Tuesday, November 23, 2021

NASA’s “Eyes on the Earth” Real-Time 3D Visualization Tool Puts the World at Your Fingertips

By JET PROPULSION LABORATORY NOVEMBER 22, 2021
With NASA’s Eyes on the Earth, you can track Earth science satellites in real time as they orbit our planet and explore the trove of information they provide. Credit: NASA/JPL-Caltech
The 3D real-time visualization tool lets users track NASA satellites as well as the vital Earth science data they provide. Recent upgrades make for an even more fascinating experience.
NASA’s real-time 3D visualization tool Eyes on the Earth got a recent upgrade to include more datasets, putting the world at your fingertips. Using the tool, you can track the planet’s vital signs – everything from carbon dioxide and carbon monoxide to sea level and soil moisture levels – as well as follow the fleet of Earth satellites providing those measurements.
Eyes on the Earth offers an engaging, interactive resource to learn more about environmental phenomena and their impacts.
For instance, to see measurements of the greenhouse gas carbon dioxide in a particular part of the globe, navigate to the Vital Signs menu and click the carbon dioxide button. Eyes on the Earth will show a visualization of data from NASA’s Orbiting Carbon Observatory 2 (OCO-2) satellite, which measures the gas from the ground to the top of the atmosphere. (To ensure the greatest accuracy, the mission reprocesses the data in the months prior to it appearing in Eyes.) Click “animate data,” specify a date range and see how levels shift over time.
There are eight vital signs to choose from, with background information on the role each plays.
The newest version of Eyes on the Earth also provides snapshots of significant events in the natural world. For instance, you can see details about the maximum wind speeds of a tropical storm, the impacts of a northern California fire, even see the scale of a phytoplankton bloom off of New Zealand and why it matters.
The improvements also include upgrades for a more seamless user experience.
“With the latest advancements in technology, we are able to harness these innovations to combine larger amounts of data and imagery for users to visualize how our planet is constantly changing,” said Jon Nelson, group supervisor of the Visualization Technology Applications and Development at NASA’s Jet Propulsion Laboratory in Southern California, which developed Eyes.
If you want to know more about the Aqua satellite, just click the icon that shows the spacecraft’s course around the globe. Along with background information about the mission, there’s an interactive 3D model to provide a closer look.
While you’re at it, you can check out the recently launched Landsat 9 as well as two powerful forthcoming missions: NISAR (short for NASA-ISRO Synthetic Aperture Radar) and SWOT (Surface Water and Ocean Topography).
The graphics are as rich as the data, making for fascinating deep dives as you learn about the science, get to know the planet better, and learn about some of the many NASA missions that track the globe’s health. And while no downloads are required, the web-based application makes a great addition to any device with a browser and an internet connection including your smartphone.

Hubble Snaps Brilliant Image of Flame Nebula
Nov 22, 2021 by Enrico de Lazaro

The NASA/ESA Hubble Space Telescope shot this image of a large star-forming region known as the Flame Nebula.

This Hubble image shows the Flame Nebula. Image credit: Hubble / NASA / ESA / N. Da Rio, University of Virginia / Gladys Kober, NASA & Catholic University of America.

The Flame Nebula is an emission nebula located about 1,400 light-years away in the constellation of Orion.

Otherwise known as NGC 2024 and Sh2-277, the nebula is approximately 12 light-years wide.

It was discovered by the German-born British astronomer William Herschel on January 1, 1786.

“The Flame Nebula is a portion of the Orion Molecular Cloud Complex, which includes such famous nebulae as the Horsehead Nebula and the Orion Nebula,” the Hubble astronomers said.

The Flame Nebula is part of the Orion Molecular Cloud Complex and is found near the Horsehead Nebula. Image credit: Hubble
/ NASA / ESA / N. Da Rio, University of Virginia / ESO / DSS2 / D. De Martin / Gladys Kober, NASA & Catholic University of America.

At the center of the nebula lies a cluster of over 800 stars, the majority of which are very young stellar objects.

“The new Hubble image focuses on the dark, dusty heart of the nebula, where the star cluster resides, mostly hidden from view,” the astronomers said.

“Nearby — but not visible in this image — is the bright star Alnitak, the easternmost star in the Belt of Orion. “

“Radiation from this star ionizes hydrogen gas in the Flame Nebula,” they explained.

“As the gas begins to cool from its higher-energy state to a lower-energy state, it emits energy in the form of light, causing the visible glow behind the swirled wisps of dust.”

“Hubble measured the mass of stars in the cluster as it looked for brown dwarfs, a type of dim object that’s too hot and massive to be classified as a planet but also too small and cool to shine like a star.”

Attack of the Galactic Clones

By ESA/HUBBLE NOVEMBER 21, 2021

Credit: ESA/Hubble & NASA, E. Wuyts

This star- and galaxy-studded image was captured by Hubble’s Wide Field Camera 3 (WFC3), using data that were collected for scientific purposes. The object of interest was a galaxy that is visible in the bottom left corner of the image, named SGAS 0033+02. What makes this particular galaxy interesting is a little unusual — it appears not just once in this image, but three times. The thrice-visible galaxy is a little difficult to spot: it appears once as a curved arc just to the upper right of the very bright star, and twice more as small round dots above the star and to the right of the star respectively.

SGAS 0033+02’s multiple appearances in the same image are not the result of an error, but instead are due to a remarkable phenomenon known as gravitational lensing. Gravitational lensing occurs when the light from a very distant galaxy — such as SGAS 0033+02 — is curved (or ‘lensed’) by the gravity of a massive celestial object that lies in the foreground, between the distant galaxy and the Earth. SGAS 0033+02 was discovered by its namesake, the Sloan Giant Arcs Survey (SGAS), which aimed to identify highly magnified galaxies that were gravitationally lensed by foreground galaxy clusters. SGAS 0033+02 is of special interest because of its highly unusual proximity in the sky to a very bright star. The star is useful, because it can be used to calibrate and correct observations of the lensed SGAS 0033+02.

Image: Hubble catches celestial prawn drifting through the cosmic deep

by NASA's Goddard Space Flight Center

The Prawn Nebula is a massive stellar nursery located in the constellation Scorpius, about 6,000 light years from Earth. Though the nebula stretches 250 light-years and covers a space four times the size of the full moon, it emits light primarily in wavelengths the human eye cannot detect, making it extremely faint to earthbound viewers. Hubble's gaze, however, shows a small section of the nebula here in both visible and invisible infrared light, capturing dazzling detail of the nebula's structure, including bright areas of glowing gas.

The Prawn Nebula, also known as IC 4628, is an emission nebula, which means its gas has been energized, or ionized, by the radiation of nearby stars. The radiation from these massive stars strips electrons from the nebula's hydrogen atoms. As the energized electrons revert from their higher-energy state to a lower-energy state by recombining with hydrogen nuclei, they emit energy in the form of light, causing the nebula's gas to glow. In this image, red indicates the presence of ionized iron (Fe II) emission.

This Hubble Space Telescope image was captured as part of a survey of massive- and intermediate-size "protostars," or newly forming stars. Astronomers used the infrared sensitivity of Hubble's Wide Field Camera 3 to look for hydrogen ionized by ultraviolet light ionized by the protostars, jets from the stars, and other features.

Image: Hubble surveys a snowman sculpted from gas and dust

Provided by NASA's Goddard Space Flight Center

Magellanic Stream arcing over Milky Way may be five times closer than previously thought

by University of Wisconsin-Madison

Our galaxy is not alone. Swirling around the Milky Way are several smaller, dwarf galaxies—the biggest of which are the Small and Large Magellanic Clouds, visible in the night sky of the Southern Hemisphere.

During their dance around the Milky Way over billions of years, the Magellanic Clouds' gravity has ripped from each of them an enormous arc of gas—the Magellanic Stream. The stream helps tell the history of how the Milky Way and its closest galaxies came to be and what their future looks like.

New astronomical models developed by scientists at the University of Wisconsin–Madison and the Space Telescope Science Institute recreate the birth of the Magellanic Stream over the last 3.5 billion years. Using the latest data on the structure of the gas, the researchers discovered that the stream may be five times closer to Earth than previously thought.

The findings suggest that the stream may collide with the Milky Way far sooner than expected, helping fuel new star formation in our galaxy.

"The Magellanic Stream origin has been a big mystery for the last 50 years. We proposed a new solution with our models," says Scott Lucchini, a graduate student in physics at UW–Madison and lead author of the paper. "The surprising part was that the models brought the stream much closer to the Milky Way."

The new models also provide a precise prediction of where to find the stream's stars. These stars would have been ripped from their parent galaxies with the rest of the stream's gas, but only a few have been tentatively identified. Future telescope observations might finally spot the stars and confirm the new reconstruction of the stream's origin is correct.

"It's shifting the paradigm of the stream," says Lucchini. "Some have thought the stars are too faint to see because they're too far away. But we now see that the stream is basically at the outer part of the disk of the Milky Way."

That's close enough to spot, says Elena D'Onghia, a professor of astronomy at UW–Madison and supervisor of the project. "With the current facilities we should be able to find the stars. That's exciting," she says.

Lucchini, D'Onghia, and Space Telescope Science Institute scientist Andrew Fox published their findings in The Astrophysical Journal Letters on Nov. 8.

The latest work was based both on fresh data and different assumptions about the history of the Magellanic Clouds and Stream. In 2020, the research team predicted that the stream is enveloped by a large corona of warm gas. So, they plugged this new corona into their simulations, while also accounting for a new model of the dwarf galaxies that suggests they have a relatively brief history of orbiting one another—a mere 3 billion years or so.

"Adding the corona to the problem changed the orbital history of the clouds," Lucchini explains.

In this new recreation, as the dwarf galaxies were captured by the Milky Way, the Small Magellanic Cloud orbited around the Large Magellanic Cloud in the opposite direction than previously thought. As the orbiting dwarf galaxies stripped gas from one another, they produced the Magellanic Stream.

The opposite-direction orbit pushed and pulled the stream so it arced toward Earth, rather than stretching farther away into intergalactic space. The stream's closest approach is likely to be just 20 kiloparsecs from Earth, or about 65,000 light-years away. The clouds themselves sit between 55 and 60 kiloparsecs away.

"The revised distance changes our understanding of the stream. It means our estimates of many of the stream's properties, such as mass and density, will need to be revised," says Fox.

If the stream is this close, then it likely has just one-fifth the mass previously thought. The closer approach of the stream also means this gas will start merging with the Milky Way in about 50 million years, providing the fresh material needed to jump-start the birth of new stars in the galaxy.

The stars in the Magellanic Stream itself have eluded researchers for decades. But the new study suggests that perhaps they were simply looking in the wrong place.

"This model tells us exactly where the stars should be," says D'Onghia.

Massive halo finally explains stream of gas swirling around the Milky Way

More information: Scott Lucchini et al, The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds, The Astrophysical Journal Letters (2021). DOI: 10.3847/2041-8213/ac3338

Journal information: Astrophysical Journal Letters

Provided by University of Wisconsin-Madison

Scientists Are Testing Astronauts In Long Mars Simulations, And The Results Are Worrying

THE CREW ARE PLACED IN ISOLATED PODS. IMAGE CREDIT: PROJECT SIRIUS - CC BY-NC-SA 2.0

By Jack Dunhill 22 NOV 2021, 16:56

In our lifetimes, it is almost certain we will see humans set foot on Mars. If the modern-day space race between private companies and nations continues, it is not out of the question that we will see a long-term human presence on either the Moon or Mars in that time frame too, an incredible yet insane concept.

But – and it is a big but – researchers simply have no idea how a team of astronauts isolated almost 380 million kilometers (236 million miles) from home would fare in such a scenario. Would they maintain constant communication with Earth and work perfectly as a team? Or would they descend into anarchy, even cutting communication with their superiors and forming an autonomous colony? Russian researchers are aiming to figure that out before they spend billions on the real deal, by placing a group of individuals in a Mars colonization simulation.

Project SIRIUS (Scientific International Research In Unique terrestrial Station – yes, they reached a bit to make the acronym cool) is an effort to understand the psychology of astronauts during long space flights. The results have recently been published in Frontiers in Physiology. Seventeen and 120-day isolation experiments in 2017 and 2019, respectively, were designed to simulate a team isolated in an extraterrestrial environment.

The results confirmed their worries – the delay in communication due to the distance, coupled with the extended period away from Mother Earth, resulted in the astronauts becoming detached from mission control and becoming almost autonomous.

Mark Watney would be proud – the crew tends to plants grown in the pods. Image Credit: Project SIRIUS - CC BY-NC-SA 2.0

Previous simulations suggested that once the astronauts left on their voyage, there was a strong chance that they would begin to disconnect from mission control, reducing the number of situations they would report on. To confirm the results of previous simulations, namely the Mars-500 missions, the researchers carried out the two isolations using a mixed-gender, international crew. The missions were testing how participants communicated with mission control and how well they worked together to form a successful colony.

They began with a take-off procedure, before landing on the inhospitable environment of a specialized area within the training facility. The crew were then locked away in pods together, given minimal rations and supplies, and subjected to the full isolation of the real deal.

Analysis of the experiments suggested a number of conclusions, some positive, while others were more problematic. The crew actually increased their communication with the mission control center (MCC) at the halfway stage of the simulation, which involved the Mars landing, but then subsequently became detached, reducing the volume of communication with MCC. They relied less on the recommendations of MCC, becoming more autonomous as they adapted to their mission.

While it is positive the crew were able to take matters into their own hands and live autonomously, a disconnect from MCC is a worrying phenomenon.

"The negative side is that the mission control loses the possibility to understand the needs and problems of the crew, which consequently hinders mission control's ability to provide support," said co-author Dmitry Shved of the Russian Academy of Sciences and the Moscow Aviation Institute, in a statement to CNET.

There was also an interesting correlation between the male and female crew members. Similar to previous experiments, the women reported on problems to the MCC more often, and expressed their support, while their communication styles were more emotional. The men, however, were less likely to report to MCC. Interestingly, by the end of the simulation, both the men and women had adapted to each other's communication styles, forming a similar level of emotion and regularity of communication.

Of course, due to only 12 people taking part in the simulations, it is also possible that deviances between groups and individuals are purely down to individual differences, so generalizations cannot be made before more research is conducted.

In the meantime, another Project SIRIUS experiment is now underway, involving an 8-month isolation that began on November 4th.

An absolutely bonkers plan to give Mars an artificial magnetosphere

by Brian Koberlein, Universe Today

Terraforming Mars is one of the great dreams of humanity. Mars has a lot going for it. Its day is about the same length as Earth's, it has plenty of frozen water just under its surface, and it likely could be given a reasonably breathable atmosphere in time. But one of the things it lacks is a strong magnetic field. So if we want to make Mars a second Earth, we'll have to give it an artificial one.

The reason magnetic fields are so important is that they shield a planet from solar wind and ionizing particles. Earth's magnetic field prevents most high-energy charged particles from reaching the surface. Instead, they are deflected from Earth, keeping us safe. The magnetic field also prevents solar winds from stripping Earth's atmosphere over time. Early Mars had a thick, water-rich atmosphere, but it was gradually depleted without the protection of a strong magnetic field.

Unfortunately, we can't just recreate Earth's magnetic field on Mars. Our field is generated by a dynamo effect in Earth's core, where the convection of iron alloys generates Earth's geomagnetic field. The interior of Mars is smaller and cooler, and we can't simply "start it up" to create a magnetic dynamo. But there are a few ways we can create an artificial magnetic field, as a recent study shows.

Ideas for generating a Martian magnetic field have been proposed before, and usually involve either ground-based or orbital solenoids that create some basic level of magnetic protection. In the TV series "The Expanse," you can see a couple of scenes where you catch a glimpse of them. While this latest study acknowledges that might work, it proposes an even better solution.

As the study points out, if you want a good planetary magnetic field, what you really need is a strong flow of charged particles, either within the planet or around the planet. Since the former isn't a great option for Mars, the team looks at the latter. It turns out you can create a ring of charged particles around Mars, thanks to its moon Phobos.

Phobos is the larger of the two Martian moons, and it orbits the planet quite closely—so closely that it makes a trip around Mars every eight hours. So the team proposes using Phobos by ionizing particles from its surface, then accelerating them so they create a plasma torus along the orbit of Phobos. This would create a magnetic field strong enough to protect a terraformed Mars.

It's a bold plan, and while it seems achievable, the engineering hurdles would be significant. But as the authors point out, this is the time for ideas. Start thinking about the problems we need to solve, and how we can solve them, so when humanity does reach Mars, we will be ready to put the best ideas to the test

Life on earth: Why we may have the moon's now defunct magnetic field to thank for it

More information: R.A. Bamford et al, How to create an artificial magnetosphere for Mars, Acta Astronautica (2021). DOI: 10.1016/j.actaastro.2021.09.023

Journal information: Acta Astronautica

Provided by Universe Today

'False fossils' littered across Mars may complicate the search for life on Red Planet

By Harry Baker about 18 hours ago

We have been "fooled before" by these convincing counterfeits.

NASA's Perseverance rover, which is searching signs of ancient life on Mars. (Image credit: NASA/JPL-Caltech/MSSS)

Mars may be covered in dozens of different nonbiological "false fossils," which could interfere with the search for life on the Red Planet, two researchers say.

NASA's Perseverance rover touched down on Mars in February, and the European Space Agency (ESA) will launch the Rosalind Franklin rover in 2022. Both will scour the Martian surface for biosignatures — traces of past life — left behind from around 4 billion years ago, when the planet may have been habitable.

However, a new paper suggests a possible complication in that search.

"There is a real chance that one day, we will observe something on Mars that looks really biological, only to realize several years later, after further research, that this thing was actually formed by nonbiological processes," co-author Julie Cosmidis, a geobiologist at the University of Oxford in England, told Live Science.

Cosmidis teamed up with Sean McMahon, an astrobiologist at The University of Edinburgh in Scotland, to itemize these potential false biosignatures before the rovers find them.

A biosignature can be evidence of either an organism itself or any product it creates. By definition, such biosignatures can't be made by natural physical or chemical processes. For decades, astrobiologists have identified biosignatures on Earth in order to recognize potential forms of primitive life on other worlds.

But this hunt for biosignatures has a major limitation. "We are so good at spotting life that we see it even when it isn't there," McMahon told Live Science.

Specifically, many things that look like biosignatures at first glance can also be created without life.

"The range of structures, materials and chemical compositions that can be produced nonbiologically overlaps quite closely with the range of things that can be produced biologically," McMahon said. "Some phenomena have been debated for decades, and we're still not sure if they're biological or not."

Paleontologists have often been confused by these fake fossils, Cosmidis said. Evidence of ancient bacteria and other single-celled organisms, like algae, can be especially tricky to identify.

In 1996, scientists claimed to have found fossils of microscopic organisms in a Martian meteorite. Their discovery was hailed as the first proof of alien life and even prompted a speech from President Bill Clinton. However, further tests revealed that these fossils were completely abiotic, meaning they were not made by life-forms.

On Mars, this confusion will be even more problematic because scientists won't be able to test samples properly until they are returned to Earth, meaning it could take years to vet the Martian samples.

"The problem is that these false biosignatures are often disproved only after further analysis by different researchers, using different techniques," Cosmidis said. "But for Mars, we won't have this option" until years after the samples get collected.
Potential biosignatures

"There is a wide diversity of potential false biosignatures on Mars," Cosmidis said.

One of the best examples is carbon-sulfur biomorphs — tiny spheres, "similar in size to bacteria," that can form spontaneously from reactions between carbon and sulfide, Cosmidis said. Both of these reactants may have been abundant on ancient Mars, and the resulting biomorphs would also "fossilize very well in rock types that are common on Mars," she added.

Artificially created carbon-sulfur biomorphs under a microscope. (Image credit: Julie Cosmidis)

"If one day we find microscopic organic filaments and spheres in Martian rocks, it will be very tempting to interpret them as fossil bacteria, but they could very well just be carbon-sulfur biomorphs," Cosmidis said.

Another example are pseudo-microbialites, which mimic physical structures created by microbes, such as stromatolites — which are large structures left behind by photosynthetic algae that grow upward as cones, domes and columns. Such structures could be left behind from marine life in Mars' past oceans, but near-identical structures can also form naturally without any microbes so it will be hard to tell if they are genuine.

McMahon and Cosmidis recreated previously known false biosignatures in Martian conditions and tried to come up with new examples not yet encountered on Earth. In total, they listed more than a dozen potential fake fossils in their new paper, but many more may be out there.

The researchers hope their work will help to prevent an erroneous discovery and the resulting disappointment, which would undermine decades of work in the search for alien life.

"These errors and their corrections are a normal process in science," Cosmidis said. "But on a topic that is receiving as much attention from the public as the search for life on Mars, there is a risk that they could generate public mistrust in scientists."

However, despite their caution, the researchers say that they are fully committed to the search for life on Mars.

"We are not trying to dismiss all the efforts that NASA and ESA are currently putting into finding traces of life on Mars," Cosmidis said. "We want to support these efforts by helping the researchers involved in these missions make better and more informed interpretations of the objects they will observe."

The paper was published online Nov. 17 in the Journal of the Geological Society.

Originally published on Live Science.

Odd Martian meteorites traced back to largest volcanic structure in the solar system

The rocks were most likely ejected from Tooting crater more than a million years ago and are now helping scientists piece together the red planet's turbulent past.

The colors on this global map of Mars represent areas with different crater sizes. By identifying about 90 million small impact craters, researchers were able to calculate the ages of different parts of Mars and then trace a group of meteorites back to one specific crater.PHOTOGRAPH BY LAGAIN ET AL. (2021), NATURE COMMUNICATIONS

BY ROBIN GEORGE ANDREWS

PUBLISHED NOVEMBER 19, 2021

About a million years ago, an asteroid smacked into the normally tranquil surface of Mars. The impact released a fountain of debris, and some of the rocky fragments pierced the sky, escaping the planet’s gravity to journey through the dark.

Some of the rocks eventually found their way to Earth and survived the plunge through our planet’s atmosphere to thud into the surface–including a hefty 15-pound shard that crashed into Morocco in 2011. Now known to scientists as the depleted shergottites, this collection of more than a dozen space rocks makes up an intriguing portion of the 317 known Martian meteorites—the only material from Mars we have on Earth.

Determining what part of Mars these meteorites came from is a critical part of piecing together the planet’s history—but it’s proven to be a major scientific challenge. Now, with the assistance of a crater-counting machine learning program, a team of researchers studying the depleted shergottites may have finally cracked the case: They concluded that these geologic projectiles came from a single crater atop Tharsis, the largest volcanic feature in the solar system.

This ancient volcanic behemoth on Mars is adorned with thousands of individual volcanoes and extends three times the area of the continental United States. It was built over billions of years by countless magma injections and lava flows. It is so heavy that, as it formed, it effectively tipped the planet over by 20 degrees.

If these meteorites do come from Tharsis, as the analysis published in Nature Communications suggests, then scientists have their hands on meteorites that can help identify the infernal forces that fueled the construction of this world-tipping edifice.

“This could really change the game about how we understand Mars,” says Luke Daly, a meteorite expert at the University of Glasgow who was not involved with the study.

Meteoritic clues

Most Martian meteorites are in a category called the shergottites, named after the Indian town of Sherghati where one was seen falling from the heavens in 1865. The shergottites are all volcanic rocks with similar compositions, but a handful of them, the depleted shergottites, possess a strange chemical signature.

On Mars, certain elements such as neodymium and lanthanum don’t like to bond with minerals in the mantle, the solid-but-squidgy part of the planet below the crust. The depleted shergottites are lacking in these elements—hence the name “depleted”—suggesting they are from Mars’s mantle.

But how did these rocks get close enough to the surface to be ejected in an impact? On Earth, mantle rock can work its way to the surface in two ways: when two tectonic plates move apart and permit the mantle to ascend, or when a fountain of superhot mantle matter known as a plume rises from the deep. Mars doesn’t appear to have ever had plate tectonics, so a mantle plume is the most likely scenario.

Scientists also know the rocks all came from a relatively young volcanic site—perhaps a stack of lava flow deposits—based on the radioactive decay of specific elements in the meteorites.

If these spacefaring volcanic rocks all came from a single impact, then it must have been quite powerful, leaving a crater at least two miles across and potentially much bigger. And the crater would have to be about 1.1 million years old, as cosmic rays that bombarded and altered the meteorites’ surfaces over time reveal how long they were traveling through space after the impact.

Even with these clues, however, tracing these bits of Martian rock back to their original location has proven extremely difficult. They are like individual jigsaw pieces separated from the rest of the puzzle: Without knowing what their original environment looked like, it is almost impossible to place them in a specific part of the planet.

“As geologists, we record loads of information about where we collect rock samples from, because context matters,” says Áine O’Brien, a doctoral student studying Martian meteorites at the University of Glasgow who was not involved with the study. “With Martian meteorites, because we don’t know the context, we have to make a very well educated guess at what happened to it to form it.”

And to make that educated guess, scientists turned to a new tool in planetary science: machine learning.

One crater among millions

The only way to definitively determine the age of a planet’s surface is to take a physical sample and study its radioactive compounds. But until NASA and the European Space Agency’s Mars Sample Return campaign brings some pristine Martian rocks back to Earth in the 2030s, researchers need to rely on a technique to estimate surface ages known as crater counting.

On Earth, strong winds, flowing water, erupting lava, and a cornucopia of living things speedily erase craters from old impacts. Not so on Mars, a geologically comatose world with weak winds and no surface water. There, sizable craters remain intact for hundreds of millions or even billions of years. Assuming the rate of impacts over time is known, a surface on Mars with more craters would be older than one with fewer craters.

Scientists can use other tricks to deduce a crater’s age. “When an asteroid impacts the surface, a bunch of debris will be ejected,” says Anthony Lagain, a planetary geologist at Curtin University and the new study’s lead author. The bits that fall back to Mars impact the surface and make small, secondary craters around the original primary crater. Even on Mars, these secondary craters are eroded by wind within a few million years, so any large crater surrounded by secondary craters must have been made very recently in the planet’s history.

“In order to get a better idea of ages, you need to get to smaller and smaller craters,” says Gretchen Benedix, an astrogeologist at Curtin University and co-author of the study. Smaller impacts are more common than larger ones, so you can use minor differences in the number of smaller craters across two surfaces to work out more detailed timelines.

To figure out if a crater was exactly 1.1 million years old, the team had to catalog Mars’s small craters and use them to precisely date the surface. Doing this manually would have been torturous. Instead, they fed orbital imagery of Mars into a machine learning program and trained it to find craters less than two-thirds of a mile long.

It quickly found about 90 million, says Kosta Servis, a data scientist at Curtin University and co-author of the study. With that timeline of craters in hand, the team was able to start narrowing down the possible origins of the depleted shergottites.

Shards of a volcanic titan

After sifting through the data, the team identified 19 large craters in volcanic regions on Mars that were surrounded by multiple secondary craters—a sign that these planetary scars could be as young as the 1.1-million-year-old crater they sought. Using the catalog of 90 million small craters, the researchers were then able to precisely date the blankets of debris radiating from the larger craters, which revealed more accurate estimates of their ages.

Some of the craters were about the right age, but that wasn’t enough. The formation age of the surrounding terrain had to match the ages of the minerals found in the meteorites as well. To check, the team once again used its crater catalog to date the volcanic plains.

Out of those 19 craters, just two were excavated from youthful volcanic deposits by an impact event 1.1 million years ago: crater 09-00015 and Tooting crater. The latter (named after a district in London) looks to have been formed by a powerful oblique impact—the kind of collision that would propel a lot of Martian meteorites into space.

“Tooting crater has a special type of multi-layered ejecta deposit that suggests there was ice or water around at the time of the impact,” says Peter Grindrod, a planetary scientist at London’s Natural History Museum who was not involved with the study. Impact simulations show that ice and water can generate more debris, plenty of which can escape into space if given enough momentum.

With all this evidence, the team identified the 19-mile-long Tooting crater as the prime suspect for the source of the depleted shergottites. “It’s a really well put together argument,” Daly says. “Everything seems to fit.”

The scientists have not completely ruled out crater 09-00015, but the important thing is that both craters “lie in the Tharsis region, where a vast hotspot, or superplume, has long been thought to have produced the massive bulge on the surface of Mars,” Grindrod says. Regardless of which specific crater the meteorites came from, they can tell us about the history of the largest volcanic region on Mars.

Crater counting has previously revealed that some of Tharsis’s features were made over 3.7 billion years ago, but the younger depleted shergottite meteorites are just a few hundred million years old. That suggests the Tharsis superplume is almost as old as Mars itself, and it continued producing magma long after many other volcanic centers on the planet died out.

Like Earth’s plumes, Mars’s mantle plumes helped shape the evolution of the planet’s surface, erupting enormous volumes of atmosphere-altering gases while dramatically changing its topography. The Tharsis superplume may have had a near-continual influence on the red planet’s development.

Mars’s days of frequent and prolific eruptions are long gone. But Tharsis’s prolonged volcanism bolsters the notion that even small planets, those that should have lost their internal heat eons ago, can remain volcanically active for far longer than anyone originally suspected.

Decoding the craters of other worlds

Buoyed by their discovery, Lagain’s team is hoping to identify the source craters of other Martian meteorites—including some of the very oldest, which could reveal more about Mars’s waterlogged past.

But future success, as well as this study’s implications, depend on whether the machine learning program properly counted its craters. Crater counting is rife with difficulties: the rate of impacts over time is estimated, for example, and small circular structures on Mars that resemble craters could potentially fool a computer program.

Machine learning “is a really inventive way of trying to tackle this problem,” says Lauren Jozwiak, a planetary volcanologist at Johns Hopkins University Applied Physics Laboratory not involved with the study. “Boy, I hope this method works,” she says, because if it does, “it would be really cool to take this and apply it to other planets.”

The study’s authors concur. “Mars is cool,” Benedix says. “But this algorithm and this methodology isn’t just applicable to Mars. It’s going to the moon. It’s going to Mercury.”

If machine learning really has solved this long-standing meteorite mystery, it opens the door to all sorts of undreamt-of possibilities. “We are arguably only just starting to see the implications of machine learning in planetary science,” Grindrod says.

Scientist reveals cause of lost magnetism at meteorite site

by Rod Boyce, University of Alaska Fairbanks

A University of Alaska Fairbanks scientist has discovered a method for detecting and better defining meteorite impact sites that have long lost their telltale craters. The discovery could further the study of not only Earth's geology but also that of other bodies in our solar system.

The key, according to work by associate research professor Gunther Kletetschka at the UAF Geophysical Institute, is in the greatly reduced level of natural remanent magnetization of rock that has been subjected to the intense forces from a meteor as it nears and then strikes the surface.

Rocks unaltered by manmade or non-Earth forces have 2% to 3% natural remnant magnetization, meaning they consist of that quantity of magnetic mineral grains—usually magnetite or hematite or both. Kletetschka found that samples collected at the Santa Fe Impact Structure in New Mexico contained less than 0.1% magnetism.

Kletetschka determined that plasma created at the moment of impact and a change in the behavior of electrons in the rocks' atoms are the reasons for the minimal magnetism.

Kletetschka reported his findings in a paper published Wednesday in the journal Scientific Reports.

The Santa Fe Impact Structure was discovered in 2005 and is estimated to be about 1.2 billion years old. The site consists of easily recognized shatter cones, which are rocks with fantail features and radiating fracture lines. Shatter cones are believed to only form when a rock is subjected to a high-pressure, high-velocity shock wave such as from a meteor or nuclear explosion.

Kletetschka's work will now allow researchers to determine an impact site before shatter cones are discovered and to better define the extent of known impact sites that have lost their craters due to erosion.

"When you have an impact, it's at a tremendous velocity," Kletetschka said. "And as soon as there is a contact with that velocity, there is a change of the kinetic energy into heat and vapor and plasma. A lot of people understand that there is heat, maybe some melting and evaporation, but people don't think about plasma."

Plasma is a gas in which atoms have been broken into free-floating negative electrons and positive ions.

"We were able to detect in the rocks that a plasma was created during the impact," he said.

Earth's magnetic field lines penetrate everything on the planet. Magnetic stability in rocks can be knocked out temporarily by a shock wave, as they are when hitting an object with a hammer, for example. The magnetic stability in rocks returns immediately after the shock wave passes.

At Santa Fe, the meteorite's impact sent a massive shock wave through the rocks, as expected. Kletetschka found that the shock wave altered the characteristics of atoms in the rocks by modifying the orbits of certain electrons, leading to their loss of magnetism.

The modification of the atoms would allow for a quick remagnetization of the rocks, but Kletetschka also found that the meteorite impact had weakened the magnetic field in the area. There was no way for the rocks to regain their 2% to 3% magnetism even though they had the capability to do so.

That's because of the presence of plasma in the rocks at the impact surface and below. Presence of the plasma increased the rocks' electrical conductivity as they converted to vapor and molten rock at the leading edge of the shock wave, temporarily weakening the ambient magnetic field.

"This plasma will shield the magnetic field away, and therefore the rock finds only a very small field, a residue," Kletetschka said.

Kletetschka is also affiliated with Charles University in Prague, Czech Republic. Charles University students Radana Kavkova and Hakan Ucar assisted in the research.Twelfth impact structure discovered in Central Finland

More information: Gunther Kletetschka et al, Plasma shielding removes prior magnetization record from impacted rocks near Santa Fe, New Mexico, Scientific Reports (2021). DOI: 10.1038/s41598-021-01451-8

Journal information: Scientific Reports

Provided by University of Alaska Fairbanks

Chinese customs seizes meteorites passed off as pyrite

A meteorite creates a streak of light across the night sky over the North Yorkshire moors at Lealholm, near Whitby, northern England, April 26, 2015 REUTERS/Steven Watt

Almost half a tonne of meteorites declared as pyrite ore on import have been seized by authorities in the southern city of Shenzhen, China's customs agency said on Monday.

Reuters | Updated: 22-11-2021

Almost half a tonne of meteorites declared as pyrite ore on import have been seized by authorities in the southern city of Shenzhen, China's customs agency said on Monday. Officers inspected the material and determined it was inconsistent with the characteristics of pyrite, the General Administration of Customs said in a statement, adding that the company involved was unable to provide relevant certification.

Pyrite, also known as fool's gold, is an iron sulphide mineral used in the paper and jewellery industries. A professional appraisal revealed the 470 kg shipment consisted of 90% iron and 8.9% nickel but lacked the sulphur content that pyrite has, said the statement, which was accompanied by a video of customs officers inspecting a number of brownish rocks.

The appraisal also found the rocks' composition was very similar to that of meteorites, and the owner of the shipment subsequently confirmed that is exactly what they were, customs said，adding that the case was under further processing. It was not immediately clear how the owner had come into possession of the meteorities.

China is stepping up its space exploration programme and last year brought back rocks from the moon https://www.reuters.com/article/us-space-exploration-china-moon-idUSKBN28D0VV in the first lunar sample retrieval mission since the 1970s.

AUSTRALIA

Man Keeps a Rock For Years, Hoping It's Gold. It Turned Out to Be Far More Valuable

(Museums Victoria)

JACINTA BOWLER
22 NOVEMBER 2021

In 2015, David Hole was prospecting in Maryborough Regional Park near Melbourne, Australia.

Armed with a metal detector, he discovered something out of the ordinary – a very heavy, reddish rock resting in some yellow clay.

He took it home and tried everything to open it, sure that there was a gold nugget inside the rock – after all, Maryborough is in the Goldfields region, where the Australian gold rush peaked in the 19th century.

To break open his find, Hole tried a rock saw, an angle grinder, a drill, even dousing the thing in acid. However, not even a sledgehammer could make a crack. That's because what he was trying so hard to open was no gold nugget. As he found out years later, it was a rare meteorite.

"It had this sculpted, dimpled look to it," Melbourne museum geologist Dermot Henry told The Sydney Morning Herald.

"That's formed when they come through the atmosphere, they are melting on the outside, and the atmosphere sculpts them."

Unable to open the 'rock', but still intrigued, Hole took the nugget to the Melbourne Museum for identification.

"I've looked at a lot of rocks that people think are meteorites," Henry told Channel 10 News.

In fact, after 37 years of working at the museum and examining thousands of rocks, Henry explains only two of the offerings have ever turned out to be real meteorites.

This was one of the two.

(Melbourne Museum)

"If you saw a rock on Earth like this, and you picked it up, it shouldn't be that heavy," another Melbourne Museum geologist, Bill Birch, told The Sydney Morning Herald in 2019.

The researchers published a scientific paper describing the 4.6 billion-year-old meteorite, which they've called Maryborough after the town near where it was found.

It's a huge 17 kilograms (37.5 pounds), and after using a diamond saw to cut off a small slice, they discovered its composition has a high percentage of iron, making it a H5 ordinary chondrite.

Once open, you can also see the tiny crystallized droplets of metallic minerals throughout it, called chondrules.

"Meteorites provide the cheapest form of space exploration. They transport us back in time, providing clues to the age, formation and chemistry of our Solar System (including Earth)," said Henry.

"Some provide a glimpse at the deep interior of our planet. In some meteorites, there is 'stardust' even older than our Solar System, which shows us how stars form and evolve to create elements of the periodic table.

"Other rare meteorites contain organic molecules such as amino acids; the building blocks of life."

(Birch et al., PRSV, 2019)

Although the researchers don't yet know where the meteorite came from and how long it may have been on Earth, they do have some guesses.

Our Solar System was once a spinning pile of dust and chondrite rocks. Eventually gravity pulled a lot of this material together into planets, but the leftovers mostly ended up in a huge asteroid belt.

"This particular meteorite most probably comes out of the asteroid belt between Mars and Jupiter, and it's been nudged out of there by some asteroids smashing into each other, then one day it smashes into Earth," Henry told Channel 10 News.

Carbon dating suggests the meteorite has been on Earth between 100 and 1,000 years, and there's been a number of meteor sightings between 1889 and 1951 that could correspond to its arrival on our planet.

The researchers argue that the Maryborough meteorite is much rarer than gold, making it far more valuable to science. It's one of only 17 meteorites ever recorded in the Australian state of Victoria, and it's the second largest chondritic mass, after a huge 55-kilogram specimen identified in 2003.

"This is only the 17th meteorite found in Victoria, whereas there's been thousands of gold nuggets found," Henry told Channel 10 News.

"Looking at the chain of events, it's quite, you might say, astronomical it being discovered at all."

It's not even the first meteorite to take a few years to make it to a museum. In a particularly amazing story ScienceAlert covered in 2018, one space rock took 80 years, two owners, and a stint as a doorstop before finally being revealed for what it truly was.

Now is probably as good a time as any to check your backyard for particularly heavy and hard-to-break rocks – you might be sitting on a metaphorical gold mine.

The study was published in Proceedings of the Royal Society of Victoria.

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Tuesday, November 23, 2021

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