The Venus Emissivity Mapper (VEM): instrument science performance requirements derived from VERITAS and EnVision

International audienceWe present the Venus Emissivity Mapper (VEM) onboard NASAs Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy (VERITAS) and ESAs (EnVision) Venus orbiter missions. The VEM instrument (on EnVision called VenSpec-M), is a multispectral imager for mapping of the Venus surface and its lower atmosphere. This is realized by observation through narrow-band atmospheric windows present in the near-infrared spectral region around 1 μm. For the first time, VEM will provide a global Venus coverage of > 70% with a high signal-to-noise ratio on the order of 100 to detect thermal emissions like volcanic activity, surface rock composition, water abundance and cloud formation. Since VEM for VERITAS and VenSpec-M for EnVision are being developed almost simultaneously, the instrument development approach can be made very efficient. By tailoring the science level, interface and environmental requirements of both missions to a joint requirements baseline, a single instrument design can be established. Focusing on the science requirement breakdown, this paper presents the key scientific requirements derived from VERITAS and EnVision and how they translate into verifiable technical instrument requirements. The VEM/VenSpec-M project is in its preliminary design phase. The instrument preliminary design review (PDR) is planned in 2025 for VERITAS and EnVision. Two flight models (FMs) are currently scheduled for delivery to the VERITAS S/C in 2028 and one FM to the EnVision S/C in 2029. First VEM/VenSpec-M data obtained from Venus orbit is expected after launch of the two missions currently scheduled in 2031

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

Sustained Increase of PKA Activity in the Postcommissural Putamen of Dyskinetic Monkeys

Levodopa-induced dyskinesias (LID) are a frequent complication of Parkinson's disease pharmacotherapy that causes significant disability and narrows the therapeutic window. Pharmacological management of LID is challenging partly because the precise molecular mechanisms are not completely understood. Here, our aim was to determine molecular changes that could unveil targetable mechanisms underlying this drug complication. We examined the expression and downstream activity of dopamine receptors (DR) in the striatum of 1-methyl-4-phenyl-1,2,3,6 tetrahydropiridine (MPTP)-lesioned monkeys with and without L-DOPA treatment. Four monkeys were made dyskinetic and other four received a shorter course of L-DOPA and did not develop LID. Our results show that L-DOPA treatment induces an increase in DRD2 and DRD3 expression in the postcommissural putamen, but only DRD3 is correlated with the severity of LID. Dyskinetic monkeys show a hyperactivation of the canonical DRD1-signaling pathway, measured by an increased phosphorylation of protein kinase A (PKA) and its substrates, particularly DARPP32. In contrast, activation of the DRD2-signaling pathway, visible in the levels of Akt phosphorylated on Thr308 and GSK3β on Ser9, is associated with L-DOPA treatment, independently of the presence of dyskinesias. Our data clearly demonstrate that dyskinetic monkeys present a dysregulation of the DRD3 receptor and the DRD1 pathway with a sustained increase of PKA activity in the postcommissural putamen. Importantly, we found that all signaling changes related to long-term L-DOPA administration are exquisitely restricted to the postcommissural putamen, which may be related to the recurrent failure of pharmacological approaches.his study was supported by grants from the department of Industry of the Basque Government, S-PE12UN030 (RSP) and from the Spanish Health Ministry (FIS PI08/1866 to MRL and FIS PI13/01250 to EP-N)