UV/Vis+ Photochemistry Database : Structure, Content and Applications

Acknowledgments This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. However, the authors are indebted to those colleagues who support us in maintaining the database through the provision of spectral and other photochemical data and information. The National Center for Atmospheric Research is operated by the University Coporation for Atmopsheric Research, under the sponsorship of the National Science Foundation. Disclaimer: The views expressed in this paper are those of the authors and do not necessarily represent the views or policies of the U.S.EPA. Mention of trade names or products does not convey and should not be interpreted as conveying official U.S. EPA approval, endorsement, or recommendation.Peer reviewedPublisher PD

Envision M5 Venus orbiter proposal

EnVision [1,2] is a Venus orbiter mission that will determine the nature and current state of geological activity on Venus, and its relationship with the atmosphere, to understand how and why Venus and Earth evolved so differently. Envision is a finalist in ESA’s M5 Space Science mission selection process, and is being developed in collaboration with NASA, with the sharing of responsibilities currently under assessment. It is currently in Phase A study; final mission selection is expected in June 2021. If selected, EnVision will launch by 2032 on an Ariane 6.2 into a six month cruise to Venus, followed by aerobraking, to achieve a near-circular polar orbit for a nominal science phase lasting at least 4 Venus sidereal days (2.7 Earth years)

Evaluation of modelled spatially distributed predictions of soil erosion by water versus field-based assessments

Policy makers concerned about soil erosion and its impacts need good quality information on which to base their decisions. There is a trend toward using erosion models to aid such decision making. Such models are based on data obtained from experimental plots. The theoretical results need to be compared with information gained from monitoring erosion in the field to assess if theory accords with reality. Data from the Minimum Information Requirement version of the Water Erosion Prediction Project model (MIRSED) are compared to information gained from field monitoring over a 5-year period (1982–1986) in 11 localities widely spread throughout England and Wales. Two of the localities, Gwent and Shropshire, are examined in detail. The model seriously over predicts erosion, both in amount and extent. Also, the statistical distributions of the data values are different. The model predicts erosion will happen where it does not. The reasons why the two assessments of erosion differ greatly are explored. This comparison shows there is an urgent need to develop models which incorporate information gained from field-based observations. Until better models are devised, policy makers and decision takers should treat the results of modelling exercises with great caution

Enabling planetary science across light-years. Ariel Definition Study Report

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution

Science objectives of the VenSpec-U channel on board EnVision

International audienceEnVision has been recently selected by ESA as a Cosmic Vision M5 finallist. This mission aims at characterizing the evolution and activity of our neighbouring planet Venus: is Venus still active today? What is its internal structure? How did it evolve (habitability, weathering, resurfacing)? How are volatile species coupled between interior, surface and atmosphere? In order to answer these science objective, the payload onboard EnVision low-Venus orbit platform consists of an interferometric radar (InSAR), a subsurface sounder (SRS) and a spectrometer suite known as VenSpec, consisting of three channels: VenSpec-M, VenSpec-H and VenSpec-U. VenSpec-U is a dual UV spectral imager (190-380 nm @ 2 nm; 210-240 nm @ 0.2 nm) aiming at measuring SO2, SO and the yet unknown UV absorber on day side cloud top of Venus. It is known from past observations, from orbiters such as Pioneer Venus and Venus Express and Earth-based telescopes such as IRTF and HST that SO2 and SO are both highly variable species, spanning at least two orders of magnitude over timescales ranging from a few hours to several decades. The physical origin of this variability is poorly constrained (volcanic plumes and/or atmospheric oscillations), and VenSpec-U, with its unprecedented accuracy, spatial and temporal coverage, will be able to provide valuable answers

The VenSpec suite on the ESA EnVision mission to Venus

International audienceThe VenSpec instrument suite 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. The broadest window at 1·02 μm is mapped with two filters to obtain information on the shape of the window. Additional filters are used to remove clouds, water, and stray light. VenSpec-M will use the methodology pioneered by VIRTIS on Venus Express but with more and wider spectral bands, the VenSAR-derived DEM, and EnVision's circular orbit to deliver near-global multichannel spectroscopy with wider spectral coverage and an order of magnitude improvement in sensitivity. It will obtain repeated imagery of surface thermal emission, constraining current rates of volcanic activity following earlier observations from Venus Express. 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 characterisation of volcanic plumes and other sources of gas exchange with the surface of Venus, complementing VenSAR and VenSpec-M surface and SRS subsurface observations. A nadir pointed high-resolution infrared spectrometer is the ideal instrument for these observations at the 1·0 μm, 1·7 μm, and 2·0 - 2·3 μm atmospheric windows that permit measurements of the lower atmosphere. Baseline observations will be performed on the night side but observations at all times of day are possible. 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. It will therefore complement the two other channels by investigating how the upper atmosphere interacts with the lower atmosphere, and especially characterise to which extent outgassing processes such as volcanic plumes are able to disturb the atmosphere through the thick Venusian clouds. A twin channel (0.2 nm in high-resolution, 2 nm in low-resolution) spectral imager in the 190-380 nm range able to operate in nadir would be especially suited to such a task. 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

Simulated spectra of CO2 isotopologues to analyze observation from MARS and VENUS

International audienc

First observation of 628 CO₂ isotopologue band at 3.3 μm in the atmosphere of Venus by solar occultation from Venus Express

The new ESA Venus Express orbiter is the first mission applying the probing technique of solar and stellar occultation to the atmosphere of Venus, with the SPICAV/SOIR instrument. SOIR is a new type of spectrometer used for solar occultations in the range 2.2-4.3 μm. Thanks to a high spectral resolving power R~15,000–20,000(unprecedented in planetary space exploration), a new gaseous absorption band was soon detected in the atmospheric transmission spectra around 2982 cm−1, showing a structure resembling an unresolved Q branch and a number of isolated lines with a regular wave number pattern. This absorption could not be matched to any species contained in HITRAN or GEISA databases, but was found very similar to an absorption pattern observed by a US team in the spectrum of solar light reflected by the ground of Mars [Villanueva, G.L., Mumma, M.J., Novak, R.E., Hewagama, T., 2008. Icarus 195 (1), 34-44]. This team then suggested to us that the absorption was due to an uncatalogued transition of the 16O12C18O molecule. The possible existence of this band was soon confirmed from theoretical considerations by Perevalov and Tashkun. Some SOIR observations of the atmospheric transmission are presented around 2982 cm−1, and rough calculations of line strengths of the Q branch are produced, based on the isotopic ratio measured earlier in the lower atmosphere of Venus. This discovery emphasizes the role of isotopologues of CO2 (as well as H2O and HDO) as important greenhouse gases in the atmosphere of Venus

EnVision: Understanding Why our most Earth-like Neighbour is so Different

International audienceVenus is our most Earth-like twin, from a geological standpoint: it is very similar in size and probably in bulk composition, and it is very likely to be geologically active today. Several Venus Express observations hint at active volcanism, including transient increases in thermal emission and high surface emissivities consistent with fresh lava flows, as well as episodic injections of sulphurous gases to the upper atmosphere. The science case is broad: to measure current volcanic, seismic, atmospheric and climatic activity; deduce its geological history to understand how and why Venus and Earth became so different; identify volatile sources and sinks; and infer its interior structure and dynamics.` EnVision therefore has four major science themes: • Activity (volcanism, tectonism, mass wasting, weathering, sedimentation, volatile sources and sinks) • History (stratigraphy, past environments, ancient terrains, signatures of past oceans, climate change) • Volatiles (water, sulphur dioxide, clouds, volcanic gases, dynamic processes) • Planet (geodesy, spin, organisation, tectonics, internal structure and long-term evolution) and three main instruments: • VenSAR, the primary synthetic aperture radar • SRS, the subsurface radar sounder • VenSPEC, the Venus IR emission mapper, IR and UV spectrometer which combined with radio science using the 3 m X- and Ka-band high gain antenna. Together, these will provide an unprecedented view of the interior, surface and atmosphere of Venus. The Phase 0 baseline study demonstrated that the mission can successfully achieve its targets within the design to cost envelope, for a baseline launch date in 2032 using chemical propulsion and 12 to 24 months aerobraking. The nominal science mission starts in June 2035, with four Cycles (one Cycle is a 243-day Venus day) providing 278 Tbits of data return. Coverage is >60% for IR mapping and subsurface sounding, and >15% for InSAR and polarimetry at 30 m resolution. Up to 2% of the surface will be imaged at 2 m resolution or better. EnVision is one of three M5 missions in Phase A study with a final down-selection expected in June 202