VERITAS (Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy): Discovering the Secrets of a Lost Habitable World

VERITAS is a selected Discovery mission launching in 2028. It will investigate Venus’ geologic evolution and processes that affect rock planetary habitability. Venus’ present condition is a geodynamic analog for early Earth, when the lithosphere was hotter and thinner, plate tectonics and continents began to form, and life emerged. Earth no longer retains a clear record of how these processes began, but Venus may have active subduction—the necessary first step to initiate plate tectonics, as well as analogs of continents. VERITAS will test whether Venus’ tessera plateaus represent the only analogs of continents in the solar system, which formed on Earth when massive quantities of basalt melted in the presence of water. VERITAS will use numerous methods to search for current volcanism and tectonism, including subduction. VERITAS produces global, foundational datasets using two instruments, the Venus Interferometric Synthetic Aperture Radar (VISAR) and the Venus Emissivity Mapper (VEM), plus a gravity science investigation. The VISAR X-band measurements include: 1) a global digital elevation model (DEM) with 250 m postings, 6 m height accuracy, 2) Synthetic aperture radar (SAR) imaging at 30 m horizontal resolution globally, 3) SAR imaging at 15 m for >25% of the surface, and 4) surface deformation from repeat pass interferometry (RPI) at 2 cm precision for >12 targeted areas. VEM covers >70% of the surface in six NIR bands located within five atmospheric windows sensitive to Fe mineralogy, plus eight atmospheric bands for calibration and water vapor measurements, with SNR ≫ VIRTIS. It is a near IR spectral imager with optimized spectral bands for observing the surface of Venus that supports the determination of rock type and the search for active and recent volcanism. VERITAS will use a low circular orbit (< 250 km) and Ka-band uplink and downlink to create a global gravity field with 3 mGal accuracy at 155 km (d&o 123) resolution. VERTIAS also constrains core size and state, using radar tie points to help find k2, the phase lag, and MOIF

A Mixed-Valence Superstructure Assembled from A Mixed-Valence Host-Guest Complex

Herein, we report an unprecedented mixed-valence crystal superstructure that consists of a 2:1 host–guest complex [MV⊂(CBPQT)_2]^(2/3+) [MV = methyl viologen, CBPQT = cyclobis(paraquat-p-phenylene)]. One electron is distributed statistically between three [MV⊂(CBPQT)_2]•+ composed of a total of 15 viologen units. The mixed-valence state is validated by single-crystal X-ray crystallography, which supports an empirical formula of [MV⊂(CBPQT)_2]_3·(PF_6)_2 for the body-centered cubic superstructure. Electron paramagnetic resonance provides further evidence of electron delocalization. Quantum chemistry calculations confirm the mixed-valence state in the crystal superstructure. Our findings demonstrate that precise tuning of the redox states in host–guest systems can lead to a promising supramolecular strategy for achieving long-range electron delocalization in solid-state devices

A Radically Configurable Six-State Compound

Most organic radicals possess short lifetimes and quickly undergo dimerization or oxidation. Here, we report on the synthesis by radical templation of a class of air- and water-stable organic radicals, trapped within a homo[2]catenane composed of two rigid and fixed cyclobis (paraquat-p-phenylene) rings. The highly energetic octacationic homo[2]catenane, which is capable of accepting up to eight electrons, can be configured reversibly, both chemically and electrochemically, between each one of six experimentally accessible redox states (0, 2+, 4+, 6+, 7+, and 8+) from within the total of nine states evaluated by quantum mechanical methods. All six of the observable redox states have been identified by electrochemical techniques, three (4+, 6+, and 7+) have been characterized by x-ray crystallography, four (4+, 6+, 7+, and 8+) by electron paramagnetic resonance spectroscopy, one (7+) by superconducting quantum interference device magnetometry, and one (8+) by nuclear magnetic resonance spectroscopy

Mechanical Bonds and Topological Effects in Radical Dimer Stabilization

While mechanical bonding stabilizes tetrathiafulvalene (TTF) radical dimers, the question arises: what role does topology play in catenanes containing TTF units? Here, we report how topology, together with mechanical bonding, in isomeric [3]- and doubly interlocked [2]catenanes controls the formation of TTF radical dimers within their structural frameworks, including a ring-in-ring complex (formed between an organoplatinum square and a {2+2} macrocyclic polyether containing two 1,5-dioxynaphthalene (DNP) and two TTF units) that is topologically isomeric with the doubly interlocked [2]catenane. The separate TTF units in the two {1+1} macrocycles (each containing also one DNP unit) of the isomeric [3]catenane exhibit slightly different redox properties compared with those in the {2+2} macrocycle present in the [2]catenane, while comparison with its topological isomer reveals substantially different redox behavior. Although the stabilities of the mixed-valence (TTF2)^(•+) dimers are similar in the two catenanes, the radical cationic (TTF^(•+))_2 dimer in the [2]catenane occurs only fleetingly compared with its prominent existence in the [3]catenane, while both dimers are absent altogether in the ring-in-ring complex. The electrochemical behavior of these three radically configurable isomers demonstrates that a fundamental relationship exists between topology and redox properties

Circadian Rhythm and Sleep Disruption: Causes, Metabolic Consequences and Countermeasures.

Circadian (∼ 24 hour) timing systems pervade all kingdoms of life, and temporally optimize behaviour and physiology in humans. Relatively recent changes to our environments, such as the introduction of artificial lighting, can disorganize the circadian system, from the level of the molecular clocks that regulate the timing of cellular activities to the level of synchronization between our daily cycles of behaviour and the solar day. Sleep/wake cycles are intertwined with the circadian system, and global trends indicate that these too are increasingly subject to disruption. A large proportion of the world's population is at increased risk of environmentally-driven circadian rhythm and sleep disruption, and a minority of individuals are also genetically predisposed to circadian misalignment and sleep disorders. The consequences of disruption to the circadian system and sleep are profound and include myriad metabolic ramifications, some of which may be compounded by adverse effects on dietary choices. If not addressed, the deleterious effects of such disruption will continue to cause widespread health problems; therefore, implementation of the numerous behavioural and pharmaceutical interventions that can help restore circadian system alignment and enhance sleep will be important

Venus Evolution Through Time: Key Science Questions, Selected Mission Concepts and Future Investigations

In this work we discuss various selected mission concepts addressing Venus evolution through time. More specifically, we address investigations and payload instrument concepts supporting scientific goals and open questions presented in the companion articles of this volume. Also included are their related investigations (observations & modeling) and discussion of which measurements and future data products are needed to better constrain Venus’ atmosphere, climate, surface, interior and habitability evolution through time. A new fleet of Venus missions has been selected, and new mission concepts will continue to be considered for future selections. Missions under development include radar-equipped ESA-led EnVision M5 orbiter mission (European Space Agency 2021), NASA-JPL’s VERITAS orbiter mission (Smrekar et al. 2022a), NASA-GSFC’s DAVINCI entry probe/flyby mission (Garvin et al. 2022a). The data acquired with the VERITAS, DAVINCI, and EnVision from the end of this decade will fundamentally improve our understanding of the planet’s long term history, current activity and evolutionary path. We further describe future mission concepts and measurements beyond the current framework of selected missions, as well as the synergies between these mission concepts, ground-based and space-based observatories and facilities, laboratory measurements, and future algorithmic or modeling activities that pave the way for the development of a Venus program that extends into the 2040s (Wilson et al. 2022)