulator 2.0: a NIR camera system for Venus analogue field measurements

Kurzfassung

Both NASA’s VERITAS [1] and ESAs EnVision missions to Venus incorporate a Venus Emissivity Mapper (VEM) [2,3] to characterise the surface and distinguish rock types and potentially their alteration states. Due to Venus visibly opaque atmosphere direct observations of the surface are challenging, however there are five atmospheric windows in the near infrared which will be exploited by the VEM instrument. In preparation for these missions and after successful preliminary work an improved emulator of the VEM instrument (VEMulator2.0) has been constructed for field measurements. The instrument was used in a two-week field campaign at Venus analogue sites in Iceland in August 2023, in the framework of the VERITAS expedition to Iceland [4,5], to collect reflectance measurements of volcanic rocks of varying age and surface conditions, as well as to measure emission from recently erupted lava with hot spots up to approximately 400 °C (see [6]). The goal of the work was to assess the capability of the VEM instrument to detect differences in surface composition with the limited spectral information provided by the 6 bands in a wide variety of realistic volcanic rock types. To achieve this, samples of the imaged regions were collected to be analysed in detail with the extensive spectroscopy facilities of the Planetary Spectroscopy Laboratory (PSL), DLR Berlin. By comparing the laboratory spectra with the field measurements insights into the effectivity and limitations of the instrument can be gained. This contribution will show the VEMulator design and calibration procedure as well as first results from field measurements in comparison with the those obtained in the laboratory. Details will be provided of the camera setup used in the field, the calibration of the camera and the application of the calibration to example data from the field.