Atmosphere Of Venus Research Articles

Spectroscopy of OSSO and Other Sulfur Compounds Thought to be Present in the Venus Atmosphere.

The spectroscopy of cis-OSSO and trans-OSSO is explored and put into the context of the Venusian atmosphere, along with other sulfur compounds potentially present there, namely, S2O, C1-S2O2, trigonal-S2O2, and S3. UV-vis spectra were calculated using the nuclear ensemble approach. The calculated OSSO spectra are shown to match well with the 320-400 nm near-UV absorption previously measured on Venus, and we discuss the challenges of assigning OSSO as the Venusian near-UV absorber. The largest source of uncertainty is getting accurate concentrations of sulfur monoxide (3SO) in the upper cloud layer of Venus (60-70 km altitude) since the 3SO self-reaction is what causes cis- and trans-OSSO to form. Additionally, we employed the matrix-isolation technique to trap OSSO formed by microwave discharging a gas mixture of argon and SO2 and then depositing the mixture onto a cold window (6-12 K). Anharmonic vibrational transition frequencies and intensities were calculated at the coupled cluster level to corroborate the matrix-isolation FTIR spectra. The computationally calculated UV-vis and experimentally recorded IR spectra presented in this work aid future attempts at detecting these sulfur compounds in the Venusian atmosphere.

Equilibrium compositions in gas phase systems

A new method of calculation of equilibrium compositions of single-phase multicomponent systems in a wide range of temperatures, pressures, and elemental compositions is proposed. It is based on the minimization of the integral characteristic of the slope of the thermodynamic potential surface in the space of coordinates of chemical reactions. The proposed algorithm is applied to the definition of area of the thermodynamic stability of freons in volcanic gases and to the construction of the equilibrium profiles of the height distribution of sulphur-containing components of Venusian atmosphere.

Исследование баллистического режима спуска маневренного посадочного аппарата на поверхность Венеры

At present, various projects to continue fundamental investigations of Venus are considered in Russia and abroad. It means that the issue of developing a landing module to reach the surface of the planet becomes topical, as the module might provide access to the regions most attractive in terms of research. We propose to use a landing module of the lifting body type, which, as compared to a ballistic class module, is not unacceptably complicated in terms of design and at the same time features a lift-to-drag ratio adequate for solving manoeuvring problems arising in the process of descent into the Venusian atmosphere to reach the target landing area. We consider potential descent trajectories available to a landing module of this type, including the possibility of performing a maximum lateral manoeuvre; we took into consideration its long-period trajectories characterised by multiple re-entries into the dense atmosphere and compared these trajectories to the descent trajectory of a conventional ballistic class landing module. We show that using a manoeuvrable craft expands the selection of potential landing regions, as well as reduces loads and broadens the scope of scientific problems to be solved and studies to be undertaken

Exploration of Extreme Environments with Currentand Emerging Robot Systems

The discovery of living organisms under extreme environmental conditions of pressure, temperature, and chemical composition on Earth has opened up the possibility of existence and persistence of life in extreme environment pockets across the solar system. These environments range from the many intriguing moons, to the deep atmospheres of Venus and even the giant gas planets, to the small icy worlds of comets and Kuiper Belt Objects (KBOs). Exploring these environments can ascertain the range of conditions that can support life and can also identify planetary processes that are responsible for generating and sustaining habitable worlds. These environments are also time capsules into early formation of the solar system and will provide vital clues of how our early solar system gave way to the current planets and moons. Over the last few decades, numerous missions started with flyby spacecraft, followed by orbiting satellites and missions with orbiter/lander capabilities. Since then, there have been numerous missions that have utilized rovers of ever-increasing size and complexity, equipped with state-of-the-art laboratories on wheels. Although current generations of rovers achieve mobility through wheels, there are fundamental limitations that prevent these rovers from accessing rugged environments, cliffs, canyons, and caves. These rugged environments are often the first places geologist look to observe stratification from geohistorical processes. There is an important need for new robot mobility solutions, like hopping, rolling, crawling, and walking that can access these rugged environments like cliffs, canyons, and caves. These new generations of rovers have some extraordinary capabilities including being able to grip onto rocks like NASA/JPL LEMUR 2, operate in swarms such as MIT’s microbots, or have high-specific energy fuel cell power supply that is approximately 40-fold higher than conventional lithium ion batteries to Stanford/NASA JPL’s Hedgehog which is able to hop and somersault in low-gravity environments such asteroids. All of these mobility options and supporting technologies have been proposed and developed to explore these hard-to-reach unconventional environments. This article provides a review of the robotic systems developed over the past few decades, in addition to new state-of-the-art concepts that are leading contenders for future missions to explore extreme environments on Earth and off-world.

Revisiting the Sulfur‐Water Chemical System in the Middle Atmosphere of Venus

AbstractSulfur‐water chemistry plays an important role in the middle atmosphere of Venus. Ground‐based observations have found that simultaneously observed SO2 and H2O at ~64 km vary with time and are temporally anticorrelated. To understand these observations, we explore the sulfur‐water chemical system using a one‐dimensional chemistry‐diffusion model. We find that SO2 and H2O mixing ratios above the clouds are highly dependent on mixing ratios of the two species at the middle cloud top (58 km). The behavior of sulfur‐water chemical system can be classified into three regimes, but there is no abrupt transition among these regimes. In particular, there is no bifurcation behavior as previously claimed. We also find that the SO2 self‐shielding effect causes H2O above the clouds to respond to the middle cloud top in a nonmonotonic fashion. Through comparison with observations, we find that mixing ratio variations at the middle cloud top can explain the observed variability of SO2 and H2O. The sulfur‐water chemistry in the middle atmosphere is responsible for the H2O‐SO2 anticorrelation at 64 km. Eddy transport change alone cannot explain the variations of both species. These results imply that variations of species abundance in the middle atmosphere are significantly influenced by the lower atmospheric processes. Continued ground‐based measurements of the coevolution of SO2 and H2O above the clouds and new spacecraft missions will be crucial for uncovering the complicated processes underlying the interaction among the lower atmosphere, the clouds, and the middle atmosphere of Venus.

Chemical Cycling in the Venusian Atmosphere: A Full Photochemical Model From the Surface to 110 km

AbstractVenus is an exceptional natural experiment to test our understanding of atmospheric sulfur chemistry. Previous modeling efforts have focused on understanding either the middle or lower atmosphere. In this work, we performed the first full atmosphere analysis of the chemical transport processes on Venus from the surface to 110 km using a 1‐D diffusion model with photochemistry. We focused on the cycling of chemical species between the upper and lower atmospheres and interactions between distinct species groups including SO , CO + OCS, chlorides, NO , O , and S . We tested different eddy diffusivity profiles and investigated their influences on the vertical profiles of important species. We find that the assumed boundary conditions in previous models strongly impacted their simulation results. This has a particularly large effect for SO . We find the high SO abundance in the lower atmosphere is readily transported into the middle atmosphere, far exceeding observed values. This implies some yet unknown chemistry or process limiting SO mixing. We summarize outstanding questions raised by this work and note chemical reactions that should be the highest priority for future laboratory studies and ab initio calculations.

Measurements of the Ka Band opacity of sulfuric acid vapor with application towards radio occultations of Venus

Radio occultation experiments are capable of providing insight into the properties of the Venus atmosphere at the boundary between the upper and lower atmosphere. To retrieve vertical profiles of atmospheric gases from Venus radio occultation experiments, accurate models for the absorption of these gases are necessary. New laboratory measurements have been made of the microwave opacity of H2SO4 vapor at Ka Band (30–45 GHz, 6.5–10 mm) in mixtures containing up to 3 bars of CO2 at temperatures ranging from 550 to 585 K, simulating the conditions of the lower atmosphere of Venus. The results of these measurements and prior microwave and millimeter-wavelength laboratory studies have been used to derive a model for H2SO4 vapor opacity valid from 1 to 150 GHz. This model is incorporated into a microwave radiative transfer model of the Venus atmosphere, which has been used to predict the penetration depth of a radio occultation signal at 32 GHz and determine the contributions of atmospheric gases to 32 GHz opacity. These results can be used to interpret signal attenuation profiles for future Ka Band radio occultations of Venus.

Spatial and Temporal Variability of the 365‐nm Albedo of Venus Observed by the Camera on Board Venus Express

AbstractWe mapped the distribution of the 365‐nm albedo of the Venus atmosphere over the years 2006–2014, using images acquired by the Venus Monitoring Camera (VMC) on board Venus Express. We selected all images with a global view of Venus to investigate how the albedo depends on longitude. Bertaux et al. (2016, https://doi.org/10.1002/2015JE004958) reported a peak in albedo around 100° longitude and speculated on an association with the Aphrodite Terra mountains. We show that this peak is most likely an artifact, resulting from long‐term albedo variations coupled with considerable temporal gaps in data sampling over longitude. We also used a subset of images to investigate how the albedo depends on local time, selecting only south pole viewing images of the dayside (local times 7–17 hr). Akatsuki observed mountain‐induced waves in the late afternoon at 283 nm and 10 μm (Fukuhara et al., 2017, https://doi.org/10.1038/ngeo2873). We expect that the presence of such waves may introduce 365‐nm albedo variations with a periodicity of one solar day (116.75 Earth days). We searched for such a periodicity peak at 15:30–16:00 local time and low latitudes but did not find it. In conclusion, we find that temporal albedo variations, both short and long term, dominate any systematic variations with longitude and local time. The nature of VMC dayside observations limits regular data sampling along longitudes, so longitudinal variations, if they exist, are difficult to extract. We conclude that any influence by the Venus surface on 365‐nm albedo is negligible within this data set.

Minimum-Mass Limits for Streamlined Venus Atmospheric Probes

Small, expendable drop probes are an attractive method for making measurements in the lower atmosphere of Venus, augmenting the capabilities of orbiters or aerial platforms that must remain in the benign temperature region above 50 km altitude. However, probe miniaturization is impeded by the need to provide thermal and pressure protection for conventional payloads. This paper determines the minimum mass limits for an insulated pressure vessel probe that operates all the way to the Venusian surface. Scaling laws for the probe performance and mass of major system components are explicitly derived using a simple model that captures the relevant physics. Streamlining the probe is found to be a highly effective strategy for lowering the system mass, but it also reduces the time available for data collection and transmission. Tradeoffs, guidelines, and design charts are presented for an array of miniaturized probes. Total system masses on the order of 5 kg are plausible with streamlined probes if the desired science measurements can be performed faster than a standard Venus descent timeline.

Balloon Design for Mars, Venus, and Titan Atmospheres

This paper studies the specifications of balloons for the exploration of bodies with different atmospheric conditions. Three types of balloons, i.e., zero-pressure, super-pressure, and over-pressurized, with four different shapes, i.e., sphere, oblate, prolate, and airship, were analysed. First, the development of a simulation tool is described, which was used for analysing the behaviour of balloons for different exploration missions. Next, the developed software was verified by comparing its output with recorded data from a set of flights at the Esrange Space Center. Based on the simulation results, recommendations are given for different balloon types and shapes for operation on Mars, Venus, and Titan.

High-temperature tribological tests of composite materials

The work is devoted to high-temperature tribological tests of carbon-containing materials during friction on 40Kh13 steel in the temperature range of 20 - 800 ° C. The choice of test temperature is based on prospects of creating spacecraft drives for operation without lubrication in the atmosphere of Venus. The studies have shown that at the same load and temperature with increasing slip speed, the friction coefficient increases. With increasing load, the friction coefficient at a given temperature decreases. At a temperature of 300 ° C for speeds of 0.05; 0.16; 0.25; 0.3; 0.37 m / s with increasing load from 0.3 MPa to 1.0 MPa, the friction coefficient decreases by 1.4; 1.8; 1.1; 1.5; 1.5 times, respectively. At a temperature of 500 ° C in the same range of speeds and loads, the friction coefficient decreases by 1.1; 1.4; 1.5; 1.7; 1.6 times, respectively.

Tribology of carbon-containing materials in the carbon dioxide environment at high temperatures

The work is devoted to high-temperature tribological testing of carbon-containing materials during friction on 40X13 steel in the temperature range from plus 20 to plus 800 ° C in a carbon dioxide environment. The choice of temperature and test environment is due to the prospects of creating spacecraft drives for operation without lubrication in the atmosphere of Venus. Studies have shown that the friction process in a carbon dioxide environment at a temperature of plus 300 ° C reduces the coefficient of friction, so at a load of 0.5 MPa, the friction coefficient is lower by 67%, and at a temperature of plus 600 ° C the coefficient of friction is lower by 38%. At a load of 1.0 MPa and a temperature of plus 300 ° C, the friction coefficient in a carbon dioxide environment is lower by 55%, and at a temperature of plus 600 ° C the friction coefficient is lower by 45%. In the range of operating temperatures from plus 300 to plus 600 ° C at a speed of 0.16 m/s and a load of 0.5 MPa and 1.0 MPa, the friction coefficient does not exceed the value of 0.3. The friction coefficient decreases with increasing load. At a temperature of plus 500 ° C and a load of 0.5 MPa, the coefficient of friction in a carbon dioxide medium is 1.9 times less than the carbon-carbon composite materials in an air atmosphere, and at a load of 1.0 MPa it is 2.1 times less than a carbon-carbon composite materials in the air atmosphere.

Molten Lithium Battery for Space Applications

Solid-state electrolytes (SEs) have gained much interest lately as a potential for mitigating the various issues inherent in a most energy dense lithium metal (anode) based batteries such as lithium ion, lithium sulfur (Li-S), and lithium oxygen. Notable high energy next generation cathodes such as sulfur have their own issues with a liquid electrolyte based system, where the polysulfides discharge product dissolve into the electrolyte causing both: a loss of cathode active material and an unwanted shuttling of the polysulfides over the polymer separator to the lithium anode limiting their practical use. Moreover, the formation of lithium dendrites in lithium batteries is yet another challenging issue that not only limits battery cycle-life but also poses safety risks. The use of SEs can potentially address most of the issues related to next generation lithium batteries such as Li-S batteries, but getting rid of dendrite issues may not be addressed completely. One way to eliminate the dendrite issue is to use molten lithium as an anode.The National Aeronautics and Space Administration (NASA) has an ambitious plan to explore one of the most challenging planets in our solar system: Venus. The surface temperature of Venus can reach as high as 465°C and at same time, the Venus atmosphere is filled with corrosive gases such as carbon dioxide, sulfur dioxide, carbon monoxide, etc. A battery for such a challenging space mission can be built only if battery components (especially the electrolyte) is stable beyond 500°C and must be stable with molten lithium and sulfur electrodes for at least hours or days if not months—longer is better. Last but not the least, yet another challenge is containment of gaseous sulfur inside the battery container at such a high temperature. The potential to replace sulfur with selenium may mitigate the issue but at cost of reduced energy density.Under a NASA funded project, the University of Dayton Research Institute (UDRI) is developing molten lithium sulfur (Li-S) or lithium-selenium (Li-Se) batteries with the help of a high temperature solid ceramic electrolyte (SCE) that can enable a operating temperature >465°C for several hours. UDRI has been working on a high temperature SCE such as phosphate-based Li1+ xAlxGe2- x(PO4)3 (LAGP) ceramic electrolyte material1 that is stable beyond 500°C and also shows broad electrochemical window (up to 5V) that is sufficient for a molten Li-S or Li-Se battery operation; provided LAGP is stable with Li and S or Se in such harsh conditions and temperature. Unfortunately, LAGP is not stable with Li (forms a highly resistive interface layer between LAGP and electrode) and its stability with sulfur or Se, needs to be determined.Under the NASA project, UDRI has been developing interface materials between LAGP and electrodes for Li-S and Li-Se cells that can be stable at wide temperature range (room temperature to 500°C). The presentation will include progress on high temperature (up to 465°C) i) SCE, ii) SCE/Li interface materials, iii) SCE/S interface material, iv) SCE/Se interface material, v) impedance and open circuit voltage of Li-S or Li-Se cells at 465°C, and vi) cycle-life of Li-S or Li-Se cells at 465°C. To the authors knowledge, there is no such report (molten Li-S or Li-Se cells that can function at 465°C) that exists in literature.B. Kumar, D. Thomas, J. Kumar, “Space-Charge-Mediated Superionic Transport in Lithium Ion Conducting Glass–Ceramics,” J. Electrochem. Soc. 156, A506 (2009)

Venus’s atmosphere is unexpectedly complex

Spacecraft first measured the chemical makeup of Venus’s atmosphere in the 1960s. By the late 1970s, scientists agreed that available data suggested the Venusian atmosphere was uniformly 3.5% nitrogen gas up to 100 km above the surface. A new analysis of data collected from the planet’s atmosphere in 2007 has found N2 concentrations 40% higher than expected. The findings could lead to revised models of Venusian chemical and physical processes and could even influence how scientists study exoplanets (Nat. Astron. 2020, DOI: 10.1038/s41550-020-1079-2). “Venus is the nearest planet to Earth, but it’s one of the planets we know the fewest things about,” says Stephen Kane of the University of California, Riverside, an exoplanet and Venus researcher who wasn’t involved in the study. Because of that lack of data—especially direct measurements of chemicals in Venus’s atmosphere at different altitudes—he says he’s not surprised that existing atmospheric models are incomplete. But he

Injection of meteoric phosphorus into planetary atmospheres

This study explores the delivery of phosphorus to the upper atmospheres of Earth, Mars, and Venus via the ablation of cosmic dust particles. Micron-size meteoritic particles were flash heated to temperatures as high as 2900 ​K in a Meteor Ablation Simulator (MASI), and the ablation of PO and Ca recorded simultaneously by laser induced fluorescence. Apatite grains were also ablated as a reference. The speciation of P in anhydrous chondritic porous Interplanetary Dust Particles was made by K-edge X-ray absorption near edge structure (XANES) spectroscopy, demonstrating that P mainly occurs in phosphate-like domains. A thermodynamic model of P in a silicate melt was then developed for inclusion in the Leeds Chemical Ablation Model (CABMOD). A Regular Solution model used to describe the distribution of P between molten stainless steel and a multicomponent slag is shown to provide the most accurate solution for a chondritic-composition, and reproduces satisfactorily the PO ablation profiles observed in the MASI. Meteoritic P is moderately volatile and ablates before refractory metals such as Ca; its ablation efficiency in the upper atmosphere is similar to Ni and Fe. The speciation of evaporated P depends significantly on the oxygen fugacity, and P should mainly be injected into planetary upper atmospheres as PO2, which will then likely undergo dissociation to PO (and possibly P) through hyperthermal collisions with air molecules. The global P ablation rates are estimated to be 0.017 ​t ​d−1 (tonnes per Earth day), 1.15 ​× ​10−3 ​t ​d−1 and 0.024 ​t ​d−1 for Earth, Mars and Venus, respectively.

Возможность расширения достижимых областей посадки в рамках проекта «Венера-Д» путем выбора окон старта

The paper considers the problem of finding accessible areas on the Venus surface and the prospect of their increasing by extension of launch windows during the period from 2026 to 2031; taking into account the restrictions on the payload weight and the maximum overload level affecting the lander during the descent in the Venus atmosphere. The project of the Venera-D mission is used as the initial data for the work. The possibility of reaching the planet on the first and second half-turns of the heliocentric transfer orbit is analyzed. As an example, the effect of the launch window expansion for 2031 on the nature of changes in the accessible landing areas is considered. Possible payload weight expenses for launch window expansion are estimated. The launch windows are selected by solving the Lambert problem, where the transit spacecraft momentum near the Earth for the flight to Venus along the first and second half-orbit paths at the period from 2026 to 2042 is calculated. The accessible landing area is shown when increasing the launch windows initially adopted for 2031.The estimation of payload weight expenses for increasing the launch windows is performed.

Dry late accretion inferred from Venus’s coupled atmosphere and internal evolution

The composition of meteoritic material delivered to the terrestrial planets after the end of core formation as late accretion remains contentious. Because the evolution of Venus' atmospheric composition is likely to be less intricate than the Earth's, we test implications of wet and dry late accretion compositions, using present-day Venus atmosphere measurements. Here we investigate the long-term evolution of Venus using self-consistent numerical models of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. Atmospheric escape is only able to remove a limited amount of water over the history of the planet. We show that late accretion of wet material exceeds this sink. CO2 and N2 contributions serve as additional constraints. A preferentially dry composition of the late accretion impactors is in agreement with observational data on H2O, CO2 and N2 in Venus' present-day atmosphere. Our study suggests that the late accreted material delivered to Venus was mostly dry enstatite chondrite, conforming to isotopic data available for Earth. Our preferred scenario indicates late accretion on Venus contained less than 2.5% wet carbonaceous chondrites. In this scenario, the majority of Venus' and Earth's water has been delivered during the main accretion phase.

The Venusian Atmospheric Oxygen Ion Escape: Extrapolation to the Early Solar System

AbstractThe present atmosphere of Venus contains almost no water, but recent measurements indicate that in its early history, Venus had an Earth‐like ocean. Understanding how the Venusian atmosphere evolved is important not only for Venus itself but also for understanding the evolution of other planetary atmospheres. In this study, we quantify the escape rates of oxygen ions from the present Venus to infer the past of the Venusian atmosphere. We show that an extrapolation of the current escape rates back in time leads to the total escape of 0.02–0.6 m of a global equivalent layer of water. This implies that the loss of ions to space, inferred from the present state, cannot account for the loss of an historical Earth‐like ocean. We find that the O+ escape rate increases with solar wind energy flux, where more energy available leads to a higher escape rate. Oppositely, the escape rate decreases slightly with increased extreme ultraviolet radiation (EUV) flux, though the small variation of EUV flux over the measured solar cycle may explain the weak dependency. These results indicate that there is not enough energy transferred from the solar wind to Venus' upper atmosphere that can lead to the escape of the atmosphere over the past 3.9 billion years. This means that the Venusian atmosphere did not have as much water in its atmosphere as previously assumed or the present‐day escape rates do not represent the historical escape rates at Venus. Otherwise, some other mechanisms have acted to more effectively remove the water from the Venusian atmosphere.

Thermal structure of the Venusian atmosphere from the sub-cloud region to the mesosphere as observed by radio occultation

We present distributions of the zonal-mean temperature and static stability in the Venusian atmosphere obtained from Venus Express and Akatsuki radio occultation profiles penetrating down to an altitude of 40 km. At latitudes equatorward of 75°, static stability derived from the observed temperature profiles is consistent with previous in-situ measurements in that there is a low-stability layer at altitudes of 50–58 km and highly and moderately stratified layers above 58 km and below 50 km, respectively. Meanwhile, at latitudes poleward of 75°, a low-stability layer extends down to 42 km, which has been unreported in analyses of previous measurements. The deep low-stability layer in the polar region cannot be explained by vertical convection in the middle/lower cloud layer, and the present result thus introduces new constraints on the dynamics of the sub-cloud atmosphere. The Venusian atmosphere is in striking contrast to the Earth’s troposphere, which generally has a deeper low-stability layer at low latitudes than at mid- and high latitudes.

Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express

One of the striking features about Venus atmosphere is its temporal variability and dynamics, with a chaotic polar vortex, large-scale atmospheric waves, sheared features and variable winds that depend on local time and possibly orographic features. The aim of this research is to combine data accumulated over several years and obtain a global mean state of the atmosphere focusing in the global structure of the clouds using the cloud opacity and upper cloud temperatures.We have first produced global maps using the integrated radiance through the infrared atmospheric windows centred around 1.74 μm and 2.25 μm, that show the spatial variations of the cloud opacity in the lower clouds around 44–48 km altitude and also provide an indirect estimation of the possible particle size. We have also produced similar global maps using the brightness temperatures seen in the thermal region at 3.8 μm and 5.0 μm, which provide direct indication of the temperatures at the top of the clouds around 60–70 km altitude.These maps have been generated using the complete dataset of the Visible and InfraRed Thermal Imaging Spectrometer mapping channel (VIRTIS-M) on board Venus Express, with a wide spatial and long temporal coverage in the period from May 2006 until October 2008.Our results provide a global view of the cloud opacity, particle size and upper cloud temperatures at both hemispheres, showing the main different dynamical regions of the planet. The profiles obtained also provide the detailed dependencies with latitude, local time and longitude, diagnostic of the global circulation flow and dynamics at various altitude layers, from about 44 up to 70 km over the surface.