The Venus Emissivity Mapper ─ Obtaining Global Mineralogy of Venus from Orbit on the ESA EnVision and NASA VERITAS missions to Venus.

International audienc

The Planetary Spectroscopy Laboratory (PSL): wide spectral range, wider sample temperature range

Spectroscopy is still the most accurate methodology to remotely study the surface composition of celestial bodies (and its evolution). For more than ten years the Planetary Emissivity Laboratory (PEL) of DLR in Berlin has provided spectral measurements of planetary analogues from the visible to the far-infrared range for comparison with remote sensing spacecraft/telescopic measurements of extra-terrestrial surfaces [1-5]. Reflection, transmission and emission spectroscopy are the techniques we used to acquire spectral data of target materials. A recent major upgrade to our laboratory set-up added a new spectrometer, three external sources, optical units, new detectors and beamsplitters to further extend the spectral range of measurements that can be performed in the laboratory, as well as the temperature range that we can cover for the measurements. The purpose of this paper is to illustrate the very wide range of capabilities that the Planetary Spectroscopy Laboratory (PSL) can offer to the planetary and to the spectroscopic community

Spectroscopy of the Surface of Venus - in the Laboratory and from Orbit

Interpretation of mineralogy using VNIR spectroscopy data from orbiters requires spectral libraries acquired under conditions matching those on the surfaces being studied. Recent advances in high-temperature laboratory spectroscopy at the Planetary Spectroscopy Laboratory at DLR provide the necessary data and enable novel instruments like the Venus Emissvity Mapper.The instrument is currently on the payload of the ESA EnVision proposal as the VenSpec-M channel in the VenSpec spectrometer suite. It is also part of the VERITAS mission proposal for the NASA Discovery call. Combining VEM with a high-resolution radar mapper will provide key insights into the divergent evolution of Venus and Earth. Flying VEM on more than one mission will enable a long timeline of monitoring for volcanic activity on Venus. Combined with the existing VenusExpress data [1-3], VEM enables detection and mapping of surface changes over decades

The Venus Emissivity Mapper (VEM): advanced development status and performance evaluation

The Venus Emissivity Mapper (VEM) has a mature design with an existing laboratory prototype verifying an achievable instrument SNR of well above 1000 as well as a predicted error in the retrieval of relative emissivity of better than 1%. VEM will provide a global map of surface composition as well as redox state of the surface by observing the surface with six narrow band filters, ranging from 0.86 to 1.18 μm. Continuous observation of Venus’ thermal emission will place tight constraints on current day volcanic activity. Eight additional channels provide measurements of atmospheric water vapor abundance as well as cloud microphysics and dynamics and permit accurate correction of atmospheric interference on the surface data. A mission combining VEM with a high-resolution radar mapper such as the ESA EnVision or NASA VERITAS mission proposals will provide key insights in the divergent evolution of Venus. Here we discuss the approach and results of the evaluation of the VEM sensor’s radiometric performance by an analysis of the corresponding signal processing chain. The passage of a simulated radiometric scene signal of the planet Venus through the VEM optics, detector, analog and digital electronics has been evaluated based on a theoretical model of the system. The goal was to verify the overall system performance with respect to the scientific requirements. This is building on our preliminary evaluation of the VEM laboratory prototype and confirms that the VEM design has significant performance margins

The VenSpec suite on the ESA EnVision mission to Venus

International audienceThe VenSpec instrument suite is part of the payload for the ESA M5 mission proposal EnVision which is currently in a competitive Phase A study. VenSpec consists of three channels: VenSpec-M, VenSpec-H and VenSpec-U. VenSpec-M will provide near-global compositional data on rock types, weathering, and crustal evolution by mapping the Venus surface in five atmospheric windows. VenSpec-H will be dedicated to extremely high-resolution atmospheric measurements. The main objective of the VenSpec-H instrument is to detect and quantify SO2, H2O and HDO in the lower atmosphere, to enable characterization of volcanic plumes and other sources of gas exchange with the surface of Venus, complementing VenSAR and VenSpecM surface and SRS subsurface observations. VenSpec-U will monitor sulphured minor species (mainly SO and SO2) and the as yet unknown UV absorber in Venusian upper clouds and just above. In combination, VenSpec will provide unprecedented insights into the current state of Venus and its past evolution. VenSpec will perform a comprehensive search for volcanic activity by targeting atmospheric signatures, thermal signatures and compositional signatures, as well as a global map of surface compositio

The Venus emissivity mapper: implementation for flight on the NASA VERITAS mission

In June 2020 NASA has selected the VERTIAS Discovery mission to Venus for flight. The Venus Emissivity Mapper (VEM) provided by DLR together with the VISAR radar system provided by JPL are the core payload of the mission. VEM is the first flight instrument designed with a focus on mapping the surface of Venus using atmospheric windows around 1 μm wavelength. It will provide a global map of surface composition by observing with six narrow band filters from 0.86 to 1.18 μm. Continuous observation of Venus’ thermal emission will place tight constraints on current day volcanic activity. Eight additional channels provide measurements of atmospheric water vapor abundance as well as cloud microphysics and dynamics and permit accurate correction of atmospheric interference on the surface data. Combining VEM with a high-resolution radar mapper on the NASA VERITAS and ESA EnVision missions will provide key insights in the divergent evolution of Venus. After several years of pre-development including the setup of a laboratory prototype the implementation for flight has started with the qualification of the flight detectors, the review of all requirements flowdowns as well as the finalizing of spacecraft interfaces