Under pressure -- space exploration in our time

In the past decade, humanity has seen the birth and expansion of a commercial space sector with new, private players, addressing technological challenges -- from space launch to communication and satellite imagery of Earth. Last year, the global space industry skyrocketed launching more than 2,660 satellites into orbit, and, into the universe, interplanetary probes, landers, and much more. In the United States, SpaceX was responsible for almost 90% of these launches. In parallel to this progression is the expansion of more than 70 countries demonstrating space capabilities. It affirms the general consensus and understanding that humanity will continue to rely on space activities to better the human experience. These developments create a novel landscape of both competition and collaboration for scientists, offering both challenges and opportunities.

In an increasingly fragmented world, the scientific community stands as an example of successful international collaboration and diplomacy.

Science is based in a long-standing tradition of knowledge exchange that often transcends political boundaries for the benefit of all humanity.

Cost-effective, commercial space technologies can enable novel research or reduce the cost of investigations opening new possibilities for the scientific community.

At the same time, international partnerships can further broaden engagement, diversity, and collaboration in science and space exploration.

While this might seem like a "win-win" scenario, the interest of the scientific community is to openly share data and analysis.

Differing principles and ideals present potential areas of conflict.

As governments and private entities fund bold, new projects, leaders, academics, and legal experts are contemplating both the larger consequences, as well as potential prospects.

High stakes leadership and landing on Mars

"When every mission is a first for humanity, the stakes are very high," says Thomas Zurbuchen who led 54 missions as NASA's longest serving Associate Administrator for the Science Mission Directorate.

"When the clock is ticking, and the world is watching, a leader's most powerful asset is a highly diverse team," he says.

Within this context, diversity can emerge from international and commercial partnerships, and can give rise to new missions.

In fact, an estimated two-thirds of science missions have international partnerships.

Now, as the Director for ETH Zurich Space, in Switzerland, Zurbuchen reflects on the value of partnerships as a leadership tool.

He uses examples from recent international missions, such as Mars InSight, to discuss how diversity creates opportunities for new and different ideas to come forward -- even if some ideas pose an element of risk.

He also addresses some of the challenges arising from partnerships.

For example, some companies and countries prefer not to share their science data gathered in space, making reproducibility challenging for scientific analysis.

Cross-border diffusion -- learning from lightning on Venus

"Scientific ideas move like space plasmas," says David Malaspina, a space plasma physicist at University of Colorado, Boulder.

"When they encounter a border, they find a way across." Malaspina describes international academic collaborations as vital engines of discovery and attributes the language of science for fostering a sense of awe and wonder for the universe that transcends cultures.

In science, and in plasmas, the most interesting physics happens at the boundaries.

Malaspina engages in international and generationally diverse research teams, including a team building a sounding rocket to explore the interface between Earth and space.

He is also a member of a team that uses data from the Parker Solar Probe mission to explore Venus, seeking to understand the importance of a planetary magnetic field for habitability of Earth-like planets.

He discusses how teams that foster inclusion of diverse perspectives create new opportunities for scientific progress.

Why protect bootprints on the Moon?

Unlike ancient footprints, cave drawings, and stone-age tools found here on Earth, the first traces of human activity on the Moon, including Neil Armstrong's bootprint, are not protected under any existing laws or regulations.

Michelle Hanlon, space lawyer and Executive Director of the Center for Air and Space Law at the University of Mississippi School of Law, thinks this is a travesty.

Read more at Science Daily

Mysterious missing component in the clouds of Venus revealed

What are the clouds of Venus made of? Scientists know it's mainly made of sulfuric acid droplets, with some water, chlorine, and iron. Their concentrations vary with height in the thick and hostile Venusian atmosphere. But until now they have been unable to identify the missing component that would explain the clouds' patches and streaks, only visible in the UV range.

In a new study published in Science Advances, researchers from the University of Cambridge synthesised iron-bearing sulfate minerals that are stable under the harsh chemical conditions in the Venusian clouds.

Spectroscopic analysis revealed that a combination of two minerals, rhomboclase and acid ferric sulfate, can explain the mysterious UV absorption feature on our neighbouring planet.

"The only available data for the composition of the clouds were collected by probes and revealed strange properties of the clouds that so far we have been unable to fully explain," said Paul Rimmer from the Cavendish Laboratory and co-author of the study.

"In particular, when examined under UV light, the Venusian clouds featured a specific UV absorption pattern. What elements, compounds, or minerals are responsible for such observation?"

Formulated on the basis of Venusian atmospheric chemistry, the team synthesized several iron-bearing sulfate minerals in an aqueous geochemistry laboratory in the Department of Earth Sciences.

By suspending the synthesized materials in varying concentrations of sulfuric acid and monitor the chemical and mineralogical changes, the team narrowed down the candidate minerals to rhomboclase and acid ferric sulfate, of which the spectroscopic features were examined under light sources specifically designed to mimic the spectrum of solar flares (Paul Rimmer and Samantha Thompson's FlareLab at the Cavendish Laboratory).

A photochemistry lab at Harvard collaborated in the research by providing measurements of the UV absorbance patterns of ferric iron under extreme acidic conditions, in an attempt to mimic the even more extreme Venusian clouds.

The scientists are part of the newly established Origins Federation, which promotes such collaborative projects.

"The patterns and level of absorption shown by the combination of these two mineral phases are consistent with the dark UV-patches observed in Venusian clouds," said co-author Clancy Zhijian Jiang, from the Department of Earth Sciences, Cambridge.

"These targeted experiments revealed the intricate chemical network within the atmosphere, and shed light on the elemental cycling on the Venusian surface."

"Venus is our nearest neighbour, but it remains a mystery," said Rimmer.

"We will have a chance to learn much more about this planet in the coming years with future NASA and ESA missions set to explore its atmosphere, clouds and surface. This study prepares the grounds for these future explorations."

Read more at Science Daily

Venus had Earth-like plate tectonics billions of years ago, study suggests

Venus, a scorching wasteland of a planet according to scientists, may have once had tectonic plate movements similar to those believed to have occurred on early Earth, a new study found. The finding sets up tantalizing scenarios regarding the possibility of early life on Venus, its evolutionary past and the history of the solar system.

Writing in Nature Astronomy, a team of scientists led by Brown University researchers describes using atmospheric data from Venus and computer modeling to show that the composition of the planet's current atmosphere and surface pressure would only have been possible as a result of an early form of plate tectonics, a process critical to life that involves multiple continental plates pushing, pulling and sliding beneath one another.

On Earth, this process intensified over billions of years, forming new continents and mountains, and leading to chemical reactions that stabilized the planet's surface temperature, resulting in an environment more conducive to the development of life.

Venus, on the other hand, Earth's nearest neighbor and sister planet, went in the opposite direction and today has surface temperatures hot enough to melt lead. One explanation is that the planet has always been thought to have what's known as a "stagnant lid," meaning its surface has only a single plate with minimal amounts of give, movement and gasses being released into the atmosphere.

The new paper posits that this wasn't always the case. To account for the abundance of nitrogen and carbon dioxide present in Venus' atmosphere, the researchers conclude that Venus must have had plate tectonics sometime after the planet formed, about 4.5 billion to 3.5 billion years ago. The paper suggests that this early tectonic movement, like on Earth, would have been limited in terms of the number of plates moving and in how much they shifted. It also would have been happening on Earth and Venus simultaneously.

"One of the big picture takeaways is that we very likely had two planets at the same time in the same solar system operating in a plate tectonic regime -- the same mode of tectonics that allowed for the life that we see on Earth today," said Matt Weller, the study's lead author who completed the work while he was a postdoctoral researcher at Brown and is now at the Lunar and Planetary Institute in Houston.

This bolsters the possibility of microbial life on ancient Venus and shows that at one point the two planets -- which are in the same solar neighborhood, are about the same size, and have the same mass, density and volume -- were more alike than previously thought before diverging.

The work also highlights the possibility that plate tectonics on planets might just come down to timing -- and therefore, so may life itself.

"We've so far thought about tectonic state in terms of a binary: it's either true or it's false, and it's either true or false for the duration of the planet," said study co-author Alexander Evans, an assistant professor of Earth, environmental and planetary sciences at Brown. "This shows that planets may transition in and out of different tectonic states and that this may actually be fairly common. Earth may be the outlier. This also means we might have planets that transition in and out of habitability rather than just being continuously habitable."

That concept will be important to consider as scientists look to understand nearby moons -- like Jupiter's Europa, which has shown proof of having Earth-like plate tectonics -- and distant exoplanets, according to the paper.

The researchers initially started the work as a way to show that the atmospheres of far-off exoplanets can be powerful markers of their early histories, before deciding to investigate that point closer to home.

They used current data on Venus' atmosphere as the endpoint for their models and started by assuming Venus has had a stagnant lid through its entire existence. Quickly, they were able to see that simulations recreating the planet's current atmosphere didn't match up with where the planet is now in terms of the amount nitrogen and carbon dioxide present in the current atmosphere and its resulting surface pressure.

The researchers then simulated what would have had to happen on the planet to get to where it is today. They eventually matched the numbers almost exactly when they accounted for limited tectonic movement early in Venus' history followed by the stagnant lid model that exists today.

Overall, the team believes the work serves as a proof of concept regarding atmospheres and their ability to provide insights into the past.

"We're still in this paradigm where we use the surfaces of planets to understand their history," Evans said. "We really show for the first time that the atmosphere may actually be the best way to understand some of the very ancient history of planets that is often not preserved on the surface."

Upcoming NASA DAVINCI missions, which will measure gasses in the Venusian atmosphere, may help solidify the study's findings. In the meantime, the researchers plan to delve deep into a key question the paper raises: What happened to plate tectonics on Venus? The theory in the paper suggests that the planet ultimately became too hot and its atmosphere too thick, drying up the necessary ingredients for tectonic movement.

"Venus basically ran out of juice to some extent, and that put the brakes on the process," said Daniel Ibarra, a professor in Brown's Department of Earth, Environmental and Planetary Sciences and co-author on the paper.

The researchers say the details of how this happened may hold important implications for Earth.

"That's going to be the next critical step in understanding Venus, its evolution and ultimately the fate of the Earth," Weller said. "What conditions will force us to move in a Venus-like trajectory, and what conditions could allow the Earth to remain habitable?"

Read more at Science Daily

Dune patterns reveal environmental change on Earth and other planets

Dunes, the mounds of sand formed by the wind that vary from ripples on the beach to towering behemoths in the desert, are incarnations of surface processes, climate change, and the surrounding atmosphere. For decades, scientists have puzzled over why they form different patterns.

Now, Stanford researchers have found a way to interpret the meaning of these patterns. Their results, published in Geology Aug. 1, can be used as a new tool for understanding environmental changes on any planetary body that harbors dunes, including Venus, Earth, Mars, Titan, Io, and Pluto.

"When you look at other planets, all you have is pictures taken from hundreds to thousands of kilometers away from the surface. You can see dunes -- but that's it. You don't have access to the surface," said senior study author Mathieu Lapôtre, an assistant professor of Earth and planetary sciences in the Stanford Doerr School of Sustainability. "These findings offer a really exciting new tool to decipher the environmental history of these other planets where we have no data."

The scientists analyzed satellite images of 46 dune fields on Earth and Mars and studied how the dunes interact, or exchange sand. Physically, dune interactions manifest themselves as locations where the crestlines of two dunes get very close to each other. Through such interactions, dunes evolve toward a pattern that is free of defects, reflecting a state of equilibrium with local conditions. Thus, the researchers hypothesized that a high number of interactions, in turn, must signal recent or local changes in those boundary conditions. To test their hypothesis, they used data from Earth and Mars to verify how known changes in environmental conditions, such as wind direction or the amount of sand available, affected dune interactions in the dune fields.

Finding a pattern

In a part of China's Tengger Desert, researchers once flattened a dune field to have a baseline for understanding its subsequent reformation. The study authors analyzed satellite images of the dune field from 2016 to 2022 to see how it grew from a flat bed to large dunes in equilibrium with their environment.

"When the dunes and their patterns were not in equilibrium with their current conditions, the interaction density was high, and through time we could see it decreased consistently, as is expected from our hypothesis," Lapôtre said.

Next, they investigated dunes migrating through a valley in the Namib Desert to see how changes in the wind conditions, triggered by topography, impacted dune patterns. They found that dunes outside the valley displayed few defects in their patterns, but as they migrated through the valley -- which starts very wide, then narrows, then becomes wide again -- dunes interacted more with each other.

"As both sand and winds get funneled into the valley, the dunes feel a change in their boundary conditions, and their pattern needs to adjust," said lead study author Colin Marvin, a PhD student in Earth and planetary sciences. "They move into the portion outside the valley and they again readjust to their unconfined conditions, and we see a drop in the number of interactions. This trend is exactly what we expected to see."

They also found that pattern to be true on Mars, where a big dune field occurs around the north pole. There, the migrating dunes have settled into their current conditions -- they're well spaced, they look the same, they're the same size -- and because of that, they interact very little with one another. But further downwind, the winds become more variable and frost locally makes it harder for grains to be blown away. There, the dunes react to that change until they have migrated far enough into these new conditions for their pattern to have once again matured, decreasing the number of dune interactions.

Testing the tool

"We have an upper bound on the time that it takes for a given dune to adjust to changes in environmental conditions, and that is the time it takes for a dune to migrate by a distance of one dune length," Marvin said. "We can use this to diagnose recent changes in environmental conditions on planetary bodies where we don't have any information other than images taken from orbit or radar for example."

Understanding the recent climate of Mars by analyzing current dune patterns could possibly help scientists better pinpoint, for example, the latitudes and depth where future astronauts might be able to find water ice in the subsurface, Lapôtre added. The study also informs experts about the mechanics of dunes on Earth, which can help them better interpret Earth's rock record, and thus, our planet's distant past. On Saturn's moon Titan, this approach could reveal information about topography around the equator and tropics, which is near where the Dragonfly Mission is going to land in the mid 2030s.

"Topography can tell you about a lot of different things; for example, the geological history of the planet: Does Titan have tectonics? How does the interior of Titan work, and how is it coupled with the surface? Is there significant erosion?" Lapôtre said. "Interpretations of dune patterns could trigger kind of a chain reaction, where you provide a new constraint, and it's going to be useful to a bunch of people to make a bunch of discoveries down the line."

Because other planets have various sizes, gravities, temperatures, and compositions, their geological processes will differ. Compared with a rover that lands on one point of a planet to collect information, the satellite data of entire dune fields can greatly increase scientists' understanding of these extraterrestrial bodies and how they can inform our understanding of Earth.

"If we want to understand what happened in the past, or if we want to predict what will happen in the future, it's hard to do when all you have to create those models is one data point, or just one planet," Lapôtre said. "Ultimately, this kind of information allows us to make much better interpretations of Earth's past and also predictions of Earth's future."

Read more at Science Daily

Evidence that Venus is volcanically active

Venus appears to have volcanic activity, according to a new research paper that offers strong evidence to answer the lingering question about whether Earth's sister planet currently has eruptions and lava flows.

Venus, although similar to Earth in size and mass, differs markedly in that it does not have plate tectonics. The boundaries of Earth's moving surface plates are the primary locations of volcanic activity.

New research by University of Alaska Fairbanks Geophysical Institute research professor Robert Herrick revealed a nearly 1-square-mile volcanic vent that changed in shape and grew over eight months in 1991. Changes on such a scale on Earth are associated with volcanic activity, whether through an eruption at the vent or movement of magma beneath the vent that causes the vent walls to collapse and the vent to expand.

The research was published today in the journal Science.

Herrick studied images taken in the early 1990s during the first two imaging cycles of NASA's Magellan space probe. Until recently, comparing digital images to find new lava flows took too much time, the paper notes. As a result, few scientists have searched Magellan data for feature formation.

"It is really only in the last decade or so that the Magellan data has been available at full resolution, mosaicked and easily manipulable by an investigator with a typical personal workstation," Herrick said.

The new research focused on an area containing two of Venus' largest volcanoes, Ozza and Maat Mons.

"Ozza and Maat Mons are comparable in volume to Earth's largest volcanoes but have lower slopes and thus are more spread out," Herrick said.

Maat Mons contains the expanded vent that indicates volcanic activity.

Herrick compared a Magellan image from mid-February 1991 with a mid-October 1991 image and noticed a change to a vent on the north side of a domed shield volcano that is part of the Maat Mons volcano.

The vent had grown from a circular formation of just under 1 square mile to an irregular shape of about 1.5 square miles.

The later image indicates that the vent's walls became shorter, perhaps only a few hundred feet high, and that the vent was nearly filled to its rim. The researchers speculate that a lava lake formed in the vent during the eight months between the images, though whether the contents were liquid or cooled and solidified isn't known.

The researchers offer one caveat: a nonvolcanic, earthquake-triggered collapse of the vent's walls might have caused the expansion. They note, however, that vent collapses of this scale on Earth's volcanoes have always been accompanied by nearby volcanic eruptions; magma withdraws from beneath the vent because it is going somewhere else.

The surface of Venus is geologically young, especially compared to all the other rocky bodies except Earth and Jupiter's moon Io, Herrick said.

"However, the estimates of how often eruptions might occur on Venus have been speculative, ranging from several large eruptions per year to one such eruption every several or even tens of years," he said.

Herrick contrasts the lack of information about Venusian volcanism with what is known about Jupiter's moon Io and about Mars.

"Io is so active that multiple ongoing eruptions have been imaged every time we've observed it," he said.

On a geological time scale, relatively young lava flows indicate Mars remains volcanically active, Herrick said.

"However, nothing has occurred in the 45 years that we have been observing Mars, and most scientists would say that you'd probably need to watch the surface for a few million years to have a reasonable chance of seeing a new lava flow," he said.

Herrick's research adds Venus to the small pool of volcanically active bodies in our solar system.

"We can now say that Venus is presently volcanically active in the sense that there are at least a few eruptions per year," he said. "We can expect that the upcoming Venus missions will observe new volcanic flows that have occurred since the Magellan mission ended three decades ago, and we should see some activity occurring while the two upcoming orbital missions are collecting images."

Read more at Science Daily

Largest potentially hazardous asteroid detected in eight years

Twilight observations with the US Department of Energy-fabricated Dark Energy Camera at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF's NOIRLab, have enabled astronomers to spot three near-Earth asteroids (NEA) hiding in the glare of the Sun. These NEAs are part of an elusive population that lurks inside the orbits of Earth and Venus. One of the asteroids is the largest object that is potentially hazardous to Earth to be discovered in the last eight years.

An international team using the Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF's NOIRLab, has discovered three new near-Earth asteroids (NEAs) hiding in the inner Solar System, the region interior to the orbits of Earth and Venus. This is a notoriously challenging region for observations because asteroid hunters have to contend with the glare of the Sun.

By taking advantage of the brief yet favorable observing conditions during twilight, however, the astronomers found an elusive trio of NEAs. One is a 1.5-kilometer-wide asteroid called 2022 AP7, which has an orbit that may someday place it in Earth's path. The other asteroids, called 2021 LJ4 and 2021 PH27, have orbits that safely remain completely interior to Earth's orbit. Also of special interest to astronomers and astrophysicists, 2021 PH27 is the closest known asteroid to the Sun. As such, it has the largest general-relativity effects of any object in our Solar System and during its orbit its surface gets hot enough to melt lead.

"Our twilight survey is scouring the area within the orbits of Earth and Venus for asteroids," said Scott S. Sheppard, an astronomer at the Earth and Planets Laboratory of the Carnegie Institution for Science and the lead author of the paper describing this work. "So far we have found two large near-Earth asteroids that are about 1 kilometer across, a size that we call planet killers."

"There are likely only a few NEAs with similar sizes left to find, and these large undiscovered asteroids likely have orbits that keep them interior to the orbits of Earth and Venus most of the time," said Sheppard. "Only about 25 asteroids with orbits completely within Earth's orbit have been discovered to date because of the difficulty of observing near the glare of the Sun."

Finding asteroids in the inner Solar System is a daunting observational challenge. Astronomers have only two brief 10-minute windows each night to survey this area and have to contend with a bright background sky resulting from the Sun's glare. Additionally, such observations are very near to the horizon, meaning that astronomers have to observe through a thick layer of Earth's atmosphere, which can blur and distort their observations.

Discovering these three new asteroids despite these challenges was possible thanks to the unique observing capabilities of DECam. The state-of-the-art instrument is one of the highest-performance, wide-field CCD imagers in the world, giving astronomers the ability to capture large areas of sky with great sensitivity. Astronomers refer to observations as 'deep' if they capture faint objects. When hunting for asteroids inside Earth's orbit, the capability to capture both deep and wide-field observations is indispensable. DECam was funded by the US Department of Energy (DOE) and was built and tested at DOE's Fermilab. "Large areas of sky are required because the inner asteroids are rare, and deep images are needed because asteroids are faint and you are fighting the bright twilight sky near the Sun as well as the distorting effect of Earth's atmosphere," said Sheppard. "DECam can cover large areas of sky to depths not achievable on smaller telescopes, allowing us to go deeper, cover more sky, and probe the inner Solar System in ways never done before."

As well as detecting asteroids that could potentially pose a threat to Earth, this research is an important step toward understanding the distribution of small bodies in our Solar System. Asteroids that are further from the Sun than Earth are easiest to detect. Because of that these more-distant asteroids tend to dominate current theoretical models of the asteroid population.

Detecting these objects also allows astronomers to understand how asteroids are transported throughout the inner Solar System and how gravitational interactions and the heat of the Sun can contribute to their fragmentation.

"Our DECam survey is one of the largest and most sensitive searches ever performed for objects within Earth's orbit and near to Venus's orbit," said Sheppard. "This is a unique chance to understand what types of objects are lurking in the inner Solar System."

Read more at Science Daily

No signs (yet) of life on Venus

The unusual behaviour of sulphur in Venus' atmosphere cannot be explained by an 'aerial' form of extra-terrestrial life, according to a new study.

Researchers from the University of Cambridge used a combination of biochemistry and atmospheric chemistry to test the 'life in the clouds' hypothesis, which astronomers have speculated about for decades, and found that life cannot explain the composition of the Venusian atmosphere.

Any life form in sufficient abundance is expected to leave chemical fingerprints on a planet's atmosphere as it consumes food and expels waste. However, the Cambridge researchers found no evidence of these fingerprints on Venus.

Even if Venus is devoid of life, the researchers say their results, reported in the journal Nature Communications, could be useful for studying the atmospheres of similar planets throughout the galaxy, and the eventual detection of life outside our Solar System.

"We've spent the past two years trying to explain the weird sulphur chemistry we see in the clouds of Venus," said co-author Dr Paul Rimmer from Cambridge's Department of Earth Sciences. "Life is pretty good at weird chemistry, so we've been studying whether there's a way to make life a potential explanation for what we see."

The researchers used a combination of atmospheric and biochemical models to study the chemical reactions that are expected to occur, given the known sources of chemical energy in Venus's atmosphere.

"We looked at the sulphur-based 'food' available in the Venusian atmosphere -- it's not anything you or I would want to eat, but it is the main available energy source," said Sean Jordan from Cambridge's Institute of Astronomy, the paper's first author. "If that food is being consumed by life, we should see evidence of that through specific chemicals being lost and gained in the atmosphere."

The models looked at a particular feature of the Venusian atmosphere -- the abundance of sulphur dioxide (SO2). On Earth, most SO2 in the atmosphere comes from volcanic emissions. On Venus, there are high levels of SO2 lower in the clouds, but it somehow gets 'sucked out' of the atmosphere at higher altitudes.

"If life is present, it must be affecting the atmospheric chemistry," said co-author Dr Oliver Shorttle from Cambridge's Department of Earth Sciences and Institute of Astronomy. "Could life be the reason that SO2 levels on Venus get reduced so much?"

The models, developed by Jordan, include a list of metabolic reactions that the life forms would carry out in order to get their 'food', and the waste by-products. The researchers ran the model to see if the reduction in SO2 levels could be explained by these metabolic reactions.

They found that the metabolic reactions can result in a drop in SO2 levels, but only by producing other molecules in very large amounts that aren't seen. The results set a hard limit on how much life could exist on Venus without blowing apart our understanding of how chemical reactions work in planetary atmospheres.

"If life was responsible for the SO2 levels we see on Venus, it would also break everything we know about Venus's atmospheric chemistry," said Jordan. "We wanted life to be a potential explanation, but when we ran the models, it isn't a viable solution. But if life isn't responsible for what we see on Venus, it's still a problem to be solved -- there's lots of strange chemistry to follow up on."

Although there's no evidence of sulphur-eating life hiding in the clouds of Venus, the researchers say their method of analysing atmospheric signatures will be valuable when JWST, the successor to the Hubble Telescope, begins returning images of other planetary systems later this year. Some of the sulphur molecules in the current study are easy to see with JWST, so learning more about the chemical behaviour of our next-door neighbour could help scientists figure out similar planets across the galaxy.

"To understand why some planets are alive, we need to understand why other planets are dead," said Shorttle. "If life somehow managed to sneak into the Venusian clouds, it would totally change how we search for chemical signs of life on other planets."

"Even if 'our' Venus is dead, it's possible that Venus-like planets in other systems could host life," said Rimmer, who is also affiliated with Cambridge's Cavendish Laboratory. "We can take what we've learned here and apply it to exoplanetary systems -- this is just the beginning."

Read more at Science Daily

NASA's Davinci mission to take the plunge through massive atmosphere of Venus

In a recently published paper, NASA scientists and engineers give new details about the agency's Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission, which will descend through the layered Venus atmosphere to the surface of the planet in mid-2031. DAVINCI is the first mission to study Venus using both spacecraft flybys and a descent probe.

DAVINCI, a flying analytical chemistry laboratory, will measure critical aspects of Venus' massive atmosphere-climate system for the first time, many of which have been measurement goals for Venus since the early 1980s. It will also provide the first descent imaging of the mountainous highlands of Venus while mapping their rock composition and surface relief at scales not possible from orbit. The mission supports measurements of undiscovered gases present in small amounts and the deepest atmosphere, including the key ratio of hydrogen isotopes -- components of water that help reveal the history of water, either as liquid water oceans or steam within the early atmosphere.

The mission's carrier, relay and imaging spacecraft (CRIS) has two onboard instruments that will study the planet's clouds and map its highland areas during flybys of Venus and will also drop a small descent probe with five instruments that will provide a medley of new measurements at very high precision during its descent to the hellish Venus surface.

"This ensemble of chemistry, environmental, and descent imaging data will paint a picture of the layered Venus atmosphere and how it interacts with the surface in the mountains of Alpha Regio, which is twice the size of Texas," said Jim Garvin, lead author of the paper in the Planetary Science Journal and DAVINCI principal investigator from NASA's Goddard Space Flight Center in Greenbelt, Maryland. "These measurements will allow us to evaluate historical aspects of the atmosphere as well as detect special rock types at the surface such as granites while also looking for tell-tale landscape features that could tell us about erosion or other formational processes."

DAVINCI will make use of three Venus gravity assists, which save fuel by using the planet's gravity to change the speed and/or direction of the CRIS flight system. The first two gravity assists will set CRIS up for a Venus flyby to perform remote sensing in the ultraviolet and the near infrared light, acquiring over 60 gigabits of new data about the atmosphere and surface. The third Venus gravity assist will set up the spacecraft to release the probe for entry, descent, science, and touchdown, plus follow-on transmission to Earth.

The first flyby of Venus will be six and half months after launch and it will take two years to get the probe into position for entry into the atmosphere over Alpha Regio under ideal lighting at "high noon," with the goal of measuring the landscapes of Venus at scales ranging from 328 feet (100 meters) down to finer than one meter. Such scales enable lander style geologic studies in the mountains of Venus without requiring landing.

Once the CRIS system is about two days away from Venus, the probe flight system will be released along with the titanium three foot (one meter) diameter probe safely encased inside. The probe will begin to interact with the Venus upper atmosphere at about 75 miles (120 kilometers) above the surface. The science probe will commence science observations after jettisoning its heat shield around 42 miles (67 kilometers) above the surface. With the heatshield jettisoned, the probe's inlets will ingest atmospheric gas samples for detailed chemistry measurements of the sort that have been made on Mars with the Curiosity rover. During its hour-long descent to the surface, the probe will also acquire hundreds of images as soon as it emerges under the clouds at around 100,000 feet (30,500 meters) above the local surface.

"The probe will touch-down in the Alpha Regio mountains but is not required to operate once it lands, as all of the required science data will be taken before reaching the surface." said Stephanie Getty, deputy principal investigator from Goddard. "If we survive the touchdown at about 25 miles per hour (12 meters/second), we could have up to 17-18 minutes of operations on the surface under ideal conditions."

DAVINCI is tentatively scheduled to launch June 2029 and enter the Venusian atmosphere in June 2031.

"No previous mission within the Venus atmosphere has measured the chemistry or environments at the detail that DAVINCI's probe can do," said Garvin. "Furthermore, no previous Venus mission has descended over the tesserae highlands of Venus, and none have conducted descent imaging of the Venus surface. DAVINCI will build on what Huygens probe did at Titan and improve on what previous in situ Venus missions have done, but with 21st century capabilities and sensors."

Read more at Science Daily

Could acid-neutralizing life-forms make habitable pockets in Venus’ clouds?

It's hard to imagine a more inhospitable world than our closest planetary neighbor. With an atmosphere thick with carbon dioxide, and a surface hot enough to melt lead, Venus is a scorched and suffocating wasteland where life as we know it could not survive. The planet's clouds are similarly hostile, blanketing the planet in droplets of sulfuric acid caustic enough to burn a hole through human skin.

And yet, a new study supports the longstanding idea that if life exists, it might make a home in Venus' clouds. The study's authors, from MIT, Cardiff University, and Cambridge University, have identified a chemical pathway by which life could neutralize Venus' acidic environment, creating a self-sustaining, habitable pocket in the clouds.

Within Venus' atmosphere, scientists have long observed puzzling anomalies -- chemical signatures that are hard to explain, such as small concentrations of oxygen and nonspherical particles unlike sulfuric acid's round droplets. Perhaps most puzzling is the presence of ammonia, a gas that was tentatively detected in the 1970s, and that by all accounts should not be produced through any chemical process known on Venus.

In their new study, the researchers modeled a set of chemical processes to show that if ammonia is indeed present, the gas would set off a cascade of chemical reactions that would neutralize surrounding droplets of sulfuric acid and could also explain most of the anomalies observed in Venus' clouds. As for the source of ammonia itself, the authors propose that the most plausible explanation is of biological origin, rather than a nonbiological source such as lightning or volcanic eruptions.

As they write in their study, the chemistry suggests that "life could be making its own environment on Venus."

This tantalizing new hypothesis is testable, and the researchers provide a list of chemical signatures for future missions to measure in Venus' clouds, to either confirm or contradict their idea.

"No life that we know of could survive in the Venus droplets," says study co-author Sara Seager, the Class of 1941 Professor of Planetary Sciences in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "But the point is, maybe some life is there, and is modifying its environment so that it is livable."

The study's co-authors include Janusz Petkowski, William Bains, and Paul Rimmer, who are affiliated with MIT, Cardiff University, and Cambridge University.

Life suspect

"Life on Venus" was a trending phrase last year, when scientists including Seager and her co-authors reported the detection of phosphine in the planet's clouds. On Earth, phosphine is a gas that is produced mainly through biological interactions. The discovery of phosphine on Venus leaves room for the possibility of life. Since then, however, the discovery has been widely contested.

"The phosphine detection ended up becoming incredibly controversial," Seager says. "But phosphine was like a gateway, and there's been this resurgence in people studying Venus."

Inspired to look more closely, Rimmer began combing through data from past missions to Venus. In these data, he identified anomalies, or chemical signatures, in the clouds that had gone unexplained for decades. In addition to the presence of oxygen and nonspherical particles, anomalies included unexpected levels of water vapor and sulfur dioxide.

Rimmer proposed the anomalies might be explained by dust. He argued that minerals, swept up from Venus' surface and into the clouds, could interact with sulfuric acid to produce some, though not all, of the observed anomalies. He showed the chemistry checked out, but the physical requirements were unfeasible: A massive amount of dust would have to loft into the clouds to produce the observed anomalies.

Seager and her colleagues wondered if the anomalies could be explained by ammonia. In the 1970s, the gas was tentatively detected in the planet's clouds by the Venera 8 and Pioneer Venus probes. The presence of ammonia, or NH3, was an unsolved mystery.

"Ammonia shouldn't be on Venus," Seager says. "It has hydrogen attached to it, and there's very little hydrogen around. Any gas that doesn't belong in the context of its environment is automatically suspicious for being made by life."

Livable clouds

If the team were to assume that life was the source of ammonia, could this explain the other anomalies in Venus' clouds? The researchers modeled a series of chemical processes in search of an answer.

They found that if life were producing ammonia in the most efficient way possible, the associated chemical reactions would naturally yield oxygen. Once present in the clouds, ammonia would dissolve in droplets of sulfuric acid, effectively neutralizing the acid to make the droplets relatively habitable. The introduction of ammonia into the droplets would transform their formerly round, liquid shape into more of a nonspherical, salt-like slurry. Once ammonia dissolved in sulfuric acid, the reaction would trigger any surrounding sulfur dioxide to dissolve as well.

The presence of ammonia then could indeed explain most of the major anomalies seen in Venus' clouds. The researchers also show that sources such as lightning, volcanic eruptions, and even a meteorite strike could not chemically produce the amount of ammonia required to explain the anomalies. Life, however, might.

In fact, the team notes that there are life-forms on Earth -- particuarly in our own stomachs -- that produce ammonia to neutralize and make livable an otherwise highly acidic environment.

"There are very acidic environments on Earth where life does live, but it's nothing like the environment on Venus -- unless life is neutralizing some of those droplets," Seager says.

Scientists may have a chance to check for the presence of ammonia, and signs of life, in the next several years with the Venus Life Finder Missions, a set of proposed privately funded missions, of which Seager is principal investigator, that plan to send spacecraft to Venus to measure its clouds for ammonia and other signatures of life.

Read more at Science Daily

Did Venus ever have oceans?

The planet Venus can be seen as the Earth's evil twin. At first sight, it is of comparable mass and size as our home planet, similarly consists mostly of rocky material, holds some water and has an atmosphere. Yet, a closer look reveals striking differences between them: Venus' thick CO2 atmosphere, extreme surface temperature and pressure, and sulphuric acid clouds are indeed a stark contrast to the conditions needed for life on Earth. This may, however, have not always been the case. Previous studies have suggested that Venus may have been a much more hospitable place in the past, with its own liquid water oceans. A team of astrophysicists led by the University of Geneva (UNIGE) and the National Centre of Competence in Research (NCCR) PlanetS, Switzerland, investigated whether our planet's twin did indeed have milder periods. The results, published in the journal Nature, suggest that this is not the case.

Venus has recently become an important research topic for astrophysicists. ESA and NASA have decided this year to send no less than three space exploration missions over the next decade to the second closest planet to the Sun. One of the key questions these missions aim to answer is whether or not Venus ever hosted early oceans. Astrophysicists led by Martin Turbet, researcher at the Department of Astronomy of the Faculty of Science of the UNIGE and member of the NCCR PlanetS, have tried to answer this question with the tools available on Earth. "We simulated the climate of the Earth and Venus at the very beginning of their evolution, more than four billion years ago, when the surface of the planets was still molten," explains Martin Turbet. "The associated high temperatures meant that any water would have been present in the form of steam, as in a gigantic pressure cooker." Using sophisticated three-dimensional models of the atmosphere, similar to those scientists use to simulate the Earth's current climate and future evolution, the team studied how the atmospheres of the two planets would evolve over time and whether oceans could form in the process.

"Thanks to our simulations, we were able to show that the climatic conditions did not allow water vapour to condense in the atmosphere of Venus," says Martin Turbet. This means that the temperatures never got low enough for the water in its atmosphere to form raindrops that could fall on its surface. Instead, water remained as a gas in the atmosphere and oceans never formed. "One of the main reasons for this is the clouds that form preferentially on the night side of the planet. These clouds cause a very powerful greenhouse effect that prevented Venus from cooling as quickly as previously thought," continues the Geneva researcher.

Small differences with serious consequences

Surprisingly, the astrophysicists' simulations also reveal that the Earth could easily have suffered the same fate as Venus. If the Earth had been just a little closer to the Sun, or if the Sun had shone as brightly in its 'youth' as it does nowadays, our home planet would look very different today. It is likely the relatively weak radiation of the young Sun that allowed the Earth to cool down enough to condense the water that forms our oceans. For Emeline Bolmont, professor at UNIGE, member of PlaneS and co-author of the study, "this is a complete reversal in the way we look at what has long been called the 'Faint Young Sun paradox'. It has always been considered as a major obstacle to the appearance of life on Earth!" The argument was that if the Sun's radiation was much weaker than today, it would have turned the Earth into a ball of ice hostile to life. "But it turns out that for the young, very hot Earth, this weak Sun may have in fact been an unhoped-for opportunity," continues the researcher.

Read more at Science Daily

Using dunes to interpret wind on Mars

Dunes develop when wind-blown sand organizes into patterns, most often in deserts and arid or semi-arid parts of the world. Every continent on Earth has dune fields, but dunes and dune-like sand patterns are also found across the solar system: on Mars, Venus, Titan, Comet 67P, and Pluto. On Earth, weather stations measure the wind speed and direction, allowing us to predict and understand airflow in the atmosphere.

On other planets and planetary bodies, we do not yet have weather stations measuring the winds (with a few recent exceptions on Mars only). Without a way to directly measure wind on the surface of another planet, we can use the patterns in dunes to interpret what the wind must be doing, based on our knowledge of dunes on Earth. Furthermore, by studying dunes across planets, we can get a better understanding of how wind and sand behave in general.

In this Geology paper, published today, Mackenzie Day of the University of California Los Angeles focuses on what happens when two dunes collide.

"On Earth, we know that dunes collide, combine, link, and merge all the time," says Day. This is what drives changes in dune-field patterns over time. When this happens, the dune-dune interaction leaves behind a particular pattern in the sand, but that pattern is usually covered by actively moving sand and difficult to see without special tools."

On Mars, many dunes look and behave similar to dunes on Earth, but in addition Mars hosts patterns of organized sand that are dune-like but have some differences that have yet to be explained by the scientific community. Whether or not these unusual features, sometimes called "transverse aeolian ridges" or "megaripples," are formed like dunes has been long debated.

"In this work, says Day, I show that these unusual wind-blown sand ridges sometimes show on their surfaces the pattern that forms when two dunes combine."

In the Iapygia region of Mars, transverse aeolian ridges incorporated both light and dark sands, leading to light-dark banding in the upwind side of the ridges. Banding occurring only on one side of the ridges suggests that the banding formed as the ridges migrated. Furthermore, the dune-interaction pattern known from Earth can be seen in some ridges where the banding is truncated and then reconnects, just like two dunes touching and then combining downwind.

The pattern associated with dune-interactions only forms when two dunes combine, therefore seeing it in these martian sand ridges demonstrates that these enigmatic features (like those shown in the image attached) behave like dunes on Earth. "Just like dunes on Earth, transvers aeolian ridges on Mars migrate, combine, and develop complex patterns in response to the wind."

Transverse aeolian ridges are incredibly common on Mars, and the results of this work allow us to better interpret the wind at the surface of Mars using these dune-like features.

Read more at Science Daily

Earth and Venus grew up as rambunctious planets

Planet formation -- the process by which neat, round, distinct planets form from a roiling, swirling cloud of rugged asteroids and mini planets -- was likely even messier and more complicated than most scientists would care to admit, according to new research led by researchers at the University of Arizona Lunar and Planetary Laboratory.

The findings challenge the conventional view, in which collisions between smaller building blocks cause them to stick together and, over time, repeated collisions accrete new material to the growing baby planet.

Instead, the authors propose and demonstrate evidence for a novel "hit-and-run-return" scenario, in which pre-planetary bodies spent a good part of their journey through the inner solar system crashing into and ricocheting off of each other, before running into each other again at a later time. Having been slowed down by their first collision, they would be more likely to stick together the next time. Picture a game of billiards, with the balls coming to rest, as opposed to pelting a snowman with snowballs, and you get the idea.

The research is published in two reports appearing in the Sept. 23 issue of The Planetary Science Journal, with one focusing on Venus and Earth, and the other on Earth's moon. Central to both publications, according to the author team, which was led by planetary sciences and LPL professor Erik Asphaug, is the largely unrecognized point that giant impacts are not the efficient mergers scientists believed them to be.

"We find that most giant impacts, even relatively 'slow' ones, are hit-and-runs. This means that for two planets to merge, you usually first have to slow them down in a hit-and-run collision," Asphaug said. "To think of giant impacts, for instance the formation of the moon, as a singular event is probably wrong. More likely it took two collisions in a row."

One implication is that Venus and Earth would have had very different experiences in their growth as planets, despite being immediate neighbors in the inner solar system. In the first paper, led by Alexandre Emsenhuber, who did this work during a postdoctoral fellowship in Asphaug's lab and is now at Ludwig Maximilian University in Munich, the young Earth would have served to slow down interloping planetary bodies, making them ultimately more likely to collide with and stick to Venus.

"We think that during solar system formation, the early Earth acted like a vanguard for Venus," Emsenhuber said.

The solar system is what scientists call a gravity well, the concept behind a popular attraction at science exhibits. Visitors toss a coin into a funnel-shaped gravity well, and then watch their cash complete several orbits before it drops into the center hole. The closer a planet is to the sun, the stronger the gravitation experienced by planets. That's why the inner planets of the solar system on which these studies were focused -- Mercury, Venus, Earth and Mars -- orbit the sun faster than, say, Jupiter, Saturn and Neptune. As a result, the closer an object ventures to the sun, the more likely it is to stay there.

So when an interloping planet hit the Earth, it was less likely to stick to Earth, and instead more likely to end up at Venus, Asphaug explained.

"The Earth acts as a shield, providing a first stop against these impacting planets," he said. "More likely than not, a planet that bounces off of Earth is going to hit Venus and merge with it."

Emsenhuber uses the analogy of a ball bouncing down a staircase to illustrate the idea of what drives the vanguard effect: A body coming in from the outer solar system is like a ball bouncing down a set of stairs, with each bounce representing a collision with another body.

"Along the way, the ball loses energy, and you'll find it will always bounce downstairs, never upstairs," he said. "Because of that, the body cannot leave the inner solar system anymore. You generally only go downstairs, toward Venus, and an impactor that collides with Venus is pretty happy staying in the inner solar system, so at some point it is going to hit Venus again."

Earth has no such vanguard to slow down its interloping planets. This leads to a difference between the two similar-sized planets that conventional theories cannot explain, the authors argue.

"The prevailing idea has been that it doesn't really matter if planets collide and don't merge right away, because they are going to run into each other again at some point and merge then," Emsenhuber said. "But that is not what we find. We find they end up more frequently becoming part of Venus, instead of returning back to Earth. It's easier to go from Earth to Venus than the other way around."

To track all these planetary orbits and collisions, and ultimately their mergers, the team used machine learning to obtain predictive models from 3D simulations of giant impacts. The team then used these data to rapidly compute the orbital evolution, including hit-and-run and merging collisions, to simulate terrestrial planet formation over the course of 100 million years. In the second paper, the authors propose and demonstrate their hit-and-run-return scenario for the moon's formation, recognizing the primary problems with the standard giant impact model.

"The standard model for the moon requires a very slow collision, relatively speaking," Asphaug said, "and it creates a moon that is composed mostly of the impacting planet, not the proto-Earth, which is a major problem since the moon has an isotopic chemistry almost identical to Earth."

In the team's new scenario, a roughly Mars-sized protoplanet hits the Earth, as in the standard model, but is a bit faster so it keeps going. It returns in about 1 million years for a giant impact that looks a lot like the standard model.

"The double impact mixes things up much more than a single event," Asphaug said, "which could explain the isotopic similarity of Earth and moon, and also how the second, slow, merging collision would have happened in the first place."

The researchers think the resulting asymmetry in how the planets were put together points the way to future studies addressing the diversity of terrestrial planets. For example, we don't understand how Earth ended up with a magnetic field that is much stronger than that of Venus, or why Venus has no moon.

Their research indicates systematic differences in dynamics and composition, according to Asphaug.

"In our view, Earth would have accreted most of its material from collisions that were head-on hits, or else slower than those experienced by Venus," he said. "Collisions into the Earth that were more oblique and higher velocity would have preferentially ended up on Venus."

This would create a bias in which, for example, protoplanets from the outer solar system, at higher velocity, would have preferentially accreted to Venus instead of Earth. In short, Venus could be composed of material that was harder for the Earth to get ahold of.

"You would think that Earth is made up more of material from the outer system because it is closer to the outer solar system than Venus. But actually, with Earth in this vanguard role, it makes it actually more likely for Venus to accrete outer solar system material," Asphaug said.

Read more at Science Daily

Ocean world: Rocky exoplanet has just half the mass of Venus

A team of astronomers have used the European Southern Observatory's Very Large Telescope (ESO's VLT) in Chile to shed new light on planets around a nearby star, L 98-59, that resemble those in the inner Solar System. Amongst the findings are a planet with half the mass of Venus -- the lightest exoplanet ever to be measured using the radial velocity technique -- an ocean world, and a possible planet in the habitable zone.

"The planet in the habitable zone may have an atmosphere that could protect and support life," says María Rosa Zapatero Osorio, an astronomer at the Centre for Astrobiology in Madrid, Spain, and one of the authors of the study published today in Astronomy & Astrophysics.

The results are an important step in the quest to find life on Earth-sized planets outside the Solar System. The detection of biosignatures on an exoplanet depends on the ability to study its atmosphere, but current telescopes are not large enough to achieve the resolution needed to do this for small, rocky planets. The newly studied planetary system, called L 98-59 after its star, is an attractive target for future observations of exoplanet atmospheres. Its orbits a star only 35 light-years away and has now been found to host rocky planets, like Earth or Venus, which are close enough to the star to be warm.

With the contribution of ESO's VLT, the team was able to infer that three of the planets may contain water in their interiors or atmospheres. The two planets closest to the star in the L 98-59 system are probably dry, but might have small amounts of water, while up to 30% of the third planet's mass could be water, making it an ocean world.

Furthermore, the team found "hidden" exoplanets that had not previously been spotted in this planetary system. They discovered a fourth planet and suspect there is a fifth, in a zone at the right distance from the star for liquid water to exist on its surface. "We have hints of the presence of a terrestrial planet in the habitable zone of this system," explains Olivier Demangeon, a researcher at the Instituto de Astrofísica e Ciências do Espaço, University of Porto in Portugal and lead author of the new study.

The study represents a technical breakthrough, as astronomers were able to determine, using the radial velocity method, that the innermost planet in the system has just half the mass of Venus. This makes it the lightest exoplanet ever measured using this technique, which calculates the wobble of the star caused by the tiny gravitational tug of its orbiting planets.

The team used the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) instrument on ESO's VLT to study L 98-59. "Without the precision and stability provided by ESPRESSO this measurement would have not been possible," says Zapatero Osorio. "This is a step forward in our ability to measure the masses of the smallest planets beyond the Solar System."

The astronomers first spotted three of L 98-59's planets in 2019, using NASA's Transiting Exoplanet Survey Satellite (TESS). This satellite relies on a technique called the transit method -- where the dip in the light coming from the star caused by a planet passing in front of it is used to infer the properties of the planet -- to find the planets and measure their sizes. However, it was only with the addition of radial velocity measurements made with ESPRESSO and its predecessor, the High Accuracy Radial velocity Planet Searcher (HARPS) at the ESO La Silla 3.6-metre telescope, that Demangeon and his team were able to find extra planets and measure the masses and radii of the first three. "If we want to know what a planet is made of, the minimum that we need is its mass and its radius," Demangeon explains.

The team hopes to continue to study the system with the forthcoming NASA/ESA/CSA James Webb Space Telescope (JWST) , while ESO's Extremely Large Telescope (ELT), under construction in the Chilean Atacama Desert and set to start observations in 2027, will also be ideal for studying these planets. "The HIRES instrument on the ELT may have the power to study the atmospheres of some of the planets in the L 98-59 system, thus complementing the JWST from the ground," says Zapatero Osorio.

Read more at Science Daily

Trace gas phosphine points to volcanic activity on Venus, scientists say

Scientists last autumn revealed that the gas phosphine was found in trace amounts in Venus' upper atmosphere. That discovery promised the slim possibility that phosphine serves as a biological signature for the hot, toxic planet.

Now Cornell scientists say the phosphine's chemical fingerprints support a different and important scientific find: evidence of explosive volcanoes on the mysterious planet.

"The phosphine is not telling us about the biology of Venus," said Jonathan Lunine, the David C. Duncan Professor in Physical Sciences and chair of the Department of Astronomy in the College of Arts and Sciences. "It's telling us about the geology. Science is pointing to a planet that has active explosive volcanism today or in the very recent past."

Lunine and Ngoc Truong, a doctoral candidate in geology, have authored the study, "Volcanically Extruded Phosphides as an Abiotic Source of Venusian Phosphine," published July 12 in the Proceedings of the National Academy of Sciences.

Truong and Lunine argue that volcanism is the means for phosphine to get into Venus' upper atmosphere, after examining observations from the ground-based, submillimeter-wavelength James Clerk Maxwell Telescope atop Mauna Kea in Hawaii, and the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile.

"Volcanism could supply enough phosphide to produce phosphine," Truong said. "The chemistry implies that phosphine derives from explosive volcanoes on Venus, not biological sources."

Our planetary neighbor broils with an almost 900-degree Fahrenheit average surface temperature and features a carbon dioxide-filled atmosphere enveloped in sulfuric acid clouds, according to NASA.

If Venus has phosphide -- a form of phosphorus present in the planet's deep mantle -- and, if it is brought to the surface in an explosive, volcanic way and then injected into the atmosphere, those phosphides react with the Venusian atmosphere's sulfuric acid to form phosphine, Truong said.

He found published laboratory data confirming that the phosphide reacts with sulfuric acid to produce phosphines efficiently.

Volcanism on Venus is not necessarily surprising, Lunine said. But while "our phosphine model suggests explosive volcanism occurring, radar images from the Magellan spacecraft in the 1990s show some geologic features could support this."

In 1978, on NASA's Pioneer Venus orbiter mission, scientists uncovered variations of sulfur dioxide in Venus' upper atmosphere, hinting at the prospect of explosive volcanism, Truong said, similar to the scale of Earth's Krakatoa volcanic eruption in Indonesia in 1883.

Said Truong: "Confirming explosive volcanism on Venus through the gas phosphine was totally unexpected."

Read more at Science Daily

'Pack ice' tectonics reveal Venus' geological secrets

A new analysis of Venus' surface shows evidence of tectonic motion in the form of crustal blocks that have jostled against each other like broken chunks of pack ice. The movement of these blocks could indicate that Venus is still geologically active and give scientists insight into both exoplanet tectonics and the earliest tectonic activity on Earth.

"We've identified a previously unrecognized pattern of tectonic deformation on Venus, one that is driven by interior motion just like on Earth," says Paul Byrne, associate professor of planetary science at North Carolina State University and lead and co-corresponding author of the work. "Although different from the tectonics we currently see on Earth, it is still evidence of interior motion being expressed at the planet's surface."

The finding is important because Venus has long been assumed to have an immobile solid outer shell, or lithosphere, just like Mars or Earth's moon. In contrast, Earth's lithosphere is broken into tectonic plates, which slide against, apart from, and underneath each other on top of a hot, weaker mantle layer.

Byrne and an international group of researchers used radar images from NASA's Magellan mission to map the surface of Venus. In examining the extensive Venusian lowlands that make up most of the planet surface, they saw areas where large blocks of the lithosphere seem to have moved: pulling apart, pushing together, rotating and sliding past each other like broken pack ice over a frozen lake.

The team created a computer model of this deformation, and found that sluggish motion of the planet's interior can account for the style of tectonics seen at the surface.

"These observations tell us that interior motion is driving surface deformation on Venus, in a similar way to what happens on Earth," Byrne says. "Plate tectonics on Earth are driven by convection in the mantle. The mantle is hot or cold in different places, it moves, and some of that motion transfers to Earth's surface in the form of plate movement.

"A variation on that theme seems to be playing out on Venus as well. It's not plate tectonics like on Earth -- there aren't huge mountain ranges being created here, or giant subduction systems -- but it is evidence of deformation due to interior mantle flow, which hasn't been demonstrated on a global scale before."

The deformation associated with these crustal blocks could also indicate that Venus is still geologically active.

"We know that much of Venus has been volcanically resurfaced over time, so some parts of the planet might be really young, geologically speaking," Byrne says. "But several of the jostling blocks have formed in and deformed these young lava plains, which means that the lithosphere fragmented after those plains were laid down. This gives us reason to think that some of these blocks may have moved geologically very recently -- perhaps even up to today."

The researchers are optimistic that Venus' newly recognized "pack ice" pattern could offer clues to understanding tectonic deformation on planets outside of our solar system, as well as on a much younger Earth.

"The thickness of a planet's lithosphere depends mainly upon how hot it is, both in the interior and on the surface," Byrne says. "Heat flow from the young Earth's interior was up to three times greater than it is now, so its lithosphere may have been similar to what we see on Venus today: not thick enough to form plates that subduct, but thick enough to have fragmented into blocks that pushed, pulled, and jostled."

Read more at Science Daily

Life on Venus? First we need to know more about molecules in the atmosphere

The search for life on other planets has received a major boost after scientists revealed the spectral signatures of almost 1000 atmospheric molecules that may be involved in the production or consumption of phosphine, a study led by UNSW Sydney revealed.

Scientists have long conjectured that phosphine -- a chemical compound made of one phosphorus atom surrounded by three hydrogen atoms (PH3) -- may indicate evidence of life if found in the atmospheres of small rocky planets like our own, where it is produced by the biological activity of bacteria.

So when an international team of scientists last year claimed to have detected phosphine in the atmosphere of Venus, it raised the tantalising prospect of the first evidence of life on another planet -- albeit the primitive, single-celled variety.

But not everyone was convinced, with some scientists questioning whether the phosphine in Venus's atmosphere was really produced by biological activity, or whether phosphine was detected at all.

Now an international team, led by UNSW Sydney scientists, has made a key contribution to this and any future searches for life on other planets by demonstrating how an initial detection of a potential biosignature must be followed by searches for related molecules.

In a paper published today in the journal Frontiers in Astronomy and Space Sciences, they described how the team used computer algorithms to produce a database of approximate infrared spectral barcodes for 958 molecular species containing phosphorus.

LOOK AND LEARN

As UNSW School of Chemistry's Dr Laura McKemmish explains, when scientists look for evidence of life on other planets, they don't need to go into space, they can simply point a telescope at the planet in question.

"To identify life on a planet, we need spectral data," she says.

"With the right spectral data, light from a planet can tell you what molecules are in the planet's atmosphere."

Phosphorus is an essential element for life, yet up until now, she says, astronomers could only look for one polyatomic phosphorus-containing molecule, phosphine.

"Phosphine is a very promising biosignature because it is only produced in tiny concentrations by natural processes. However, if we can't trace how it is produced or consumed, we can't answer the question of whether it is unusual chemistry or little green men who are producing phosphine on a planet," says Dr McKemmish.

To provide insight, Dr McKemmish brought together a large interdisciplinary team to understand how phosphorus behaves chemically, biologically and geologically and ask how this can be investigated remotely through atmospheric molecules alone.

"What was great about this study is that it brought together scientists from disparate fields -- chemistry, biology, geology -- to address these fundamental questions around the search for life elsewhere that one field alone could not answer," says astrobiologist and co-author on the study, Associate Professor Brendan Burns.

Dr McKemmish continues: "At the start, we looked for which phosphorus-bearing molecules -- what we called P-molecules -- are most important in atmospheres but it turns out very little is known. So we decided to look at a large number of P-molecules that could be found in the gas-phase which would otherwise go undetected by telescopes sensitive to infrared light."

Barcode data for new molecular species are normally produced for one molecule at a time, Dr McKemmish says, a process that often takes years. But the team involved in this research used what she calls "high-throughput computational quantum chemistry" to predict the spectra of 958 molecules within only a couple of weeks.

"Though this new dataset doesn't yet have the accuracy to enable new detections, it can help prevent misassignments by highlighting the potential for multiple molecular species having similar spectral barcodes -- for example, at low resolution with some telescopes, water and alcohol could be indistinguishable.

"The data can also be used to rank how easy a molecule is to detect. For example, counter-intuitively, alien astronomers looking at Earth would find it much easier to detect 0.04% CO2 in our atmosphere than the 20% O2. This is because CO2 absorbs light much more strongly than O2 -- this is actually what causes the greenhouse effect on Earth."

LIFE ON EXOPLANETS

Regardless of the outcomes from the debate about the existence of phosphine in Venus's atmosphere and the potential signs of life on the planet, this recent addition to the knowledge of what can be detected using telescopes will be important in the detection of potential signs of life on exoplanets -- planets in other solar systems.

"The only way we're going to be able to look at exoplanets and see whether there's life there is to use spectral data collected by telescopes -- that is our one and only tool," says Dr McKemmish.

"Our paper provides a novel scientific approach to following up the detection of potential biosignatures and has relevance to the study of astrochemistry within and outside the Solar System," says Dr McKemmish. "Further studies will rapidly improve the accuracy of the data and expand the range of molecules considered, paving the way for its use in future detections and identifications of molecules."

Fellow co-author and CSIRO astronomer Dr Chenoa Tremblay says the team's contribution will be beneficial as more powerful telescopes come online in the near future.

"This information has come at a critical time in astronomy," she says.

"A new infrared telescope called the James Web Space Telescope is due to launch later this year and it will be far more sensitive and cover more wavelengths than its predecessors like the Herschel Space Observatory. We will need this information at a very rapid rate to identify new molecules in the data."

She says although the team's work was focused on the vibrational motions of molecules detected with telescopes sensitive to infrared light, they are currently working to extend the technique to the radio wavelengths as well.

Read more at Science Daily

Purported phosphine on Venus more likely to be ordinary sulfur dioxide

 In September, a team led by astronomers in the United Kingdom announced that they had detected the chemical phosphine in the thick clouds of Venus. The team's reported detection, based on observations by two Earth-based radio telescopes, surprised many Venus experts. Earth's atmosphere contains small amounts of phosphine, which may be produced by life. Phosphine on Venus generated buzz that the planet, often succinctly touted as a "hellscape," could somehow harbor life within its acidic clouds.

Since that initial claim, other science teams have cast doubt on the reliability of the phosphine detection. Now, a team led by researchers at the University of Washington has used a robust model of the conditions within the atmosphere of Venus to revisit and comprehensively reinterpret the radio telescope observations underlying the initial phosphine claim. As they report in a paper accepted to the Astrophysical Journal and posted Jan. 25 to the preprint site arXiv, the U.K.-led group likely wasn't detecting phosphine at all.

"Instead of phosphine in the clouds of Venus, the data are consistent with an alternative hypothesis: They were detecting sulfur dioxide," said co-author Victoria Meadows, a UW professor of astronomy. "Sulfur dioxide is the third-most-common chemical compound in Venus' atmosphere, and it is not considered a sign of life."

The team behind the new study also includes scientists at NASA's Caltech-based Jet Propulsion Laboratory, the NASA Goddard Space Flight Center, the Georgia Institute of Technology, the NASA Ames Research Center and the University of California, Riverside.

The UW-led team shows that sulfur dioxide, at levels plausible for Venus, can not only explain the observations but is also more consistent with what astronomers know of the planet's atmosphere and its punishing chemical environment, which includes clouds of sulfuric acid. In addition, the researchers show that the initial signal originated not in the planet's cloud layer, but far above it, in an upper layer of Venus' atmosphere where phosphine molecules would be destroyed within seconds. This lends more support to the hypothesis that sulfur dioxide produced the signal.

Both the purported phosphine signal and this new interpretation of the data center on radio astronomy. Every chemical compound absorbs unique wavelengths of the electromagnetic spectrum, which includes radio waves, X-rays and visible light. Astronomers use radio waves, light and other emissions from planets to learn about their chemical composition, among other properties.

In 2017 using the James Clerk Maxwell Telescope, or JCMT, the U.K.-led team discovered a feature in the radio emissions from Venus at 266.94 gigahertz. Both phosphine and sulfur dioxide absorb radio waves near that frequency. To differentiate between the two, in 2019 the same team obtained follow-up observations of Venus using the Atacama Large Millimeter/submillimeter Array, or ALMA. Their analysis of ALMA observations at frequencies where only sulfur dioxide absorbs led the team to conclude that sulfur dioxide levels in Venus were too low to account for the signal at 266.94 gigahertz, and that it must instead be coming from phosphine.

In this new study by the UW-led group, the researchers started by modeling conditions within Venus' atmosphere, and using that as a basis to comprehensively interpret the features that were seen -- and not seen -- in the JCMT and ALMA datasets.

"This is what's known as a radiative transfer model, and it incorporates data from several decades' worth of observations of Venus from multiple sources, including observatories here on Earth and spacecraft missions like Venus Express," said lead author Andrew Lincowski, a researcher with the UW Department of Astronomy.

The team used that model to simulate signals from phosphine and sulfur dioxide for different levels of Venus' atmosphere, and how those signals would be picked up by the JCMT and ALMA in their 2017 and 2019 configurations. Based on the shape of the 266.94-gigahertz signal picked up by the JCMT, the absorption was not coming from Venus' cloud layer, the team reports. Instead, most of the observed signal originated some 50 or more miles above the surface, in Venus' mesosphere. At that altitude, harsh chemicals and ultraviolet radiation would shred phosphine molecules within seconds.

"Phosphine in the mesosphere is even more fragile than phosphine in Venus' clouds," said Meadows. "If the JCMT signal were from phosphine in the mesosphere, then to account for the strength of the signal and the compound's sub-second lifetime at that altitude, phosphine would have to be delivered to the mesosphere at about 100 times the rate that oxygen is pumped into Earth's atmosphere by photosynthesis."

The researchers also discovered that the ALMA data likely significantly underestimated the amount of sulfur dioxide in Venus' atmosphere, an observation that the U.K.-led team had used to assert that the bulk of the 266.94-gigahertz signal was from phosphine.

"The antenna configuration of ALMA at the time of the 2019 observations has an undesirable side effect: The signals from gases that can be found nearly everywhere in Venus' atmosphere -- like sulfur dioxide -- give off weaker signals than gases distributed over a smaller scale," said co-author Alex Akins, a researcher at the Jet Propulsion Laboratory.

This phenomenon, known as spectral line dilution, would not have affected the JCMT observations, leading to an underestimate of how much sulfur dioxide was being seen by JCMT.

"They inferred a low detection of sulfur dioxide because of that artificially weak signal from ALMA," said Lincowski. "But our modeling suggests that the line-diluted ALMA data would have still been consistent with typical or even large amounts of Venus sulfur dioxide, which could fully explain the observed JCMT signal."

"When this new discovery was announced, the reported low sulfur dioxide abundance was at odds with what we already know about Venus and its clouds," said Meadows. "Our new work provides a complete framework that shows how typical amounts of sulfur dioxide in the Venus mesosphere can explain both the signal detections, and non-detections, in the JCMT and ALMA data, without the need for phosphine."

Read more at Science Daily

Venus might be habitable today, if not for Jupiter

 Venus might not be a sweltering, waterless hellscape today, if Jupiter hadn't altered its orbit around the sun, according to new UC Riverside research.

Jupiter has a mass that is two-and-a-half times that of all other planets in our solar system -- combined. Because it is comparatively gigantic, it has the ability to disturb other planets' orbits.

Early in Jupiter's formation as a planet, it moved closer to and then away from the sun due to interactions with the disc from which planets form as well as the other giant planets. This movement in turn affected Venus.

Observations of other planetary systems have shown that similar giant planet migrations soon after formation may be a relatively common occurrence. These are among the findings of a new study published in the Planetary Science Journal.

Scientists consider planets lacking liquid water to be incapable of hosting life as we know it. Though Venus may have lost some water early on for other reasons, and may have continued to do so anyway, UCR astrobiologist Stephen Kane said that Jupiter's movement likely triggered Venus onto a path toward its current, inhospitable state.

"One of the interesting things about the Venus of today is that its orbit is almost perfectly circular," said Kane, who led the study. "With this project, I wanted to explore whether the orbit has always been circular and if not, what are the implications of that?"

To answer these questions, Kane created a model that simulated the solar system, calculating the location of all the planets at any one time and how they pull one another in different directions.

Scientists measure how noncircular a planet's orbit is between 0, which is completely circular, and 1, which is not circular at all. The number between 0 and 1 is called the eccentricity of the orbit. An orbit with an eccentricity of 1 would not even complete an orbit around a star; it would simply launch into space, Kane said.

Currently, the orbit of Venus is measured at 0.006, which is the most circular of any planet in our solar system. However, Kane's model shows that when Jupiter was likely closer to the sun about a billion years ago, Venus likely had an eccentricity of 0.3, and there is a much higher probability that it was habitable then.

"As Jupiter migrated, Venus would have gone through dramatic changes in climate, heating up then cooling off and increasingly losing its water into the atmosphere," Kane said.

Recently, scientists generated much excitement by discovering a gas in the clouds above Venus that may indicate the presence of life. The gas, phosphine, is typically produced by microbes, and Kane says it is possible that the gas represents "the last surviving species on a planet that went through a dramatic change in its environment."

For that to be the case, however, Kane notes the microbes would have had to sustain their presence in the sulfuric acid clouds above Venus for roughly a billion years since Venus last had surface liquid water -- a difficult to imagine though not impossible scenario.

"There are probably a lot of other processes that could produce the gas that haven't yet been explored," Kane said.

Ultimately, Kane says it is important to understand what happened to Venus, a planet that was once likely habitable and now has surface temperatures of up to 800 degrees Fahrenheit.

Read more at Science Daily

Venus' ancient layered, folded rocks point to volcanic origin

 An international team of researchers has found that some of the oldest terrain on Venus, known as tesserae, have layering that seems consistent with volcanic activity. The finding could provide insights into the enigmatic planet's geological history.

Tesserae are tectonically deformed regions on the surface of Venus that are often more elevated than the surrounding landscape. They comprise about 7% of the planet's surface, and are always the oldest feature in their immediate surroundings, dating to about 750 million years old. In a new study appearing in Geology, the researchers show that a significant portion of the tesserae have striations consistent with layering.

"There are generally two explanations for tesserae -- either they are made of volcanic rocks, or they are counterparts of Earth's continental crust," says Paul Byrne, associate professor of planetary science at North Carolina State University and lead author of the study. "But the layering we find on some of the tessera isn't consistent with the continental crust explanation."

The team analyzed images of Venus' surface from NASA's 1989 Magellan mission, which used radar to image 98% of the planet through its dense atmosphere. While researchers have studied the tesserae for decades, prior to this work the layering of the tesserae hasn't been recognized as widespread. And according to Byrne, that layering would not be possible if the tesserae were portions of continental crust.

"Continental crust is composed mainly of granite, an igneous rock formed when tectonic plates move and water is subducted from the surface," Byrne says. "But granite doesn't form layers. If there's continental crust on Venus, then it's below the layered rocks we see.

"Aside from volcanic activity, the other way to make layered rock is through sedimentary deposits, like sandstone or limestone. There isn't a single place today on Venus where these kinds of rocks could form. The surface of Venus is as hot as a self-cleaning oven and the pressure is equivalent to being 900 meters (about 985 yards) underwater. So the evidence right now points to some portions of the tesserae being made up of layered volcanic rock, similar to that found on Earth."

Byrne hopes that the work will help to shed light on more of Venus' complicated geological history.

"While the data we have now point to volcanic origins for the tesserae, if we were one day able to sample them and find that they are sedimentary rocks, then they would have had to have formed when the climate was very different -- perhaps even Earth-like," Byrne says.

Read more at Science Daily

Possible marker of life spotted on venus

 

Planet Venus

An international team of astronomers today announced the discovery of a rare molecule -- phosphine -- in the clouds of Venus. On Earth, this gas is only made industrially or by microbes that thrive in oxygen-free environments. Astronomers have speculated for decades that high clouds on Venus could offer a home for microbes -- floating free of the scorching surface but needing to tolerate very high acidity. The detection of phosphine could point to such extra-terrestrial 'aerial' life.

"When we got the first hints of phosphine in Venus's spectrum, it was a shock!," says team leader Jane Greaves of Cardiff University in the UK, who first spotted signs of phosphine in observations from the James Clerk Maxwell Telescope (JCMT), operated by the East Asian Observatory, in Hawai'i. Confirming their discovery required using 45 antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a more sensitive telescope in which the European Southern Observatory (ESO) is a partner. Both facilities observed Venus at a wavelength of about 1 millimetre, much longer than the human eye can see -- only telescopes at high altitude can detect it effectively.

The international team, which includes researchers from the UK, US and Japan, estimates that phosphine exists in Venus's clouds at a small concentration, only about twenty molecules in every billion. Following their observations, they ran calculations to see whether these amounts could come from natural non-biological processes on the planet. Some ideas included sunlight, minerals blown upwards from the surface, volcanoes, or lightning, but none of these could make anywhere near enough of it. These non-biological sources were found to make at most one ten thousandth of the amount of phosphine that the telescopes saw.

To create the observed quantity of phosphine (which consists of hydrogen and phosphorus) on Venus, terrestrial organisms would only need to work at about 10% of their maximum productivity, according to the team. Earth bacteria are known to make phosphine: they take up phosphate from minerals or biological material, add hydrogen, and ultimately expel phosphine. Any organisms on Venus will probably be very different to their Earth cousins, but they too could be the source of phosphine in the atmosphere.

While the discovery of phosphine in Venus's clouds came as a surprise, the researchers are confident in their detection. "To our great relief, the conditions were good at ALMA for follow-up observations while Venus was at a suitable angle to Earth. Processing the data was tricky, though, as ALMA isn't usually looking for very subtle effects in very bright objects like Venus," says team member Anita Richards of the UK ALMA Regional Centre and the University of Manchester. "In the end, we found that both observatories had seen the same thing -- faint absorption at the right wavelength to be phosphine gas, where the molecules are backlit by the warmer clouds below," adds Greaves, who led the study published today in Nature Astronomy.

Another team member, Clara Sousa Silva of the Massachusetts Institute of Technology in the US, has investigated phosphine as a "biosignature" gas of non-oxygen-using life on planets around other stars, because normal chemistry makes so little of it. She comments: "Finding phosphine on Venus was an unexpected bonus! The discovery raises many questions, such as how any organisms could survive. On Earth, some microbes can cope with up to about 5% of acid in their environment -- but the clouds of Venus are almost entirely made of acid."

The team believes their discovery is significant because they can rule out many alternative ways to make phosphine, but they acknowledge that confirming the presence of "life" needs a lot more work. Although the high clouds of Venus have temperatures up to a pleasant 30 degrees Celsius, they are incredibly acidic -- around 90% sulphuric acid -- posing major issues for any microbes trying to survive there.

ESO astronomer and ALMA European Operations Manager Leonardo Testi, who did not participate in the new study, says: "The non-biological production of phosphine on Venus is excluded by our current understanding of phosphine chemistry in rocky planets' atmospheres. Confirming the existence of life on Venus's atmosphere would be a major breakthrough for astrobiology; thus, it is essential to follow-up on this exciting result with theoretical and observational studies to exclude the possibility that phosphine on rocky planets may also have a chemical origin different than on Earth."

More observations of Venus and of rocky planets outside our Solar System, including with ESO's forthcoming Extremely Large Telescope, may help gather clues on how phosphine can originate on them and contribute to the search for signs of life beyond Earth.

Read more at Science Daily