Mars Express finds clues of water flow on Mars

Newswand: Mars Express recently has taken a look at the Holden Basin – part of a region that is a high-ranking target in the search for signs of past life on the Red Planet and found that water may have flown in this area. It has taken few images on 24 April 2022 by the spacecraft’s High Resolution Stereo Camera.

Photo credit: ESA

A barren landscape shaped by water

The Holden Basin is part of a series of channels and sinks called the Uzboi-Ladon-Morava (ULM) outflow system that may have once drained up to 9% of the Martian surface. The complex history of the ULM outflow system makes it an interesting target to explore in more detail with Mars orbiters and rovers.

The maps of Mars show us the Holden Basin and the full ULM outflow system in context. They show how water once flowed across this region of Mars; it would have started in channels that drain into the Argyre Planitia, then flowed through Uzboi Vallis into the location now scarred by the Holden Crater. From there it would have collected in the Holden Basin before streaming through Ladon Valles to Ladon Basin and beyond.

The maps also shows Mars’ ‘Grand Canyon’ Valles Marineris, which we delved into in our previous Mars Express image release.

A closer look at Holden Basin

Few other images show close ups of the Holden Basin from inside the once water-filled reservoir.

An image shows a distinct crater and the basin walls, which slope gently down to around 1500 metres below the level of the surrounding ground.

Another image is from the northeast of the Holden Basin and it takes a closer look at the location where water would have flowed from Holden Basin to Ladon Valles. The bumps in the rough terrain were formed when water ice under the surface of Mars melted.

The entire region could be an interesting target in the search for ancient life on Mars. Our experience on Earth tells us that where there is water, there is life: could the same have been true billions of years ago on Mars?

Phyllosilicates are a type of mineral also found on Earth, with one example being clay. They could serve as a reaction centre for organic molecules, which make up all living things on Earth; past experiments suggest that phyllosilicates could have played a role in the origin of life.

The 140-km wide Holder Crater formed when Mars was hit by a space rock; the material that was ejected during the impact filled Holden Basin, which is itself a much older impact crater. As the crater shows no evidence that significant amounts of water flowed through it, it very likely formed after the ULM system had mostly dried out. Due to its interesting geology and potential for clues to past life, Holden Crater was on the shortlist of landing sites for NASA’s Mars Science Laboratory and Perseverance rover.

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The sands of Mars are green as well as red

Newswand: So far we have believed that everything on the Mars is red. But Perseverance Rover has been proving it wrong as there some ‘green areas’ on that planet.

Photo credit: NASA/JPL-Caltech/ASU

 The accepted view of Mars is red rocks and craters as far as the eye can see. That’s much what scientists expected when they landed the rover Perseverance in the Jezero Crater, a spot chosen partly for the crater’s history as a lake and as part of a rich river system, back when Mars had liquid water, air and a magnetic field.

What the rover found once on the ground was startling: Rather than the expected sedimentary rocks – washed in by rivers and accumulated on the lake bottom – many of the rocks are volcanic in nature. Specifically, they are composed of large grains of olivine, the muddier less-gemlike version of peridot that tints so many of Hawaii’s beaches dark green.

Planetary scientists Roger Wiens, professor of earth, atmospheric, and planetary sciences, and Briony Horgan, associate professor of earth, atmospheric, and planetary sciences, in Purdue’s College of Science, were instrumental in the discovery and analysis of this data, recently published in a suite of papers in the journals Science and Science Advances.

Wiens led the design and construction of Perseverance’s SuperCam, which helps analyze the rock samples and determine their type and origin. Horgan helped select Jezero Crater as the rover’s landing site and now uses the Mastcam-Z cameras on Perseverance to put its discoveries into geological context.

“We started to realize that these layered igneous rocks we were seeing look different from the igneous rocks we have these days on Earth,” Wiens said. “They’re very like igneous rocks on Earth early in its existence.”

The rocks and lava the rover is examining on Mars are nearly 4 billion years old. Rocks that old exist on Earth but are incredibly weathered and beaten, thanks to Earth’s active tectonic plates as well as the weathering effects of billions of years of wind, water and life. On Mars, these rocks are pristine and much easier to analyze and study.

Understanding the rocks on Mars, their evolution and history, and what they reveal about the history of planetary conditions on Mars helps researchers understand how life may have arisen on Mars and how that compares with early life and conditions on ancient Earth.

“One of the reasons we don’t have a great understanding of where and when life first evolved on Earth is because those rocks are mostly gone, so it’s really hard to reconstruct what ancient environments on Earth were like,” Horgan said. “The rocks Perseverance is roving over in Jezero have more or less just been sitting at the surface for billions of years, waiting for us to come look at them. That’s one of the reasons that Mars is an important laboratory for understanding the early solar system.”

Scientists can use conditions on early Mars to help extrapolate the environment and conditions on Earth at the same time when life was beginning to arise. Understanding how, and under what conditions, life began will help scientists know where to look for it on other planets and moons, as well as lead to a deeper understanding of biological processes here on Earth.

The search for life is one of Perseverance’s main goals and one of the reasons it landed in Jezero Crater in the first place. Discovering the potential for habitable environments in something as uninhabitable as Jezero Crater’s aged lava flows raises hopes for what lies in the sedimentary rocks the mission is examining now.

The equipment and innovative instruments are helping the rover carry out its mission in a way no other rover yet has, emphasizing the need to land on the planet so scientists can examine and understand what’s really going on.

“From orbit, we looked at these rocks and said, ‘Oh, they have beautiful layers!’ So we thought they were sedimentary rocks,” Horgan said. “And it wasn’t until we were very close up and looked at them, at the millimeter scale, that we understood that these are not sedimentary rocks. They’re actually ancient lava. It was a huge moment when we figured that out on the ground, and it really illustrated why we need this kind of exploration. The tools we have on the rover are vital because it was impossible to understand the origin of these rocks until we got up close and used all our amazing microscopic instruments to look at them.”

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Researchers found “Ocean Planet”

Newswand: An international team of researchers led by Charles Cadieux, a Ph.D. student at the Université de Montréal and member of the Institute for Research on Exoplanets (iREx), has announced the discovery of an “Ocean Planet” orbiting TOI-1452, one of two small stars in a binary system located in the Draco constellation about 100 light-years from Earth.

Photo Credit: Benoit Gougeon, Université de Montréal.

The exoplanet, known as TOI-1452 b, is slightly greater in size and mass than Earth and is located at distance from its star where its temperature would be neither too hot nor too cold for liquid water to exist on its surface. The astronomers believe it could be an “ocean planet,” a planet completely covered by a thick layer of water, similar to some of Jupiter’s and Saturn’s moons.

In an article published on August 12th in The Astronomical Journal, Cadieux and his team describe the observations that elucidated the nature and characteristics of this unique exoplanet.

The host star TOI-1452 is much smaller than our Sun and is one of two of similar size stars in a binary system. The two stars orbit each other and are separated by such a small distance — 97 astronomical units, or about two and a half times the distance between the Sun and Pluto — that the TESS telescope sees them as a single point of light. But PESTO’s resolution is high enough to distinguish the two objects, and the images showed that the exoplanet does orbit TOI-1452, which was confirmed through  subsequent observations by a Japanese team.

 To determine the planet’s mass, the researchers then observed the system with SPIRou, an instrument installed on the Canada-France-Hawaii Telescope in Hawai’i. Designed in large part in Canada, SPIRou is ideal for studying low-mass stars such as TOI-1452 because it operates in the infrared spectrum, where these stars are brightest. Even then, it took more than 50 hours of observation to estimate the planet’s mass, which is believed to be nearly five times that of Earth.

TOI-1452 b is probably rocky like Earth, but its radius, mass, and density suggest a world very different from our own. Earth is essentially a very dry planet; even though we sometimes call it the Blue Planet because about 70% of its surface is covered by ocean, water actually only makes up only a negligible fraction of its mass — less than 1%.

Water may be much more abundant on some exoplanets. In recent years, astronomers have identified and determined the radius and mass of many exoplanets with a size between that of Earth and Neptune (about 3.8 times larger than Earth). Some of these planets have a density that can only be explained if a large fraction of their mass is made up of volatiles such as water. These hypothetical worlds have been dubbed “ocean planets.”

“TOI-1452 b is one of the best candidates for an ocean planet that we have found to date,” said Cadieux. “Its radius and mass suggest a much lower density than what one would expect for a planet that is basically made up of metal and rock, like Earth.”

The University of Toronto’s Mykhaylo Plotnykov and Diana Valencia are specialists in exoplanet interior modeling. Their analysis of TOI-1452 b shows that water may make up as much as 30% of its mass, a proportion similar to that of some natural satellites in our Solar System, such as Jupiter’s moons Ganymede and Callisto, and Saturn’s moons Titan and Enceladus.

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Perseverance makes new discoveries in Mars’ Jezero crater

Newswand: In a new finding Perseverance Mars Rover found that Jezero Crater’s floor is made up of volcanic rocks that have interacted with water.

Photo credit: NASA/JPL-Caltech/MSSS

Scientists got a surprise when NASA’s Perseverance Mars rover began examining rocks on the floor of Jezero Crater in spring of 2021: Because the crater held a lake billions of years ago, they had expected to find sedimentary rock, which would have formed when sand and mud settled in a once-watery environment. Instead, they discovered the floor was made of two types of igneous rock – one that formed deep underground from magma, the other from volcanic activity at the surface.

Photo credit: NASA/JPL-Caltech/ASU/MSSS

The findings are described in four new papers published Thursday, Aug. 25. In Science, one offers an overview of Perseverance’s exploration of the crater floor before it arrived at Jezero’s ancient river delta in April 2022; a second study in the same journal details distinctive rocks that appear to have formed from a thick body of magma. The other two papers, published in Science Advances, detail the unique ways that Perseverance’s rock-vaporizing laser and ground-penetrating radar established that igneous rocks cover the crater floor.

Rock of ages

Igneous rocks are excellent timekeepers: Crystals within them record details about the precise moment they formed.

“One great value of the igneous rocks we collected is that they will tell us about when the lake was present in Jezero. We know it was there more recently than the igneous crater floor rocks formed,” said Ken Farley of Caltech, Perseverance’s project scientist and the lead author of the first of the new Science papers. “This will address some major questions: When was Mars’ climate conducive to lakes and rivers on the planet’s surface, and when did it change to the very cold and dry conditions we see today?”

However, because of how it forms, igneous rock isn’t ideal for preserving the potential signs of ancient microscopic life Perseverance is searching for. In contrast, determining the age of sedimentary rock can be challenging, particularly when it contains rock fragments that formed at different times before the rock sediment was deposited. But sedimentary rock often forms in watery environments suitable for life and is better at preserving ancient signs of life.

That’s why the sediment-rich river delta Perseverance has been exploring since April 2022 has been so tantalizing to scientists. The rover has begun drilling and collecting core samples of sedimentary rocks there so that the Mars Sample Return campaign could potentially return them to Earth to be studied by powerful lab equipment too large to bring to Mars.

Mysterious magma-formed rocks

A second paper published in Science solves a longstanding mystery on Mars. Years ago, Mars orbiters spotted a rock formation filled with the mineral olivine. Measuring roughly 27,000 square miles (70,000 square kilometers) – nearly the size of South Carolina – this formation extends from the inside edge of Jezero Crater into the surrounding region.

Scientists have offered various theories why olivine is so plentiful over such a large area of the surface, including meteorite impacts, volcanic eruptions, and sedimentary processes. Another theory is that the olivine formed deep underground from slowly cooling magma – molten rock – before being exposed over time by erosion.

Yang Liu of NASA’s Jet Propulsion Laboratory in Southern California and her co-authors have determined that last explanation is the most likely. Perseverance abraded a rock to reveal its composition; studying the exposed patch, the scientists homed in on the olivine’s large grain size, along with the rock’s chemistry and texture.

Using Perseverance’s Planetary Instrument for X-ray Lithochemistry, or PIXL, they determined the olivine grains in the area measure 1 to 3 millimeters – much larger than would be expected for olivine that formed in rapidly cooling lava at the planet’s surface.

“This large crystal size and its uniform composition in a specific rock texture require a very slow-cooling environment,” Liu said. “So, most likely, this magma in Jezero wasn’t erupting on the surface.”

The science team is excited by what they’ve found so far, but they’re even more excited about the science that lies ahead.

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This is how the Webb saw Jupiter

Newswand: With giant storms, powerful winds, auroras, and extreme temperature and pressure conditions, Jupiter has a lot going on. Now, NASA’s James Webb Space Telescope has captured new images of the planet. Webb’s Jupiter observations will give scientists even more clues to Jupiter’s inner life. 

Photo credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt.

“We hadn’t really expected it to be this good, to be honest,” said planetary astronomer Imke de Pater, professor emerita of the University of California, Berkeley. De Pater led the observations of Jupiter with Thierry Fouchet, a professor at the Paris Observatory, as part of an international collaboration for Webb’s Early Release Science program.

The two images come from the observatory’s Near-Infrared Camera (NIRCam), which has three specialized infrared filters that showcase details of the planet. Since infrared light is invisible to the human eye, the light has been mapped onto the visible spectrum. Generally, the longest wavelengths appear redder and the shortest wavelengths are shown as more blue. Scientists collaborated with citizen scientist Judy Schmidt to translate the Webb data into images.

In the standalone view of Jupiter, created from a composite of several images from Webb, auroras extend to high altitudes above both the northern and southern poles of Jupiter. The auroras shine in a filter that is mapped to redder colors, which also highlights light reflected from lower clouds and upper hazes. A different filter, mapped to yellows and greens, shows hazes swirling around the northern and southern poles. A third filter, mapped to blues, showcases light that is reflected from a deeper main cloud. 

The Great Red Spot, a famous storm so big it could swallow Earth, appears white in these views, as do other clouds, because they are reflecting a lot of sunlight.

“The brightness here indicates high altitude – so the Great Red Spot has high-altitude hazes, as does the equatorial region,” said Heidi Hammel, Webb interdisciplinary scientist for solar system observations and vice president for science at AURA. “The numerous bright white ‘spots’ and ‘streaks’ are likely very high-altitude cloud tops of condensed convective storms.” By contrast, dark ribbons north of the equatorial region have little cloud cover. 

In a wide-field view, Webb sees Jupiter with its faint rings, which are a million times fainter than the planet, and two tiny moons called Amalthea and Adrastea. The fuzzy spots in the lower background are likely galaxies “photobombing” this Jovian view.  

“This one image sums up the science of our Jupiter system program, which studies the dynamics and chemistry of Jupiter itself, its rings, and its satellite system,” Fouchet said. Researchers have already begun analyzing Webb data to get new science results about our solar system’s largest planet.

Data from telescopes like Webb doesn’t arrive on Earth neatly packaged. Instead, it contains information about the brightness of the light on Webb’s detectors. This information arrives at the Space Telescope Science Institute (STScI), Webb’s mission and science operations center, as raw data. STScI processes the data into calibrated files for scientific analysis and delivers it to the Mikulski Archive for Space Telescopes for dissemination. Scientists then translate that information into images like these during the course of their research (here’s a podcast about that). While a team at STScI formally processes Webb images for official release, non-professional astronomers known as citizen scientists often dive into the public data archive to retrieve and process images, too.

Judy Schmidt of Modesto California, a longtime image processor in the citizen science community, processed these new views of Jupiter. For the image that includes the tiny satellites, she collaborated with Ricardo Hueso, a co-investigator on these observations, who studies planetary atmospheres at the University of the Basque Country in Spain.  

Jupiter is actually harder to work with than more distant cosmic wonders, Schmidt says, because of how fast it rotates. Combining a stack of images into one view can be challenging when Jupiter’s distinctive features have rotated during the time that the images were taken and are no longer aligned. Sometimes she has to digitally make adjustments to stack the images in a way that makes sense.

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NASA identifies candidate regions for landing next Americans on Moon

Newswand: As NASA prepares to send astronauts back to the Moon under Artemis, the agency has identified 13 candidate landing regions near the lunar South Pole. Each region contains multiple potential landing sites for Artemis III, which will be the first of the Artemis missions to bring crew to the lunar surface, including the first woman to set foot on the Moon.

Photo credit: NASA

“Selecting these regions means we are one giant leap closer to returning humans to the Moon for the first time since Apollo,” said Mark Kirasich, deputy associate administrator for the Artemis Campaign Development Division at NASA Headquarters in Washington. “When we do, it will be unlike any mission that’s come before as astronauts venture into dark areas previously unexplored by humans and lay the groundwork for future long-term stays.”

NASA identified 1. Faustini Rim A, 2. Peak Near Shackleton, 3. Connecting Ridge, 4. Connecting Ridge Extension, 5. de Gerlache Rim 1, 6. de Gerlache Rim 2, 7. de Gerlache-Kocher Massif, 8. Haworth, 9. Malapert Massif, 10. Leibnitz Beta Plateau, 11. Nobile Rim 1, 12. Nobile Rim 2, 13. Amundsen Rim for an Artemis III lunar landing.

Each of these regions is located within six degrees of latitude of the lunar South Pole and, collectively, contain diverse geologic features. Together, the regions provide landing options for all potential Artemis III launch opportunities. Specific landing sites are tightly coupled to the timing of the launch window, so multiple regions ensure flexibility to launch throughout the year.

To select the regions, an agency wide team of scientists and engineers assessed the area near the lunar South Pole using data from NASA’s Lunar Reconnaissance Orbiter and decades of publications and lunar science findings. In addition to considering launch window availability, the team evaluated regions based on their ability to accommodate a safe landing, using criteria including terrain slope, ease of communications with Earth, and lighting conditions. To determine accessibility, the team also considered combined capabilities of the Space Launch System rocket, the Orion spacecraft, and the SpaceX-provided Starship human landing system.

All regions considered are scientifically significant because of their proximity to the lunar South Pole, which is an area that contains permanently shadowed regions rich in resources and in terrain unexplored by humans.

“Several of the proposed sites within the regions are located among some of the oldest parts of the Moon, and together with the permanently shadowed regions, provide the opportunity to learn about the history of the Moon through previously unstudied lunar materials,” said Sarah Noble, Artemis lunar science lead for NASA’s Planetary Science Division.

The analysis team weighed other landing criteria with specific Artemis III science objectives, including the goal to land close enough to a permanently shadowed region to allow crew to conduct a moonwalk, while limiting disturbance when landing. This will allow crew to collect samples and conduct scientific analysis in an uncompromised area, yielding important information about the depth, distribution, and composition of water ice that was confirmed at the Moon’s South Pole.

The team identified regions that can fulfill the moonwalk objective by ensuring proximity to permanently shadowed regions, and also factored in other lighting conditions. All 13 regions contain sites that provide continuous access to sunlight throughout a 6.5-day period – the planned duration of the Artemis III surface mission. Access to sunlight is critical for a long-term stay at the Moon because it provides a power source and minimizes temperature variations.

“Developing a blueprint for exploring the solar system means learning how to use resources that are available to us while also preserving their scientific integrity”, said Jacob Bleacher, chief exploration scientist for NASA. “Lunar water ice is valuable from a scientific perspective and also as a resource, because from it we can extract oxygen and hydrogen for life support systems and fuel.”

NASA will discuss the 13 regions with broader science and engineering communities through conferences and workshops to solicit input about the merits of each region. This feedback will inform site selections in the future, and NASA may identify additional regions for consideration. The agency will also continue to work with SpaceX to confirm Starship’s landing capabilities and assess the options accordingly.

NASA will select sites within regions for Artemis III after it identifies the mission’s target launch dates, which dictate transfer trajectories and surface environment conditions.

Through Artemis, NASA will land the first woman and the first person of color on the Moon, paving the way for a long-term, sustainable lunar presence and serving as a steppingstone for future astronaut missions to Mars.

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Voyager logs 45 years in space

Newswand: Voyager, NASA’s longest-lived mission, has logged 45 years in space.  Launched in 1977, the twin Voyager probes are NASA’s longest-operating mission and the only spacecrafts ever to explore interstellar space.

Voyager under preparation in 1977. Phto credit: NASA/JPL-Caltech

NASA’s twin Voyager probes have become, in some ways, time capsules of their era: They each carry an eight-track tape player for recording data, they have about 3 million times less memory than modern cell phones, and they transmit data about 38,000 times slower than a 5G internet connection.

Yet the Voyagers remain on the cutting edge of space exploration. Managed and operated by NASA’s Jet Propulsion Laboratory in Southern California, they are the only probes to ever explore interstellar space – the galactic ocean that our Sun and its planets travel through.

The Sun and the planets reside in the heliosphere, a protective bubble created by the Sun’s magnetic field and the outward flow of solar wind (charged particles from the Sun). Researchers – some of them younger than the two distant spacecraft – are combining Voyager’s observations with data from newer missions to get a more complete picture of our Sun and how the heliosphere interacts with interstellar space.

“The heliophysics mission fleet provides invaluable insights into our Sun, from understanding the corona or the outermost part of the Sun’s atmosphere, to examining the Sun’s impacts throughout the solar system, including here on Earth, in our atmosphere, and on into interstellar space,” said Nicola Fox, director of the Heliophysics Division at NASA Headquarters in Washington. “Over the last 45 years, the Voyager missions have been integral in providing this knowledge and have helped change our understanding of the Sun and its influence in ways no other spacecraft can.”

The Voyagers are also ambassadors, each carrying a golden record containing images of life on Earth, diagrams of basic scientific principles, and audio that includes sounds from nature, greetings in multiple languages, and music. The gold-coated records serve as a cosmic “message in a bottle” for anyone who might encounter the space probes. At the rate gold decays in space and is eroded by cosmic radiation, the records will last more than a billion years.

Beyond expectations

Voyager 2 launched on Aug 20, 1977, quickly followed by Voyager 1 on Sept 5. Both probes traveled to Jupiter and Saturn, with Voyager 1 moving faster and reaching them first. Together, the probes unveiled much about the solar system’s two largest planets and their moons. Voyager 2 also became the first and only spacecraft to fly close to Uranus (in 1986) and Neptune (in 1989), offering humanity remarkable views of – and insights into – these distant worlds.

While Voyager 2 was conducting these flybys, Voyager 1 headed toward the boundary of the heliosphere. Upon exiting it in 2012, Voyager 1 discovered that the heliosphere blocks 70 per cent of cosmic rays, or energetic particles created by exploding stars.

Voyager 2, after completing its planetary explorations, continued to the heliosphere boundary, exiting in 2018. The twin spacecraft’s combined data from this region has challenged previous theories about the exact shape of the heliosphere.

“Today, as both Voyagers explore interstellar space, they are providing humanity with observations of uncharted territory,” said Linda Spilker, Voyager’s deputy project scientist at JPL. “This is the first time we’ve been able to directly study how a star, our Sun, interacts with the particles and magnetic fields outside our heliosphere, helping scientists understand the local neighborhood between the stars, upending some of the theories about this region, and providing key information for future missions.”

The long journey

Over the years, the Voyager team has grown accustomed to surmounting challenges that come with operating such mature spacecraft, sometimes calling upon retired colleagues for their expertise or digging through documents written decades ago.

Each Voyager is powered by a radioisotope thermoelectric generator containing plutonium, which gives off heat that is converted to electricity. As the plutonium decays, the heat output decreases and the Voyagers lose electricity. To compensate, the team turned off all nonessential systems and some once considered essential, including heaters that protect the still-operating instruments from the frigid temperatures of space. All five of the instruments that have had their heaters turned off since 2019 are still working, despite being well below the lowest temperatures they were ever tested at.

Recently, Voyager 1 began experiencing an issue that caused status information about one of its onboard systems to become garbled. Despite this, the system and spacecraft otherwise continue to operate normally, suggesting the problem is with the production of the status data, not the system itself. The probe is still sending back science observations while the engineering team tries to fix the problem or find a way to work around it.

“The Voyagers have continued to make amazing discoveries, inspiring a new generation of scientists and engineers,” said Suzanne Dodd, project manager for Voyager at JPL. “We don’t know how long the mission will continue, but we can be sure that the spacecraft will provide even more scientific surprises as they travel farther away from the Earth.”

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Underwater snow gives clues about Europa’s icy shell

Newswand: A new study has found that below Europa’s thick icy crust is a massive, global ocean where the snow floats upwards onto inverted ice peaks and submerged ravines. The bizarre underwater snow is known to occur below ice shelves on Earth, but this study shows that the same is likely true for Jupiter’s moon, where it may play a role in building its ice shell.

The underwater snow is much purer than other kinds of ice, which means Europa’s ice shell could be much less salty than previously thought. That’s important for mission scientists preparing NASA’s Europa Clipper spacecraft, which will use radar to peek beneath the ice shell to see if Europa’s ocean could be hospitable to life.

The new information will be critical because salt trapped in the ice can affect what and how deep the radar will see into the ice shell, so being able to predict what the ice is made of will help scientists make sense of the data.

The study, published in the August edition of the journal Astrobiology, was led by The University of Texas at Austin, which is also leading the development of Europa Clipper’s ice penetrating radar instrument. Knowing what kind of ice Europa’s shell is made of will also help decipher the salinity and habitability of its ocean.

“When we’re exploring Europa, we’re interested in the salinity and composition of the ocean, because that’s one of the things that will govern its potential habitability or even the type of life that might live there,” said the study’s lead author Natalie Wolfenbarger, a graduate student researcher at the University of Texas Institute for Geophysics (UTIG) in the UT Jackson School of Geosciences.

Europa is a rocky world about the size of the Earth’s moon that is surrounded by a global ocean and a miles-thick ice shell. Previous studies suggest the temperature, pressure and salinity of Europa’s ocean nearest to the ice is similar to what you would find beneath an ice shelf in Antarctica.

Armed with that knowledge, the new study examined the two different ways that water freezes under ice shelves, congelation ice and frazil ice. Congelation ice grows directly from under the ice shelf. Frazil ice forms as ice flakes in super cooled seawater, which float upwards through the water, settling on the bottom of the ice shelf.

Both ways make ice that’s less salty than seawater, which Wolfenbarger found would be even less salty when scaled up to the size and age of Europa’s ice shell. What’s more, according to her calculations, frazil ice – which keeps only a tiny fraction of the salt in seawater – could be very common on Europa. That means its ice shell could be orders of magnitude purer than previous estimates. This affects everything from its strength, to how heat moves through it, and forces that might drive a kind of ice tectonics.

“This paper is opening up a whole new batch of possibilities for thinking about ocean worlds and how they work,” said Steve Vance, a research scientist at NASA’s Jet Propulsion Laboratory (JPL) who was not involved in the study. “It sets the stage for how we might prepare for Europa Clipper’s analysis of the ice.”

According to co-author Donald Blankenship, a senior research scientist at UTIG and principal investigator for Europa Clipper’s ice penetrating radar instrument, the research is validation for using the Earth as a model to understand the habitability of Europa.

“We can use Earth to evaluate Europa’s habitability, measure the exchange of impurities between the ice and ocean, and figure out where water is in the ice,” he said.

Wolfenbarger is currently pursuing a doctoral degree in geophysics at the UT Jackson School and is a graduate student affiliate member of the Europa Clipper science team.

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Parker Solar Probe thriving four years after launch

Newswand: As it orbits the Sun, NASA’s Parker Solar Probe encounters some of the most challenging conditions ever faced by a spacecraft: temperatures up to nearly 1,500 degrees Fahrenheit (800 degrees Celsius), space dust that could easily degrade materials and instruments, and intense light and high-speed particles escaping from our closest star.

Photo credit: NASA/Johns Hopkins APL/Magda Saina

But four years after launch, the spacecraft is operating exceptionally well and sending back more than twice the planned amount of science data.

“Despite operating in such an extreme environment, Parker is performing well beyond our expectations,” said Helene Winters, Parker Solar Probe project manager at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “The spacecraft and its payload are making spectacular observations that will revolutionize our understanding of the Sun and the heliosphere, and that is a testament to the innovation and tireless dedication of the team.”

Building a spacecraft to withstand these conditions for years was a monumental challenge. The mission team at APL had to prepare the spacecraft to operate in an environment that had never been explored before. Parker has weathered it all while flying approximately 2.7 billion miles (4.4 billion kilometers) — roughly the distance from the Sun to Neptune — and doing it faster than any mission before. By comparison, NASA’s New Horizons — the APL-led mission that captured the first images of Pluto — took 8 1/2 years to fly the same distance.

“We designed to worst-case assumptions for things like the thermal environment and the effects of solar radiation on the spacecraft,” said Jim Kinnison, the Parker Solar Probe mission systems engineer at APL. “We’re pleased that all the hard work during the design phase to define those worst-case assumptions has paid off.”

The spacecraft’s stellar performance has opened the door for the team to optimize the amount of science returned from the mission.

“Our telecommunications links are more robust than our worst-case predictions, allowing us to downlink at higher bit rates,” said Kinnison. “As a result, the scientists have been able to collect and downlink about three times more data than planned before launch. This means we’re able to study the Sun in more detail during each encounter but also greatly increase science return when we’re farther away. It also means we can collect data in special circumstances like Venus flybys, well beyond our basic science objectives.”

Over the course of the mission, Parker has sent back roughly 2.8 terabytes of scientific data, approximately equivalent to the amount of data in 200 hours of 4K video. Scientists worldwide will use this data for years to come to develop a better understanding of the Sun’s effects on Earth and our solar system.

“I couldn’t be happier with how the mission is going,” said John Wirzburger, the Parker spacecraft systems engineer at APL. “The spacecraft is operating normally, we’re well within all of our performance margins, and we have plenty of propellant to fly for a long time. Everything is working at least as well, if not better, than expected and modeled on the ground.”

Next month, Parker will complete its 13th perihelion, its closest approach to the Sun in this orbit. During that encounter, it will fly through the Sun’s upper atmosphere, the corona, for the sixth time.

That environment, though, is getting only more extreme. Parker makes its 13th approach as the Sun’s activity ramps up prior to solar maximum in 2025 — activity that NASA has reported is already exceeding predictions. This means there are more sunspots, solar flares, and solar eruptions than predicted. However, according to Wirzburger, the Parker team is not concerned about the spacecraft’s continued performance.

“Parker was designed to handle things like radiation and solar flares,” he said. “As some of the bigger solar flares have been released, the spacecraft has weathered the storm each time without issue.”

“Exploration is inherently risky, but the spacecraft has proven to be robust and able to autonomously keep itself safe,” added Kinnison. “We’re looking forward to the rest of the mission, and that closest perihelion at the end of the primary mission.”

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New Analysis Shows How Sulfur Clouds Can Form in Venus’ Atmosphere

Newswand: Scientists using sophisticated computational chemistry techniques have identified a new pathway for how sulfur particles can form in the atmosphere of Venus. These results may help to understand the long sought-after identity of the mysterious ultraviolet absorber on Venus.

Photo credit: NASA/JPL-Caltech

“We know that the atmosphere of Venus has abundant SO2 and sulfuric acid particles. We expect that ultraviolet destruction of SO2 produces sulfur particles. They are built up from atomic S (sulfur) to S2, then S4 and finally S8. But how is this process initiated, that is, how does S2 form?” said Planetary Science Institute Senior Scientist James Lyons, an author on the Nature Communications paper “Photochemical and thermochemical pathways to S2 and polysulfur formation in the atmosphere of Venus.”

One possibility is to form S2 from two sulfur atoms, that is, reaction of S and S. Molecules of S2 and S2 can then combine to form S4, and so on. Sulfur particles can form either by condensation of S8 or by condensation of S2, S4 and other allotropes – different physical forms in which an element can exist – which then rearrange to form condensed S8.

“Sulfur particles, and the yellow sulfur we more commonly encounter, are made up of mostly S8, which has a ring structure. The ring structure makes S8 more stable against destruction by UV light than the other allotropes. To form S8, we can either start with two S atoms and make S2, or we can produce S2 by another pathway, which is what we’ve done in the paper,” said Lyons.

“We found a new pathway for S2 formation, the reaction of sulfur monoxide (SO) and disulfur monoxide (S2O), which is much faster than combining two S atoms to make S2,” Lyons said.

“For the first time, we are using computational chemistry techniques to determine which reactions are most important, rather than waiting for laboratory measurements to be done or using highly inaccurate estimates of the rate of unstudied reactions. This is a new and very much needed approach for studying the atmosphere of Venus,” Lyons said. “People are reluctant to go in the lab to measure rate constants for molecules made up of S, chlorine (Cl), and oxygen (O) – these are difficult and sometimes dangerous compounds to work with. Computational methods are the best – and really only – alternative.

Computational methods were used to compute the rate constants and to determine the expected reaction products. These are state-of-the-art computational models (what we call ab initio models). These ab initio calculations were done by the authors from Spain and from the University of Pennsylvania.

“This research illustrates another pathway to S2 and sulfur particle formation. Sulfur chemistry is dominant in Venus’ atmosphere, and very likely plays a key role in the formation of the enigmatic UV absorber. More generally, this work opens the doors to using molecular ab initio techniques to disentangle the complex chemistry of Venus,” Lyons said.

Antonio Francés-Monerris of Departament de Química Física, Universitat de València, Spain is lead author on the paper. Coauthors include Javier Carmona-García and Daniel Roca-Sanjuán also of the Universitat de València, Alfonso Saiz-Lopez of the Institute of Physical Chemistry Rocasolano in Madrid, and Tarek Trabelsi and Joseph S. Francisco of the University of Pennsylvania.

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