The recently selected missions to Venus have opened a new era for the exploration of this planet. These missions will provide information about the chemistry of the atmosphere, the geomorphology, local-to-regional surface composition, and the rheology of the interior. One key scientific question to be addressed by these future missions is whether Venus remains volcanically active, and if so, how its volcanism is currently evolving. Hence, it is fundamental to analyze appropriate terrestrial analog sites for the study of possibly active volcanism on Venus. To this regard, we propose Mount Etna - one of the most active and monitored volcanoes on Earth - as a suitable terrestrial laboratory for remote and in-situ investigations to be performed by future missions to Venus. Being characterized by both effusive and explosive volcanic products, Mount Etna offers the opportunity to analyze multiple eruptive styles, both monitoring active volcanism and identifying the possible occurrence of pyroclastic activity on Venus. We directly compare Mount Etna with Idunn Mons, one of the most promising potentially active volcanoes of Venus. Despite the two structures show a different topography, they also show some interesting points of comparison, and in particular: a) comparable morpho-structural setting, since both volcanoes interact with a rift zone, and b) morphologically similar volcanic fields around both Mount Etna and Idunn Mons. Given its ease of access, we also propose Mount Etna as an analog site for laboratory spectroscopic studies to identify the signatures of unaltered volcanic deposits on Venus.

Серии последовательных УФ-изображений (365 нм) облачного покрова Венеры позволяют исследовать динамику мезосферы. Беспрецедентный по продолжительности ряд таких изображений получен камерами VMC на борту космического аппарата (КА) Venus Express (ESA) и UVI на борту КА Akatsuki (JAXA) c 2006 по 2022 гг. На 10° ю. ш. наблюдаются долговременные изменения средней зональной и меридиональной скоростей ветра с периодом 12.5 ± 0.5 лет. Анализ поведения среднего зонального ветра около полудня 12 ± 1 ч. при фазовых углах 60°–90° в ограниченные по времени интервалы наблюдения показывает, что вблизи минимума долгопериодической зависимости торможение горизонтального потока наблюдается над областью Овды, наиболее высокой частью Земли Афродиты, как для VMC, так и для UVI. И наоборот, ускорение наблюдается над областью Овды вблизи максимума долгопериодической зависимости. Рассматриваемые долготные вариации зональной скорости простираются от экватора до средних широт (0°–40°). Меридиональная скорость показывает долготные вариации, связанные с рельефом подстилающей поверхности, вне зависимости от того, торможение или ускорение горизонтального потока наблюдается над высокогорной частью Земли Афродиты.

Series of consecutive UV (365 nm) images of Venus cloud coverage provide a way to investigate dynamics of the mesosphere. An unprecedented series of such images was obtained by the VMC/Venus Express (ESA) and UVI/Akatsuki (JAXA) cameras from 2006 to 2022. At 10°S long-term variations in the mean zonal and meridional wind speed are observed with a period of 12.5 ± 0.5 years. Analysis of the of the mean zonal wind behavior around noon (12 ± 1 h) at phase angles of 60°–90° in limited observation time intervals shows that near the minimum of the long-term dependence the deceleration of the horizontal flow is observed above the highest part of Aphrodite Terra, Ovda Regio, for both VMC and UVI. Conversely, acceleration is observed above the Ovda Regio near the maximum of the long-term dependence. The considered longitudinal variations of the zonal wind speed extend from the equator to middle latitudes (0°–40°). The meridional wind speed shows longitudinal variations associated with the topography of the underlying surface, regardless of whether the horizontal flow is slowing down or accelerating above the highlands of Aphrodite Terra.

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 ).

This research studies the O 2 (a 1 Δ g ) nightglow distribution in 1.27 μm to understand the dynamics of the atmosphere of Venus. Several factors were considered in the retrieval process, such as thermal emission of the lower atmosphere, reflection by the clouds. Results show deviation from SS-AS circulation mode: the area where horizontal flows from the dayside converge and where oxygen recombines and emits shifts from the midnight to 22–23 hours local time. This shift is caused by solar-induced thermal tide on Venus nightside. Some conclusions about the upper mesosphere dynamics are also presented.

In the framework of the project "Venera-D" a problem of landing the descent module in a given area of the surface of Venus is considered. With the standard approach to selection of the launch window and with limitations on the value of the re-entry angle into the atmosphere, as well as on the maximum allowable overload for lander during descent, a significant part of the planet’s surface is inaccessible for landing. The simplest way to expand the landing area could be to increase the launch window by moderate reducing the payload mass. However, the potential for such an increase is significantly limited, primarily by the required characteristic velocity cost. In this study a new approach is proposed to ensure landing of the descent module at any point on the surface of Venus. The basis of the proposed approach is the use of the gravitational field of the planet to transfer the spacecraft to the heliocentric orbit, resonant at a ratio of 1:1 with the orbit of Venus, and the subsequent return to its original position in one Venusian year, when another part of the surface will be available for landing. In the presented paper it is shown that application of new approach allows to provide radical expansion of achievable landing areas, and also to provide access to any point on the surface of Venus due to increase of duration of flight and small increase of characteristic velocity costs

A problem of determining attainable landing sites on the surface of Venus is an essential part of the Venera-D project aimed to explore the planet using a lander. This problem appears due to the inability for the descent module to land at any point on the surface of Venus because of the short duration of the launch window (about 2 weeks from the optimal launch date), as well as restrictions on the maximum permissible overload. An additional factor affecting the reduction of attainable landing sites is the low angular velocity of Venus' own rotation. This study proposes a new approach to expand the attainable landing areas. The approach is based on the use of the gravitational field of Venus to transfer the spacecraft to an orbit resonant to the Venusian one with a ratio of periods of 1:1. All the simulations were performed at the patched conic approximation. As an example, we considered a flight to Venus at launch in 2029 or 2031. For both cases maps of attainable landing areas on the Venus surface were plotted. It has been demonstrated that there is always at least one launch date within the launch window allowing the spacecraft to reach almost any point on the surface of Venus. It is shown that the application of the proposed approach makes it possible to achieve a significant expansion of the attainable landing areas (over 70% of the surface) and, in some cases, provide access to any point on the surface of Venus. However, the price of this advantage is an increase in the flight duration by one Venusian year.

We present joint analysis of the UV (365 nm) images captured by the cameras on board ESA’s Venus Express and JAXA’s Akatsuki spacecraft. These observations enabled almost continuous characterization of the cloud top circulation over the longest period of time so far (2006–2021). More than 46,000 wind vectors were derived from tracking the UV cloud features and revealed changes in the atmospheric circulation with the period of 12.5 ± 0.5 years. The zonal wind component is characterized by an annual mean of −98.6 ± 1.3 m/s and an amplitude of 10.0 ± 1.6 m/s. The mean meridional wind velocity is −2.3 ± 0.2 m/s and has an amplitude of 3.4 ± 0.3 m/s. Plausible physical explanations of the periodicity include both internal processes and external forcing. Both missions observed periodical changes in the UV albedo correlated with the circulation variability. This could result in acceleration or deceleration of the winds due to modulation of the deposition of the radiative energy in the clouds. The circulation can be also affected by the solar cycle that has a period of approximately 11 years with a large degree of deviation from the mean. The solar cycle correlated with the wind observations can probably influence both the radiative balance and chemistry of the mesosphere. The discovered periodicity in the cloud top circulation of Venus, and especially its similarity with the solar cycle, is strongly relevant to the study of exoplanets in systems with variable “suns”.

The recently selected NASA VERITAS and DAVINCI missions, the ESA EnVision, the Roscosmos Venera‐D will open a new era in the exploration of Venus. One of the key targets of the future orbiting and in situ investigations of Venus is the identification of volcanically active areas on the planet. The study of the areas characterized by recent or ongoing volcano‐tectonic activity can inform us on how volcanism and tectonism are currently evolving on Venus. Following this key target, Brossier et al. (2022, https://doi.org/10.1029/2022GL099765 ) extend the successful approach and methodology used by previous works to Ganis Chasma in Atla Regio. Here we comment on the main results published in Brossier et al. (2022, https://doi.org/10.1029/2022GL099765 ) and discuss the important implications of their work for the future orbiting and in situ investigation of Venus. Their results add further lines of evidence indicating possibly recent volcanism on Venus.

We present more than 250,000 wind vectors derived from the visible (513 nm) images captured by the Venus Monitoring Camera (VMC) onboard ESA's Venus Express orbiter in the Southern hemisphere from 01 July 2007 to 29 January 2013. From comparison to the wind velocity derived from tracking of the descent probes, these measurements correspond to 60 ± 3 km altitude, being between two levels 70 ± 2 km and 55 ± 2 km, probed by VMC in ultraviolet (UV) (365 nm) and NIR (965 nm) channels, respectively. The mean zonal wind suggests retrograde circulation with mean zonal wind speed decreasing from 76.5 to 61.5 m/s at 30°–65°S. In low latitudes, 10–20°S, it increased to 82 m/s over the course of the mission. The mean zonal flow depends on local solar time and latitude and is affected by the large‐scale topography. The meridional winds indicated equatorward flow of up to 7 m/s in the middle and low cloud opposite to that derived from simultaneous UV observations at the cloud top.

The goal of this white paper is to advocate for a thorough monitoring of Venus' upper atmosphere, through future space missions.Venus is a natural laboratory, which enables the study of solar wind interactions with planetary bodies without intrinsic magnetic field.Beyond the basic knowledge of the composition, structure, and dynamics of an atmosphere, aeronomic emissions provide further elements toward answering fundamental questions related to dynamics, energy transport, escape processes, solar wind/magnetospheric interactions with the upper atmospheres and the history of water at Venus.This paper includes an overview of the current state of knowledge on the upper atmosphere circulation regimes, identifies knowledge gaps that need to be addressed, and emphasizes strong arguments on why we need to go back to Venus.Additionally, we highlight which upper atmosphere observations are necessary to improve Global Climate Models (GCM) and our understanding of atmospheric physical processes at play.

Combining geologic mapping and stratigraphic reconstruction of lava flows at Sapas, Maat and Ozza Montes, three potentially young volcanic structures of Atla Regio on Venus, with analysis of the spectral signature (radar emissivity anomalies) characterizing each mapped flow, Brossier et al. (2021, https://doi.org/10.1029/2020je006722), conclude that some of the lava flows at Maat Mons may be geologically recent (∼25 Ma) (Smrekar et al., 2010, https://doi.org/10.1126/science.1186785; D'Incecco et al., 2017, https://doi.org/10.1016/j.pss.2016.12.002; Zolotov, 2018, https://doi.org/10.1515/rmg.2018.84.10; Brossier et al., 2020, https://doi.org/10.1016/j.icarus.2020.113693, 2021, https://doi.org/10.1029/2020je006722). The lava flows of Sapas and Ozza Montes are consistent with weathered lava flows forming chlorapatite and some perovskite oxides. We discuss the reasons why, besides the importance of the results they obtained, the methodology they used can be very valuable for future investigations with higher resolution datasets.

We consider the concept of applying gravity assist maneuvers near Venus using resonant orbits with a period equal to the Venusian one. We show that the proposed operations based on this concept allow the reachable landing areas on the surface of Venus to be expanded radically. The price of this approach is an increase of the time interval needed to solve this problem by a value equal to the orbital period of Venus. The cost of the characteristic velocity in this case remains within limits close to the standard variants of planning missions to Venus.

The horizontal wind velocity vectors at the lower cloud layer were retrieved by tracking the displacement of cloud features using the 1.74 µm images of the full Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS-M) dataset. This layer was found to be in a superrotation mode with a westward mean speed of 60–63 m s−1 in the latitude range of 0–60° S, with a 1–5 m s−1 westward deceleration across the nightside. Meridional motion is significantly weaker, at 0–2 m s−1; it is equatorward at latitudes higher than 20° S, and changes its direction to poleward in the equatorial region with a simultaneous increase of wind speed. It was assumed that higher levels of the atmosphere are traced in the equatorial region and a fragment of the poleward branch of the direct lower cloud Hadley cell is observed. The fragment of the equatorward branch reveals itself in the middle latitudes. A diurnal variation of the meridional wind speed was found, as east of 21 h local time, the direction changes from equatorward to poleward in latitudes lower than 20° S. Significant correlation with surface topography was not found, except for a slight decrease of zonal wind speed, which was connected to the volcanic area of Imdr Regio.

In 2010 the ESA Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument first observed 1 μ m emissivity anomalies over the top and eastern flank of Idunn Mons (46° S; 146° W), a 200 km wide volcano located in Imdr Regio, a volcano-dominated large volcanic rise of Venus. The anomalies suggest the presence of chemically unweathered and fresh volcanic deposits, which provided the first hint that volcanism in this area may have been active during the past few million years. Subsequent studies have investigated the geologic and atmospheric evolution at Idunn Mons, but no study has comprehensively investigated the evolution and the implication for recent activity in Idunn Mons. Previous work, using both VIRTIS data and Magellan radar emissivity data, confirmed the occurrence of unaltered basaltic lava flows at Idunn Mons. Building on that previous work, experimental laboratory studies have revealed that chemical weathering on Venus may act much faster than previously expected, which suggests very young ages for these flows. This inference has been supported by investigations of the tectonic fracturing surrounding Idunn Mons. Finally, atmospheric data from VIRTIS also show regional anomalies in the speed of the winds in the lower atmosphere over Imdr Regio, which may be related to very recent or ongoing volcanism. In this paper, we take a comprehensive approach, using atmospheric to surface measurements, including recent laboratory experiments, to constrain the evolution of Idunn Mons. Our work suggests that Idunn Mons may be geologically both volcanically and tectonically active today.

A number of new Venus mission concepts are being currently evaluated for final approval, such as the NASA VERITAS and DAVINCI+, the Roscosmos-NASA Venera-D and the ESA EnVision proposals. These missions would analyze different aspects of the Earth's twin planet: the chemistry and structure of its atmosphere, the spectral characteristics and composition of its surface, and its gravity anomalies. The wealth of high-resolution data to be produced by these future missions would likely shed new light on the major science questions. In this regard, one of the major debates concerns whether Venus underwent (and it is currently undergoing) through several episodes of abrupt and catastrophic resurfacing which rejuvenated its entire surface in a short amount of time, or its volcanism has been more steady and constant in time. Recent studies of Imdr Regio, one of the young volcanic rises, have provided hints indicating that volcanic as well as tectonic activity may be still ongoing in that area. The young volcanic rises are generated and supported by underlying active mantle plumes and can be considered as the some of the youngest geologic terrains of Venus. Studying how the rate and styles of volcanic and tectonic activities are evolving through time will tell us more about the interior structure of Venus, shedding some light on the major debate between catastrophic and equilibrium resurfacings. For this reason, we propose here the young volcanic rises, and in particular Idunn Mons of Imdr Regio, as potential target sites for future orbital and in-situ investigations.

The baseline Venera-D mission, proposed to be launched after 2026, consists of an orbiter and a landing module, which includes a lander and a small long-lived station. In this work, we present the possibility of augmenting the mission with one or two micro-spacecraft in Lagrange point orbits to significantly enhance the science return. Both L1 and L2 collinear points, situated at about 1 million km from Venus, are considered for scientific objectives. The paper focuses on trajectory design for the micro-spacecraft to be deployed by the Venera-D mission. The transfer scenario we propose performs the insertion of micro-spacecraft into Lagrange point orbit by making use of the main orbiter’s propulsion, while the propulsion on board micro-spacecraft is used only for trajectory correction and station-keeping manoeuvres. This scenario allows the Venera-D mission to add one or two micro-spacecraft of mass about 50 kg with only a total ΔV budget 30 m/s over 3 years on orbit.

This research is aimed to understand circulation of the Venusian atmosphere at the lower cloud level (44-48 km) and its variations with time, latitude, longitude and local time. On the nightside winds at these altitudes can be tracked from the orbit by using infrared imaging instruments. Here we compare results obtained in the same spectral window of 1.74 μm by two instruments flown on two most recent missions to Venus. Comparison of the results shows accordance in the meridional component direction and magnitude, however a significant difference in the values of the zonal component of the wind. Mean zonal speed measured from IR2 data in 2016 exceeds that of VIRTIS-M data in 2006-2008 by a value up to 16 m s -1 . Because of recent investigations of the stationary gravity waves and their potential influence on the atmospheric circulation [3], we examined longitude-latitude dependence of the wind velocities and found variations that can be attributed to such mechanisms.