It is winter on Mars

Newswand: When winter comes to Mars, the surface is transformed into a truly otherworldly holiday scene. Snow, ice, and frost accompany the season’s sub-zero temperatures. Some of the coldest of these occur at the planet’s poles, where it gets as low as minus 190 degrees Fahrenheit (minus 123 degrees Celsius).

Photo credit: NASA/JPL-Caltech/University of Arizona

Cold as it is, don’t expect snow drifts worthy of the Rocky Mountains. No region of Mars gets more than a few feet of snow, most of which falls over extremely flat areas. And the Red Planet’s elliptical orbit means it takes many more months for winter to come around: a single Mars year is around two Earth years.

Still, the planet offers unique winter phenomena that scientists have been able to study, thanks to NASA’s robotic Mars explorers. Here are a few of the things they’ve discovered.

Two kinds of snow

Martian snow comes in two varieties: water ice and carbon dioxide, or dry ice. Because Martian air is so thin and the temperatures so cold, water-ice snow sublimates, or becomes a gas, before it even touches the ground. Dry-ice snow actually does reach the ground.

“Enough falls that you could snowshoe across it,” said Sylvain Piqueux, a Mars scientist at NASA’s Jet Propulsion Laboratory in Southern California whose research includes a variety of winter phenomena. “If you were looking for skiing, though, you’d have to go into a crater or cliffside, where snow could build up on a sloped surface.”

How we know it is snows

Snow occurs only at the coldest extremes of Mars: at the poles, under cloud cover, and at night. Cameras on orbiting spacecraft can’t see through those clouds, and surface missions can’t survive in the extreme cold. As a result, no images of falling snow have ever been captured. But scientists know it happens, thanks to a few special science instruments.

NASA’s Mars Reconnaissance Orbiter can peer through cloud cover using its Mars Climate Sounder instrument, which detects light in wavelengths imperceptible to the human eye. That ability has allowed scientists to detect carbon dioxide snow falling to the ground. And in 2008, NASA sent the Phoenix lander within 1,000 miles (about 1,600 kilometers) of Mars’ north pole, where it used a laser instrument to detect water-ice snow falling to the surface.

Cubic snowflakes

Because of how water molecules bond together when they freeze, snowflakes on Earth have six sides. The same principle applies to all crystals: The way in which atoms arrange themselves determines a crystal’s shape. In the case of carbon dioxide, molecules in dry ice always bond in forms of four when frozen.

“Because carbon dioxide ice has a symmetry of four, we know dry-ice snowflakes would be cube-shaped,” Piqueux said. “Thanks to the Mars Climate Sounder, we can tell these snowflakes would be smaller than the width of a human hair.”

Water and carbon dioxide can each form frost on Mars, and both types of frost appear far more widely across the planet than snow does. The Viking landers saw water frost when they studied Mars in the 1970s, while NASA’s Odyssey orbiter has observed frost forming and sublimating away in the morning Sun.

Winter’s wondrous end

Perhaps the most fabulous discovery comes at the end of winter, when all the ice that built up begins to “thaw” and sublimate into the atmosphere. As it does so, this ice takes on bizarre and beautiful shapes that have reminded scientists of spiders, Dalmatian spots, fried eggs, and Swiss cheese.

This “thawing” also causes geysers to erupt: Translucent ice allows sunlight to heat up gas underneath it, and that gas eventually bursts out, sending fans of dust onto the surface. Scientists have actually begun to study these fans as a way to learn more about which way Martian winds are blowing.

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Is there life on Enceladus, moon of Saturn?

Newswand: Surrounded by a vast ocean underneath a thick ice shell, Enceladus is a hot candidate for potentially harboring alien life. A team of researchers led by the University of Arizona concluded that a future mission could provide answers even without landing on the tiny world. 

Photo credit: NASA/JPL-Caltech

The mystery of whether microbial alien life might inhabit Enceladus, one of Saturn’s 83 moons, could be solved by an orbiting space probe, according to a new study led by University of Arizona researchers. In a paper published in The Planetary Science Journal, the researchers map out how a hypothetical space mission could provide definite answers. 

When Enceladus was initially surveyed in 1980 by NASA’s Voyager 1 spacecraft, it looked like a small, not overly exciting “snowball” in the sky. Later, between 2005 and 2017, NASA’s Cassini probe zipped around the Saturnian System and studied Saturn’s complex rings and moons in unprecedented detail. Scientists were stunned when Cassini discovered that Enceladus’ thick layer of ice hides a vast, warm saltwater ocean outgassing methane, a gas that typically originates from microbial life on Earth. 

The methane, along with other organic molecules that build the foundations of life, was detected when Cassini flew through giant water plumes erupting from the surface of Enceladus. As the tiny moon orbits the ringed gas giant, it is being squeezed and tugged by Saturn’s immense gravitational field, heating up its interior due to friction. As a result, spectacular plumes of water jet from cracks and crevices on Enceladus’ icy surface into space. 

Last year, a team of scientists at UArizona and Université Paris Sciences et Lettres in Paris calculated that if life could have emerged on Enceladus, there is a high likelihood that its presence could explain why the moon is burping up methane. 

“To know if that is the case, we must go back to Enceladus and look,” said Régis Ferrière, senior author of the new paper and associate professor in the UArizona Department of Ecology and Evolutionary Biology.

In their latest paper, Ferrière and his collaborators report that while the hypothetical total mass of living microbes in Enceladus’ ocean would be small, a visit from an orbiting spacecraft is all that would be needed to know for sure whether Earthlike microbes populate Enceladus’ ocean underneath its shell. 

“By simulating the data that a more prepared and advanced orbiting spacecraft would gather from just the plumes alone, our team has now shown that this approach would be enough to confidently determine whether or not there is life within Enceladus’ ocean without actually having to probe the depths of the moon,” he said. “This is a thrilling perspective.”

Located about 800 million miles from Earth, Enceladus completes an orbit around Saturn every 33 hours. While the moon isn’t even as wide as the state of Arizona, it visually stands out because of its surface; like a frozen pond glinting in the sun, the moon reflects light like no other object in the solar system. Along the moon’s south pole, at least 100 giant water plumes erupt through cracks in the icy landscape much like lava from a violent volcano. 

Scientists believe that water vapor and ice particles ejected by these geyser-like features contribute to one of Saturn’s iconic rings. This ejected mixture, which brings up gases and other particles from deep inside Enceladus’ ocean, was sampled by the Cassini spacecraft.

The excess methane Cassini detected in the plumes conjures images of extraordinary ecosystems found in the lightless depths of Earth’s oceans: hydrothermal vents. Here, at the edges of two adjacent tectonic plates, hot magma below the seafloor heats the ocean water in porous bedrock, creating “white smokers,” vents spewing scorching hot, mineral-saturated seawater. With no access to sunlight, organisms depend on energy stored in chemical compounds released by the white smokers to make a living.  

“On our planet, hydrothermal vents teem with life, big and small, in spite of darkness and insane pressure,” Ferrière said. “The simplest living creatures there are microbes called methanogens that power themselves even in the absence of sunlight.” 

Methanogens convert dihydrogen and carbon dioxide to gain energy, releasing methane as a byproduct. Ferrière’s research group modeled its calculations based on the hypothesis that Enceladus has methanogens that inhabit oceanic hydrothermal vents resembling the ones found on Earth. In this way, the researchers calculated what the total mass of methanogens on Enceladus would be, as well as the likelihood that their cells and other organic molecules could be ejected through the plumes.

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Jupiter’s troposphere has a lot in common with Earth’s

Newswand: Scientists have completed the longest-ever study tracking temperatures in Jupiter’s upper troposphere, the layer of the atmosphere where the giant planet’s weather occurs and where its signature colorful striped clouds form.

Photo credit: ESO / L.N. Fletcher

The work, conducted over four decades by stitching together data from NASA spacecraft and ground-based telescope observations, found unexpected patterns in how temperatures of Jupiter’s belts and zones change over time. The study is a major step toward a better understanding of what drives weather at our solar system’s largest planet and eventually being able to forecast it.

Jupiter’s troposphere has a lot in common with Earth’s: It’s where clouds form and storms churn. To understand this weather activity, scientists need to study certain properties, including wind, pressure, humidity, and temperature. They have known since NASA’s Pioneer 10 and 11 missions in the 1970s that, in general, colder temperatures are associated with Jupiter’s lighter and whiter bands (known as zones), while the darker brown-red bands (known as belts) are locations of warmer temperatures.

But there weren’t enough data sets to understand how temperatures vary over the long-term. The new research, published Dec. 19 in Nature Astronomy, breaks ground by studying images of the bright infrared glow (invisible to the human eye) that rises from warmer regions of the atmosphere, directly measuring Jupiter’s temperatures above the colorful clouds. The scientists collected these images at regular intervals over three of Jupiter’s orbits around the Sun, each of which lasts 12 Earth years.

In the process, they found that Jupiter’s temperatures rise and fall following definite periods that aren’t tied to the seasons or any other cycles scientists know about. Because Jupiter has weak seasons – the planet is tilted on its axis only 3 degrees, compared to Earth’s jaunty 23.5 degrees – scientists didn’t expect to find temperatures on Jupiter varying in such regular cycles.

The study also revealed a mysterious connection between temperature shifts in regions thousands of miles apart: As temperatures went up at specific latitudes in the northern hemisphere, they went down at the same latitudes in the southern hemisphere – like a mirror image across the equator.

“That was the most surprising of all,” said Glenn Orton, senior research scientist at NASA’s Jet Propulsion Laboratory and lead author of the study. “We found a connection between how the temperatures varied at very distant latitudes. It’s similar to a phenomenon we see on Earth, where weather and climate patterns in one region can have a noticeable influence on weather elsewhere, with the patterns of variability seemingly ‘teleconnected’ across vast distances through the atmosphere.”

The next challenge is to find out what causes these cyclical and seemingly synchronized changes.

“We’ve solved one part of the puzzle now, which is that the atmosphere shows these natural cycles,” said co-author Leigh Fletcher of the University of Leicester in England. “To understand what’s driving these patterns and why they occur on these particular timescales, we need to explore both above and below the cloudy layers.”

One possible explanation became apparent at the equator: The study authors found that temperature variations higher up, in the stratosphere, seemed to rise and fall in a pattern that is the opposite of how temperatures behave in the troposphere, suggesting changes in the stratosphere influence changes in the troposphere and vice versa.

Decades of observations

Orton and his colleagues began the study in 1978. For the duration of their research, they would write proposals several times a year to win observation time on three large telescopes around the world: the Very Large Telescope in Chile as well as NASA’s Infrared Telescope Facility and the Subaru Telescope at the Maunakea Observatories in Hawaii.

During the first two decades of the study, Orton and his teammates took turns traveling to those observatories, gathering the information on temperatures that would eventually allow them to connect the dots. (By the early 2000s, some of the telescope work could be done remotely.)

Then came the hard part – combining multiple years’ worth of observations from several telescopes and science instruments to search for patterns. Joining these veteran scientists on their long-duration study were several undergraduate interns, none of whom had been born when the study began. They are students at Caltech in Pasadena, California; Cal Poly Pomona in Pomona, California; Ohio State University in Columbus, Ohio; and Wellesley College in Wellesley, Massachusetts.

Scientists hope the study will help them eventually be able to predict weather on Jupiter, now that they have a more detailed understanding of it. The research could contribute to climate modeling, with computer simulations of the temperature cycles and how they affect weather – not just for Jupiter, but for all giant planets across our solar system and beyond.

“Measuring these temperature changes and periods over time is a step toward ultimately having a full-on Jupiter weather forecast, if we can connect cause and effect in Jupiter’s atmosphere,” Fletcher said. “And the even bigger-picture question is if we can someday extend this to other giant planets to see if similar patterns show up.”

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Astronomers found two exoplanets in habitable zone around star GJ 1002

Newswand: An international scientific team led by researchers at the Instituto de Astrofísica de Canarias (IAC) has discovered the presence of two planets with Earth-like masses in orbit around the star GJ 1002, a red dwarf not far from the Solar System. Both planets are in the habitability zone of the star

Photo credit: Alejandro Suárez Mascareño and Inés Bonet (IAC)

“Nature seems bent on showing us that Earth-like planets are very common. With these two we now know 7 in planetary systems quite near to the Sun” explains Alejandro Suárez Mascareño, an IAC researcher, who is the first author of the study accepted for publication in Astronomy & Astrophysics.

The newly discovered planets orbit the star GJ 1002, which is at a distance of less than 16 light years from the Solar System. Both of them have masses similar to that of the Earth, and they are in the habitability zone of their star. GJ 1002b, the inner of the two, takes little more than 10 days to complete an orbit around the star, while GJ 1002c needs a little over 21 days. “GJ 1002 is a red dwarf star, with barely one eighth the mass of the Sun. It is quite a cool, faint star. This means that its habitability zone is very close to the star” explains Vera María Passegger, a co-author of the article and an IAC researcher.

The proximity of the star to our Solar System implies that the two planets, especially GJ 1002c, are excellent candidates for the characterization of their atmospheres based either on their reflected light, or on their thermal emission. “The future ANDES spectrograph for the ELT telescope at ESO in which the IAC is participating, could study the presence of oxygen in the atmosphere of GJ 1002c” notes Jonay I. González Hernández, an IAC researcher who is a co-author of the article. In addition, both planets satisfy the characteristics needed for them to be objectives for the future LIFE mission, which is presently in a study phase.

The discovery was made during a collaboration between the consortia of the two instruments ESPRESSO and CARMENES. GJ 1002 was observed by CARMENES between 2017 and 2019, and by ESPRESSO between 2019 and 2021. “Because of its low temperature the visible light from GJ 1002 is too faint to measure its variations in velocity with the majority of spectrographs” says Ignasi Ribas, researcher at the Institute of Space Sciences (ICE-CSIC) and director of the Institut d’Estudis Espacials de Catalunya (IEEC). CARMENES has a sensitivity over a wide range of near infrared wavelengths which is superior to those of other spectrographs aimed at detecting variations in the velocities of stars, and this allowed it to study GJ 1002, from the 3.5m telescope at Calar Alto observatory.

The combination of ESPRESSO, and the light gathering power of the VLT 8m telescopes at ESO allowed measurements to be made with an accuracy of only 30 cm/sec, not attainable with any other instrument in the world. “Either of the two groups would have had many difficulties if they had tackled this work independently. Jointly we have been able to get much further than we would have done acting independently” states Suárez Mascareño.

Other members of the IAC who have collaborated in this publication are the researchers Rafael Rebolo López, Víctor Sánchez Béjar and Enric Pallé.

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Two exoplanets found to be water worlds

Newswand: A team led by researchers at the University of Montreal has found evidence that two exoplanets orbiting a red dwarf star are “water worlds,” where water makes up a large fraction of the entire planet. These worlds, located in a planetary system 218 light-years away in the constellation Lyra, are unlike any planet found in our solar system.

Photo credit: NASA, ESA, and Leah Hustak (STScI)

The team, led by Caroline Piaulet of the Trottier Institute for Research on Exoplanets at the University of Montreal, published a detailed study of this planetary system, known as Kepler-138, in the journal Nature Astronomy.

Piaulet and colleagues observed exoplanets Kepler-138 c and Kepler-138 d with NASA’s Hubble and the retired Spitzer space telescopes and discovered that the planets could be composed largely of water. These two planets and a smaller planetary companion closer to the star, Kepler-138 b, had been discovered previously by NASA’s Kepler Space Telescope. The new study found evidence for a fourth planet, too.

Water wasn’t directly detected at Kepler-138 c and d, but by comparing the sizes and masses of the planets to models, astronomers conclude that a significant fraction of their volume – up to half of it – should be made of materials that are lighter than rock but heavier than hydrogen or helium (which constitute the bulk of gas giant planets like Jupiter). The most common of these candidate materials is water.

“We previously thought that planets that were a bit larger than Earth were big balls of metal and rock, like scaled-up versions of Earth, and that’s why we called them super-Earths,” explained Björn Benneke, study co-author and professor of astrophysics at the University of Montreal. “However, we have now shown that these two planets, Kepler-138 c and d, are quite different in nature and that a big fraction of their entire volume is likely composed of water. It is the best evidence yet for water worlds, a type of planet that was theorized by astronomers to exist for a long time.”

With volumes more than three times that of Earth and masses twice as big, planets c and d have much lower densities than Earth. This is surprising because most of the planets just slightly bigger than Earth that have been studied in detail so far all seemed to be rocky worlds like ours. The closest comparison, say researchers, would be some of the icy moons in the outer solar system that are also largely composed of water surrounding a rocky core.

“Imagine larger versions of Europa or Enceladus, the water-rich moons orbiting Jupiter and Saturn, but brought much closer to their star,” explained Piaulet. “Instead of an icy surface, they would harbor large water-vapor envelopes.”

Researchers caution the planets may not have oceans like those on Earth directly at the planet’s surface. “The temperature in Kepler-138 d’s atmosphere is likely above the boiling point of water, and we expect a thick dense atmosphere made of steam on this planet. Only under that steam atmosphere there could potentially be liquid water at high pressure, or even water in another phase that occurs at high pressures, called a supercritical fluid,” Piaulet said.

In 2014, data from NASA’s Kepler Space Telescope allowed astronomers to announce the detection of three planets orbiting Kepler-138. This was based on a measurable dip in starlight as the planet momentarily passed in front of their star.

Benneke and his colleague Diana Dragomir, from the University of New Mexico, came up with the idea of re-observing the planetary system with the Hubble and Spitzer space telescopes between 2014 and 2016 to catch more transits of Kepler-138 d, the third planet in the system, in order to study its atmosphere.

A new exoplanet in the system

The two possible water worlds, Kepler-138 c and d, are not located in the habitable zone, the area around a star where temperatures would allow liquid water on the surface of a rocky planet. But in the Hubble and Spitzer data, researchers additionally found evidence for a new planet in the system, Kepler-138 e, in the habitable zone.

This newly found planet is small and farther from its star than the three others, taking 38 days to complete an orbit. The nature of this additional planet, however, remains an open question because it does not seem to transit its host star. Observing the exoplanet’s transit would have allowed astronomers to determine its size.

With Kepler-138 e now in the picture, the masses of the previously known planets were measured again via the transit timing-variation method, which consists of tracking small variations in the precise moments of the planets’ transits in front of their star caused by the gravitational pull of other nearby planets.

The researchers had another surprise: they found that the two water worlds Kepler-138 c and d are “twin” planets, with virtually the same size and mass, while they were previously thought to be drastically different. The closer-in planet, Kepler-138 b, on the other hand, is confirmed to be a small Mars-mass planet, one of the smallest exoplanets known to date.

“As our instruments and techniques become sensitive enough to find and study planets that are farther from their stars, we might start finding a lot more of these water worlds,” Benneke concluded.

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A planet with giant lava ocean

Newswand: New research sheds light on how the “hell planet” got so devilishly hot and how other worlds might become too toasty for life. That rocky world, 55 Cnc e (nicknamed “Janssen”), orbits its star so closely that a year lasts just 18 hours, its surface is a giant lava ocean, and its interior may be chock-full of diamond.

Photo credit: Lucy Reading-Ikkanda/Simons Foundation

It orbits its star so closely that its entire surface is a lava ocean that reaches temperatures of around 2,000 degrees Celsius.

The fresh insights come thanks to a new tool called EXPRES that captured ultra-precise measurements of the starlight shining from Janssen’s sun, known as Copernicus or 55 Cnc. The light measurements ever-so-slightly shifted as Janssen moved between Earth and the star (an effect akin to our moon blocking the sun during a solar eclipse).

By analyzing those measurements, astronomers discovered that Janssen orbits Copernicus along the star’s equator — unlike Copernicus’ other planets, which are on such different orbital paths that they never even cross between the star and Earth, the researchers report December 8 in Nature Astronomy.

The implication is that Janssen probably formed in a relatively cooler orbit further out and slowly fell toward Copernicus over time. As Janssen moved closer in, the stronger gravitational pull from Copernicus altered the planet’s orbit.

“We’ve learned about how this multi-planet system — one of the systems with the most planets that we’ve found — got into its current state,” says study lead author Lily Zhao, a research fellow at the Flatiron Institute’s Center for Computational Astrophysics (CCA) in New York City.

Even in its original orbit, the planet “was likely so hot that nothing we’re aware of would be able to survive on the surface,” Zhao says. Still, the new findings could help scientists better understand how planets form and move around over time. Such information is critical to finding out just how common Earth-like environments are in the universe and, therefore, how abundant extraterrestrial life may be.

Our solar system, after all, is the only place in the cosmos where we know life exists. It’s also flat as a pancake — all the planets orbit within a few degrees of one another, having formed from the same disk of gas and dust. When exoplanet-hunting missions started discovering worlds around distant stars, they found many planets that didn’t orbit their host stars on a flat plane. This raised the question of whether our pancake like solar system is truly a rarity.

Copernicus’ planetary system, which is 40 light-years away from Earth, is of particular interest given how well studied and complex it is: Five exoplanets orbit a main-sequence star (the most common category of star) in a binary pair with a red dwarf star. In fact, Janssen was the first ‘super-Earth’ discovered around a main-sequence star. While Janssen has a similar density to Earth and is likely rocky, it’s about eight times as massive and twice as wide.

Upon its discovery and confirmation, Janssen became the first known example of an ultra-short-period planet. Janssen’s orbit has a minimum radius of roughly 2 million kilometers. (For comparison, Mercury’s is 46 million kilometers, and Earth’s is around 147 million.) Janssen’s orbit is so snug around Copernicus that at first some astronomers doubted its existence.

Determining Janssen’s path around Copernicus could reveal much about the planet’s history, but making such measurements is incredibly hard. Astronomers have studied Janssen by measuring the dip in Copernicus’ brightness every time the planet comes between the star and Earth.

That method doesn’t tell you what direction the planet is moving in. To find that out, astronomers take advantage of the same Doppler effect used in speeding cameras. When a light source is moving toward you, the wavelength of the light you see is shorter (and therefore bluer). When it’s moving away, the frequency is shifted wider, and the light is redder.

As Copernicus rotates, half of the star is twirling toward us, and the other half is moving away. That means half the star is a bit bluer, and the other half is slightly redder (and the space in the middle is unshifted). So astronomers can track Janssen’s orbit by measuring when it’s blocking light from the redder side, the bluer side and the unaltered midsection.

The resulting difference in the starlight, however, is almost immeasurably small. Teams had tried before but couldn’t accurately determine the planet’s orbital path. The breakthrough in the new research came from the EXtreme PREcision Spectrometer (EXPRES) at the Lowell Observatory’s Lowell Discovery Telescope in Arizona. True to its name, the spectrometer offered the precision needed to notice the light’s tiny red and blue shifts.

The EXPRES measurements revealed that Janssen’s orbit is roughly aligned with Copernicus’ equator, a path that makes Janssen unique among its siblings.

Previous research suggests that the nearby orbit of the red dwarf resulted in the misalignment of the planets relative to Copernicus. In the new study, the researchers propose that interactions between the heavenly bodies shifted Janssen toward its hellish present-day location. As Janssen approached Copernicus, the star’s gravity became increasingly dominant. Because Copernicus is spinning, the centrifugal force caused its midsection to bulge outward slightly and its top and bottom to flatten. That asymmetry affected the gravity felt by Janssen, pulling the planet into alignment with the star’s thicker equator.

With Janssen’s history illuminated, Zhao and her colleagues now plan to study other planetary systems. “We’re hoping to find planetary systems similar to ours,” she says, “and to better understand the systems that we do know about.”

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Mars is not a dead planet!

Newswand: Discovery of an active mantle plume pushing the surface upward and causing earthquakes and volcanic eruptions suggests that Mars’s deceptively quiet surface may hide a more tumultuous interior than previously thought.

Photo credit: ESA/DLR/FU Berlin

On Earth, shifting tectonic plates reshuffle the planet’s surface and make for a dynamic interior, so the absence of such processes on Mars led many to think of it as a dead planet, where not much happened in the past 3 billion years.

In a study published in Nature Astronomy, scientists from the University of Arizona challenge current views of Martian geodynamic evolution with a report on the discovery of an active mantle plume pushing the surface upward and causing earthquakes and volcanic eruptions. The finding suggests that the planet’s deceptively quiet surface may hide a more tumultuous interior than previously thought.

“Our study presents multiple lines of evidence that reveal the presence of a giant active mantle plume on present-day Mars,” said Adrien Broquet, a postdoctoral research associate in the UArizona Lunar and Planetary Laboratory and co-author of the study with Jeff Andrews-Hanna, an associate professor of planetary science at the LPL.

Mantle plumes are large blobs of warm and buoyant rock that rise from deep inside a planet and push through its intermediate layer – the mantle – to reach the base of its crust, causing earthquakes, faulting and volcanic eruptions. The island chain of Hawaii, for example, formed as the Pacific plate slowly drifted over a mantle plume.

“We have strong evidence for mantle plumes being active on Earth and Venus, but this isn’t expected on a small and supposedly cold world like Mars,” Andrews-Hanna said. “Mars was most active 3 to 4 billion years ago, and the prevailing view is that the planet is essentially dead today.”

“A tremendous amount of volcanic activity early in the planet’s history built the tallest volcanoes in the solar system and blanketed most of the northern hemisphere in volcanic deposits,” Broquet said. “What little activity has occurred in recent history is typically attributed to passive processes on a cooling planet.”

The researchers were drawn to a surprising amount of activity in an otherwise nondescript region of Mars called Elysium Planitia, a plain within Mars’ northern lowlands close to the equator. Unlike other volcanic regions on Mars, which haven’t seen major activity for billions of years, Elysium Planitia experienced large eruptions over the past 200 million years.

“Previous work by our group found evidence in Elysium Planitia for the youngest volcanic eruption known on Mars,” Andrews-Hanna said. “It created a small explosion of volcanic ash around 53,000 years ago, which in geologic time is essentially yesterday.”

Volcanism at Elysium Planitia originates from the Cerberus Fossae, a set of young fissures that stretch for more than 800 miles across the Martian surface. Recently, NASA’s InSight team found that nearly all Martian quakes, or marsquakes, emanate from this one region. Although this young volcanic and tectonic activity had been documented, the underlying cause remained unknown.

On Earth, volcanism and earthquakes tend to be associated with either mantle plumes or plate tectonics, the global cycle of drifting continents that continually recycles the crust.

“We know that Mars does not have plate tectonics, so we investigated whether the activity we see in the Cerberus Fossae region could be the result of a mantle plume,” Broquet said.

Study on features of Elysium Planitia revealed that the surface has been uplifted by more than a mile, making it one of the highest regions in Mars’ vast northern lowlands. Analyses of subtle variations in the gravity field indicated that this uplift is supported from deep within the planet, consistent with the presence of a mantle plume.

Other measurements showed that the floor of impact craters is tilted in the direction of the plume, further supporting the idea that something pushed the surface up after the craters formed. Finally, when researchers applied a tectonic model to the area, they found that the presence of a giant plume, 2,500 miles wide, was the only way to explain the extension responsible for forming the Cerberus Fossae.

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JWST to turn its cameras on Titan

Newswand: The James Webb Space Telescope (JWST) has turned its infrared cameras on Saturn’s moon Titan, giving astronomers another eye on the largest and one of the most unusual moons in the solar system.

Photo credit: NASA/STScI/Keck Observatory/Judy Schmidt

The only satellite with a dense atmosphere, it’s also the only world besides Earth that has standing bodies of liquid on its surface, including rivers, lakes and seas — though the liquid is thought to be methane, ethane and other hydrocarbons that are toxic to humans.

The new observations, combined with those from Earth-bound telescopes, will help astronomers understand the weather patterns on Titan in advance of a NASA mission to the moon, called Dragonfly, that is scheduled for launch in 2027. A multirotor lander, Dragonfly will assess the habitability of Titan’s unique environment, investigate the moon’s unusual chemical stew, and search for signatures of water-based or hydrocarbon-based life.

Astronomers have observed Titan for decades, since before the Voyager encounter in 1980. Over approximately the past 25 years, they focused powerful ground-based and orbital telescopes on the satellite, complementing observations by NASA’s Cassini mission to Saturn, which observed Titan between 2004 and 2017. University of California, Berkeley, astronomer Imke de Pater led many Titan observations using high-resolution adaptive optics on the Keck Telescopes in Hawai’i.

After the JWST imaged Titan on Nov. 4, the telescope’s Titan team saw what looked like two clouds in the atmosphere. Titan team lead Conor Nixon quickly emailed de Pater and Katherine de Kleer — a UC Berkeley Ph.D. who is now an assistant professor of planetary science and astronomy at the California Institute of Technology — to help confirm the clouds and track their movement with the Keck Telescope.

A series of Keck images taken about 30 and 54 hours later showed similar clouds — likely the same ones — but slightly displaced because of the moon’s rotation relative to Earth.

“We were concerned that the clouds would be gone when we looked at Titan one and two days later with Keck, but to our delight there were clouds at the same positions, looking like they might have changed in shape,” said de Pater, a UC Berkeley Professor of the Graduate School.

Though the quality of the JWST and Keck images may look about the same to the untrained eye, de Pater noted that JWST has instruments that can measure aspects of Titan’s atmosphere that Keck cannot, complementing one another. In particular, JWST’s infrared spectroscopic capability allows it to pinpoint the altitudes of clouds and hazes with much better accuracy.

“By using spectrometers on JWST together with the optical image quality with Keck, we get a really complete picture of Titan,” she said, such as the heights of clouds, the atmosphere’s optical thickness, and the elevation of haze in the atmosphere.

In particular, at wavelengths where Earth’s atmosphere is opaque — that is, Titan cannot be seen from any Earth-based telescope — JWST can observe and provide information on the lower atmosphere and surface.

In early September, and again earlier this week, de Pater and de Kleer participated in an international observing campaign to catch the occultation by Titan of a distant star. Organized by Eliot Young, a senior program manager at the Southwest Research Institute in Boulder, Colorado, the occultation offered an opportunity to probe Titan’s atmospheric structure in more detail using the Keck Telescope and the Very Large Telescope in Chile. These observations are coordinated with occultations observed from other large telescopes and Doppler wind retrievals on Titan from the Atacama Large Millimeter Array, a radio telescope in Chile.

In conjunction with recent wind modeling results, these observations contribute to a broader understanding of atmospheres on Earth, on planets around other stars, and on our neighboring planets and moons in the solar system.

“This is some of the most exciting data we have seen of Titan since the end of the Cassini-Huygens mission in 2017, and some of the best we will get before NASA’s Dragonfly arrives in 2032,” said Zibi Turtle of Johns Hopkins University, who is Dragonfly’s principal investigator. “The analysis should really help us to learn a lot about Titan’s atmosphere and meteorology.”

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