Universe Today

Back in the 1960s and 1970s, Apollo astronauts set up a collection of lunar seismometers to detect possible Moon quakes. These instruments monitored lunar activity for eight years and gave planetary scientists an indirect glimpse into the Moon’s interior. Now, researchers are developing new methods for lunar quake detection techniques and technologies. If all goes well, the Artemis astronauts will deploy them when they return to the Moon.

Fiber optic cable is the heart of a seismology network to be deployed on the Moon by future Artemis astronauts.

The new approach, called distributed acoustic sensing (DAS), is the brainchild of CalTech geophysics professor Zhongwen Zhan. It sends laser beams through a fiber optic cable buried just below the surface. Instruments at either end measure how the laser light changes during the shake-induced tremors. Basically Zhan’s plan turns the cable into a sequence of hundreds of individual seismometers. That gives precise information about the strength and timing of the tremors. Amazingly, a 100-kilometer fiber optic cable would function as the equivalent of 10,000 seismometers. This cuts down on the number of individual seismic instruments astronauts would have to deploy. It probably also affords some cost savings as well.

A seismometer station deployed on the Moon during the Apollo 15 mission. Courtesy NASA. DAS and Apollo on the Moon

Compare DAS the Apollo mission seismometer data and it becomes obvious very quickly that DAS is a vast improvement. In the Apollo days, the small collection of instruments left behind on the Moon provided information that was “noisy”. Essentially, when the seismic waves traveled through different parts of the lunar structure, they got scattered. This was particularly true when they encountered the dusty surface layer. The “noise” basically muddied up the signals.

The layout for the Apollo Lunar Seismic Profiling Experiment for the Apollo 17 mission. Courtesy Nunn, et al. What DAS Does to Detect Quakes on the Moon

The DAS system stations laser emitters and data collectors at each end of a fiber optic cable. This allows for multiple widely spaced installations that measure light as it transits the network. The cable consists of glass strands, and each strand contains tiny imperfections. That sounds bad, but each imperfection provides a useful “waypoint” that reflects a little bit of the light back to the source. That information gets recorded as part of a larger data set. Setting up such a system of telecommunications cables over a large area provides millions of waypoints that scientists can use to measure seismic movements on Earth.

A recent study led by CalTech postdoctoral researcher Qiushi Zhai deployed this type of DAS-enabled fiber optic cable system in Antarctica. The conditions mimic some of the environmental challenges of a lunar deployment—it’s freezing cold, very dry, and far removed from human activities. The sensors measured the small movements of caused by ice cracking and moving around. Those types of signals are perfect analogs to lunar quakes.

Aerial view of Antarctica. A prototype of the lunar DAS system for the Artemis missions to the Moon detected tiny tremors from ice movements here. Photo credit: L. McFadden 2008 Measuring a Lunar Quake Using DAS

Since DAS works well measuring tiny tremors induced by ice, it seems like the perfect “next step” in doing lunar seismology. On the Moon, the fiber optic cable would be buried (just as cables are on Earth) a few centimeters below the level of the regolith. It will sit there waiting for the next quake, which probably won’t take long, since the Moon seems to quiver frequently. When one strikes, its seismic waves will move through the ground from the source. They’ll wiggle the cable. That will affect the light-travel path inside. The actions of light hitting thousands of imperfections inside the cable will provide lunar geologists with high-precision data about moonquakes. That includes their origins, travel time, and other aspects of the wave that will help them understand more about the lunar structure they travel through.

The distributed nature of the seismic network will have a big advantage over the Apollo-style individual seismometers used in the past. And, there are other reasons to use DAS, according to Zhai. “Another advantage of using DAS on the Moon is that a fiber optic cable is physically quite resilient to the harsh lunar environment: high radiation, extreme temperatures, and heavy dust,” Zhai said.

Moon Structure and DAS

Zhai is the first author of a paper describing the DAS system, which should allow scientists to detect close to 100 percent of Moon tremors. The paper offers insight into the advantages that DAS offers. In particular, such an array stretched across large areas of the Moon should provide much higher-quality data about even the smallest tremors that shake the surface.

Since the Moon is not tectonically active, its quakes don’t occur from the same causes as they do on Earth. Some happen during the sunset/sunrise period when temperature changes affect the surface. Others happen thanks to Earth’s pull on the Moon, and still others occur because the Moon is still cooling and contracting. Zhai’s paper suggests that DAS could detect about 15 moonquakes per day, and perhaps help better characterize the thermal moonquakes that happen at sunrise/sunset and the deeper ones that occur during perigee and apogee portions of its orbit, and those intrinsic to the Moon’s contraction. In addition, impacts on the Moon also generate quakes. Information about all these events should give planetary scientists a big leg up on understanding more about the lunar interior structure.

The deployment of DAS and other science experiments will be part of the surface operations of the Artemis missions. It will be part of one of the proposed seven-month stays for astronaut teams. Although there is no specific planned date for seismometer deployment, it’s likely to take place no sooner than the mid-2030s. That’s after the planned missions to build shelters, deploy power stations, and other activities to create the lunar bases.

For More Information

A New Type of Seismic Sensor to Detect Moonquakes
Assessing the feasibility of Distributed Acoustic Sensing (DAS) for Moonquake Detection
Lunar Seismology: A Data and Instrumentation Review

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The dwarf planet Ceres has some permanently dark craters that hold ice. Astronomers thought the ice was ancient when they were discovered, like in the moon’s permanently shadowed regions. But something was puzzling.

Why did some of these shadowed craters hold ice while others did not?

Ceres was first discovered in 1801 and was considered a planet. Later, it was thought to be the first asteroid ever discovered, since it’s in the main asteroid belt. Since then, our expanding knowledge has changed its definition: we now know it as a dwarf planet.

Even though it was discovered over 200 years ago, it’s only in the last couple of decades that we’ve gotten good looks at its surface features. NASA’s Dawn mission is responsible for most of our knowledge of Ceres’ surface, and it found what appeared to be ice in permanently shadowed regions (PSRs.)

New research shows that these PSRs are not actually permanent and that the ice they hold is not ancient. Instead, it’s only a few thousand years old.

The new research is titled “History of Ceres’s Cold Traps Based on Refined Shape Models,” published in The Planetary Science Journal. The lead author is Norbert Schorghofer, a senior scientist at the Planetary Science Institute.

“The results suggest all of these ice deposits must have accumulated within the last 6,000 years or less.”

Norbert Schorghofer, senior scientist, Planetary Science Institute.

Dawn captured its first images of Ceres while approaching the dwarf planet in January 2015. At that time, it was close enough to capture images as good as Hubble’s. Those images showed craters and a high-albedo site on the surface. Once captured by Ceres, Dawn followed a polar orbit with decreasing altitude. It eventually reached 375 km (233 mi) above the surface, allowing it to see the poles and surface in greater detail.

“For Ceres, the story started in 2016, when the Dawn spacecraft, which orbited around Ceres at the time, glimpsed into these permanently dark craters and saw bright ice deposits in some of them,” Schorghofer said. “The discovery back in 2016 posed a riddle: Many craters in the polar regions of Ceres remain shadowed all year – which on Ceres lasts 4.6 Earth years – and therefore remain frigidly cold, but only a few of them harbor ice deposits.”

As scientists continued to study Ceres, they made another discovery: its massive Solar System neighbours make it wobble.

“Soon, another discovery provided a clue why: The rotation axis of Ceres oscillates back and forth every 24,000 years due to tides from the Sun and Jupiter. When the axis tilt is high and the seasons strong, only a few craters remain shadowed all year, and these are the craters that contain bright ice deposits,” said lead author Schorghofer.

This figure from the research shows how Ceres’ obliquity has changed over the last 25,000 years. As the obliquity varies, sunlight reaches some crater floors that were thought to be PSRs. Image Credit: Schorghofer et al. 2023.

Researchers constructed digital elevation maps (DEMs) of the craters to uncover these facts. They wanted to find out how large and deep the shadows in the craters were, not just now but thousands of years ago. But that’s difficult to do since portions of these craters were in deep shadow when Dawn visited. That made it difficult to see how deep the craters were.

Robert Gaskell, also from the Planetary Science Institute, took on the task. He developed a new technique to create more accurate maps of the craters with data from Dawn’s sensitive Framing Cameras, contributed to the mission by Germany. With improved accuracy, these maps of the crater floors could be used in ray tracing to show sunlight penetrated the shadows as Ceres wobbled over thousands of years.

This figure from the study shows some of the DEMs the researchers developed for craters on Ceres. White regions represent sunlit areas, while the coloured contours represent PSRs for different axial tilts. Image Credit: Schorghofer et al. 2023.

The DEMs in the above image show that at 20 degrees obliquity, none of the craters are in permanent shadow. That means none of them have truly permanent PSRs. “A PSR starts to emerge in Bilwis crater at about 18°, and they emerge at lower obliquities at the other six study sites. This implies that the ice deposits are remarkably young,” the researchers write in their paper.

This figure from the research shows PSRs in the north-polar region of Ceres. The colour scale shows how oblique each crater is. The research shows that 14,000 years ago, none of these were PSRs, and the ice they hold now is only 6,000 years old. Image Credit: Schorghofer et al. 2023.

About 14,000 years ago, Ceres reached its maximum axial tilt. At that time, no craters were PSRs. Any ice in these craters would’ve been sublimated into space. “That leaves only one plausible explanation: The ice deposits must have formed more recently than that. The results suggest all of these ice deposits must have accumulated within the last 6,000 years or less. Considering that Ceres is well over 4 billion years old, that is a remarkably young age,” Schorghofer said.

So, where did the ice come from?

There must be some source if the ice is young and keeps reforming during maximum obliquity. The only plausible one is Ceres itself.

“Ceres is an ice-rich object, but almost none of this ice is exposed on the surface. The aforementioned polar craters and a few small patches outside the polar regions are the only ice exposures. However, ice is ubiquitous at shallow depths – as discovered by PSI scientist Tom Prettyman and his team back in 2017 – so even a small dry impactor could vaporize some of that ice.” Schorghofer said. “A fragment of an asteroid may have collided with Ceres about 6,000 years ago, which created a temporary water atmosphere. Once a water atmosphere is generated, ice would condense in the cold polar craters, forming the bright deposits that we still see today. Alternatively, the ice deposits could have formed by avalanches of ice-rich material. This ice would then survive in only the cold shadowed craters. Either way, these events were very recent on an astronomical time scale.”

There are other potential sources of water ice. Ceres has a very thin, transient water atmosphere. The water could come from cryovolcanic processes and then be trapped and frozen in shadowed regions.

Ceres also has a single cryovolcano: Ahuna Mons. It’s at least a couple hundred million years old and long dormant. There are dozens of other dormant potential cryovolcanoes, too. But these likely aren’t the water source.

There’s ample water ice at shallow levels in Ceres. If the dwarf planet erodes over time, mass-wasting could expose and release water that freezes in the craters. “The few ice deposits that have been detected spectroscopically outside the polar regions are indeed often associated with landslides, and the sunlit portion of the ice deposit in Zatik crater is best explained by a recent mass wasting event,” the authors explain.

Ceres has been through a lot. As an ancient protoplanet that’s survived to this day, it holds important clues to the Solar System. Though its craters don’t hold ancient ice like once thought, deeper study is revealing the dwarf planet’s true nature.

“The ice deposits in the Cerean PSRs indicate an active water cycle; ice is either repeatedly captured and lost or frequently exposed, or both,” the authors conclude.

The post Ice Deposits on Ceres Might Only Be a Few Thousand Years Old appeared first on Universe Today.

Cosmic rays are high-energy particles accelerated to extreme velocities approaching the speed of light. It takes an extremely powerful event to send these bits of matter blazing through the Universe. Astronomers theorize that cosmic rays are ejected by supernova explosions that mark the death of supergiant stars. But recent data collected by the Fermi Gamma-ray space telescope casts doubt on this production method for cosmic rays, and has astronomers digging for an explanation.

It’s not easy to tell where a cosmic ray comes from. Most cosmic rays are hydrogen nuclei, others are protons, or free-flying electrons. These are charged particles, meaning that every time they come across other matter in the Universe with a magnetic field, they change course, causing them to zig-zag through space.

The direction a cosmic ray comes from when it hits Earth, then, is not likely the direction it started in.

But there are ways to indirectly track down their origin. One of the more promising methods is by observing gamma rays (which do travel in straight lines, thankfully).

When cosmic rays bump into other bits of matter, they produce gamma rays. So when a supernova goes off and sends cosmic rays out into the Universe, it should also send a gamma-ray signal letting us know it’s happening.

That’s the theory, anyway.

But the evidence hasn’t matched expectations. Studies of old, distant supernovas show some gamma ray production occurring, but not as much as predicted. Astronomers explained away the missing radiation as a result of the supernovas’ age and distance. But in 2023, the Fermi telescope captured a bright new supernova occurring nearby. Named SN 2023ixf, the supernova went off just 22 million light-years away in a galaxy called Messier 101 (better known as the ‘Pinwheel Galaxy’). And yet again, gamma rays were conspicuously absent.

NASA Goddard.

“Astrophysicists previously estimated that supernovae convert about 10% of their total energy into cosmic ray acceleration,” said Guillem Martí-Devesa, University of Trieste. “But we have never observed this process directly. With the new observations of SN 2023ixf, our calculations result in an energy conversion as low as 1% within a few days after the explosion. This doesn’t rule out supernovae as cosmic ray factories, but it does mean we have more to learn about their production.”

So where is all the missing gamma radiation?

It’s possible that interstellar material around the exploding star could have blocked gamma rays from reaching the Fermi telescope. But it might also mean that astronomers need to look for alternative explanations for the production of cosmic rays.

Nobody likes a good mystery better than astronomers, and digging into the missing gamma radiation could eventually tell us a whole lot more about cosmic rays and where they come from.

Astronomers plan to study SN 2023ixf in other wavelengths to improve their models of the event, and will of course keep an eye out for the next big supernova, in an effort to understand what is going on.

The most recent gamma-ray data from SN 2023ixf will be published in Astronomy and Astrophysics in a paper led by Martí-Devesa.

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NASA is in the business of launching things into orbit. But what goes up must come down, and if whatever is coming down doesn’t burn up in the atmosphere, it will strike Earth somewhere.

Even Florida isn’t safe.

Careful consideration goes into releasing debris from the International Space Station. Its mass is measured and calculated so that it burns up during re-entry to Earth’s atmosphere. But in March 2024, something didn’t go as planned.

It all started in 2021 when astronauts replaced the ISS’s nickel hydride batteries with lithium-ion batteries. It was part of a power system upgrade, and the expired batteries added up to about 2,630 kg (5,800 lbs.) On March 8th, 2021, ground controllers used the ISS’s robotic arm to release a pallet full of the expired batteries into space, where orbital decay would eventually send them plummeting into Earth’s atmosphere.

The Canadarm 2 robotic arm releases a pallet of spent batteries into space on March 8th, 2021. Image Credit: NASA

It was the most massive debris release from the ISS. According to calculations, it should have burned up when it entered the atmosphere on March 8th, 2024. But it didn’t.

Alejandro Otero owns a home in Naples, Florida. He wasn’t home on March 8th when there was a loud crash as something smashed into his roof. But his son was. “It was a tremendous sound. It almost hit my son,” Otero told CNN affiliate WINK News in March. “He was two rooms over and heard it all.”

“Something ripped through the house and then made a big hole in the floor and on the ceiling,” Otero explained. “I’m super grateful that nobody got hurt.”

This time, nobody got hurt. But NASA is taking the accident seriously.

Otero cooperated with NASA, and NASA examined the object at the Kennedy Space Center in Florida. They determined the debris was from a stanchion used to mount the old batteries on a special cargo pallet.

This image shows an intact stanchion and the recovered stanchion from the NASA flight support equipment used to mount International Space Station batteries on a cargo pallet. The stanchion survived re-entry through Earth’s atmosphere on March 8, 2024, and impacted a home in Naples, Florida. Image Credit: NASA

The stanchion is made of the superalloy Inconel to understand extreme environments, including extreme heat. It weighs 725 grams (1.6 lbs.) It’s about 10 cm (4 inches) in height and 4 cm (1.6 inches) in diameter.

Even though it’s a tiny object, it’s the type of accident that NASA and the ISS are determined to avoid. “The International Space Station will perform a detailed investigation of the jettison and re-entry analysis to determine the cause of the debris survival and to update modelling and analysis, as needed,” a NASA statement read.

Investigators want to know how the debris survived without burning up on re-entry. Engineers use models to understand how objects react to re-entry heat and break apart, and this event will refine those models. In fact, every time an object reaches the ground, the models are updated.

For Otero, this accident amounted to little more than a great story and an insurance claim. But the chunk of stanchion could’ve seriously injured someone or even killed someone.

In January 1997, Lottie Williams was walking through a park with friends in Tulsa, Oklahoma, in the early morning. They saw a huge fireball in the sky and felt a rush of excitement, thinking they were seeing a shooting star. “We were stunned, in awe,” Williams told FoxNews.com. “It was beautiful.”

Then, something struck her lightly on the shoulder before falling to the ground. It was like a piece of metallic fabric, and after reaching out to some authorities, she learned that it was part of a fuel tank from a Delta II rocket. She’s the first person known to have been hit with space debris. Had it been something with more mass, who knows if Williams would’ve been injured or worse?

That’s why NASA takes debris survival so seriously. The guilt of injuring or even killing someone would be overwhelming. A serious debris accident could also make things very uncomfortable going forward, as people can be fickle and not prone to critical thinking. NASA’s already struggling with budget constraints; the organization doesn’t need any nasty public relations to imperil its progress further.

Complicating matters is that the ESA warned that not all the battery debris would burn up. There wasn’t much else they could do. Fluctuating atmospheric drag made it impossible to predict where debris would strike Earth.

Those who follow space know how complicated and unpredictable this is. And they likewise know how improbable an injury is. But there’s always a non-zero chance of injury or death from space debris for someone going about their life here on the Earth’s surface. If that ever happened, the scrutiny would be intense.

Is it statistical fear-mongering to consider space debris striking someone, injuring them, or worse? Probably. When we see a shooting star in the sky, it’s safe to enjoy the spectacle without worry.

But maybe, just in case, out of an abundance of caution, Don’t Look Up.

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A new theory suggests that Titan’s majestic dune fields may have come from outer space. Researchers had always assumed that the sand making up Titan’s dunes was locally made, through erosion or condensed from atmospheric hydrocarbons. But researchers from the University of Colorado want to know: Could it have come from comets?

The dunes of Titan

When the Cassini spacecraft arrived in orbit around Saturn, nobody had ever seen beneath the thick soupy atmosphere of Titan. So when it dropped the Huygens lander, and began probing Titan with cloud-penetrating radar, scientists were surprised to learn that Titan has a very earth-like appearance. It has a thick nitrogen atmosphere, rain, rivers, oceans and massive dune fields. But unlike the dunes of Earth’s sandy deserts in Namibia and southern Arabia, Titan’s dunes are enormous, and fill massive fields covering more than an eighth of the giant moon’s surface. These dunes are about 100 meters tall, 1 to 2 km wide at the base, and can stretch for hundreds of kilometers in length.

Dunes on Earth are made from sand, which is blown by the wind and heaped into drifts. Individual sand particles are nudged and blown by the wind with enough force to make them bounce and scatter in a process called saltation. If the particles don’t bounce, then they cannot pile up on top of each other, but if the wind is able to lift them off the ground completely then they simply blow away. Saltation depends on the size and mass of the sand particles and the strength of the wind, but also needs the particles to be dry so that they can move freely without sticking together.

Titan’s geology

Titan is the second largest moon in the entire Solar System, beaten only by Ganymede, orbiting Jupiter. It is Saturn’s largest moon, and very old. Unlike most of Saturn’s moons, which were captured over time, Titan would have formed together with Saturn billions of years ago. Despite having so many features in common with Earth, it is a very different place. It is so intensely cold that, instead of water, its rain and rivers are made from liquid hydrocarbons like methane. Water, on the other hand, is frozen into hard ice; rocks on Titan are made from water ice, instead of granite and basalt, and Titan’s equivalent of lava and magma are made from liquid water and ammonia.

This means that sand on Titan is not made from silica eroded from larger rocks, since those materials are not found on the surface. One popular theory is that it could instead be made from ice. When liquid methane rains and flows, it could erode the water-ice bedrock, grinding chunks together to a sand of ice grains. An alternative idea is that the sand particles are instead made from tholins. These are found all over the colder regions of the Solar System, where cold hydrocarbons in comets or the outer atmospheres of planets and moons react with ultraviolet light from the Sun to create complex compounds. Tholins formed in the dry atmosphere of Titan could clump together with static electricity to form small grains of soot that then settle to the ground, creating both dust and sand.

Comet 109P/Swift-Tuttle captured during its last pass by Earth on Nov. 1, 1992. Credit: Gerald Rhemann What do comets have to do with this?

A paper presented at this year’s Lunar and Planetary Science Conference (LPSC) suggests a new idea: What if the sand came from comets? Comets, as we know, are made from materials left over from the creation of the Solar System. Most of the primordial gas and dust that collapsed from an ancient nebula to form the Solar System would have ended up in the Sun, with the bulk of the remains forming the planets. But this would still have left a lot of material floating free, and some of that would have gradually coalesced into lumps of dust and ice, which we see today as comets. When comets are nudged into elliptical orbits and pass through the inner Solar System, some of their ice heats up and sublimates into gas which blows out, carrying dust with it. This dust is scattered throughout the Solar System, concentrated along the various comet’s orbits. Individual grains often collide with the Earth, which we see as meteors, burning high in our atmosphere. Recent surveys in Antarctic ice fields, where there is no surface sand, have found many such particles which have survived atmospheric reentry.

But Earth is not the only place where these grains can end up. According to the researchers, there was a time when a great many comets were passing close by Saturn and its moons. They ran simulations to study the evolution of the Kuiper Belt, using a version of the Nice model. The Nice model, named for the city in which it was first presented, says that the Solar System was originally arranged very differently from how it is today. Over time, the planets migrated to their current locations. During this period, Neptune passed through the Kuiper belt, nudging many comets into new orbits. Many of these comets passed close by Saturn and its moons, and some even collided with the moons. The researchers suggest that much of the sand making up Titan’s dunes may be debris from all these comets.

Artist’s concept of Dragonfly soaring over the dunes of Saturn’s moon Titan. Credit: NASA/Johns Hopkins APL/Steve Gribben

But is it true? This idea does fit with what we currently know, and is supported by computer modelling, but so do the other theories. Fortunately, NASA recently confirmed that the Dragonfly mission will be launched in July 2028. Dragonfly is a lander, which will be sent to Titan. But unlike previous missions, this one is an 8-rotor flying drone. Like the rovers on Mars, it will be able to move to any areas of interest that scientists would like to study further. When it arrives in 2034, it will fly to dozens of locations on Titan’s surface, and should settle the question once and for all: Are the dunes of Titan really built from comet dust?

https://www.hou.usra.edu/meetings/lpsc2024/pdf/1550.pdf

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The BepiColombo mission, a joint effort between JAXA and the ESA, was only the second (and most advanced) mission to visit Mercury, the least explored planet in the Solar System. With two probes and an advanced suite of scientific instruments, the mission addressed several unresolved questions about Mercury, including the origin of its magnetic field, the depressions with bright material around them (“hollows”), and water ice around its poles. As it turns out, BepiColombo revealed some interesting things about Venus during its brief flyby.

Specifically, the two probes studied a previously unexplored region of Venus’ magnetic environment when they made their second pass on August 10th, 2021. In a recent study, an international team of scientists analyzed the data and found traces of carbon and oxygen being stripped from the upper layers of Venus’ atmosphere and accelerated to speeds where they can escape the planet’s gravitational pull. This data could provide new clues about atmospheric loss and how interactions between solar wind and planetary atmospheres influence planetary evolution.

The study was led by Lina Hadid, a CNRS researcher at the Plasma Physics Laboratory (LPP) and the Observatoire de Paris. She was joined by researchers from the Institute of Space and Astronautical Science (ISAS) at JAXA, the Max Planck Institute for Solar System Research (MPS), the CNRS Research Institute in Astrophysics and Planetology (IRAP), the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), the Institute for Geophysics and Extraterrestrial Physics (IGEP), the Space Research Institute (SRI), and multiple universities.

Schematic view of planetary material escaping through Venus magnetosheath flank. Credit: Thibaut Roger/Europlanet 2024 RI/Hadid et al.

While Venus does not have an intrinsic magnetic field like Earth, it has a weak magnetic field that results from the interaction of solar wind and electrically charged particles in Venus’ upper atmosphere. Surrounding this “induced magnetosphere” is the “magnetosheath,” a region where the solar wind is slowed and heated. In August 2021, BepliColombo’s two spacecraft – the ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO, aka. Mio) – passed by Venus on the final leg of their journey toward Mercury, using the planet’s gravity to adjust its course and its upper atmosphere to shed speed.

The two spacecraft spent 90 minutes passing through the tail of the magnetosheath and the magnetic regions closest to the Sun. The mission controllers used this opportunity to gather data on the number and mass of charged particles it encountered using Mio‘s Mass Spectrum Analyzer (MSA) and the Mercury Ion Analyzer (MIA), which are part of the probe’s Mercury Plasma Particle Experiment (MPPE). The team also relied on Europlanet’s Sun Planet Interactions Digital Environment on Request (SPIDER) space weather modeling tools to track how atmospheric particles propagated through the magnetosheath.

As Hadid explained in a Europlanet Society release, analysis of this data provides insight into the chemical and physical processes driving atmospheric escape from this region of the magnetosheath:

“This is the first time that positively charged carbon ions have been observed escaping from Venus’s atmosphere. These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play. It may be that an electrostatic ‘wind’ is lifting them away from the planet, or they could be accelerated through centrifugal processes.”

In particular, these findings could help scientists to deduce what happened to Venus’ surface water. Like Earth, much of Venus’ surface was once covered in oceans, which disappeared about 700 million years ago. The most widely-held theory is that this coincided with a massive resurfacing event that flooded the atmosphere with carbon dioxide, leading to a runaway Greenhouse Effect that vaporized the oceans. Over time, solar wind stripped away the water, leaving a thick atmosphere over 90 times as dense as Earth’s, and composed of carbon dioxide with smaller amounts of nitrogen and trace gases.

Artist’s impression of Venus with the solar wind flowing around the planet, which has little magnetic protection. Credit: ESA – C. Carreau

Two spacecraft that previously visited Venus – NASA’s Pioneer Venus Orbiter and ESA’s Venus Express -conducted detailed studies of atmospheric loss. However, their orbital paths left some areas unexplored, leaving many questions about the planet’s atmospheric dynamics unanswered. Said Moa Persson, a researcher from the Swedish Institute of Space Physics and a co-author on the study:

“Recent results suggest that the atmospheric escape from Venus cannot fully explain the loss of its historical water content. This study is an important step to uncover the truth about the historical evolution of the Venusian atmosphere, and upcoming missions will help fill in many gaps.”

Over the next decade, several more spacecraft are destined for Venus, including the ESA’s Envision mission, NASA’s Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy (VERITAS) orbiter and Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) probe, and India’s Shukrayaan orbiter. Collectively, these spacecraft will characterize the Venusian environment, magnetosphere, atmosphere, surface, and interior. This research could lead to improved models that predict how once-habitable planets could become hostile to life as we know it.

Further Reading: Euro Planet Society, Nature Astronomy

The post The Solar Wind is Stripping Oxygen and Carbon Away From Venus appeared first on Universe Today.

You had to be in the right part of North America to get a great view of the recent solar eclipse. But a particular telescope may have had the most unique view of all. Even though that telescope is in Hawaii and only experienced a partial eclipse, its images are interesting.

You had to be in the right part of North America to get a great view of the recent eclipse. Image Credit: DKIST/NSO/NSF/AURA

The Daniel K. Inouye Solar Telescope (DKIST) is at the Haleakala Observatory in Hawaii. With its four-meter mirror, it’s the largest solar telescope in the world. It observes in visible to near-infrared light, and its sole target is the Sun. It can see features on the Sun’s surface as small as 20 km (12 miles.) It began science operations in February 2022, and its primary objective is to study the Sun’s magnetic fields.

This is a collage of solar images captured by the Inouye Solar Telescope. Images include sunspots and quiet regions of the Sun, known as convection cells. (Credit: NSF/AURA/NSO)

Though seeing conditions weren’t perfect during the eclipse and the eclipse was only partial when viewed from Hawaii, the telescope still gathered enough data to create a movie of the Moon passing in front of the Sun. The bumps on the Moon’s dark edge are lunar mountains.

via GIPHY

“The team’s primary mission during Maui’s partial eclipse was to acquire data that allows the characterization of the Inouye’s optical system and instrumentation,” shares National Solar Observatory scientist Dr. Friedrich Woeger.

The Moon plays a critical role in measuring the telescope’s performance. Its edge is well-known and as a dark object in front of the Sun, it acts as a unique tool to measure the Inouye telescope’s performance and to understand the data it collects. Since the telescope has to correct for Earth’s turbulent atmosphere with adaptive optics, the Moon’s known qualities help researchers work with the telescope’s optical elements.

The Daniel Inouye Solar Telescope at the Haleakala Observatory on the Hawaiian island of Maui. Image Credit: DKIST/NSO

“With the Inouye’s high order adaptive optics system operating, the blurring due to the Earth’s atmosphere was greatly reduced, allowing for extremely high spatial resolution images of the moving lunar edge,” said Woeger. “The appearance of the edge is not straight but serrated because of mountain ranges on the Moon!” This serrated dark edge covers the granular convection pattern that governs the “surface of the Sun.”

The Inouye Solar Telescope studies the Sun’s magnetic fields, which drive space weather. What we see in the video is visually interesting, but there’s a lot of data behind it.

It’ll take several months to analyze all of the data it gathered during the eclipse.

The post The Solar Eclipse Like We’ve Never Seen it Before appeared first on Universe Today.

Astronomers have found the largest stellar mass black hole in the Milky Way so far. At 33 solar masses, it dwarfs the previous record-holder, Cygnus X-1, which has only 21 solar masses. Most stellar mass black holes have about 10 solar masses, making the new one—Gaia BH3—a true giant.

Supermassive black holes (SMBH) like Sagittarius A Star at the heart of the Milky Way capture most of our black hole attention. Those behemoths can have billions of solar masses and have enormous influence on their host galaxies.

But stellar-mass holes are different. Unlike SMBHs that grow massive through mergers with other black holes, stellar black holes result from massive stars exploding as supernovae. SMBHs are always found in the center of a massive galaxy, but stellar black holes can be hidden anywhere.

“This is the kind of discovery you make once in your research life.”

Pasquale Panuzzo, National Centre for Scientific Research (CNRS) at the Observatoire de Paris

Astronomers found BH3 in data from the ESA’s Gaia spacecraft. It’s Gaia’s third stellar black hole. BH3 has a stellar companion, and the black hole’s 33 combined solar masses tugged on its aged, metal-poor companion. The star’s tell-tale wobbling betrayed BH3’s presence. At only 2,000 light-years away, BH3 is awfully close in cosmic terms.

Astronomers have found the most massive stellar black hole in our galaxy, thanks to the wobbling motion it induces on a companion star. This artist’s impression shows the star’s orbits and the black hole, dubbed Gaia BH3, around their common centre of mass. The European Space Agency’s Gaia mission measured this wobbling over several years. Image Credit: ESO/L. Calçada

A new research letter in Astronomy and Astrophysics presented the discovery. Its title is “Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry.” The lead author is Pasquale Panuzzo, an astronomer from the National Centre for Scientific Research (CNRS) at the Observatoire de Paris.

“No one was expecting to find a high-mass black hole lurking nearby, undetected so far,” said Panuzzo. “This is the kind of discovery you make once in your research life.”

This black hole is remarkable for its considerable mass. Researchers have found stellar black holes with similar masses, but always in other galaxies. The size is confounding, but astrophysicists have pieced together how they may become so massive.

They could result from the collapse of metal-poor stars. These stars are composed almost entirely of hydrogen and helium, the primordial elements. Scientists think these stars lose less mass over their lifetimes of fusion than other stars. They retain more mass, so they collapse into more massive black holes. This idea is based on theory; there’s no direct evidence.

But BH3 could change that.

Binary stars tend to form together and have the same metallicity. Follow-up observations showed that BH3’s companion star is likely a remnant of a globular cluster that the Milky Way absorbed more than eight billion years ago. Since binary stars tend to have the same metallicity, this metal-poor companion bolsters the idea that low-metallicity stars can retain more mass and form larger stellar black holes. This is the first evidence supporting the idea that ancient and metal-poor massive stars collapse into massive black holes. It also supports the idea that these early stars may have evolved differently than modern stars of similar masses.

But there’s another interpretation.

Artist’s impression of a Type II supernova explosion, which involves the destruction of a massive supergiant star. When stars explode as supernovae, they eject matter into space, potentially polluting nearby companion stars. Image Credit: ESO

When stars explode as supernovae, they forge heavier elements that are blown out into space. Shouldn’t the companion show evidence of contamination by the metals from BH3’s supernova?

“What strikes me is that the chemical composition of the companion is similar to what we find in old metal-poor stars in the galaxy,” explains Elisabetta Caffau of CNRS, Observatoire de Paris, also a member of the Gaia collaboration. “There is no evidence that this star was contaminated by the material flung out by the supernova explosion of the massive star that became BH3.” From this perspective, the pair may not have formed together. Instead, the black hole could’ve acquired its companion only after its birth, capturing it from another system.

BH3 and the two other black holes found by Gaia are dormant. That means there’s nothing close enough for them to “feed” on. Even though BH3 has a companion, it’s about 16 AU away. If BH3 was actively accreting matter, it would release energy that would betray its presence. Its dormancy enabled it to remain undetected.

Simulation of glowing gas around a spinning black hole. As the gas heats up, it emits energy that makes it visible. If the black hole has no nearby companion, it’s dormant and harder to find. Image Credit: Chris White, Princeton University

At only 2,000 light years away, astronomers are bound to keep studying BH3.

“Finally, the bright magnitude of the system and its relatively small distance makes it an easy target for further observations and detailed analyses by the astronomical community,” the discoverers write in their research letter.

This discovery may have been serendipitous, but it was no accident. A dedicated team of researchers scours Gaia data for stars with odd companions. This includes light and heavy exoplanets, other stars, and black holes. Gaia can’t spot planets or dormant black holes but can spot their effect on their stellar companions.

The researchers behind the discovery released their findings before Gaia’s next official data release. They felt it was too important to sit on. “We took the exceptional step of publishing this paper based on preliminary data ahead of the forthcoming Gaia release because of the unique nature of the discovery,” said co-author Elisabetta Caffau, also a Gaia collaboration member and CNRS scientist from the Observatoire de Paris – PSL.

“We have been working extremely hard to improve the way we process specific datasets compared to the previous data release (DR3), so we expect to uncover many more black holes in DR4,” said Berry Holl of the University of Geneva, in Switzerland, member of the Gaia collaboration.

“This discovery should also be seen as a preliminary teaser for the content of Gaia DR4, which will undoubtedly reveal other binary systems hosting a BH,” the authors conclude.

Gaia DR4 is scheduled to be released no sooner than the end of 2023. If past data releases are any indication, the data will be full of new discoveries. If there are enough binary stellar mass black holes in the data, astronomers may get closer to understanding where they come from and if massive stars behaved differently in the early Universe.

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