Universe Today

It’s been just over a week since millions of people flocked to places across North America for a glimpse of moonshadow. The total solar eclipse of April 8th, 2024 was a spectacular sight for many on the ground. From space, however, it was even more impressive as Earth-observing satellites such as GOES-16 captured the sight of the shadow sweeping over Earth.

NASA even got a snap of the eclipse from the Moon, as taken by the Lunar Reconnaissance Orbiter Camera (LROC). Unlike most Earth-based photographers, however, LROC’s view was a tricky one to get. The cameras are line scanners and their images get built up line-by-line. That process requires the spacecraft to slew to keep up with the action and build up a complete view. Amazingly, it took only 20 seconds to capture all the action.

A short video of the eclipse shadow along the path of totality, captured by NASA’s Deep Space Climate Observatory.

NASA’s Deep Space Climate Observatory got an amazing view from Earth orbit, capturing the entire eclipse as it passed over the continent. That observatory “lives” out at LaGrange Point 1, which enabled it to get a full view of Earth and the Moon’s shadow.

Eclipse as Experience

For most viewers, the chase to see an eclipse meant driving (or flying) to somewhere along the path of totality to get the best view. That path stretched from the Pacific Ocean off the coast of Mexico up toward the northern Canadian provinces. That meant a wide swath of the U.S. experienced totality. Or course, the weather had to be good to see it all. In most places, that actually turned out reasonably well. Social media immediately came alive with images of the eclipse, people enjoying it, and others waiting vainly for a break in the clouds.

A composite of images taken during the total solar eclipse showing all the phases leading up to and after totality. NASA/Keegan Barber.

This writer was stationed off the coast of Mazatlán, Mexico, on a cruise ship with a group of amateur and professional astronomers. Although there were a few clouds, the view of the eclipsed Sun was nearly pristine. From the ship, everyone was able to watch the shadow approach, feel the temperature drop, and marvel at 4 minutes and 20 seconds of totality.

A projection of the partially eclipsed Sun on the stack of a cruise ship off the coast of Mazatlan. Image credit: Carolyn Collins Petersen.

In a few regions, however, people were only able to watch clouds get dark. And, for the majority of viewers outside of the path of totality, they could only get a partial view. Still, in many places, people went out to experience the event using eclipse glasses or pinhole projection methods to see those partial phases.

Eclipse from the Air

For those who could “fly the eclipse” it was an opportunity to take a jet plane along the path and prolong the experience. During the eclipse, flight-tracking apps showed a huge increase in traffic along the path. Several airlines had flights that tracked the path, giving lucky passengers the view of a lifetime for a short period.

A pilot flying a WB-57 jet during the total solar eclipse on April 8, 2024. Credit: NASA/Mallory Yates

At least one NASA jet pilot captured a view as the aircraft passed through the shadow. In space, the astronauts aboard the International Space Station got a great shot of the umbra and penumbra passing over the maritime provinces of Canada.

A view of the eclipse shadow from the International Space Station. Courtesy NASA. Future Eclipses

The 2024 eclipse across North America left many with a taste for more moonshadow experience. Unfortunately, that was the last one for this part of the world until 2045. That’s when another one will sweep across the continent. Before that, however, there are other total solar eclipses, as well as lunar and annular events. The years 2026, 2027, and 2028 will feature totalities across parts of Europe, Egypt, and Australia. You can find out locations and dates for others at Mr. Eclipse, as well as NASA’s own eclipse site. For each event, there’ll be plenty of information about safe viewing, as well as “broadcasts” on social media for those outside of the paths of totality.

For More Information

2024 Eclipse as Seen From The Moon
The April 8 Total Solar Eclipse: Through the Eyes of NASA

The post More Views of the 2024 Eclipse, from the Moon and Earth Orbit appeared first on Universe Today.

I’m really not sure what to call it but a ‘dusty sneeze’ is probably as good as anything. We have known for some years that stars surround themselves with a disk of gas and dust known as the protostellar disk. The star interacts with it, occasionally discharging gas and dust regularly. Studying the magnetic fields revealed that they are weaker than expected. A new proposal suggests that the discharge mechanism ‘sneezes’ some of the magnetic flux out into space. Using ALMA, the team are hoping to understand the discharges and how they influence stellar formation. 

In a fairly inconspicuous part of the Galaxy, a star slowly formed out of a cloud of gas and dust. This event took place around 4.6 billion years ago and soon, the hot young star began to clear the surrounding area of gas and dust. What remained was a disk surrounding the star known as a protostellar disk. Eventually the planets of our Solar System formed. It is not unique to our own system though as there have been disks like this found around many stars. A very well known example are the stars in the Trapezium cluster inside the Orion Nebula. 

Behind the Gas and Dust of Orion’s Trapezium Cluster

A team in Japan, from the Kyushu University have been examining data from the ALMA radio telescope to learn more about stars in the earliest stages of development. To their surprise they discovered the disks around new stars seem to emit jets or plumes of dust and gas and even electromagnetic energy. The team dubbed them ‘sneezes’ and its this process that seems to slowly erode the magnetic flux of a young star system. 

ALMA’s high-resolution images of nearby protoplanetary disks, which are results of the Disk Substructures at High Angular Resolution Project (DSHARP). The observatory is often used to look for planet birth clouds like these and the one around HD 169142. Credit: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello

One phenomenon of the disks is a powerful magnetic field which permeates through the region. It therefore carries a magnetic flux and herein lies the problem. The magnetic fields would be far stronger than those observed if the magnetic flux had been retained from day one. History shows us, they didn’t seem to retain them so the flux has been slowly eroded away in new star and planetary systems. 

One such proposal was that the field slowly decreased as the surrounding dust cloud collapsed into the core of the star. To explore the phenomenon the team studied MC 27, a system 450 light years away using ALMA, the Atacama Large Millimetre Array. In total, 66 radio telescopes pointed to the object from an altitude of 5,000 metres. They found that there were ‘spike like’ structures that seemed to extend out by a few astronomical units (average distance between Sun and Earth.)

The Atacama Large Millimeter/submillimeter Array (ALMA). Credit: C. Padilla, NRAO/AUI/NSF

The team found that the features contained gas and dust but had a magnetic flux. Known as ‘interchange instability’, the field exhibits instabilities when it reacts with different densities of gas. They referred to these, not as interchange instability but as a baby star’s sneeze. Just like a human sneeze which expels dust and gas or rather air from our bodies, so a young hot star ‘sneezing’ releases gas and dust from the disk. 

Further exploration revealed signs of other plumes several thousands of astronomical units from the protostellar disk. They suggest that these are evidence of other sneezes in the past. It’s not just on MC 27 though, the spikes have been seen in other star systems but more time is needed to be able to fully understand the implications of the discovery. 

Source : Twinkle twinkle baby star, ‘sneezes’ tell us how you are

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The most recognizable feature on Pluto is its “heart,” a relatively bright valentine-shaped area known as Tombaugh Regio. How that heart got started is one of the dwarf planet’s deepest mysteries — but now researchers say they’ve come up with the most likely scenario, involving a primordial collision with a planetary body that was a little more than 400 miles wide.

The scientific term for what happened, according to a study published today in Nature Astronomy, is “splat.”

Astronomers from the University of Bern in Switzerland and the University of Arizona looked for computer simulations that produced dynamical results similar to what’s seen in data from NASA’s New Horizons probe. They found a set of simulations that made for a close match, but also ran counter to previous suggestions that Pluto harbors a deep subsurface ocean. They said their scenario doesn’t depend on the existence of a deep ocean — which could lead scientists to rewrite the history of Pluto’s geological evolution.

An artist’s conception shows the presumed collision of a planetary body with Pluto. (Thibaut Roger/University of Bern)

University of Arizona astronomer Adeene Denton, one of the study’s co-authors, said the formation of the heart “provides a critical window into the earliest periods of Pluto’s history.”

“By expanding our investigation to include more unusual formation scenarios, we’ve learned some totally new possibilities for Pluto’s evolution,” Denton said in a news release. Similar scenarios could apply to other objects in the Kuiper Belt, the ring of icy worlds on the edge of our solar system.

The study focuses on the western half of the heart, a roughly 1,000-mile-wide, teardrop-shaped region called Sputnik Planitia. That region contains an assortment of ices and is roughly 2.5 miles lower in elevation than the rest of Pluto. It’s clearly the result of a massive impact.

“While the vast majority of Pluto’s surface consists of methane ice and its derivatives, covering a water-ice crust, the Planitia is predominantly filled with nitrogen ice which most likely accumulated quickly after the impact due to the lower altitude,” said study lead author Harry Ballantyne, a research associate at the University of Bern.

The eastern half of the heart is covered by a similar but much thinner layer of nitrogen ice. The origins of that part of Tombaugh Regio are still unclear, but it’s probably related to the processes that shaped Sputnik Planitia.

Ballantyne and his colleagues ran a wide assortment of computer simulations for the ancient impact. Those simulations reflected a range of sizes and compositions for the impacting body, at different velocities and angles of approach. The best fit for Sputnik Planitia’s shape involved a 400-mile-wide object, composed of 15% rock, coming in at an angle of 30 degrees and hitting Pluto at a relatively low velocity.

Based on those parameters, the object would have plowed through Pluto’s surface with a splat. The resulting shape wouldn’t look like your typical impact crater. Instead, it would look like a bright, icy teardrop, with the rocky core of the impacting body ending up at the tail of the teardrop.

“Pluto’s core is so cold that the rocks remained very hard and did not melt despite the heat of the impact, and thanks to the angle of impact and the low velocity, the core of the impactor did not sink into Pluto’s core, but remained intact as a splat on it,” Ballantyne explained.

Previous scenarios for Sputnik Planitia’s origin relied on the presence of a deep ocean beneath Pluto’s surface to explain why the impact region hasn’t drifted toward Pluto’s nearest pole over time. But the researchers behind the newly published study found that the best matches in their simulations called for an ocean measuring no more than 30 miles in depth. “If the influence of ammonia proves negligible, Pluto might not possess a subsurface ocean at all, in accordance with our nominal case,” they wrote.

The researchers say they’ll continue their work to model Pluto’s geological history — and how those models could apply to other Kuiper Belt objects as well.

Meanwhile, the New Horizons spacecraft is continuing its journey through the solar system’s far reaches, nearly nine years after its Pluto flyby. Mission scientists recently reported detecting higher than expected levels of interplanetary dust, which suggests there may be more to the Kuiper Belt than they thought. They’re hoping to identify yet another icy world that the spacecraft can observe up close in the late 2020s or the 2030s.

In addition to Ballantyne and Denton, the authors of the Nature Astronomy study, titled “Sputnik Planitia as an Impactor Remnant Indicative of an Ancient Rocky Mascon in an Oceanless Pluto,” include Erik Asphaug, Alexandre Emsenhuber and Martin Jutzi.

The post How Did Pluto Get Its Heart? Scientists Suggest an Answer appeared first on Universe Today.

Look through the names and origins of the constellations and you will soon realise that many cultures had a hand in their conceptualisation. Among them are the Egyptians who were fantastic astronomers. The movement of the sky played a vital role in ancient Egypt including the development of the 365 day year and the 24 hour day. Like many other cultures they say the Sun, Moon and planets as gods. Surprisingly though, the bright Milky Way seems not to have played a vital role. Some new research suggests that this may not be the case and it may have been a manifestation of the sky goddess Nut! 

It’s a fairly well accepted theory that the pyramids of Egypt were constructed in some way as a representation of or tribute to the sky. The Sun god Ra was often depicted sailing the Sun across the sky in a boat but the Milky Way was never seemed to be a big part, other than perhaps some consideration that the river Nile could represent it. 

Nile River, Lake Nasser and the Red Sea, Egypt

Back in the days of ancient Egypt, light pollution really wasn’t a thing. The Milky Way would have been far more prominent than for many stargazers today. A recent study by astrophysicists at the University of Portsmouth suggest that a lesser heard god by the name of Nut had something to do with it. 

Hunt through Egyptian artwork and you will often see a star-filled woman arched over another person. The woman is Nut, the goddess of the sky and the other figure represents her brother, the god of Earth, Geb. Nut has a very specific job though, she protects the Earth from being flooded from waters of the void! Presumably this would be the void of space but of course back then we didn’t have such a great understanding of the cosmos. She also swallowed the Sun as it sets, giving birth to it again in the morning. 

Thankfully the Egyptians were fabulous at recording things and so there have been plenty of Egyptian texts to refer to. Running simulations from the evidence in the documents, the team (led by Dr Or Graur Associate Professor in Astrophysics) suggest that the Milky Way represented Nut’s outstretched arms in the winter and her backbone in the summer. This suggestion aligns with the broad patterns in the Milky Way. 

The arch of the Milky Way seen over Bisei Town in Japan. It prides itself on its dark skies, but faces scattered light pollution from other nearby municipalities. Courtesy DarkSky.Org.

Dr Graur went on to explain that their results revealed that Nut had far more of a functional role too. She was involved in the transition of deceased souls to the afterlife and had a connection with annual bird migrations. This is in line with many cultures like those in North and Central America believing the Milky Way was a road used by spirits or those in Finland and the Baltics who believed it was a path for birds. 

Source : The hidden role of the Milky Way in ancient Egyptian mythology

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In 2011, astronomers with the Wide Angle Search for Planets (WASP) consortium detected a gas giant orbiting very close to a Sun-like (G-type) star about 700 light-years away. This planet is known as WASP-39b (aka. “Bocaprins”), one of many “hot Jupiters” discovered in recent decades that orbits its star at a distance of less than 5% the distance between the Earth and the Sun (0.05 AU). In 2022, shortly after the James Webb Space Telescope (JWST) it became the first exoplanet to have carbon dioxide and sulfur dioxide detected in its atmosphere.

Alas, researchers have not constrained all of WASP-39b’s crucial details (particularly its size) based on the planet’s light curves, as observed by Webb. which is holding up more precise data analyses. In a new study led by the Max Planck Institute for Solar System Research (MPS), an international team has shown a way to overcome this obstacle. They argue that considering a parent star’s magnetic field, the true size of an exoplanet in orbit can be determined. These findings are likely to significantly impact the rapidly expanding field of exoplanet study and characterization.

The study was led by Dr. Nadiia M. Kostogryz and her fellow researchers from the MPS. They were joined by astronomers and astrophysicists from the Center for Astronomy (Heidelberg University), the Astrophysics Group at Keele University, the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT), and the Space Telescope Science Institute (STScI). The paper describing their research, “Magnetic origin of the discrepancy between stellar limb-darkening models and observations,” was recently published in Nature Astronomy.

The “hot Jupiter” exoplanet WASP-69b orbits its star so closely that its atmosphere is being blown into space. Credit: Adam Makarenko/W. M. Keck Observatory

A light curve is the measurement of a star’s brightness over longer periods. Using the Transit Method (Transit Photometry), astronomers monitor stars for periodic dips in brightness, which can result from an exoplanet passing (transiting) in front of their face relative to the observer. In addition to being the most widely used method for detecting exoplanets, precise observations of light curves allow astronomers to estimate the size and orbital period of the exoplanets.

These curves can also reveal information about the composition of the planet’s atmosphere based on light passing through its atmosphere as it makes a transit – a technique known as “transit spectroscopy.” Unfortunately, estimates on planet size suffer from an observational issue known as “limb darkening.” Dr. Kostogryz explained in an MPS press statement:

“The problems arising when interpreting the data from WASP-39b are well known from many other exoplanets – regardless [of] whether they are observed with Kepler, TESS, James Webb, or the future PLATO spacecraft. As with other stars orbited by exoplanets, the observed light curve of WASP-39 is flatter than previous models can explain.”

The edge of the stellar disk (or “limb”) plays a decisive role in interpreting a star’s light curve. Since the limb corresponds to the star’s outer (and cooler) layers, it appears darker to the observer than the inner area. However, the star does not actually shine less brightly further out. This “limb darkening” affects the shape of the exoplanet signal in the light curve, as the dimming determines how steeply the curve falls during a planetary transit and then rises again. Historically, astronomers have not been able to reproduce observational data using conventional stellar models accurately.

In every case, the decrease in the star’s brightness was less abrupt than model calculations predicted. Clearly, something was missing from the models that prevented astronomers from reproducing exoplanet transit signals. As Dr. Kostogryz and her team discovered, the missing piece is stellar magnetic fields, which are generated by the motion of conductive plasma inside a star. The team first noticed this when examining selected light curves obtained by NASA’s Kepler Space Telescope between 2009 and 2018.

An illustration of Earth’s magnetic field. Credit: ESA/ATG medialab

The researchers also proved that the discrepancy between observational data and model calculations disappears if the star’s magnetic field is included in the computations. To this end, the team turned to selected data from NASA’s Kepler Space Telescope, which captured the light of thousands and thousands of stars from 2009 to 2018. To this end, they modeled the atmosphere of typical Kepler stars in the presence of a magnetic field and then simulated observational data based on these calculations. When they compared their results to real data, they found it accurately reproduced Kepler’s observations.

They also found that the strength of the magnetic field can have a profound effect, where limb darkening is more pronounced in stars with weak magnetic fields and less in stars with strong ones. Lastly, they extended their simulations to emission spectra data obtained by the JWST and found that the magnetic field of the parent star influences limb darkening differently at different wavelengths. These findings will help inform future exoplanet studies, leading to more precise estimates of the planets’ characteristics. Said Dr. Alexander Shapiro, coauthor of the current study and head of an ERC-funded research group at the MPS:

“In the past decades and years, the way to move forward in exoplanet research was to improve the hardware, the space telescopes designed to search for and characterize new worlds. The James Webb Space Telescope has pushed this development to new limits. The next step is now to improve and refine the models to interpret this excellent data.”

The researchers now plan to extend their analyses to stars different from the Sun, which could lead to refined estimates of exoplanet mass for rocky planets (similar to Earth). In addition, their findings indicate that the light curves of stars could be used to constrain the strength of stellar magnetic fields, another characteristic that is challenging to measure.

Further Reading: MPS, Nature Astronomy

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An international research team led by the University of Vienna has made a major breakthrough. In a study recently published in Nature Astronomy, they describe how they conducted the first direct measurements of stellar wind in three Sun-like star systems. Using X-ray emission data obtained by the ESA’s X-ray Multi-Mirror-Newton (XMM-Newton) of these stars’ “astrospheres,” they measured the mass loss rate of these stars via stellar winds. The study of how stars and planets co-evolve could assist in the search for life while also helping astronomers predict the future evolution of our Solar System.

The research was led by Kristina G. Kislyakova, a Senior Scientist with the Department of Astrophysics at the University of Vienna, the deputy head of the Star and Planet Formation group, and the lead coordinator of the ERASMUS+ program. She was joined by other astrophysicists from the University of Vienna, the Laboratoire Atmosphères, Milieux, Observations Spatiales (LAMOS) at the Sorbonne University, the University of Leicester, and the Johns Hopkins University Applied Physics Laboratory (JHUAPL).

Astrospheres are the analogs of our Solar System’s heliosphere, the outermost atmospheric layer of our Sun, composed of hot plasma pushed by solar winds into the interstellar medium (ISM). These winds drive many processes that cause planetary atmospheres to be lost to space (aka. atmospheric mass loss). Assuming a planet’s atmosphere is regularly replenished and/or has a protective magnetosphere, these winds can be the deciding factor between a planet becoming habitable or a lifeless ball of rock.

Logarithmic scale of the Solar System, Heliosphere, and Interstellar Medium (ISM). Credit: NASA-JPL

While stellar winds mainly comprise protons, electrons, and alpha particles, they also contain trace amounts of heavy ions and atomic nuclei, such as carbon, nitrogen, oxygen, silicon, and even iron. Despite their importance to stellar and planetary evolution, the winds of Sun-like stars are notoriously difficult to constrain. However, these heavier ions are known to capture electrons from neutral hydrogen that permeates the ISM, resulting in X-ray emissions. Using data from the XXM-Newton mission, Kislyakova and her team detected these emissions from other stars.

These were 70 Ophiuchi, Epsilon Eridani, and 61 Cygni, three main sequence Sun-like stars located 16.6, 10.475, and 11.4 light-years from Earth (respectively). Whereas 70 Ophiuchi and 61 Cygni are binary systems of two K-type (orange dwarf) stars, Epsilon Eridani is a single K-type star. By observing the spectral lines of oxygen ions, they could directly quantify the total mass of stellar wind emitted by all three stars. For the three stars surveyed, they estimated the mass loss rates to be 66.5±11.1, 15.6±4.4, and 9.6±4.1 times the solar mass loss rate, respectively.

In short, this means that the winds from these stars are much stronger than our Sun’s, which could result from the stronger magnetic activity of these stars. As Kislyakova related in a University of Vienna news release:

“In the solar system, solar wind charge exchange emission has been observed from planets, comets, and the heliosphere and provides a natural laboratory to study the solar wind’s composition. Observing this emission from distant stars is much more tricky due to the faintness of the signal. In addition to that, the distance to the stars makes it very difficult to disentangle the signal emitted by the astrosphere from the actual X-ray emission of the star itself, part of which is “spread” over the field-of-view of the telescope due to instrumental effects.”

XMM-Newton X-ray image of the star 70 Ophiuchi (left) and the X-ray emission from the region (“Annulus”) surrounding the star represented in a spectrum over the energy of the X-ray photons (right). Credit: C: Kislyakova et al. (2024)

For their study, Kislyakova and her team also developed a new algorithm to disentangle the contributions made by the stars and their astrospheres to the emission spectra. This allowed them to detect charge exchange signals from the stellar wind oxygen ions and the neutral hydrogen in the surrounding ISM. This constitutes the first time X-ray charge exchange emissions from the extrasolar astrospheres have been directly detected. Moreover, the mass loss rate estimates they derived could be used by astronomers as a benchmark for stellar wind models, expanding on what little observational evidence there is for the winds of Sun-like stars. As co-author Manuel Güdel, also of the University of Vienna, indicated:

“There have been world-wide efforts over three decades to substantiate the presence of winds around Sun-like stars and measure their strengths, but so far only indirect evidence based on their secondary effects on the star or its environment alluded to the existence of such winds; our group previously tried to detect radio emission from the winds but could only place upper limits to the wind strengths while not detecting the winds themselves. Our new X-ray based results pave the way to finding and even imaging these winds directly and studying their interactions with surrounding planets.”

In the future, this method of direct detection of stellar winds will be facilitated by next-generation missions like the European Athena mission. This mission will include a high-resolution X-ray Integral Field Unit (X-IFU) spectrometer, which Athena will use to resolve the finer structure and ratio of faint emission lines that are difficult to distinguish using XMM-Newton’s instruments. This will provide a more detailed picture of the stellar winds and astrospheres of distant stars, helping astronomers constrain their potential habitability while also improving solar evolution models.

Further Reading: University of Vienna, Nature Astronomy

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One of the big mysteries about dark matter particles is whether they interact with each other. We still don’t know the exact nature of what dark matter is. Some models argue that dark matter only interacts gravitationally, but many more posit that dark matter particles can collide with each other, clump together, and even decay into particles we can see. If that’s the case, then objects with particularly strong gravitational fields such as black holes, neutron stars, and white dwarfs might capture and concentrate dark matter. This could in turn affect how these objects appear. As a case in point, a recent study looks at the interplay between dark matter and neutron stars.

Neutron stars are made of the most dense matter in the cosmos. Their powerful gravitational fields could trap dark matter and unlike black holes, any radiation from dark matter won’t be trapped behind an event horizon. So neutron stars are a perfect candidate for studying dark matter models. For this study, the team looked at how much dark matter a neutron star could capture, and how the decay of interacting dark matter particles would affect its temperature.

The details depend on which specific dark matter model you use. Rather than addressing variant models, the team looked at broad properties. Specifically, they focused on how dark matter and baryons (protons and neutrons) might interact, and whether that would cause dark matter to be trapped. Sure enough, for the range of possible baryon-dark matter interactions, neutron stars can capture dark matter.

The team then went on to look at how dark matter thermalization could occur. In other words, as dark matter is captured it should release heat energy into the neutron star through collisions and dark matter annihilation. Over time the dark matter and neutron star should reach a thermal equilibrium. The rate at which this occurs depends on how strongly particles interact, the so-called scattering cross-section. The team found that thermal equilibrium is reached fairly quickly. For simple scalar models of dark matter, equilibrium can be reached within 10,000 years. For vector models of dark matter, equilibrium can happen in just a year. Regardless of the model, neutron stars can reach thermal equilibrium in a cosmic blink of an eye.

If this model is correct, then dark matter could play a measurable role in the evolution of neutron stars. We could, for example, identify the presence of dark matter by observing neutron stars that are warmer than expected. Or perhaps even distinguish different dark matter models by the overall spectrum of neutron stars.

Reference: Bell, Nicole F., et al. “Thermalization and annihilation of dark matter in neutron stars.” Journal of Cosmology and Astroparticle Physics 2024.04 (2024): 006.

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After a journey lasting about two billion years, photons from an extremely energetic gamma-ray burst (GRB) struck the sensors on the Neil Gehrels Swift Observatory and the Fermi Gamma-Ray Space Telescope on October 9th, 2022. The GRB lasted seven minutes but was visible for much longer. Even amateur astronomers spotted the powerful burst in visible frequencies.

It was so powerful that it affected Earth’s atmosphere, a remarkable feat for something more than two billion light-years away. It’s the brightest GRB ever observed, and since then, astrophysicists have searched for its source.

NASA says GRBs are the most powerful explosions in the Universe. They were first detected in the late 1960s by American satellites launched to keep an eye on the USSR. The Americans were concerned that the Russians might keep testing atomic weapons despite signing 1963’s Nuclear Test Ban Treaty.

Now, we detect about one GRB daily, and they’re always in distant galaxies. Astrophysicists struggled to explain them, coming up with different hypotheses. There was so much research into them that by the year 2,000, an average of 1.5 articles on GRBs were published in scientific journals daily.

There were many different proposed causes. Some thought that GRBs could be released when comets collided with neutron stars. Others thought they could come from massive stars collapsing to become black holes. In fact, scientists wondered if quasars, supernovae, pulsars, and even globular clusters could be the cause of GRBs or associated with them somehow.

GRBs are confounding because their light curves are so complex. No two are identical. But astrophysicists made progress, and they’ve learned a few things. Short-duration GRBs are caused by the merger of two neutron stars or the merger of a neutron star and a black hole. Longer-duration GRBs are caused by a massive star collapsing and forming a black hole.

This sample of 12 GRB light curves shows how no two are the same. Image Credit: NASA

New research in Nature examined the ultra-energetic GRB 221009A, dubbed the “B.O.A.T: Brightest Of All Time,” and found something surprising. When it was initially discovered, scientists said it was caused by a massive star collapsing into a black hole. The new research doesn’t contradict that. But it presents a new mystery: why are there no heavy elements in the newly uncovered supernova?

The research is “JWST detection of a supernova associated with GRB 221009A without an r-process signature.” The lead author is Peter Blanchard, a Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) postdoctoral fellow.

“The GRB was so bright that it obscured any potential supernova signature in the first weeks and months after the burst,” Blanchard said. “At these times, the so-called afterglow of the GRB was like the headlights of a car coming straight at you, preventing you from seeing the car itself. So, we had to wait for it to fade significantly to give us a chance of seeing the supernova.”

“When we confirmed that the GRB was generated by the collapse of a massive star, that gave us the opportunity to test a hypothesis for how some of the heaviest elements in the universe are formed,” said lead author Blanchard. “We did not see signatures of these heavy elements, suggesting that extremely energetic GRBs like the B.O.A.T. do not produce these elements. That doesn’t mean that all GRBs do not produce them, but it’s a key piece of information as we continue to understand where these heavy elements come from. Future observations with JWST will determine if the B.O.A.T.’s ‘normal’ cousins produce these elements.”

Scientists know that supernova explosions forge heavy elements. They’re an important source of elements from oxygen (atomic number 8) to rubidium (atomic number 37) in the interstellar medium. They also produce heavier elements than that. Heavy elements are necessary to form rocky planets like Earth and for life itself. But it’s important to note that astrophysicists don’t completely understand how heavy elements are produced.

This periodic table from the NASA Scientific Visualization Studio shows where the elements come from, though scientists still have some uncertainty. Image Credit: NASA’s Goddard Space Flight Center

Scientists naturally wondered if an extremely luminous GRB like GRB 221009A would produce even more heavy elements. But that’s not what they found.

“This event is particularly exciting because some had hypothesized that a luminous gamma-ray burst like the B.O.A.T. could make a lot of heavy elements like gold and platinum,” said second author Ashley Villar of Harvard University and the Center for Astrophysics | Harvard & Smithsonian. “If they were correct, the B.O.A.T. should have been a goldmine. It is really striking that we didn’t see any evidence for these heavy elements.”

Stars forge heavy elements by nucleosynthesis. Three processes are responsible for that: the p-process, the s-process and the r-process (proton capture process, slow neutron capture process, and the rapid neutron capture process.) The r-process captures neutrons faster than the s-process and is responsible for about half of the elements heavier than iron. The r-process is also responsible for the most stable isotopes of these heavy elements.

That’s all to illustrate the importance of the r-process in the Universe.

The researchers used the JWST to get to the bottom of GRB 221009A. The GRB was obscured by the Milky Way, but the JWST senses infrared light and saw right through the Milky Way’s gas and dust. The telescope’s NIRSpec (Near Infrared Spectrograph) senses elements like oxygen and calcium, usually found in supernovae. But the signatures weren’t very bright, a surprise considering how bright the supernova was.

“It’s not any brighter than previous supernovae,” lead author Blanchard said. “It looks fairly normal in the context of other supernovae associated with less energetic GRBs. You might expect that the same collapsing star producing a very energetic and bright GRB would also produce a very energetic and bright supernova. But it turns out that’s not the case. We have this extremely luminous GRB, but a normal supernova.”

Confirming the presence of the supernova was a big step to understanding GRB 221009A. But the lack of an r-process signature is still confounding.

Scientists have only confirmed the r-process in the merger of two neutron stars, called a kilonova explosion. But there are too few neutron star mergers to explain the abundance of heavy elements.

This artist’s illustration shows two neutron stars colliding. Known as a “kilonova” event, they’re the only confirmed location of the r-process that forges heavy elements. Credits: Elizabeth Wheatley (STScI)

“There is likely another source,” Blanchard said. “It takes a very long time for binary neutron stars to merge. Two stars in a binary system first have to explode to leave behind neutron stars. Then, it can take billions and billions of years for the two neutron stars to slowly get closer and closer and finally merge. But observations of very old stars indicate that parts of the universe were enriched with heavy metals before most binary neutron stars would have had time to merge. That’s pointing us to an alternative channel.”

Researchers have wondered if luminous supernovae like this can account for the rest. Supernovae have an inner layer where more heavy elements could be synthesized. But that layer is obscured. Only after things calm down is the inner layer visible.

“The exploded material of the star is opaque at early times, so you can only see the outer layers,” Blanchard said. “But once it expands and cools, it becomes transparent. Then you can see the photons coming from the inner layer of the supernova.”

All elements have spectroscopic signatures, and the JWST’s NIRSpec is a very capable instrument. But it couldn’t detect heavier elements, even in the supernova’s inner layer.

“Upon examining the B.O.A.T.’s spectrum, we did not see any signature of heavy elements, suggesting extreme events like GRB 221009A are not primary sources,” lead author Blanshard said. “This is crucial information as we continue to try to pin down where the heaviest elements are formed.”

Scientists are still uncertain about the GRB and its lack of heavy elements. But there’s another feature that might offer a clue: jets.

“A second proposed site of the r-process is in rapidly rotating cores of massive stars that collapse into an accreting black hole, producing similar conditions as the aftermath of a BNS merger,” the authors write in their paper. “Theoretical simulations suggest that accretion disk outflows in these so-called ‘collapsars’ may reach the neutron-rich state required for the r-process to occur.”

The “accretion disk outflows” the researchers refer to are relativistic jets. The narrower the jets are, the brighter and more focused their energy is.

Could they play a role in forging heavy elements?

“It’s like focusing a flashlight’s beam into a narrow column, as opposed to a broad beam that washes across a whole wall,” Laskar said. “In fact, this was one of the narrowest jets seen for a gamma-ray burst so far, which gives us a hint as to why the afterglow appeared as bright as it did. There may be other factors responsible as well, a question that researchers will be studying for years to come.”

The researchers also used NIRSpec to gather a spectrum from the GRB’s host galaxy. It has the lowest metallicity of any galaxy known to host a GRB. Could that be a factor?

“This is one of the lowest metallicity environments of any LGRB, which is a class of objects that prefer low-metallicity galaxies, and it is, to our knowledge, the lowest metallicity environment of a GRB-SN to date,” the authors write in their research. “This may suggest that very low metallicity is required to produce a very energetic GRB.”

The host galaxy is also actively forming stars. Is that another clue?

“The spectrum shows signs of star formation, hinting that the birth environment of the original star may be different than previous events,” Blanshard said.

Yijia Li is a graduate student at Penn State and a co-author of the paper. “This is another unique aspect of the B.O.A.T. that may help explain its properties,” Li said. “The energy released in the B.O.A.T. was completely off the charts, one of the most energetic events humans have ever seen. The fact that it also appears to be born out of near-primordial gas may be an important clue to understanding its superlative properties.”

This is another case where solving one mystery leads to another unanswered one. The JWST was launched to answer some of our foundational questions about the Universe. By confirming that a supernova is behind the most powerful GRB ever detected, it’s done part of its job.

But it also found another mystery and has left us hanging again.

The JWST is working as intended.

The post The Brightest Gamma Ray Burst Ever Seen Came from a Collapsing Star appeared first on Universe Today.

It’s an exciting time for the fields of astronomy, astrophysics, and cosmology. Thanks to cutting-edge observatories, instruments, and new techniques, scientists are getting closer to experimentally verifying theories that remain largely untested. These theories address some of the most pressing questions scientists have about the Universe and the physical laws governing it – like the nature of gravity, Dark Matter, and Dark Energy. For decades, scientists have postulated that either there is additional physics at work or that our predominant cosmological model needs to be revised.

While the investigation into the existence and nature of Dark Matter and Dark Energy is ongoing, there are also attempts to resolve these mysteries with the possible existence of new physics. In a recent paper, a team of NASA researchers proposed how spacecraft could search for evidence of additional physical within our Solar Systems. This search, they argue, would be assisted by the spacecraft flying in a tetrahedral formation and using interferometers. Such a mission could help resolve a cosmological mystery that has eluded scientists for over half a century.

The proposal is the work of Slava G. Turyshev, an adjunct professor of physics and astronomy at the University of California Los Angeles (UCLA) and research scientist with NASA’s Jet Propulsion Laboratory. He was joined by Sheng-wey Chiow, an experimental physicist at NASA JPL, and Nan Yu, an adjunct professor at the University of South Carolina and a senior research scientist at NASA JPL. Their research paper recently appeared online and has been accepted for publication in Physical Review D.

A new study shows how measuring the Sun’s gravitational field could search for additional physics. Credit: NASA/ESA

Turyshev’s experience includes being a Gravity Recovery And Interior Laboratory (GRAIL) mission science team member. In previous work, Turyshev and his colleagues have investigated how a mission to the Sun’s solar gravitational lens (SGL) could revolutionize astronomy. The concept paper was awarded a Phase III grant in 2020 by NASA’s Innovative Advanced Concepts (NIAC) program. In a previous study, he and SETI astronomer Claudio Maccone also considered how advanced civilizations could use SGLs to transmit power from one solar system to the next.

To summarize, gravitational lensing is a phenomenon where gravitational fields alter the curvature of spacetime in their vicinity. This effect was originally predicted by Einstein in 1916 and was used by Arthur Eddington in 1919 to confirm his General Relativity (GR). However, between the 1960s and 1990s, observations of the rotational curves of galaxies and the expansion of the Universe gave rise to new theories regarding the nature of gravity over larger cosmic scales. On the one hand, scientists postulated the existence of Dark Matter and Dark Energy to reconcile their observations with GR.

On the other hand, scientists have advanced alternate theories of gravity (such as Modified Newtonian Dynamics (MOND), Modified Gravity (MOG), etc.). Meanwhile, others have suggested there may be additional physics in the cosmos that we are not yet aware of. As Turyshev told Universe Today via email:

“We are eager to explore questions surrounding the mysteries of dark energy and dark matter. Despite their discovery in the last century, their underlying causes remain elusive. Should these ‘anomalies’ stem from new physics—phenomena yet to be observed in ground-based laboratories or particle accelerators—it’s possible that this novel force could manifest on a solar system scale.”

Artist’s impression of a proposed Solar Gravity Lens telescope. Credit: The Aerospace Corporation

For their latest study, Turyshev and his colleagues investigated how a series of spacecraft flying in a tetrahedral formation could investigate the Sun’s gravitational field. These investigations, said Turyshev, would search for deviations from the predictions of general relativity at the Solar System scale, something that has not been possible to date:

“These deviations are hypothesized to manifest as nonzero elements in the gravity gradient tensor (GGT), fundamentally akin to a solution of the Poisson equation. Due to their minuscule nature, detecting these deviations demands precision far surpassing current capabilities—by at least five orders of magnitude. At such a heightened level of accuracy, numerous well-known effects will introduce significant noise. The strategy involves conducting differential measurements to negate the impact of known forces, thereby revealing the subtle, yet nonzero, contributions to the GGT.”

The mission, said Turyshev, would employ local measurement techniques that rely on a series of interferometers. This includes interferometric laser ranging, a technique demonstrated by the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, a spacecraft pair that relies on laser range finding to track Earth’s oceans, glaciers, rivers, and surface water. The same technique will also be used to investigate gravitational waves by the proposed space-based Laser Interferometry Space Antenna (LISA).

The spacecraft will also be equipped with atom interferometers, which use the wave character of atoms to measure the difference in phase between atomic matter waves along different paths. This technique will allow the spacecraft to detect the presence of non-gravitational noise (thruster activity, solar radiation pressure, thermal recoil forces, etc.) and negate them to the necessary degree. Meanwhile, flying in a tetrahedral formation will optimize the spacecraft’s ability to compare measurements.

“Laser ranging will offer us highly accurate data on the distances and relative velocities between spacecraft,” said Turyshev. “Furthermore, its exceptional precision will allow us to measure the rotation of a tetrahedron formation relative to an inertial reference frame (via Sagnac observables), a task unachievable by any other means. Consequently, this will establish a tetrahedral formation leveraging a suite of local measurements.”

Artist’s impression of the path of the star S2 as it passes very close to the supermassive black hole at the center of the Milky Way. Credit: ESO/M. Kornmesser

Ultimately, this mission will test GR on the smallest of scales, which has been sorely lacking to date. While scientists continue to probe the effect of gravitational fields on spacetime, these have been largely confined to using galaxies and galaxy clusters as lenses. Other instances include observations of compact objects (like white dwarf stars) and supermassive black holes (SMBH) like Sagittarius A* – which resides at the center of the Milky Way.

“We aim to enhance the precision of testing GR and alternative gravitational theories by more than five orders of magnitude. Beyond this primary objective, our mission has additional scientific goals, which we will detail in our subsequent paper. These include testing GR and other gravitational theories, detecting gravitational waves in the micro-Hertz range—a spectrum not reachable by existing or envisioned instruments— and exploring aspects of the solar system, such as the hypothetical Planet 9, among other endeavors.”

Further Reading: Physical Review D

The post Formation-Flying Spacecraft Could Probe the Solar System for New Physics appeared first on Universe Today.

Most satellites share the same fate at the end of their lives. Their orbits decay, and eventually, they plunge through the atmosphere toward Earth. Most satellites are destroyed during their rapid descent, but not always

Heavy pieces of the satellite, like reaction wheels, can survive and strike the Earth. Engineers are trying to change that.

Satellite debris can strike Earth and is a potential hazard, though the chances of debris striking anything other than ocean or barren land are low. Expired satellites usually just re-enter the atmosphere and burn up. But there are a lot of satellites, and their number keeps growing.

In February 2024, the ESA’s European Remote Sensing 2 (ERS2) satellite fell to Earth. The ESA tracked the satellite and concluded that it posed no problem. “The odds of a piece of satellite falling on someone’s head is estimated at one in a billion,” ESA space debris system engineer Benjamin Bastida Virgili said.

That would be fine if ERS 2 was an isolated incident. But, according to the ESA, an object about as massive as ERS 2 reenters Earth’s atmosphere every one to two weeks. The statistics may show there’s no threat to people, but statistics are great until you’re one of them.

The ESA’s ERS-2 Earth observation satellite was destroyed when it re-entered Earth’s atmosphere on February 21st, 2004. Heavy parts of satellites, like reaction wheels, don’t always burn up in the atmosphere and can pose a hazard. ESA engineers are working on reaction wheels that will break into pieces to reduce the hazard. Image Credit: Fraunhofer FHR

The risk of being struck by chunks of a satellite isn’t zero. In 1997, a piece of mesh from a Delta II rocket struck someone’s shoulder in Oklahoma. It was a light piece of debris, so the person was okay. But it was an instructive event.

The heaviest parts of satellites, like reaction wheels, can be hazardous because they may not be destroyed during re-entry. Reaction wheels provide three-axis control for satellites without the need for rockets. They give satellites fine pointing accuracy and are useful for rotating satellites in very small amounts.

Reaction wheels can be quite massive. The Hubble Space Telescope has four reaction wheels weighing 45 kg (100 lbs) each. Other satellites don’t have such massive wheels, but the Hubble’s hefty wheels indicate the extent of the hazard. ESA engineers are designing reaction wheels that will break up during re-entry to reduce the hazard of one striking Earth.

“… the need is becoming urgent as more and more satellites are placed in space.”

Kobyé Bodjona, Mechanisms Engineer at the ESA

As part of the design process, they’re testing their wheels in a plasma wind tunnel at the University of Stuttgart Institute of Space Systems. The heated plasma in the tunnel moves at several km/sec, mimicking the friction a satellite is exposed to when it plunges through Earth’s atmosphere. The wheel is rotated inside the tunnel as if tumbling through the atmosphere.

At a recent Space Mechanisms Workshop at ESA’s ESTEC technical center in the Netherlands, engineers showed a clip of the blow-torch effect that the atmosphere has on falling debris.

“Space mechanisms cover everything that enables movement aboard a satellite, from deployment devices to reaction wheels,” explains workshop co-organizer Geert Smet.

“But these mechanisms often use materials such as steel or titanium that are more likely to survive reentry into the atmosphere. This is a problem because our current regulations say reentering satellites should present less than one in 10,000 risks of harming people or property on the ground or even one in 100 000 for large satellite constellations. ESA’s Clean Space group is reacting by D4D—devising methods to make total disintegration of a mission more likely, including mechanisms.”

The effort to make satellites disintegrate completely goes back a few years. The ESA program Design for Demise (D4D) is helping satellite manufacturers comply with the Space Debris Mitigation (SDM) requirements. It’s aimed at eliminating debris falling to Earth, removing debris already in orbit, and designing satellites that don’t linger in orbit after their missions have ended.

At the recent workshop, the ESA revealed more of its plans for active debris removal. There’s a push to develop dedicated spacecraft that can attach themselves to derelict satellites and force them into reentry. This will help remove dead satellites from the congested Low Earth Orbit.

“The idea behind this event is to present the mechanisms community with the latest research on space debris to see how they might contribute to the work going on,” said Kobyé Bodjona, Mechanisms Engineer at the ESA. “It’s important because large system integrators—the big companies that lead satellite projects—are going to need systems that are fully compliant with debris mitigation regulations. And the need is becoming urgent as more and more satellites are placed in space.”

The post Watch a Satellite Reaction Wheel Melt in a Simulated Orbital Re-Entry appeared first on Universe Today.

Exploration of the Moon or other dusty environments comes with challenges. The lunar surface is covered in material known as regolith and its a jaggy, glassy material. It can cause wear and tear on equipment and can pose a health risk to astronauts too. Astronauts travelling to Mars would experience dust saucing to everything, including solar panels leading to decrease in power. To combat the problems created by dust, NASA is working on an innovative electrodynamic dust shield to remove dust and protect surfaces from solar panels to space suits. 

Dust is common on Earth as much as it is on other worlds although of course the source can be very different. It plagues are homes and leads to the constant battle to remove it from our homes in the almost ritualistic activity of dusting. Even here there are a multitude of sprays, brushes and rags that claim to help. Some even employ the electrostatic force to help repel dust from surfaces. It is a mere annoyance to us, perhaps causing the odd electrical device to over heat but largely its a small part of our lives. On alien worlds, it can lead to serious equipment malfunction and serious health hazards. 

Researchers at NASAs Kennedy Space Centre in Florida are now turning to electrostatic forces for help to keep astronauts and equipment dust free. Technology is being developed that has been called the Electrodynamic Dust Shield (EDS) –  I rather wish they dropped the word dust from the title to make it sound a little more StarTrek! The shield uses transparent electrodes and electric fields to electrically remove dust from surfaces.The idea was inspired by the electric curtain concept that was developed by NASA in 1967 but this new EDS has been in development since 2004. 

A close-up view of astronaut Buzz Aldrin’s bootprint in the lunar soil, photographed with the 70mm lunar surface camera during Apollo 11’s sojourn on the moon. Image by NASA

Dust exposure is a real concern for Commercial Lunar Payload Services and Artemis missions as the material can get into gaskets and seals, hatches and even potentially lunar habitats compromising their integrity. Dr Charles Buhler, lead scientist said “For these CPLS and Artemis missions, dust exposure is a concern because the lunar surface is far different than what we’re used to here.”

It’s the nature of the stuff to, not just that it gets everywhere like sand after a day at the beach. It is really abrasive like tiny pieces of glass because, unlike Earth where weathering tends to dull sharp edges, no such process occurs on the Moon. Even brushing the stuff off surfaces can lead to problems. 

The technology has been tested in vacuum chambers to simulate the space environment and results looked very promising. The Apollo missions collected samples of lunar regolith and some of this was used in the testing. The material was ejected from the surface within seconds. Following the successful tests, EDS materials were embedded on glass panels and test spacesuit fabrics on board the International Space Station and more recently Intuitive Machines first lunar lander too. EDS technology was used in lenses in the EagleCam CubeSat camera. Data is now being collected and future missions will carry the EDS concept to further test its capability to keep machines and humans safe on dusty worlds. 

Source : NASA Technology Helps Guard Against Lunar Dust

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The Martian moons Phobos and Deimos are oddballs. While other Solar System moons are round, Mars’ moons are misshapen and lumpy like potatoes. They’re more like asteroids or other small bodies than moons.

Because of their odd shapes and unusual compositions, scientists are still puzzling over their origins.

Two main hypotheses attempt to explain Phobos and Deimos. One says they’re captured asteroids, and the other says they are debris from an ancient impactor that collided with Mars. Earth’s moon was likely formed by an ancient collision when a planetesimal slammed into Earth, so there’s precedent for the impact hypothesis. There’s also precedent for the captured object scenario because scientists think some other Solar System moons, like Neptune’s moon Triton, are captured objects.

Phobos and Deimos have lots in common with carbonaceous C-type asteroids. They’re the most plentiful type of asteroid in the Solar System, making up about 75% of the asteroid population. The moons’ compositions and albedos support the captured asteroid theory. But their orbits are circular and close to Mars’ equator. Captured objects should have much more eccentric orbits.

This illustration shows Phobos and Deimos’ orbits along with the orbits of spacecraft at Mars. The moons’ near-circular orbits don’t support the captured asteroid theory. Image Credit: By NASA/JPL-Caltech – http://photojournal.jpl.nasa.gov/jpeg/PIA19396.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=39982795

The moons are less dense than silicate, the most abundant material in Mars’ crust. That fact works against the impact theory. A powerful impact would’ve blasted material from Mars into space, forming a disk of material rotating around the planet. Phobos and Deimos would’ve formed from that material. If they result from an ancient planetesimal impact, they should contain more Martian silica.

Here’s the problem in a nutshell. The captured asteroid theory can explain the moons’ observed physical characteristics but not their orbits. The impact theory can explain their orbits but not their compositions.

Phobos and Deimos look like potatoes more than moons. Image Credit: Left: By NASA / JPL-Caltech / University of Arizona – http://photojournal.jpl.nasa.gov/catalog/PIA10368, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5191977. Right: By NASA/JPL-Caltech/University of Arizona – http://marsprogram.jpl.nasa.gov/mro/gallery/press/20090309a.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6213773

In research presented at the 55th Lunar and Planetary Science Conference, three researchers proposed a different origin story for Phobos and Deimos. They suggest that an impactor is responsible for creating the moons, but the impactor was icy.

The research is titled “THE ICY ORIGINS OF THE MARTIAN MOONS.” The first author is Courteney Monchinski from the Earth-Life Science Institute at the Tokyo Institute of Technology.

If a rocky impactor slammed into Mars, it would’ve created a massive debris disk around the planet. Previous researchers have examined the idea using simulations and found that an impact could’ve created the moons. But the disk created by the impact would’ve been far more massive than Phobos and Deimos combined. The simulations showed that there would’ve been a third, much more massive moon created within Phobos’ orbit that would’ve fallen back down to Mars. But there’s no strong evidence of something that massive striking Mars.

This illustration shows how a giant impact could’ve created Phobos and Deimos. The collision would’ve created a massive debris disk where a third more massive moon formed before falling back to Mars. Image Credit: Antony Trinh / Royal Observatory of Belgium

Other impact studies used basaltic impactors. But those showed that the temperature in the debris disk would’ve been so high it would’ve melted the disk material and destroyed ancient chondritic materials. Since the pair of moons appear to contain those materials, a basaltic impactor is ruled out.

According to the research presented at the conference, an icy impactor can explain Phobos and Deimos’ origins. There are three reasons for that.

The extra disk mass created by a rocky impactor would not be present. Instead, much of the mass in the impactor would’ve been vapourized on impact and escaped the system rather than persisting in the disk and being taken up by the formation of moons. There would’ve been no large third moon and no need to explain how it fell back to Mars.

The second reason concerns the composition of the moons. With abundant water ice in the collision, the temperature in the debris disk would’ve been lower. That would’ve preserved the carbonaceous materials in Phobos and Deimos today. It also can help explain their density and possible porosity. An icy impactor could’ve also delivered water to Mars, and we know Mars was wetter in its past.

The third reason concerns Deimos’ orbit. It’s not synchronous with Mars, and an icy impactor can explain that. With more water ice in the disk, there would’ve been a viscous interaction between the disk’s dust and vapour that extended the disk, allowing Deimos to occupy its orbit.

The researchers used Smoothed Particle Hydrodynamic (SPH) simulations to test the icy impactor idea. They simulated giant impactors with varying quantities of water ice and watched as disks formed around Mars and moons formed in the disk.

They first found that an impactor with any amount of water ice produced a more massive debris disk. It could be because an impactor containing water ice would be larger, though less massive, than one without any ice. That allowed more material to spray from the planet into the disk. It could also be because the water ice absorbs some of the impact energy when it vapourizes. That would cool the disk temperature, lowering the velocities of particles in the disk and making them less likely to escape.

This figure from the research shows that any amount of ice in an impactor increases the size of the debris disk. Image Credit: Monchinski et al. 2024. LPSC

Varying the ice content in the impactor also affected the makeup of the disk. Different amounts of ice lead to disks with different amounts of Martian rock and impactor rock in the disk.

This graph from the study shows impactor ice content (x-axis) affects the debris disk composition. Image Credit: Monchinski et al. 2024. LPSC

The temperature in the disk is a critical part of this. Different amounts of water ice in the impactor change the disk temperature and what types of materials in the disk would melt. Impactors with more than 30% ice create disk temperatures too low to melt silicates. Perhaps more tellingly, impactors with more than 70% ice result in a disk temperature too low to alter or destroy chondritic material, which both Phobos and Deimos are expected to contain.

According to the researchers, an icy impactor can also explain other features. “The existence of water in the impact-generated disk also suggests that water may condense, accounting for the possible water-ice content of the moons,” they write.

Ultimately, the researchers say an icy impactor with 70% to 90% water ice mantles can explain the pair of moons.

“The best case for reproducing the moons’ proposed compositions are the 70% and 90% water-ice mantle impactor cases, as they allow for low disk temperatures and more chances for chondritic materials to survive,” they explain.

Unfortunately, that may not be realistic. “In our current solar system, an object with around 70% or 90% water-ice content is not exactly realistic, as the object with the highest amount of water content in our current solar system, Ganymede, is only about 50% water,” they write.

The ESA’s Mars Express orbiter captured this image of Phobos over the Martian landscape in this image taken in November 2010. Irregularly shaped and only 27 km long, Phobos is actually much darker (due to its carbon-rich surface) than is apparent in this contrast-enhanced view. Image Credit: ESA / DLR / G. neukum

But could things have been different in the past? Samples from asteroid Ryugu suggest that its parent body could’ve been up to 90% water. That number is based on the types of minerals in Ryugu. But unfortunately, scientists don’t now for sure. Ryugu’s parent body could have contained as little as 20% water.

But it’s at least plausible that early in the Solar System’s life, an impactor with 70% water ice could have existed. If so, then the icy impactor scenario could be a robust theory to explain the origins of Phobos and Deimos.

“This impactor would have come from the outer solar system around the time of giant planet instability,” the authors write. During that time, outer Solar System bodies were perturbed and sent flying into the inner Solar System. But in this case, the impact’s timing needs to be constrained by Phobos’ and Deimos’ formation ages.

Scientists need more evidence to deepen their understanding of Mars and its moons. Japan’s Martian Moons eXploration (MMX) mission will provide that. MMX’s mission is to return a sample of Phobos to Earth. The goal is to determine if it is a captured asteroid or the result of an impact.

Unfortunately, JAXA just delayed MMX’s launch. It was scheduled to launch in September 2024 but has been delayed until 2026. That means we won’t get samples until 2031 instead of 2029.

JAXA has completed successful sample return missions, so they have the expertise to bring a piece of Phobos back to Earth. If scientists can determine how Phobos and Deimos formed, it’ll be part of a much larger, detailed picture of how the Solar System formed.

It’ll be worth it if we have to wait a couple extra years.

The post Did An Ancient Icy Impactor Create the Martian Moons? appeared first on Universe Today.

Everyone knows that solar energy is free and almost limitless here on Earth. The same is true for spacecraft operating in the inner Solar System. But in space, the Sun can do more than provide electrical energy; it also emits an unending stream of solar wind.

Solar sails can harness that wind and provide propulsion for spacecraft. NASA is about to test a new solar sail design that can make solar sails even more effective.

Solar pressure pervades the entire Solar System. It weakens with distance, but it’s present. It affects all spacecraft, including satellites. It affects longer-duration spaceflights dramatically. A spacecraft on a mission to Mars can be forced off course by thousands of kilometres during its voyage by solar pressure. The pressure also affects a spacecraft’s orientation, and they’re designed to deal with it.

Though it’s a hindrance, solar pressure can be used to our advantage.

A few solar sail spacecraft have been launched and tested, beginning with Japan’s Ikaros spacecraft in 2010. Ikaros proved that radiation pressure from the Sun in the form of photons can be used to control a spacecraft. The most recent solar sail spacecraft is the Planetary Society’s LightSail 2, launched in 2019. LightSail 2 was a successful mission that lasted over three years.

The Red Sea and the Nile River, from the LightSail 2 spacecraft. LightSail 2 was a successful demonstration mission that lasted more than two years. Image Credit: The Planetary Society.

Solar sail spacecraft have some advantages over other spacecraft. Their propulsion systems are extremely lightweight and never run out of fuel. Solar sail spacecraft can perform missions more cheaply than other spacecraft and can last longer, though they have limitations.

The solar sail concept is now proven to work, but the technology needs to advance for it to be truly effective. A critical part of a solar sail spacecraft is its booms. Booms support the sail material; the lighter and stronger they are, the more effective the spacecraft will be. Though solar sails are much lighter than other spacecraft, the weight of the booms is still a hindrance.

“Booms have tended to be either heavy and metallic or made of lightweight composite with a bulky design – neither of which work well for today’s small spacecraft.”

Keats Wilkie, ACS3 principal investigator, NASA

NASA is about to launch a new solar sail design with a better support structure. Called the Advanced Composite Solar Sail System (ACS3), it’s stiffer and lighter than previous boom designs. It’s made of carbon fibre and flexible polymers.

Though solar sails have many advantages, they also have a critical drawback. They’re launched as small packages that must be unfurled before they start working. This operation can be fraught with difficulties and induces stress in the poor ground crew, who have to wait and watch to see if it’s successful.

This image shows the ACS3 being unfurled at NASA’s Langley Research Center. The solar wind is reliable but not very powerful. It requires a large sail area to power a spacecraft effectively. The ACS2 is about 9 meters (30 ft) per side, requiring a strong, lightweight boom system. Image Credit: NASA

ACS3 will launch with a twelve-unit (12U) CubeSat built by NanoAvionics. The primary goal is to demonstrate boom deployment, but the ACS3 team also hopes the mission will prove that their solar sail spacecraft works.

To change direction, the spacecraft angles its sails. If boom deployment is successful, the ACS3 team hopes to perform some maneuvers with the spacecraft, angling the sails and changing the spacecraft’s orbit. The goal is to build larger sails that can generate more thrust.

“The hope is that the new technologies verified on this spacecraft will inspire others to use them in ways we haven’t even considered.”

Alan Rhodes, ACS3 lead systems engineer, NASA’s Ames Research Center

The ACS3 boom design is made to overcome a problem with booms: they’re either heavy and slim or light and bulky.

“Booms have tended to be either heavy and metallic or made of lightweight composite with a bulky design – neither of which work well for today’s small spacecraft,” said NASA’s Keats Wilkie. Wilke is the ACS3 principal investigator at Langley Research Center. “Solar sails need very large, stable, and lightweight booms that can fold down compactly. This sail’s booms are tube-shaped and can be squashed flat and rolled like a tape measure into a small package while offering all the advantages of composite materials, like less bending and flexing during temperature changes.”

ACS3 will launch from Rocket Lab’s launch complex 1 on New Zealand’s north island. Image Credit: Rocket Lab

ACS3 will be launched on an Electron rocket from Rocket Lab’s launch complex in New Zealand. It’ll head for a Sun-synchronous orbit 1,000 km (600 miles) above Earth. Once it arrives, the spacecraft will unroll its booms and deploy its sail. It’ll take about 25 minutes to deploy the sail, with a photon-gathering area of 80 square meters, or about 860 square feet. That’s much larger than Light Sail 2, which had a sail area of 32 square meters or about 340 square feet.

As it deploys itself, cameras on the spacecraft will watch and monitor the shape and symmetry. The data from the maneuvers will feed into future sail designs.

“Seven meters of the deployable booms can roll up into a shape that fits in your hand,” said Alan Rhodes, the mission’s lead systems engineer at NASA’s Ames Research Center. “The hope is that the new technologies verified on this spacecraft will inspire others to use them in ways we haven’t even considered.”

ACS3 is part of NASA’s Small Spacecraft Technology program. The program aims to deploy small missions that demonstrate unique capabilities rapidly. With unique composite and carbon fibre booms, the ACS3 system has the potential to support sails as large as 2,000 square meters, or about 21,500 square feet. That’s about half the area of a soccer field. (Or, as our UK friends mistakenly call it, a football field.)

With large sails, the types of missions they can power change. While solar sails have been small demonstration models so far, the system can potentially power some serious scientific missions.

“The Sun will continue burning for billions of years, so we have a limitless source of propulsion. Instead of launching massive fuel tanks for future missions, we can launch larger sails that use “fuel” already available,” said Rhodes. “We will demonstrate a system that uses this abundant resource to take those next giant steps in exploration and science.”

A solar flare as it appears in extreme ultraviolet light. The Sun is a free source of energy that’s not going away anytime soon, yet it’s also hazardous. Credit: NASA/SFC/SDO

Solar sail spacecraft don’t have the instantaneous thrust that chemical or electrical propulsion systems do. But the thrust is constant and never really wavers. They can do things other spacecraft struggle to do, such as taking up unique positions that allow them to study the Sun. They can serve as early warning systems for coronal mass ejections and solar storms, which pose hazards.

The new composite booms also have other applications. Since they’re so lightweight, strong, and compact, they could serve as the structural framework for lunar and Mars habitats. They could also be used to support other structures, like communication systems. If the system works, who knows what other applications it may serve?

“This technology sparks the imagination, reimagining the whole idea of sailing and applying it to space travel,” said Rudy Aquilina, project manager of the solar sail mission at NASA Ames. “Demonstrating the abilities of solar sails and lightweight, composite booms is the next step in using this technology to inspire future missions.”

The post NASA’s Next Solar Sail is About to Go to Space appeared first on Universe Today.

How can future lunar exploration communicate from the far side of the Moon despite never being inline with the Earth? This is what a recent study submitted to IEEE Transactions on Aerospace and Electronic Systems hopes to address as a pair of researchers from the Polytechnique Montréal investigated the potential for a wireless power transmission method (WPT) comprised of anywhere from one to three satellites located at Earth-Moon Lagrange Point 2 (EMLP-2) and a solar-powered receiver on the far side of the Moon. This study holds the potential to help scientists and future lunar astronauts maintain constant communication between the Earth and Moon since the lunar far side of the Moon is always facing away from Earth from the Moon’s rotation being almost entirely synced with its orbit around the Earth.

Here, Universe Today discusses this research with Dr. Gunes Karabulut Kurt, who is an associate professor at IEEE Polytechnique Montréal and the study’s co-author, regarding the motivation behind the study, significant results, follow-up research, and implications for WPT. So, what was the motivation behind this study?

“This research is motivated by the objective of overcoming the logistical and technical challenges associated with using traditional cables on the Moon’s surface,” Dr. Kurt tells Universe Today. “Laying cables on the Moon’s rough, dusty surface would lead to ongoing maintenance and wear problems, as lunar dust is highly abrasive. On the other hand, transporting large quantities of cables to the Moon requires a significant amount of fuel, which adds considerably to the mission’s costs.”

For the study, the researchers used a myriad of calculations and computer models to ascertain if one, two, or three satellites are sufficient within an EMLP-2 halo orbit to maintain both constant coverage of the lunar far side (LFS) and line of sight with the Earth. For context, EMLP-2 is located on the far side of the Moon with the halo orbit being perpendicular—or sideways—to the Moon’s orbit. The calculations involved in the study included the distances between each satellite, the antenna angles between the satellites and surface receiver, the amount of LFS surface coverage, and the amount of transmitted power between the satellites and LFS surface antennae. So, what were the most significant results from this study?

Dr. Kurt tells Universe Today their models concluded that three satellites in an EMLP-2 halo orbit and operating at equal distances from each other could “achieve continuous power beaming to a receiver optical antenna anywhere on the lunar far side” while maintaining 100 percent LFS coverage and line of sight with the Earth. “Aside triple satellite scheme that provides continuous LFS full coverage, even a two-satellite configuration provides full coverage during 88.60% of a full cycle around the EMLP-2 halo orbit,” Dr. Kurt adds.

Schematic from Figure 1 of the study displaying the wireless power transmission and receiver on the lunar far side with three satellites (SPS-1, SPS-2, and SPS-3) in a halo orbit at the Earth-Moon Lagrange Point 2. (Credit: Donmez & Kurt (2024))

Regarding follow-up research, Dr. Kurt tells Universe Today, “Our future studies will focus on more complex harvesting and transmission models to get closer to reality. On the other hand, an approach that takes into account the irregular nature of lunar dust and the variation in its density due to environmental factors such as subsolar angle and others. In the future, if research in this field continues, explore this experimentally with lunar dust simulants and lasers.”

This study comes as NASA is preparing to send astronauts to the Moon for the first time since 1972 with the Artemis program, whose goal will be to land the first woman and person of color on the lunar surface. With the success of the Artemis 1 mission in November 2022 that consisted of an uncrewed Orion capsule orbiting the Moon, NASA is currently targeting September 2025 for their Artemis 2 mission, which is scheduled to be a 10-day, 4-person crewed mission using the Orion capsule for a lunar flyby, whose goal will be to conduct a full systems checkout of the Orion capsule. Therefore, what implications can this study have for the upcoming Artemis missions, or any future human exploration of the Moon?

“The findings have implications for the design of energy transmission systems on the Moon,” Dr. Kurt tells Universe Today. “A better understanding of the wireless transmission disruptors such as lunar dust can lead to the development of more efficient and reliable systems for powering lunar missions and infrastructure, including those related to the Artemis program and future human exploration efforts.”

If successful, Artemis 2 will be followed by Artemis 3 in September 2026, which will also consist of a 4-person crew with two crew members landing on the lunar surface and an approximate mission duration of 30 days. This will be followed by Artemis 4, Artemis 5, and Artemis 6, which are currently scheduled for September 2028, September 2029, and September 2030, respectively, with each mission increasing in both the number of astronauts landing on the lunar surface along with anticipated deliveries of lunar habitat modules and lunar rovers, as well.

“Moreover, the Artemis mission is targeting the lunar south pole for its landing sites,” Dr. Kurt tells Universe Today. “This region is of particular interest due to the presence of peaks of eternal light (PELs), which receive almost continuous sunlight and permanently shadowed regions (PSRs), which are potential sites for resources such as water ice. These contrasting conditions are ideal for the application of wireless energy transmission (laser power beaming technology), which could provide a continuous power supply in shadowed areas by transmitting energy wirelessly from illuminated regions.”

The reason these PSRs exist is due to the Moon’s low obliquity, or axial tilt, which the study notes is 6.68 degrees. For context, the Earth’s obliquity is 23.44 degrees. This means there are areas, and specifically craters, at both the north and south poles on the Moon that do not receive any sunlight, hence the name “permanently shadowed regions”. As noted by Dr. Kurt, these PSRs could be home to deposits of water ice within these deep, dark craters that astronauts could use for water, fuel, and other needs.

The Artemis missions plan to deliver not only astronauts to the lunar surface, but a habitat and lunar rovers with the goal of establishing a permanent human presence on the Moon. This will provide opportunities for demonstrating new space technologies that can be used for both lunar exploration and future human missions to Mars, which are a part of NASA’s Moon to Mars Architecture.

“Current missions plan to re-use Earth-proven technology,” Dr. Kurt tells Universe Today. “This mindset may undermine the blue-sky design approach, where researchers are encouraged to think freely, explore creative ideas, and push the boundaries of what’s possible without being confined by constraints such as specific project requirements or backward compatibility. In our work we aim to include multi-functionality aspects, which are not a necessity for terrestrial applications but may turn out to be essential for future space missions.”

How will this wireless power transmission method help improve communication from the far side of the Moon to Earth in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

The post Wireless Power Transmission Could Enable Exploration of the Far Side of the Moon appeared first on Universe Today.

Millions of people took a trip over to the US or Mexico to try and catch a glimpse of the 2024 total solar eclipse. Whether you took the trip or not, if you have since been bitten by the eclipse bug then there are three upcoming eclipses over the next couple of years. August 2026 sees an eclipse passing from Greenland, Iceland and Spain, 2027 sees an eclipse over North Africa and in 2028 Australia all be the place to be. With loads of possibilities for all locations, it’s time to get planning. 

Many people across the World make attempts to witness solar eclipses, often travelling hundreds if not thousands of kilometres. I tried such a journey back in 1999 travelling from my home in Norfolk, UK to Cornwall, a journey of over 600 kilometres. Alas, and like many eclipse chasers before me, cloud thwarted my view. However, the experience of the daylight turning to dusk in a few seconds at the onset of totality, the birds singing as the ‘Sun came out again’, it was all such an incredible amazing experience. 

Since that cloudy experience in Cornwall I committed to one day, actually seeing a total solar eclipse. I have seen partials, and they are wonderful but nothing like the majesty of a total solar eclipse.

What are we talking about? Well, the Moon travels around the Earth and the Earth travels around the Sun. It’s these changing relative positions that lead to the lunar phases. When the Moon is broadly between the Sun and Earth we experience a new moon phase. You might therefore wonder why we don’t experience a total solar eclipse every new moon! The answer lies in the obits; the orbit of the Moon around Earth is tilted by about 5 degrees in reference to the Earth’s orbit around the Sun. During most new moons the Moon is slightly above or below the Sun when viewed from Earth. It’s only when the two orbits intersect at a new moon that we see a total solar eclipse. 

This is exactly what happened on 8 April 2024, a total solar eclipse became visible as the Moon silently passed directly between the Earth and Sun. When we get a perfect alignment of three celestial bodies like this its called a Syzygy, a wonderful word and great for a game of Scrabble. Totality for this eclipse lasted for about 4 minutes depending on the location of the observer. That’s the chief difference between a solar eclipse and a lunar eclipse. Lunar eclipses are visible anywhere on Earth that the Moon is visible but solar eclipses are only visible from very specific locations on Earth. 

Over the next few years there are some great opportunities to see total solar eclipses. Unless you are lucky, you will have to travel but the next opportunity takes place on 12 August 2026. You will need to be travelling to either Greenland, Iceland or Spain to catch this eclipse. Greenland and Iceland are the best option as Spain will only get the eclipse toward the end of the day. Next up is 2027 when an eclipse takes place on the 2 August visible from North Africa. After that, it’s 2028 but for southern hemisphere observers so its a trip to Australia. 

Wherever you venture to observe a total solar eclipse, it is imperative that you be careful when observing it. The ONLY time it is safe to observe a solar eclipse directly is during the moments of totality. As soon as the bright parts of the solar photosphere are visible, then direct observing is dangerous and will lead to damage to your eyes. If you are planning a trip to observe a total solar eclipse, be sure you are prepared and know exactly when and how you can observe it to ensure your eyesight remains safe. 

Source : Time and Date Eclipse Calendar

The post Here are the Next Three Total Solar Eclipses Coming Up appeared first on Universe Today.

It’s a measure of human ingenuity and curiosity that scientists debate the possibility of life on Venus. They established long ago that Venus’ surface is absolutely hostile to life. But didn’t scientists find a biomarker in the planet’s clouds? Could life exist there, never touching the planet’s sweltering surface?

It seems to depend on who you ask.

We’ll start with phosphine.

Phosphine is a biomarker, and in 2020, researchers reported the detection of phosphine in Venus’ atmosphere. There should be no phosphine because phosphorous should be oxidized in the planet’s atmosphere. According to the paper, no abiotic source could explain the quantity found, about 20 ppb.

Subsequently, the detection was challenged. When others tried to find it, they couldn’t. Also, the original paper’s authors informed everyone of an error in their data processing that could’ve affected the conclusions. Those authors examined the issue again and mostly stood by their original detection.

At this point, the phosphine issue seems unsettled. But if it is present in Venus’ atmosphere and is biological in nature, where could it be coming from? Venus’s surface is out of the question.

That leaves Venus’ cloud-filled atmosphere as the only abode of life. While the idea might seem ridiculous at first glance, researchers have dug into the idea and generated some interesting results.

In a new paper, researchers examine the idea of microscopic life that lives and reproduces in water droplets in Venus’s clouds. The title is “Necessary Conditions for Earthly Life Floating in the Venusian Atmosphere.” The lead author is Jennifer Abreu from the Department of Physics and Astronomy, Lehman College, City University of New York. The paper is currently in pre-print.

Spacecraft have struggled to contend with the harsh conditions on Venus’s surface. The Soviet Venera 13 lander captured this image of the planet’s surface in March of 1982. NASA/courtesy of nasaimages.org

“It has long been known that the surface of Venus is too harsh an environment for life,” the authors write. “Contrariwise, it has long been speculated that the clouds of Venus offer a favourable habitat for life but regulated to be domiciled at an essentially fixed altitude.” So, if life existed in the clouds, it wouldn’t be spread throughout. Only certain altitudes appear to have what’s needed for life to survive.

The type of life the authors envision aligns with other thinking about Venusian atmospheric life. “The archetype living thing <being> the spherical hydrogen gasbag isopycnic organism,” they state. (Isopycnic means constant density; the other terms are self-explanatory.)

Here’s how the authors think it could work.

Venus is shrouded in clouds so thick we can only see the surface with radar. The clouds reach all the way around the globe. The cloud base is about 47 km (29 miles) from the surface, where the temperature is about 100 C (212 F.) At equatorial and mid-latitudes, they extend up to a 74 km (46 miles) altitude, and at the poles, they extend up to about 65 km (40 miles.)

Cloud structure in the Venusian atmosphere in 2016, revealed by observations in two ultraviolet bands by the Japanese spacecraft Akatsuki. Image Credit: Kevin M. Gill

The clouds can be subdivided into three layers based on the size of aerosol particles: the upper layer from
56.5 to 70 km altitude, the middle layer from 50.5 to 56.5 km, and the lower layer from 47.5 to 50.5 km. The smallest droplets can float in all three layers. But the largest droplets, which the authors call type 3 droplets with a radius of 4 µm, are only present in the middle and lower layers.

“It has long been suspected that the cloud decks of Venus offer an aqueous habitat where microorganisms can grow and flourish,” the authors write. Everything life needs is there: “Carbon dioxide, sulfuric acid compounds, and ultraviolet (UV) light could give microbes food and energy.”

Because of temperature, life in Venus’ clouds would be restricted to a specific altitude range. At 50 km, the temperature is between 60 and 90 degrees Celsius (140 and 194 degrees Fahrenheit). The pressure at that altitude is about 1 Earth atmosphere.

This figure from the research shows the temperature and pressure throughout Venus’s atmosphere. Image Credit: Image Credit: S. Seager et al. 2021. doi:10.1089/ast.2020.2244

There’s a precedent for life existing in the clouds. It happens here on Earth, where scientists have observed bacteria, pollen, and even algae at altitudes as high as 15 km (9.3 miles.) There’s even evidence of bacteria growing in droplets in a super-cooled cloud high in the Alps. The understanding is that these organisms were carried aloft by wind, evaporation, eruptions, or even meteor impacts. But there’s an important difference between Earth’s and Venus’ clouds.

Earth’s clouds are transient. They form and dissolve constantly. But Venus’ clouds are long-lasting. They’re a stable environment compared to Earth’s clouds. In Earth’s clouds, aerosol particles are sustained for only a few days, while in Venus’ clouds, the particles can be sustained for much longer periods of time.

Add it all up, and you get stable cloud environments where aerosol particles can sustain themselves in an environment where energy and nutrients are available. The researchers say that though eventually aerosol particles and the life within them will fall to the surface, they have time to reproduce before that happens.

This image shows the cycle of Venusian aerial microbial life. Image Credit: S. Seager et al. 2021. doi:10.1089/ast.2020.2244

The idea of a microbial life cycle in Venusian clouds was developed by other researchers in their 2021 paper “The Venusian Lower Atmosphere Haze as a Depot for Desiccated Microbial Life: A Proposed Life Cycle for Persistence of the Venusian Aerial Biosphere.”

There are five steps in Venus’s proposed cloud lifecycle:

1. Dormant desiccated spores (black blobs) partially populate the lower haze layer of the atmosphere.
2. Updrafts transport them up to the habitable layer. The spores could travel up to the clouds via gravity waves.
3. Shortly after reaching the (middle and lower cloud) habitable layer, the spores act as cloud condensation nuclei, and more and more water gathers into a single droplet. Once the spores are surrounded by liquid with the necessary chemicals, they germinate and become metabolically active.
4. Metabolically active microbes (dashed blobs) grow and divide within liquid droplets (shown as solid circles in the figure). The liquid droplets continue to grow by coagulation.
5. Eventually, the droplets are large enough to settle out of the atmosphere gravitationally; higher temperatures and droplet evaporation trigger cell division and sporulation. The spores are smaller than the microbes and resist further downward sedimentation. They remain suspended in the lower haze layer (a depot of hibernating microbial life) to restart the cycle.

In this new work, the researchers focus on time.

“One of the key assumptions of the aerial life cycle put forward in Seager et al. 2021 is the timescale on which droplets would persist in the habitable layer to empower replication,” the authors write. “It is this that we now turn to study.”

This table from the research shows generation times for some common Earth bacteria. Image Credit: Abreu et al. 2024.

The authors used E. Coli generation times under optimal conditions in their work. In aerobic and nutrient-rich conditions, E. Coli can reproduce in 20 minutes. So, the E. Coli population will double three times in one hour. Bacteria must reproduce faster than they fall to the surface to sustain itself. They need to form a colony.

The researchers calculated that to sustain itself, the time it takes for bacteria to fall from the habitable part of the atmosphere to the inhabitable has to be longer than half an Earth day. As droplet size increases, the droplets would begin to sink. “As the droplet size approaches 100 µm, the droplets would start sinking to the lower haze layers,” they explain. However, their detailed calculations show that reproduction outpaces the fallout rate.

According to the team’s work, a population of bacteria could sustain itself in Venus’ clouds.

There are, obviously, still some questions. How certain are we that nutrients are available? Is there enough energy? Are there updrafts that can loft spores into the right layer of the atmosphere?

But the real big question is how was this all set in motion?

“An optimist might even imagine that the microbial life actually arose in a good-natured surface habitat, perhaps in a primitive ocean, before the planet suffered a runaway greenhouse, and the microbes lofted into the clouds,” the authors write. If that’s the case, this unique situation arose billions of years ago. Is there any other possibility? Could life have originated in the clouds?

Much scientific investigation into Venus, phosphine, clouds, and life relies on scant evidence. Few are willing to go out on a limb and proclaim that Venus can and does support life. We need more evidence.

For that, we have to wait for missions like the Venus Life Finder Mission. It’s a private mission being developed by Rocket Lab and a team from MIT. Who knows what VLF and other missions like DAVINCI and VERITAS will find? Stronger evidence of phosphine? Better data on Venus’ atmospheric layers and the conditions in them?

Life itself?

Artist’s impression of the Rocket Lab Mission to Venus. Credit: Rocket Lab

The post Could Life Exist in Water Droplet Worlds in Venus’ Atmosphere? appeared first on Universe Today.

Pink Floyd was wrong, there is no dark side to the Moon. There is however, a far side. The tidal effects between the Earth and Moon have caused this captured or synchronous rotation. The two sides display very different geographical features; the near side with mare and ancient volcanic flows while the far side displaying craters within craters. New research suggests the Moon has turned itself inside out with heavy elements like titanium returning to the surface. It’s now thought that a giant impact on the far side pushed titanium to the surface, creating a thinner more active near side. 

There have been a number of theories for the formation of the Moon; the capture theory and the accretion theory to name two of them. Perhaps the most accepted theory now is the giant impact theory which suggests Earth was struck by a large object, causing a lot of debris to be ejected into orbit. This material eventually coalesced to form the Moon we know and love today. 

In the decades that followed the Apollo missions, scientists studied the rocks returned by the astronauts. The studies revealed that many of the surface rocks contained unexpectedly high concentrations of titanium. More surprisingly was that satellite observations revealed these titanium rich minerals were far more common on the nearside and absent on the far-side. What is known is that the Moon formed fast and hot and would have been covered for a short period in an ocean of molten magma. The magma cooled and solidified forming the Moon’s crust but trapped below was the more dense material including titanium and iron. 

Sample collection on the surface of the Moon. Apollo 16 astronaut Charles M. Duke Jr. is shown collecting samples with the Lunar Roving Vehicle in the left background. Image: NASA

The dense material should have sunk to greater depths inside the Moon however over the years that followed something strange seems to have happened. The denser material did indeed sink, mixed with mantle but melted and returned to the surface as titanium rich lava flows. Debates have been raging whether this is exactly what happened but a new piece of research by a team at the University of Arizona Lunar and Planetary Laboratory offer more details about the process and how the interior of the Moon evolved.

It has already been suggested that the Moon may have suffered a giant impact on the far side causing the heavier elements to be forced over to the near side but the new study highlighted supporting evidence from gravitational anomalies. The team measured tiny variations in the Moon’s gravitational field from data from the GRAIL mission. GRAIL – or Gravity Recovery and Interior Laboratory – orbited the Moon to create the most accurate gravitational map of the Moon to date. Using GRAIL data the team discovered that titanium-iron oxide minerals had migrated to the near side and sunk to the interior in sheetlike cascades. This was consistent with models suggesting the event occurred more than 4.22 billion years ago. 

Global map of the Moon, as seen from the Clementine mission, showing the differences between the lunar near- and farside. Credit: NASA.

As paper co-author and LPL associate professor Jeff Andrews-Hanna said “The moon is fundamentally lopsided in every respect.” The near side feature known as Oceanus Procellarum is a great example. It is lower in elevation and has a lava flow covered thinner crust with high concentrations of titanium rich elements. This is very different on the far side. The strange and unique structure of the region is thought to be key in understanding the event that happened billions of years ago to shape the Moon we see today.

Source : How the Moon turned itself inside out

The post Finally, an Explanation for the Moon’s Radically Different Hemispheres appeared first on Universe Today.

There’s a lot we don’t know about the planet nearest to us. Venus is shrouded in clouds, making speculation about what’s happening on its surface a parlor game for many planetary scientists for decades. But one idea that always seems to come up in those conversations – volcanoes. It’s clear that Venus has plenty of volcanoes – estimates center around about 85,000 of them in total. However, science is still unclear as to whether there is any active volcanism on Venus or not. A new set of missions to the planet will hopefully shed some light on the topic – and a new paper from researchers from Europe looks at how we might use information from those missions to do so.

The authors break the question of whether there is active volcanism on Venus into two distinct approaches. First, can Venus maintain its current atmospheric composition without adding gases from volcanic sources? Second, is there any evidence for “transient” effects that would only be possible if active volcanoes existed? 

Let’s explore the first approach first. One major data point to consider with this approach is the variability of sulfur dioxide in the atmosphere over periods as long as decades. Some researchers have pointed to this variability as clear evidence of volcanism. Still, some take a more nuanced view and point out that the variability could be caused by unknown surface-atmosphere interactions or even interactions between two layers of the atmosphere itself.

Fraser has a particular interest in Venus – here’s why.

Transient effects in the atmosphere could include any number of features, ranging from water vapor to particulate matter (e.g., volcanic ash). So far, data collected on this has been limited and mainly done with remote sensing missions. However, at least a few of the new missions to Venus will involve taking data as they descend through the atmosphere. 

One of those – DAVINCI – plans to take measurements in situ in the atmosphere. It will come with a couple of spectrometers, inertial measurement units, and high-tech cameras to collect data in the planet’s lower atmosphere. The spectrometers themselves should be able to directly and clearly detect trace volcanic gases in the atmosphere. Ionic concentrations, such as the deuterium/hydrogen ratio, would also indicate ongoing volcanic outgassing.

But what about gases higher up in the atmosphere? EnVision, another mission, will specialize in that area of the planet using different types of near-IR and ultraviolet spectroscopy. It might help solve some mysteries in Venus’ cloud tops, including where an unknown reservoir of sulfur dioxide is located, as it seems to be a feedstock to an unknown process taking place in the clouds that defies current modeling efforts.

Venera was one of the previous efforts to map the surface of Venus. Fraser discusses its history here.

Though it is beyond the scope of the current paper, another potentially interesting sensor on a cloud-based platform would be an infrasound sensor – as it would be able to directly detect pressure differences caused by volcanic eruptions. Unfortunately, no current planned mission would maintain position in the atmosphere for long enough for such a sensor to do its work, though a few have been proposed in recent years.

There’s still going to be a long wait time before any of these analytical techniques can be put to good use. Of the three main missions heading to Venus shortly, the earliest – DAVINCI – isn’t planned to launch for at least another five years, with arrival at Venus a few years later. That’s plenty of time for theorists to fine-tune their ideas about what the mission might find. And hopefully, it will help us answer the question of volcanism on our closest neighbor once and for all.

Learn More:
Wilson et al. – Possible Effects of Volcanic Eruptions on the Modern Atmosphere of Venus
UT – Potentially Active Volcanoes Have Been Found on Venus
UT – We Now Have a Map of all 85,000 Volcanoes on Venus
UT – Volcanoes on Venus May Still Be Active

Lead Image:
Maat Mons Volcano on Venus
Credit – NASA / JPL

The post How Much of Venus’s Atmosphere is Coming from Volcanoes? appeared first on Universe Today.

In 2009, NASA launched the Lunar Reconnaissance Orbiter (LRO.) Its ongoing mission is to map the lunar surface in detail, locating potential landing sites, resources, and interesting features like lava tubes. The mission is an ongoing success, another showcase of NASA’s skill. It’s mapped about 98.2% of the lunar surface, excluding the deeply shadowed regions in the polar areas.

But recently, the LRO team’s skill was on display for another reason: it captured images of another satellite speeding over the lunar surface.

The Republic of Korea, or what most of us call South Korea, launched their Danuri lunar orbiter in August 2022. It’s the nation’s first lunar orbiter, and its mission is to develop and test technologies—including the space internet—and make a topographic map of the lunar surface. The map will help select future landing sites and identify resources such as uranium, helium-3, silicon, aluminum, and water ice. Danuri carries a suite of instruments, including a spectrometer, a magnetometer, and different cameras. Significantly, it contains a camera that will allow it to image the shadowed polar regions beyond the LRO’s capabilities.

A rendering of South Korea’s Danuri, Korean Pathfinder Lunar Orbiter (KPLO). Image Credit: Korean Aerospace Research Institute.

NASA contributed to the Korea Aerospace Research Institute’s (KARI) Danuri mission. NASA built the Shadowcam instrument that images the shadowed regions at the lunar poles.

As a sort of high-five to their fellow space-faring nation, the LRO captured images of Danuri as it sped by under the LRO.

On March 5th and 6th, the pair of orbiters sped by each other at a combined velocity of 11,500 km/h (7,200 mp/h). There were three orbits that put the LRO in a position to capture images of the swiftly moving Danuri. During each orbit, the vertical separation between the two was different.

The LRO was 5 km (3 miles) above Danuri in the first image. The LRO had to change its angle. To catch Danuri, it had to aim 43 degrees down from its usual angle.

Danuri looks like a streak in this LRO image taken 5 km above it. Image Credit: NASA/Goddard/Arizona State University

On the second orbit, only 4 km (2.5 miles) separated the pair of orbiters.

During the second orbit, the LRO captured this image of Danuri from only 4 km (2.5 miles) above it. The LRO was oriented 25 degrees toward the South Korean orbiter. Image Credit: NASA/Goddard/Arizona State University

On the third and final orbit, the separation between the two spacecraft was greater: 8 km (5 miles.) This time, the LRO was oriented at a 60-degree angle.

In the image on the right, the Danuri pixels are unsmeared. The LRO was 8 km (5 miles) above Danuri when it captured this image. The image is rotated 90 degrees to look like what a person would see if they onboard the LRO and looking out a window. Image Credit: NASA/Goddard/Arizona State University

Danuri is difficult to see in the final image.

NASA says Danuri is in the white box near the right-hand corner of the image. If you can see it, you should consider becoming a citizen scientist. For perspective, the crater above the white box is 12 km (7.5 miles) wide. Image Credit: NASA/Goddard/Arizona State University

This isn’t the first time the pair of orbiters have played the imaging game. Back in April 2023, it was Danuri’s turn to take a picture of the LRO. At the time, the Korean spacecraft passed about 18 km (11 miles) above the LRO and imaged it with its ShadowCam instrument.

Danuri captured this image of the LRO when the NASA satellite was 18 km (11 miles) below it. The combined velocity of both spacecraft was 11,000 km/h (7,000 mp/h.) Image Credit: NASA/KARI/Arizona State University

This isn’t the first time lunar orbiters have captured each other’s portraits. In 2014, the LRO captured NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) before it was sent to impact the lunar surface. Read about it here.

The post US Satellite Photographs a South Korean Satellite from Lunar Orbit appeared first on Universe Today.

On Monday, April 8th, people across North America witnessed a rare celestial event known as a total solar eclipse. This phenomenon occurs when the Moon passes between the Sun and Earth and blocks the face of the Sun for a short period. The eclipse plunged the sky into darkness for people living in the Canadian Maritimes, the American Eastern Seaboard, parts of the Midwest, and northern Mexico. Fortunately for all, geostationary satellites orbiting Earth captured images of the Moon’s shadow as it moved across North America.

One such satellite was the Geostationary Operational Environmental Satellite-16 (GOES-16), part of the Earth observation network jointly run by NASA and the National Oceanic and Atmospheric Administration (NOAA). The GOES-16 (GOES-East) satellite is the first of the series, regularly monitoring space weather and providing continuous imagery and atmospheric measurements of Earth’s western hemisphere. From its orbit at a distance of 36,000 km (~22,370 mi) from Earth, GOES-16 captured the passage of the eclipse across North America from approximately 10:00 A.M. to 05:00 P.M. EST (07:00 A.M. to 02:00 P.M. PST).

Solar eclipses take several forms, which include what many residents in North America witnessed yesterday (i.e., the Moon completely blocking the face of the Sun). There’s also an annual eclipse, which happens when the Moon passes between the Sun and Earth when it is at or near its farthest point from Earth. As a result, the face of the Sun is not completely obscured and is visible as a bright ring in the sky. There’s also a partial eclipse, which happens when the Sun, Moon, and Earth are not perfectly lined up, making the Sun appear crescent-shaped.

There’s also what is known as a hybrid solar eclipse, which can appear to shift between annular and total (due to Earth’s curvature) as the Moon’s shadow moves across the globe. A total eclipse, however, is the rarest of these events, where people located directly in the center of the Moon’s shadow will see only the Sun’s outer atmosphere (the corona). The next total eclipse is not expected to occur until August 12th, 2026, and will be visible to residents in Greenland, Iceland, Spain, Russia, and a small area of Portugal. For people in Europe, Africa, and North America, the same eclipse will appear as a partial one.

The passage of the Moon’s shadow across Earth’s surface is known as the “path of totality.” As the images show, this path spanned across the North American continent from Mexico to the eastern tip of Canada. Aside from GEOS-16, images were also taken by the European Space Agency’s (ESA) Copernicus Sentinel-3 mission using its Sea and Land Surface Temperature Radiometer (SLSTR). This satellite monitors Earth’s oceans, land, glaciers, and atmosphere to monitor and improve our understanding of global weather dynamics.

In addition to providing a rare glimpse at what a total eclipse looks like from space, the combined images are also an effective tool for researching how an eclipse influences Earth’s weather. As the Moon obscures light and heat from the Sun, air temperatures drop in the path of totality and can cause cloud formations to evolve in different ways. Data from GOES-16, Sentinel-3, and other Earth Observation satellites is now being used to explore these effects.

Further Reading: ESA

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