Examining the Recent Volcanic Activity on Venus' Idunn Mons by Venus Express

Idunn Mons on Venus: location and extent of recently active lava flows

Authors:

D'Inecco et al

Abstract:

From 2006 until 2014 the ESA Venus Express probe observed the atmosphere and surface of the Earth's twin planet. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) has provided data that indicate the occurrence of recent volcanic activity on Venus. We selected the eastern flank of Idunn Mons - Imdr Regio's single large volcano – as the study area, since it was identified in VIRTIS data as one of the regions with relatively high values of thermal emissivity at 1 μm wavelength. Using the capabilities of specific techniques developed in the Planetary Emissivity Laboratory group at DLR in Berlin, our study intends to identify location and extent of the sources of such anomalies, thus the lava flows responsible for the relatively high emissivity observed by VIRTIS over the eastern flank of Idunn Mons. We map the lava flow units on the top and eastern flank of Idunn Mons, varying the values of simulated 1 μm emissivity assigned to the mapped units. For each configuration we calculate the total RMS error in comparison with the VIRTIS observations. In the best-fit configuration, the flank lava flows are characterized by high values of 1 μm simulated emissivity. Hence, the lava flow units on the eastern flank on Idunn Mons are likely responsible for the relatively high 1 μm emissivity anomalies observed by VIRTIS. This result is supported by the reconstructed post-eruption stratigraphy, displaying the relative dating of the mapped lava flows, that is independent of the 1 μm emissivity modeling. Values of average microwave emissivity extracted from the lava flow units range around the global mean, which is consistent with dry basalts.

Exploring Venus' Atmospheric Superrotation With Simulations

Exploring the Venus global super-rotation using a comprehensive General Circulation Model

Authors:

Mendonça et al

Abstract:

The atmospheric circulation in Venus is well known to exhibit strong super-rotation. However, the atmospheric mechanisms responsible for the formation of this super-rotation are still not fully understood. In this work, we developed a new Venus general circulation model to study the most likely mechanisms driving the atmosphere to the current observed circulation. Our model includes a new radiative transfer, convection and suitably adapted boundary layer schemes and a dynamical core that takes into account the dependence of the heat capacity at constant pressure with temperature.

The new Venus model is able to simulate a super-rotation phenomenon in the cloud region quantitatively similar to the one observed. The mechanisms maintaining the strong winds in the cloud region were found in the model results to be a combination of zonal mean circulation, thermal tides and transient waves. In this process, the semi-diurnal tide excited in the upper clouds has a key contribution in transporting axial angular momentum mainly from the upper atmosphere towards the cloud region. The magnitude of the super-rotation in the cloud region is sensitive to various radiative parameters such as the amount of solar radiative energy absorbed by the surface, which controls the static stability near the surface. In this work, we also discuss the main difficulties in representing the flow below the cloud base in Venus atmospheric models.

Our new radiative scheme is more suitable for 3D Venus climate models than those used in previous work due to its easy adaptability to different atmospheric conditions. This flexibility of the model was crucial to explore the uncertainties in the lower atmospheric conditions and may also be used in the future to explore, for example, dynamical-radiative-microphysical feedbacks.

Was Venus Habitable Until the the Start of Earth's Sturtian Glaciations (Snowball Earth)

Was Venus the First Habitable World of our Solar System?

Authors:

Way et al

Abstract:

Present-day Venus is an inhospitable place with surface temperatures approaching 750K and an atmosphere over 90 times as thick as present day Earth's. Billions of years ago the picture may have been very different. We have created a suite of 3D climate simulations using topographic data from the Magellan mission, solar spectral irradiance estimates for 2.9 and 0.715 billion years ago, present day Venus orbital parameters, an ocean volume consistent with current theory and measurements, and an atmospheric composition estimated for early Venus. Using these parameters we find that such a world could have had moderate temperatures if Venus had a rotation period slower than about 16 Earth days, despite an incident solar flux 46-70% higher than modern Earth receives. At its current rotation period of 243 days, Venus's climate could have remained habitable until at least 715 million years ago if it hosted a shallow primordial ocean. These results demonstrate the vital role that rotation and topography play in understanding the climatic history of exoplanetary Venus-like worlds being discovered in the present epoch.

Extraordinary Claim: Venus COuld be the Source of Complex Life on Earth

The Venus Hypothesis

Author:

Cartwright

Abstract:

Current models indicate that Venus may have been habitable. Complex life may have evolved on the highly irradiated Venus, and transferred to Earth on asteroids. This model fits the pattern of pulses of highly developed life appearing, diversifying and going extinct with astonishing rapidity through the Cambrian and Ordovician periods, and also explains the extraordinary genetic variety which appeared over this period.

Was Venus Habitable for 2 Billion Years?

Venus may have had a shallow liquid-water ocean and habitable surface temperatures for up to 2 billion years of its early history, according to computer modeling of the planet's ancient climate by scientists at NASA's Goddard Institute for Space Studies (GISS) in New York.

The findings, published this week in the journal Geophysical Research Letters, were obtained with a model similar to the type used to predict future climate change on Earth.

"Many of the same tools we use to model climate change on Earth can be adapted to study climates on other planets, both past and present," said Michael Way, a researcher at GISS and the paper's lead author. "These results show ancient Venus may have been a very different place than it is today."

Venus today is a hellish world. It has a crushing carbon dioxide atmosphere 90 times as thick as Earth's. There is almost no water vapor. Temperatures reach 864 degrees Fahrenheit (462 degrees Celsius) at its surface.

Scientists long have theorized that Venus formed out of ingredients similar to Earth's, but followed a different evolutionary path. Measurements by NASA's Pioneer mission to Venus in the 1980s first suggested Venus originally may have had an ocean. However, Venus is closer to the sun than Earth and receives far more sunlight. As a result, the planet's early ocean evaporated, water-vapor molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space. With no water left on the surface, carbon dioxide built up in the atmosphere, leading to a so-called runaway greenhouse effect that created present conditions.

Previous studies have shown that how fast a planet spins on its axis affects whether it has a habitable climate. A day on Venus is 117 Earth days. Until recently, it was assumed that a thick atmosphere like that of modern Venus was required for the planet to have today's slow rotation rate. However, newer research has shown that a thin atmosphere like that of modern Earth could have produced the same result. That means an ancient Venus with an Earth-like atmosphere could have had the same rotation rate it has today.

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Lush Venus & Crispy Earth: Solar System Sister Planets Could Have 'Swapped' Climates

If conditions had been just a little different an eon ago, there might be plentiful life on Venus and none on Earth.

The idea isn't so far-fetched, according to a hypothesis by Rice University scientists and their colleagues who published their thoughts on life-sustaining planets, the planets' histories and the possibility of finding more in Astrobiology this month.

The researchers maintain that minor evolutionary changes could have altered the fates of both Earth and Venus in ways that scientists may soon be able to model through observation of other solar systems, particularly ones in the process of forming, according to Rice Earth scientist Adrian Lenardic.

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Obliquity Variability of a Potentially Habitable Early Venus

Obliquity Variability of a Potentially Habitable Early Venus

Authors:

Barnes et al

Abstract:

Venus currently rotates slowly, with its spin controlled by solid-body and atmospheric thermal tides. However, conditions may have been far different 4 billion years ago, when the Sun was fainter and most of the carbon within Venus could have been in solid form, implying a low-mass atmosphere. We investigate how the obliquity would have varied for a hypothetical rapidly rotating Early Venus. The obliquity variation structure of an ensemble of hypothetical Early Venuses is simpler than that Earth would have if it lacked its large moon (Lissauer et al., 2012), having just one primary chaotic regime at high prograde obliquities. We note an unexpected long-term variability of up to ±7° for retrograde Venuses.

Venus' Electric Wind' Helped Render it Uninhabitable

Venus has an "electric wind" strong enough to remove the components of water from its upper atmosphere, which may have played a significant role in stripping Earth's twin planet of its oceans, according to new results from ESA's (European Space Agency) Venus Express mission by NASA-funded researchers.

"It's amazing, shocking," said Glyn Collinson, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "We never dreamt an electric wind could be so powerful that it can suck oxygen right out of an atmosphere into space. This is something that has to be on the checklist when we go looking for habitable planets around other stars." Collinson is lead author of a paper about this research published June 20, 2016, in the journal Geophysical Research Letters.

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No Statistic Evidence of Lightning on Venus

No statistical evidence of lightning in Venus night-side atmosphere from VIRTIS-Venus Express Visible observations

Authors:

Cardesín Moinelo et al

Abstract:

In this study we describe a dedicated analysis of luminous transient events on Venus night side atmosphere with the visible channel of the VIRTIS instrument (280–1100 nm), this being the most comprehensive search of lightning conducted so far with Venus Express data. Our search results in thousands of signal detections, but unfortunately they can be all explained by cosmic rays impinging on the detector, and further statistical analysis shows that all of the events are randomly distributed along the spectral dimension, therefore not showing any clear evidence of signal coming from lightning emission in the Venus atmosphere. This does not exclude the existence of lightning, but imposes some constraints on their occurrence that are important for future research.

Recent volcanic resurfacing of Venusian craters

Recent volcanic resurfacing of Venusian craters

Authors:

Whitten et al

Abstract:

Ejecta from impact craters on Venus are a major source of fine-grained materials across the planet, and crater spatial distribution has been studied as a guide to the relative age and resurfacing rates of large regions. Of particular interest is the potential intersection of distal crater deposits and tesserae, highly deformed landforms that may be the oldest materials on Venus. The composition of tesserae is unknown, but is key to understanding whether water played a role in crustal differentiation. Thus, tesserae are ideal sites for future landed missions to identify possible felsic materials, but the short lifespan of surface landers means that efforts must be made to avoid contaminating surface materials from craters. Here we develop a method to detect distal crater ejecta on tessera terrain across Venus using NASA Magellan radar data. Our results show that fine-grained ejecta are unevenly distributed in the tesserae with respect to nearby craters. Many tesserae within a few hundred kilometers of plains craters do not have evidence for thick (greater than 5–10 cm) mantling material, indicating that eolian or mass-wasting processes have moved the debris off the highland ridge slopes. At Sudenitsa Tesserae, within the young Beta-Atla-Themis region, we observe a radar signature of mantling debris, but there is no apparent source crater to which this material can be traced. We infer that the source crater has been resurfaced by volcanic activity within the past 80 m.y., and suggest that similar fine-grained ejecta deposits may have built up over time in other tesserae across Venus.

Atmospheric nitrogen evolution on Earth and Venus

Atmospheric nitrogen evolution on Earth and Venus

Author:

Wordsworth et al

Abstract:

Nitrogen is the most common element in Earth's atmosphere and also appears to be present in significant amounts in the mantle. However, its long-term cycling between these two reservoirs remains poorly understood. Here a range of biotic and abiotic mechanisms are evaluated that could have caused nitrogen exchange between Earth's surface and interior over time. In the Archean, biological nitrogen fixation was likely strongly limited by nutrient and/or electron acceptor constraints. Abiotic fixation of dinitrogen becomes efficient in strongly reducing atmospheres, but only once temperatures exceed around 1000 K. Hence if atmospheric N2 levels really were as low as they are today 3.0 - 3.5 Ga, the bulk of Earth's mantle nitrogen must have been emplaced in the Hadean, most likely at a time when the surface was molten. The elevated atmospheric N content on Venus compared to Earth can be explained abiotically by a water loss redox pump mechanism, where oxygen liberated from H2O photolysis and subsequent H loss to space oxidises the mantle, causing enhanced outgassing of nitrogen. This mechanism has implications for understanding the partitioning of other Venusian volatiles and atmospheric evolution on exoplanets.

Venus was Recently Resurfaced

Mantle potential temperature estimates of basalt from the surface of Venus

Author:

Shellnutt

Abstract:

The crater density and distribution of Venus indicates the average surface age is younger (≤1 Ga) than most terrestrial planets and satellites in the Solar System. The type and rate (i.e. equilibrium, catastrophic or differential) of volcanism associated with the stagnant lid tectonic system of Venus is a first order problem that has yet to be resolved but is directly related to the thermal conditions of the mantle. The calculated primary melt composition of basalt at the Venera 14 landing site is high-Mg basalt to picrite with a mantle potential temperature estimate similar to terrestrial ambient mantle (1370 ± 70 °C). The calculated accumulated fractional melting curves indicate the olivine compositions from the melt have Mg# of 89–91. The results show that the thermal regime required to generate the primary melt composition of the Venera 14 basalt was not anomalously high (i.e. mantle-plume system) but rather consistent with a lithospheric tensional rift system. The juxtaposition of high thermal regime structures (e.g. Beta Regio) and ‘ambient’ mantle potential temperature estimates of the Venera 14 basalt suggests that the relatively young surface of Venus is the result of volcanism from a combination of thermal systems that resurfaced the planet at variable rates.

Japan's Akatsuki Spacecraft Entered Orbit Around Venus

In space exploration, second chances are rare. Yet today, just before 4 p.m. U.S. Pacific time, a Japanese spacecraft called Akatsuki fired its thrusters and attempted to rendezvous with Venus.

An hour later, the team commanding the spacecraft shared some good news.

“It is in orbit!!” reported Sanjay Limaye of the University of Wisconsin-Madison, who is working with the science team in Sagamihara, Japan.

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Venus has Stronger Surface Winds Than Earth

Surface winds on Venus: Probability distribution from in-situ measurements

Author:

Lorenz

Abstract:

A surface wind specification is needed for future landed missions to Venus. While sparse, there exist enough data from the limited surface and near-surface measurements to date to define a probability density function that guides expectations of winds for rational design of landing systems. Following a review of all available data (mostly from the Venera missions), a Weibull function, used previously for Mars and Titan, and widely used in terrestrial engineering applications, is proposed. Best-estimate wind measurements are reasonably described by P( greater than V) = exp[−(V/c)k], with c = 0.8 m/s, k = 1.9: this function yields a 95% chance of winds less than 1.4 m/s and 99% less than 1.8 m/s. A worst-case function, allowing the high end of Venera measurement uncertainties to force the fit, has slightly higher values (c = 0.9 m/s, k = 1.7; 95% wind 1.7 m/s; 99%, 2.2 m/s). The data suggest that winds strong enough to move dust and sand on Venus are rather common (more so than is typical for Mars, Earth or Titan), a prediction testable with radar interferometry on future orbital missions and/or from landed observations. More elaborate analyses should take site-specific factors such as slope or time of day into account, but cannot be meaningfully constrained by present data.

NASA Weighing two Discovery Mission Awards

NASA might end up funding two of the five mission concepts just selected for further study in the latest Discovery-class planetary science mission competition, a senior agency official said.

“We are not committing to selecting two, but we are stating that we may choose either one or two,” David Schurr, NASA’s deputy director for Planetary Science, wrote in an Oct. 1 email.

NASA winnowed a field of 27 competitors down to five Sept. 30, evenly splitting $15 million in one-year study money among two Venus concepts and three asteroid concepts in the long-awaited first down-select for the agency’s 13th small robotic solar-system mission competition. Final selection, of either one mission or two, is expected in September 2016, NASA said in a press release.

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Lessons From Venus: Impact Origin of Archean Cratons

Impact origin of Archean cratons

Author:

Hansen

Abstract:

Archean cratons consist of crustal granite-greenstone terrains (GGTs) coupled to roots of strong, buoyant cratonic lithospheric mantle (CLM). Although this association is unique to the Archean and formed from ca. 4.0 to 2.5 Ga, the origins of terrestrial cratons are debated. I propose that crustal plateaus, quasi-circular craton-like features (∼1400−2400 km diameter, 0.5−4 km high), on Earth’s sister planet Venus might serve as analogs for Archean cratons. Crustal plateaus, which are isostatically supported by a compositionally controlled low-density root, host a distinctive surface called ribbon-tessera terrain. Ribbon-tessera also occurs as arcuate-shaped inliers in the Venus lowlands, widely interpreted as remnants of rootless crustal plateaus. Within each crustal plateau, surface ribbon-tessera terrain comprises a vast igneous province analogous to terrestrial GGTs, and the plateau root is analogous to CLM. Crustal plateaus and ribbon-tessera terrain collectively represent Venus’ oldest preserved features and surfaces, and they formed during an ancient period of globally thin lithosphere. To explain the linked features of crustal plateaus, a bolide impact hypothesis has been proposed in which a large bolide pierces ancient thin lithosphere, leading to massive partial melting in the sublithospheric mantle. In this model, melt escapes to the surface, forming an enormous lava pond, which evolves to form ribbon-tessera terrain; mantle melt residue forms a strong, resilient buoyant root, leading to plateau support and long-term stability of an individual crustal plateau. Building on the similarity of GGT−CLM and Venus crustal plateaus, I propose an exogenic hypothesis for Archean craton formation in which a large bolide pierces thin Archean lithosphere, causing localized high-temperature, high-fraction partial melting in the sublithospheric mantle; melt rises, forming an igneous province that evolves as a GGT, and melt residue develops a complementary CLM. By this mechanism, Archean cratons may have formed in a spatially and temporally punctuated fashion at a time when large bolides showered Archean Earth.

Short PR.

How Well can we Detect Volcanic Activity on Venus With Radar Imaging Space Probes

Probabilistic Constraints from Existing and Future Radar Imaging on Volcanic Activity on Venus

Author:

Lorenz

Abstract:

We explore the quantitative limits that may be placed on Venus' present-day volcanic activity by radar imaging of surface landforms. The apparent nondetection of new lava flows in the areas observed twice by Magellan suggests that there is a ~60% chance that the eruption rate is ~1 km3/yr or less, using the eruption history and area/volume flow geometry of terrestrial volcanos (Etna, Mauna Loa and Merapi) as a guide. However, if the detection probability of an individual flow is low (e.g. ~10%) due to poor resolution or quality and unmodeled viewing gemetry effects, the constraint (less than 10 km3/yr) is not useful. Imaging at Magellan resolution or better of only ~10% of the surface area of Venus on a new mission (30 years after Magellan) would yield a better than 99% chance of detecting a new lava flow, even if volcanic activity is at the low end of predictions (~0.01 km3/yr) and is expressed through a single volcano with a stochastic eruption history. Closer re-examination of Magellan data may be worthwhile, both to search for new features, but also to establish formal (location-dependent) limits on activity against which data from future missions can be tested. While Magellan-future and future-future comparisons should offer much lower detection thresholds for erupted volumes, a probabilistic approach will be required to properly understand the implications.

Venus has Active Volcanoes

An international team of scientists has found some of the best evidence yet that Venus, Earth's nearest neighbor, is volcanically active.

In combing through data from the European Space Agency's Venus Express mission, the scientists found transient spikes in temperature at several spots on the planet's surface. The hotspots, which were found to flash and fade over the course of just a few days, appear to be generated by active flows of lava on the surface.

"We were able to show strong evidence that Venus is volcanically, and thus internally, active today," said James W. Head, a geologist at Brown University and co-author of a paper describing the new research. "This is a major finding that helps us understand the evolution of planets like our own."

The research is published online in Geophysical Research Letters.

The hotspots turned up in thermal imaging taken by the Venus Express spacecraft's Venus Monitoring Camera. The data showed spikes in temperature of several hundred degrees Fahrenheit in spots ranging in size from 1 square kilometer to over 200 kilometers.

The spots were clustered in a large rift zone called Ganiki Chasma. Rift zones are formed by stretching of the crust by internal forces and hot magma that rises toward the surface. Head and Russian colleague Mikhail Ivanov had previously mapped the region as part of a global geologic map of Venus generated from the Soviet Venera missions in the 1980s and U.S. Magellan mission in the 1990s. The mapping work had shown that Ganiki Chasma was quite young, geologically speaking, but just how young wasn't clear until now.

"We knew that Ganiki Chasma was the result of volcanism that had occurred fairly recently in geological terms, but we didn't know if it formed yesterday or was a billion years old," Head said. "The active anomalies detected by Venus Express fall exactly where we had mapped these relatively young deposits and suggest ongoing activity."

The latest finding is consistent with other data from Venus Express that have hinted at very recent volcanic activity. In 2010, infrared imaging from several volcanoes seemed to indicate lava flows from thousands to a few million years old. A few years later, scientists reported transient spikes in sulfur dioxide in Venus' upper atmosphere, another potential signal of active volcanism.

The observation of hotspots by Venus Express, combined with the geologic mapping from Venera and Magellan, make a strong case for a volcanically active Venus, Head says.

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VAMP: Northrop's Venus Aircraft Proposal for the Next New Frontiers Mission

Northrop Grumman is developing an inflatable, propeller-powered aircraft for a years-long cruise in the sulfurous skies of Venus and is gearing up to enter the concept in NASA’s next New Frontiers planetary science competition.

That Northrop believes its Venus Atmospheric Maneuverable Platform, or VAMP, could be ready to compete for about $1 billion in NASA funding as soon as Oct. 1 is a testament to the company’s confidence in the concept, which despite arousing the intrigue of some Venus scientists is technically immature and likely to face competition from finalists of NASA’s last New Frontiers contest.

“I think we can be ready,” Ron Polidan, Northrop’s Redondo, California-based chief architect of civil systems, told SpaceNews.

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Photochemical Control of the Distribution of Venusian Water

Photochemical control of the distribution of Venusian water

Authors:

Parkinson et al

Abstract:

We use the JPL/Caltech 1-D photochemical model to solve the continuity diffusion equation for the atmospheric constituent abundances and total number density as a function of radial distance from the planet Venus. The photochemistry of the Venus atmosphere from 58 to 112 km is modeled using an updated and expanded chemical scheme (Zhang et al., 2010 and Zhang et al., 2012), guided by the results of recent observations and we mainly follow these references in our choice of boundary conditions for 40 species. We model water from between 10–35 ppm at our 58 km lower boundary using an SO2 mixing ratio of 25 ppm as our nominal reference value. We then vary the SO2 mixing ratio at the lower boundary between 5 and 75 ppm holding the water mixing ratio of 18 ppm at the lower boundary and find that it can control the water distribution at higher altitudes. SO2 and H2O can regulate each other via formation of H2SO4. In regions of high mixing ratios of SO2 there exists a “runaway effect” such that SO2 gets oxidized to SO3, which quickly soaks up H2O causing a major depletion of water between 70 and 100 km. Eddy diffusion sensitivity studies performed characterising variability due to mixing show less of an effect than varying the lower boundary mixing ratio value. However, calculations using our nominal eddy diffusion profile multiplied and divided by a factor of four can give an order of magnitude maximum difference in the SO2 mixing ratio and a factor of a few difference in the H2O mixing ratio when compared with the respective nominal mixing ratio for these two species. In addition to explaining some of the observed variability in SO2 and H2O on Venus, our work can also shed light on the observations of dark and bright contrasts at the Venus cloud tops observed in the ultraviolet spectrum. Our calculations produce results in agreement with the SOIR Venus Express results of 1 ppm at 70–90 km (Bertaux et al. (2007) by and using an SO2 mixing ratio of 25 ppm SO2 and 18 ppm water as our nominal reference values. Timescales for a chemical bifurcation causing a collapse of water concentrations above the cloudtops (greater than 64 km) are relatively short and on the order of a less than a few months, decreasing with altitude to less than a few days.