Surface Of Venus Research Articles

Aerostat Probe for Studying the Atmosphere and Surface of Venus

Aerostat Probe for Studying the Atmosphere and Surface of Venus

Frequency Channel Selection and Performance Simulation of a Microwave Radiometer for Temperature and Sulfuric Compound Profiling of the Venusian Lower Atmosphere

AbstractExploring the Venusian lower atmosphere is crucial for studying the atmospheric circulation, surface‐atmosphere interactions, and origin and evolution of the Venusian atmosphere and climate. In this study, we investigate the theoretical capabilities of a downward‐looking passive microwave sounder placed in low Venus orbit to measure the temperature, sulfur dioxide (SO2) and gaseous sulfuric acid (H2SO4(g)) profiles. A nonlinear iterative retrieval algorithm combining a radiative transfer (RT) model and an optimal‐estimation‐based inversion algorithm is established. With the RT model adapted to the Venusian atmosphere, simulations under different atmospheric conditions are performed to optimize the selection of frequency channels. The achievable altitude coverage, vertical resolution and corresponding expected precision of the temperature, SO2 and H2SO4(g) retrievals from the multi‐channel brightness temperature measurements are quantified via retrieval simulations. The temperature can be retrieved from the surface of Venus to an altitude of ∼61 km with a precision of 1–3.5 K and a vertical resolution of 6–15 km. A precision of 10%–35% is expected for SO2 in the ∼12–64 km altitude range and with a vertical resolution of 8–19 km. H2SO4(g) can be retrieved in the ∼36–54 km altitude range with a precision of 10%–30% and a vertical resolution of 6–13 km.

Thermo-mechanical modeling of pancakelike domes on Venus

In this paper, we present a mathematical model aimed at describing both the effusive and relaxing phase of pancakelike lava domes on the Venus surface. Our model moves from the recent paper by Quick et al. [“New approaches to inferences for steep-sided domes on Venus,” J. Volcanol. Geotherm. Res. 319, 93–105 (2016)] but generalizes it under several respects. Indeed, we consider a temperature field, playing a fundamental role in the flow evolution, whose dynamics is governed by the heat equation. In particular, we suggest that the main mechanism that drives cooling is radiation at the dome surface. We obtain a generalized form of the equation describing the dome shape, where the dependence of viscosity on temperature is taken into account. Still following Quick et al. [“New approaches to inferences for steep-sided domes on Venus,” J. Volcanol. Geothermal Res. 319, 93–105 (2016)], we distinguish an isothermal relaxing phase preceded by a non-isothermal (cooling) effusive phase, but the fluid mechanical model, developed in an axisymmetric thin-layer approximation, takes into account both shear thinning and thermal effects. In both cases (relaxing and effusive phase), we show the existence of self-similar solutions. In particular, this allows to obtain a likely scenario of the volumetric flow rate which originated this kind of domes. Indeed, the model predicts a time varying discharge, which is maximum at the beginning of the formation process and decreases until vanishing when the effusive phase is over. The model, in addition to fitting well the dome shape, suggests a possible forming scenario, which may help the largely debated questions about the emplacement and lava composition of these domes.

Heng-o Corona, Venus: Dyke swarms record evolution of its underlying mantle plume

Coronae are enigmatic, quasi-circular/elliptical tectono-magmatic features, common across the surface of Venus ranging in size from 60 to 2600 km This study undertook a detailed mapping (1:500,000 scale) of Heng-o Corona, the second largest on Venus. 24,600 graben-fissure lineaments were mapped, interpreted to be underlain by mafic dykes, and grouped into radiating, circumferential and linear swarms. A series of 5 nearly-concentric rings were identified from unflooded or partially flooded circumferential swarms. The largest of these has a diameter of 1970 km, which almost doubles Heng-o's known size (previously 1060 km based on its topographic annulus). This new diameter also narrows the gap between it and Artemis Corona, the largest on Venus, to only 630 km. Three major radiating graben swarms were identified, extending >700–1000 km from their sources within the central annulus. From cross-cutting relationships, we interpreted that the major radiating swarms formed first, upon initial plume arrival and flattening against the base of the lithosphere. The circumferential swarms followed, starting with the innermost ring, migrating with the leading edge of the plume head as it spread outward against the base of the lithosphere. The distinctive annular ridge/trough system (at about 500 km radius) is associated with the transition between plume head arrival and spreading. The centers of most of the radiating and circumferential swarms are aligned along a NNW-SSE trend that is interpreted to represent an underlying zone of lithospheric weakness. Additional graben-fissure systems in the study area are not associated with Heng-o Corona; some are linked with other magmatic centers nearly up to 1000 km outside the study area.

Different Scenarios for the Origin and the Subsequent Succession of a Hypothetical Microbial Community in the Cloud Layer of Venus.

The possible existence of a microbial community in the venusian clouds is one of the most intriguing hypotheses in modern astrobiology. Such a community must be characterized by a high survivability potential under severe environmental conditions, the most extreme of which are very low pH levels and water activity. Considering different scenarios for the origin of life and geological history of our planet, a few of these scenarios are discussed in the context of the origin of hypothetical microbial life within the venusian cloud layer. The existence of liquid water on the surface of ancient Venus is one of the key outstanding questions influencing this possibility. We link the inherent attributes of microbial life as we know it that favor the persistence of life in such an environment and review the possible scenarios of life's origin and its evolution under a strong greenhouse effect and loss of water on Venus. We also propose a roadmap and describe a novel methodological approach for astrobiological research in the framework of future missions to Venus with the intent to reveal whether life exists today on the planet.

Formation of coronae topography and fractures via plume buoyancy and melting

Coronae are volcanic-tectonic features seemingly unique to the surface of Venus. As such they offer potential insights into differences in geodynamic processes on Venus and Earth. Largely due to limitations in processing power and computational complexity, models of corona formation generally ignore the effect of melt and magmatism despite the presence of volcanic features like domes and lava flows. Here we present a new model of corona formation integrating visco-plastic rheology with two-phase flow melt migration. Additionally, we model brittle failure of surface material, viscous flow of partially molten material at depth, and cracking of solid rock from fluid pressure in one model. The model consists of a two-dimensional half space with a round plume body ascending through an asthenosphere and interacting with a Venusian lithosphere and crust. The size and temperature of the plume body, lithosphere thickness, crustal thickness, and regional strain rate are all varied over 20 model runs. Most models show deflection of the plume as it rises due to the increased viscosity of the base of the lithosphere. As the plume spreads and rises against the base of the lithosphere, melting occurs. Melt rises and accumulates in the lithosphere which supports surface topography. Brittle failure occurs at the surface due to the induced stress of the migrating plume body and rising melt. Increased temperatures and sizes of initial plumes result in larger topographies occurring over smaller timescales. Decreased temperatures and sizes of initial plumes result in smaller topographies over larger timescales. Increased lithosphere thickness generates smaller topographies. Thinner crusts result in more viscous lithosphere and more strain accumulation, creating surface depressions seen in approximately half of real corona. Both thicker crusts and increased regional strain result in lower viscosities at the base of the lithosphere, preventing the deflection of the plume body, which instead rises through the lithosphere relatively unimpeded. The varied model parameters generally result in an evolutionary sequence of topographies and fracture patterns which resemble actual corona, without requiring a collapsing dome to create outer rims, as is often invoked for corona formation via upwelling plumes. Corona rim topography is generally created within 105 and 106 year timescales, while multiple rims or central depressions are generally observed over 106 year timescales. Observed topography is actively supported by partially molten regions in the lithosphere, supporting the notion of an active squishy-lid Venus. These partially molten regions are not centrally located and may provide a source for observed lava flows away from corona centers.

Far-travelled 3700 km lateral magma propagation just below the surface of Venus

The Great Dyke of Atla Regio (GDAR) is traced for ~3700 km on Venus, as a surface graben (narrow trough) interpreted to overlie a continuous laterally-emplaced underlying mafic dyke (vertical magma-filled crack). The GDAR belongs to a giant radiating dyke swarm associated with Ozza Mons (volcano), Atla Regio plume, and was fed from a magma reservoir ~600 km south of the Ozza Mons centre. A 50-degree counter-clockwise swing of the GDAR at 1200 km from the centre is consistent with a 1200 km radius for the underlying Ozza Mons plume head, and a stress link to the 10,000 km long Parga Chasmata rift system. Our discovery of the GDAR, should spur the search for additional long continuous single dykes on Venus (and Earth), with implications for estimating plume head size, locating buffered magma reservoirs, mapping regional stress variation at a geological instant, and revealing relative ages (through cross-cutting relationships) over regional-scale distances.

Electrostatic modelling of the Groza-2 discharge sensor on the Venera missions to Venus

The Soviet Venera 13 and 14 missions landed on the surface of Venus five days apart in 1982. An instrument called Groza-2, designed to search for thunderstorms, carried an electrode that recorded discharge currents in the lower atmosphere. In this paper a possible location and likely geometry of the electrode are deduced using the limited information available on Groza-2, combined with electrostatic modelling. The spacecraft’s geometry significantly screens the electrode potential, which helps to constrain the sensor’s size, shape and location. Due to its high atmospheric pressure, Venus is anticipated to have a high breakdown field, approximately 300 MV/m near the surface if linear scaling with pressure is assumed. The existence of a signal in the discharge sensor combined with the electrostatic screening of the spacecraft geometry implies there is a substantial potential difference between the atmosphere and the electrode.

Joint determination of Venus gravity and atmospheric density through EnVision radio science investigation

The ESA mission EnVision will address its main scientific questions through a detailed mapping of the surface and interior properties of Venus. A precise reconstruction of the spacecraft trajectory is a key requirement for the EnVision scientific investigations, including radio science. To precisely constrain the orbit evolution, refined models of the dynamical forces are included in the Precise Orbit Determination (POD) process. We developed a methodology based on a batch-sequential filter that enables a joint estimation of Venus gravity and atmospheric density. Our approach yields an accurate compensation of atmospheric mismodeling, simulated through semi-empirical predictions of the atmospheric density provided by general circulation models (GCM), e.g., Venus Climate Database (VCD). Numerical simulations of the EnVision radio science investigation were carried out by using a perturbative analysis of the dynamical forces, which accounts for atmospheric density errors ≥ 200%. By adjusting a set of atmospheric scale factors, our proposed strategy enables an estimation of the atmospheric density at the spacecraft altitudes with an accuracy of 25%. The improved dynamical model yields accuracies in the orbit reconstruction of 1–2 m, 30–40 m and 20–30 m in the radial, transverse and normal directions.

Pt/HTCC Alumina based Electronic Packaging System and Integration Processes for High Temperature Harsh Environment Applications

Electronic devices capable of operation at 500°C are required for long term Venus surface missions, as well as for in situ monitoring and control of next generation aeronautical engines. High temperature sensors and electronics can also find many applications in military, and energy and automobile industries. Various silicon carbide (SiC) sensors and electronic devices have been developed for operation at 500 °C, and a compatible packaging system is needed for long term test and deployment of these high temperature devices. High temperature co-fired ceramics (HTCC) alumina with platinum (Pt) conductor was proposed for high temperature electronic packaging. A prototype Pt/HTCC alumina packaging system including chip-level package and circuit board has been briefly reported previously for long-term electrical testing of SiC integrated circuits at 500 °C, and brief testing at much higher temperatures. HTCC alumina is an excellent dielectric material with acceptable dielectric constant and low dielectric loss over wide temperature and frequency ranges. Pt is chemically noble and can be co-fired with HTCC alumina in air ambient producing a viable electronic packaging material system for high temperature applications. This paper presents a more detailed description of this packaging system including prototype low power packages and circuit boards based on HTCC alumina and Pt metallization for 500°C and other harsh environment applications. The key technical considerations for chip-level packaging and circuit board assembly, including materials and processes for 500 °C durable wire-bonding and SiC die attach, and integration of multi-chip circuit boards, are presented. Experimental test results of this packaging approach applied to SiC integrated circuits at 500 °C and 700°C are discussed as well.

A WISPR of the Venus Surface: Analysis of the Venus Nightside Thermal Emission at Optical Wavelengths

Parker Solar Probe (PSP) conducted several flybys of Venus while using Venus’ gravity for orbital adjustments to enable its daring passes of the Sun. During these flybys, PSP turned to image the nightside of Venus using the Wide-field Imager for Solar PRobe (WISPR) optical telescopes, which unexpectedly observed Venus’ surface through its thick and cloudy atmosphere in a theorized, but until-then unobserved near-visible spectral window below 0.8 μm. We use observations taken during PSP’s fourth Venus gravity assist flyby to examine the origin of the Venus nightside flux and confirm the presence of this new atmospheric window through which to observe the surface geology of Venus. The WISPR images are well explained by emission from the hot Venus surface escaping through a new atmospheric window in the optical with an overlying emission component from the atmosphere at the limb that is consistent with O2 nightglow. The surface thermal emission correlates strongly with surface elevation (via temperature) and emission angle. Tessera and plains units have distinct WISPR brightness values. Controlling for elevation, Ovda Regio tessera is brighter than Thetis Regio; likewise, the volcanic plains of Sogolon Planitia are brighter than the surrounding regional plains units. WISPR brightness at 0.8 μm is predicted to be positively correlated to FeO content in minerals; thus, the brighter units may have a different starting composition, be less weathered, or have larger particle sizes.

System engineering research of a multirotor aircraft as a prospective technical means of exploring the atmosphere and surface of the planet Venus

Currently, the exploration of the planet Venus is a very relevant and developing direction in space science. The development of rocket and space technologies has expanded the boundaries of accessibility of spacecraft to objects in the Solar System, allow for entire interplanetary expeditions, including flights to terrestrial planets, giant planets, and the outskirts of the Solar System. Currently, a program of planetary exploration for the next decades is being formed. Studying the history of expeditions to Venus and Mars clarifies the need to develop and improve methods for studying the atmosphere of the nearest planets to Earth, in particular, Venus, using vailable technical means, making them as efficient as possible. The exploration of Venus is proposed to be carried out using a technical means– a multirotor aircraft. This object is allocated as a system, and its role in the composition of the supersystem is also defined and described. The paper identifies scenarios for the functioning of the flying apparatus are highlighted, the tasks of its subsystems are described, as well as their interaction with each other. The main external factors affecting the work of the subsystems of the multirotor aircraft are presented. A functional scheme of the system is developed, as well as the main indicators used to assess the effectiveness of achieving the target task. This work is a preliminary stage before building a mathematical model.

Mass Transfer Theory Based Analysis of Influencing Factors on Component Gradient of Near-surface Atmosphere on Venus

The atmosphere of Venus differs completely from that of Earth despite the planets’ similarity in size and mass. At Venus's surface, the atmosphere is hot and dense, with a temperature of approximately 735 K and a pressure of approximately 92 bar. The temperature profile from the Soviet VeGa-2 probe shows high instability of the near-ground potential temperature, which, according to relevant research, can be explained by the vertical gradient of N2 mole fraction. Based on the Maxwell–Stefan mass transfer theory, we propose a theoretical model of binary gas component for a quantitative discussion of influencing factors for the N2 vertical concentration gradient, which consist of temperature, gravity, specific heat ratio, mass relative factor, thermal diffusion factor, and CO2 flux. Our model shows that the 0%–3.5% N2 concentration gradient cannot be generated without CO2 flux in the near-ground atmosphere of Venus. And the result with CO2 source indicates that the 0.000001%–3.5% N2 concentration gradient at 0–7 km atmosphere can be generated by the 2.7 × 10−6 mol m−2 s−6 CO2 flux on Venusian surface, which is in agreement of gradient reckoned by VeGa-2's data. This magnitude of CO2 flux is close to the one produced by volcanic eruptions on Earth, indicating possible existence of volcanic activities on the surface of Venus. This work has provided the community a new vision to understand the influencing factors of Venusian atmospheres composition distribution.

A cool runaway greenhouse without surface magma ocean.

Water vapour atmospheres with content equivalent to the Earth's oceans, resulting from impacts1 or a high insolation2,3, were found to yield a surface magma ocean4,5. This was, however, a consequence of assuming a fully convective structure2-11. Here, we report using a consistent climate model that pure steam atmospheres are commonly shaped by radiative layers, making their thermal structure strongly dependent on the stellar spectrum and internal heat flow. The surface is cooler when an adiabatic profile is not imposed; melting Earth's crust requires an insolation several times higher than today, which will not happen during the main sequence of the Sun. Venus's surface can solidify before the steam atmosphere escapes, which is the opposite of previous works4,5. Around the reddest stars (Teff < 3,000 K), surface magma oceans cannot form by stellar forcing alone, whatever the water content. These findings affect observable signatures of steam atmospheres and exoplanet mass-radius relationships, drastically changing current constraints on the water content of TRAPPIST-1 planets. Unlike adiabatic structures, radiative-convective profiles are sensitive to opacities. New measurements of poorly constrained high-pressure opacities, in particular far from the H2O absorption bands, are thus necessary to refine models of steam atmospheres, which are important stages in terrestrial planet evolution.

Characterizing basalt-atmosphere interactions on Venus: A review of thermodynamic and experimental results

Abstract The surface of Venus is in contact with a hot (~470 °C), high pressure (92 bars), and caustic (CO2 with S, but little H2O) atmosphere, which should cause progressive alteration of the crust in the form of sulfate and iron-oxide coatings; however, the exact rate of alteration and mineral species are not well constrained. Different experimental approaches, each with its own limitations, are currently being used to constrain mineralogy and alteration rates. One note is that no experimental approach has been able to fully replicate the necessary conditions and sustain them for a significant length of time. Furthermore, geochemical modeling studies can also constrain surface alteration mineralogy, again with different assumptions and limitations. Here, we review recent geochemical modeling and experimental studies to constrain the state of the art for alteration mineralogy, rate of alteration, open questions about the surface mineralogy of Venus, and what can be constrained before the fleet of missions arrives later this decade. Combining the new results confirms that basalt on the surface of Venus should react quickly and form coatings of sulfates and iron-oxides; however, the mineralogy and rate of alteration are dependent on physical properties of the protolith (including bulk composition, mineralogy, and crystallinity), as well as atmospheric composition, and surface temperature. Importantly, the geochemical modeling results show that the mineralogy is largely controlled by atmospheric oxygen fugacity, which is not well constrained for the near-surface environment on Venus. Therefore, alteration experiments run over a range of oxygen and sulfur fugacities are needed across a wide range of Venus analog materials with varying mineralogy and crystallinity.

Adaptation of a Thermorheological Lava Flow Model for Venus Conditions

AbstractActive volcanism was (and potentially still is) an important process that shapes the Venus surface and its detection is a primary goal for the planned VERITAS and EnVision missions. Therefore, understanding lava flow emplacement and timing on Venus is important. We adapt the terrestrial PyFLOWGO thermorheological model to Venus conditions to assess the effects on channelized lava flow propagation. We first initiate the model with terrestrial basaltic parameters and progressively adapt it to Venusian conditions in five steps: (a) gravity, (b) ambient atmospheric temperature, (c) specific heat capacity and wind speed, (d) atmospheric density, and (e) coupled convective and radiative heat flux. Compared to Earth, the slightly lower gravity on Venus resulted in a lower flow velocity, a higher crust coverage, and a very minor increase in flow length (0.1%). Increasing the ambient atmospheric temperature reduced heat loss and produced a (77%) longer flow; whereas next accounting for the atmospheric specific heat capacity and wind speed increased the flow length slightly more (81%). However, increasing the atmospheric density resulted in a shorter lava flow (13%) due to more efficient cooling. Finally, accounting for coupled convective and radiative heat loss due to the strong CO2 infrared absorption resulted in an increase of the flow length (∼75%). Although the model applies only to channelized, cooling‐limited flows, these results reveal that for the same effective effusion rate and topography, a Venusian lava flow travels a longer distance than the equivalent flow on Earth and its cooling should be detectable by future orbital instruments.

Feasibility of power beaming through the Venus atmosphere

Despite great interest by the planetary science community in the robotic exploration of Venus, solutions for operating in this extreme environment present significant challenges to mission architects. A particular challenge in designing any in situ Venus mission of reasonable duration is the selection of a suitable power source. State-of-the-art space power technologies comprising solar arrays, batteries and radioisotope thermoelectric generators are not capable of operating on the surface of Venus, limited by the high temperatures, high pressures and corrosive environment. Despite its proximity to the Sun, the solar resource on the surface is limited by the dense cloud layers. One potential approach for circumventing this limitation includes collecting the abundant visible solar energy above the Venus atmosphere, and wirelessly transferring this power to the surface at a wavelength that can more effectively penetrate the dense cloud layer. The feasibility of such an approach and other related mission concepts are discussed herein from a perspective of atmospheric absorption and scattering of the beamed energy.

Analysis of prospective flight schemes to Venus accompanied by an asteroid flyby

This paper deals with the problem of constructing a flight scheme to Venus, in which a spacecraft flying to the planet after a gravity assist maneuver and transition to a resonant orbit in order to re-encounter with Venus, makes a passage of a minor celestial body. The 117 candidate asteroids from the NASA JPL catalogue, whose diameter exceeds 1 km, were selected. The flight trajectories which meet the criteria of impulse-free both flyby Venus and asteroid, and the subsequent landing on the surface of Venus were found within the interval of launch dates from 2029 to 2050. The trajectory of the spacecraft flight from the Earth to Venus including flyby of Venus and asteroids with a subsequent landing on the surface of Venus was analyzed.

Characterization of a 2700 ​km long bolide airburst chain, Phoebe Regio, Venus

Detailed geological mapping of Phoebe Regio on Venus, located near 10°S, 282°W, at a scale of 1:500,000, provided the basis for the discovery of a linear trend with 12 splotches, herein termed the Phoebe Regio Splotch Chain. The formation of splotches on the surface is associated with an explosion that occurs as a result of the interaction of a cosmic body penetrating through the dense atmosphere of Venus. The shockwave from such an air-blast could affect the surface in different ways, leading to both radar darkening and brightening. It was found that the 12 splotches differ in size but have a similar morphology and include a dark center and a radar-bright ring. The presence of such characteristics makes it possible to distinguish splotches from other geological features such as volcano-tectonic features (volcanic edifices, pyroclastic mantles, portions of lava flows and associated structures), which, when analyzed on a broad scale, can look similar. Splotches are known to be among the youngest geological features on the surface of Venus, and the elongated distribution of 12 splotches is suggested to have been formed by a stream of individual fragments of a parent body that disrupted well before entering the atmosphere of Venus.

A method for constructing an interplanetary trajectory of a spacecraft to Venus using resonant orbits to ensure landing in the desired region

A problem of constructing the trajectory of a spacecraft flight to Venus within the framework of a mission including landing of a lander in a given region of the planet's surface is being considered. A new celestial mechanics related method based on the use of gravity assist maneuver near Venus is proposed to transfer the spacecraft to a heliocentric orbit resonant with the orbit of Venus, so that, at the next approach the planet, the given region of the surface becomes attainable for landing. It is shown that the best resonant orbit in terms of the cost of the characteristic velocity is an orbit with a 1:1 ratio of the period to the orbital period of Venus. A procedure for choosing one of possible resonant orbits depending on coordinates of the desired landing point on the surface and the launch date of the mission is described. An example of calculating the flight trajectory that ensures landing in the Vellamo-South region of the Venus surface at launch from the Earth in 2031 is considered.