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In several billion years, our Sun will become a white dwarf. What will happen to Jupiter and Saturn when the Sun transitions to become a stellar remnant? Life could go on, though the giant planets will likely drift further away from the Sun.

Stars end their lives in different ways. Some meet their end as supernovae, cataclysmic explosions that destroy any orbiting planets and even sterilize planets light-years away. But only massive stars explode like that.

Our Sun is not massive enough to explode as a supernova. Instead, it’ll spend time as a red giant. The red giant phase occurs when a star runs out of hydrogen to feed fusion. It’s a complicated process that astronomers are still working hard to understand. But red giants shed layers of material into space that light up as planetary nebulae. Eventually, the red giant is no more, and only a tiny, yet extraordinarily dense, white dwarf resides in the middle of all the expelled material.

Researchers think that some white dwarfs have debris disks around them, out of which a new generation of planets can form. But researchers have also wondered if some planets can survive as stars transition from the main sequence to red giant to white dwarf.

Researchers at the Space Telescope Science Institute, Goddard Space Flight Center, and other institutions have found what seem to be two giant planets orbiting two white dwarfs in two different systems. Their research is titled “JWST Directly Images Giant Planet Candidates Around Two Metal-Polluted White Dwarf Stars,” and it’s in pre-print right now. The lead author is Susan Mullally, Deputy Project Scientist for JWST.

Theoretical thinking shows that exoplanets should exist around white dwarfs. Outer planets beyond where the asteroid belt is in our Solar System should survive their star’s transition from the main sequence to a red giant to a white dwarf. But stars inside this limit will be engulfed by the red giant as it expands. In our Solar System, the Sun will likely completely engulf or tidally disrupt and destroy Mercury, Venus, and Earth. Maybe even Mars.

Artist’s impression of a red giant star. As these stars lose mass, they expand and can envelop planets that are too close. Credit: NASA/ Walt Feimer

Planets that survive this will likely drift further from the star since the star loses mass and its gravity weakens during the red giant phase.

But the problem is that it’s difficult to detect planets around white dwarfs. Despite pointed efforts, astronomers have only found a few planetary-mass objects orbiting white dwarfs.

As it stands now, Mullally and her colleagues have found two candidate planets around white dwarfs. They’re about 11.5 and 34.5 AU from their stars, which are 5.3 billion and 1.6 billion years old. If the planets are as old as the stars, then MIRI photometry shows that the planets are between 1 to 7 Jupiter masses. They could be false positives, but there’s only a 1 in 3,000 chance that that’s the case.

“If confirmed, these would be the first directly imaged planets that are similar in both age and separation
to the giant planets in our own solar system, and they would demonstrate that widely separated giant
planets like Jupiter survive stellar evolution,” the authors write.

If the researchers are correct, and the planets formed at the same time as the stars, this is an important leap in our understanding of exoplanets and the stars they orbit. It may also have implications for life on any moons that might be orbiting these planets.

But this discovery relates to another issue with white dwarfs: white dwarf metallicity.

Some white dwarfs appear to be polluted with metals, elements heavier than hydrogen and helium. Astronomers think that these metals come from asteroids in the asteroid belt, perturbed and sent into the white dwarf by giant planets. “Confirmation of these two planet candidates with future MIRI imaging would provide evidence that directly links giant planets to metal pollution in white dwarf stars,” the authors write.

Astronomers have found that up to 50% of isolated white dwarfs with hydrogen atmospheres have metals in their photospheres, the stars’ surface layer. These white dwarfs must be actively accreting metals from their surroundings. The favoured source for these metals is asteroids and comets.

“In this scenario, planets that survive the red-giant phase occasionally perturb the orbits of asteroids and comets, which then fall in towards the WD,” the authors write.

This artist’s illustration shows rocky debris being drawn toward a white dwarf. Astronomers think that giant planets perturb smaller objects like asteroids and comets inside the WD’s Roche limit. They’re destroyed, and the debris is drawn onto the star’s surface. Image Credit: NASA, ESA, Joseph Olmsted (STScI)

Astronomers have struggled to find planets around WDs. The main methods of finding planets aren’t very effective around white dwarfs. The transit method used by Kepler and TESS is ineffective because WDs are so tiny and dim. The other method is the radial velocity method. It senses how a star wobbles due to a planet’s influence. It measures the change in the star’s spectrum due to the wobbling. However, WDs have nearly featureless spectra, making radial changes difficult to detect.

But now we have the JWST.

“JWST’s infrared capabilities offer a unique opportunity to directly image Jupiter-mass planets orbiting
nearby WDs,” the researchers write in their paper.

The JWST is powerful enough to directly image large planets around tiny stars without using a coronagraph, as long as the planets are far enough away from the star. “Taking advantage of JWST’s superb resolution, it is possible to directly image a planet at only a few au from nearby WDs without the use of a coronagraph,” Mullally and her colleagues explain.

Part of the effort in this work is identifying point sources. In astronomy, a point source is a single, identifiable source of light. Its opposite is a resolved source or an extended source. The researchers had to be confident that what they’re seeing around the white dwarfs are point sources, which are mostly likely planets in this case. “We expect these to appear as point sources that increase in brightness at longer wavelengths,” they write.

To determine if what they’re seeing are point sources, astronomers use a process called reference differential imaging. It’s a complex procedure, but basically, it involves subtracting the sources from the images. It’s especially effective at finding planets close to stars.

This figure from the research explains some of the findings. Each row is a separate white dwarf and planet candidate. In the top row, the large object in the north is a background galaxy unrelated to the research. The researchers went through a process of subtracting and then adding back in both the stars and the giant planet candidates. Image Credit: Mullally et al. 2024.

The figure above shows how the team worked with the images, subtracting both the white dwarf and the candidate planets and identifying the planets as point sources. “In both cases, the candidate is removed cleanly, indicating it is point-source in nature,” the authors write. The researchers examined four separate white dwarfs and only two of them have candidate exoplanets.

“If confirmed, these two planet candidates provide concrete observational evidence that outer giant planets like Jupiter survive the evolution of low-mass stars,” the authors write. Confirmation would also support the idea that 25%-50% of white dwarfs host large planets. That’s a big step forward in understanding.

But these results unfortunately can’t answer another question: are large planets responsible for sending debris onto the surface of white dwarfs? “The confirmation of these planets are not, however, sufficient to fully validate that large-mass giant planets are the driver of accretion without further observations,” writes Mullally and her co-authors.

An answer to that question can only come from observing more white dwarfs, especially with the JWST. Hopefully, we won’t have to wait long.

The post Webb Directly Images Two Planets Orbiting White Dwarfs appeared first on Universe Today.

NGC 4753 is a prime example of what happens after a galactic merger. It looks like a twisted mess, with dust lanes looping around the massive galactic nucleus. Astronomers long wondered what happened to this galaxy, and with a sharp new image created by the Gemini South telescope, they can finally explain its tortured past.

Officially, NGC 4753 is classified as a “peculiar” galaxy due to its odd appearance. But, like other survivors of galactic mergers and acquisitions, it has probably had several “shapes” throughout its history. Most galaxies are classified as spirals, ellipticals, lenticulars, and irregulars. For this one, astronomers suspect it was formerly a lenticular with a substantial disk and not much in the way of spiral arms. Then, more than a billion years ago, it encountered a neighboring dwarf galaxy and they tangled together. A team led by astronomer Tom Steiman-Cameron at Indian University studied this galaxy in great detail to understand how it got the way it is today. “Galaxies that gobble up another galaxy often look like train wrecks,” he said, ”and this is a train-wreck galaxy.”

NGC 4753 lies in the Virgo Cluster of galaxies, at a distance of about 60 million light-years. It lies within its own smaller galactic collective, called the NGC 4753 group. The galaxy itself appears to have a dark matter shell, and about a thousand globular clusters orbiting its core. Its peculiar dust lanes first caught astronomers’ attention in the 20th Century, although the galaxy itself was discovered by William Herschel in 1784.

Galactic Mergers and Acquisitions

Galaxies have merged throughout the history of the Universe. In the beginning, small shreds of galaxies mixed with their neighbors to form larger ones. That process continued, creating the amazing diversity of galactic forms we see today. When galaxies meet like this, they mingle their stars and material. Gravitational forces sculpt the galaxies, and shock waves induce waves of star birth. This makes galaxies very dynamic objects, changing over time as they meet and mingle with their neighbors.

An HST image of the interacting galaxies in IC 1623. They are plunging headlong into one another in a process known as a galactic merger. That ignited a frenzied spate of star formation known as a starburst, creating new stars at a rate more than twenty times that of the Milky Way galaxy.

We see this process playing out across the Universe. Our own Milky Way Galaxy is the result of numerous galactic mergers since it began to form about 13 billion years ago. Each collision brought infusions of new stars and interstellar gas and dust and changed our galaxy’s appearance. Today, the Milky Way is a barred spiral shape, but it began as an indistinct lump of stars, gas, and dust in the early Universe. It continues its merger history in modern times. Astronomers are tracking the action as our galaxy gobbles up several smaller galaxies, including the Sagittarius Dwarf. In addition, the Milky Way and Andromeda galaxies will merge in about five billion years. That process will radically alter their shapes, too, resulting in a vast galaxy known as Milkdromeda.

View of Milkdromeda from Earth “shortly” after the galactic merger of the Milky Way and Andromeda, around 3.85-3.9 billion years from now Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger A Tale of NGC 4753’s Galactic Merger

When NGC 4753 began its cosmic dance, it tangoed with a gas-rich dwarf galaxy. Bursts of star formation triggered by the collision (and influx of gas) injected huge amounts of dust into the region. The galaxy followed a spiraling path into the collision, and that smeared out the dust into the disk. Ultimately, the activity gave the galaxy its peculiar look. “For a long time nobody knew what to make of this peculiar galaxy,” said Steiman-Cameron. “But by starting with the idea of accreted material smeared out into a disk, and then analyzing the three-dimensional geometry, the mystery was solved. It’s now incredibly exciting to see this highly-detailed image by Gemini South 30 years later.”

Steiman-Cameron and his team explain the galaxy’s peculiarity with a phenomenon known as “differential precession”. Precession occurs when a rotating object’s axis of rotation changes orientation, like a spinning top. Differential means that the rate of precession varies depending on the radius. For the dusty accretion disk orbiting the galactic nucleus in this collision, the rate of precession is faster toward the center and slower near the edges. This galactic wobble-like motion results from the angle at which NGC 4753 and its former dwarf companion collided. That resulted in the strongly twisted dust lanes threading through this galaxy.

Implications for Other Peculiar Galaxies

Interestingly, although this galaxy certainly looks weird enough in the Gemini image, it’s all a matter of viewing perspective. We’re looking at it from an edge-on view. That’s how we can spot the dust lanes and other features in the disk.

A model of NGC 4753 as seen from various viewing orientations. From left to right and top to bottom, the angle of the line of sight to the galaxy’s equatorial plane ranges from 10° to 90° in steps of 10°. Although galaxies similar to NGC 4753 may not be rare, only certain viewing orientations allow for easy identification of a highly twisted disk. This infographic is a recreation of Figure 7 from a 1992 research paper.

But, if we could get in a spaceship and fly directly “north” of NGC 4753 to get a “top-down” view, it would look pretty much like a standard spiral galaxy. Now that astronomers know about its galactic merger history, they can do further studies to understand its stellar populations and interactions of those bizarre dust lanes. And, its history may go a long way toward explaining the appearances of other “peculiar” galaxies in the Universe.

For More Information

Gemini South Captures Twisted Dusty Disk of NGC 4753, Showcasing the Aftermath of Past Merger
The Remarkable Twisted Disk of NGC 4753 and the Shapes of Galactic Halos

The post The Aftermath of a Recent Galactic Merger appeared first on Universe Today.

If you’re fascinated by Nature, these images of spiral galaxies won’t help you escape your fascination.

These images show incredible detail in 19 spirals, imaged face-on by the JWST. The galactic arms with their multitudes of stars are lit up in infrared light, as are the dense galactic cores, where supermassive black holes reside.

The JWST captured these images as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) programme. PHANGS is a long-running program aimed at understanding how gas and star formation interact with galactic structure and evolution. One of Webb’s four primary science goals is to study how galaxies form and evolve, and the PHANGS program feeds that effort. The VLT, ALMA, the Hubble, and now the JWST have all contributed to it.

But Webb’s images are the juiciest.

“Webb’s new images are extraordinary. They’re mind-blowing even for researchers who have studied these same galaxies for decades.”

Janice Lee, Project Scientists, Space Telescope Science Institute.

The JWST can see in both near-infrared (NIR) and mid-infrared (MIR) light. That means it reveals different details, and more details, than even the powerful Hubble Space Telescope, which operates in visible light, UV light, and a small portion of infrared light.

This is NGC 4254 (Messier 99), a spiral galaxy about 50 million light-years away. It has a peculiarity to it, as one spiral arm is normal looking, and one is extended and less tightly wound. Though not a starburst galaxy, it forms stars three times as fast as other similar galaxies. This rapid star formation rate may have been triggered by interaction with another galaxy about 280 million years ago. With the JWST’s help, the PHANGS program will help astronomers understand NGC 4254’s history. Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team

In these JWST high-resolution images, the red colour is gas and dust emitting infrared light, which the JWST excels at seeing. Some of the images have bright diffraction spikes in the galactic center, which are caused by an enormous amount of light. That can indicate that a supermassive black hole is active, or it could be from an extremely high concentration of stars.

“That’s a clear sign that there may be an active supermassive black hole,” said Eva Schinnerer, a staff scientist at the Max Planck Institute for Astronomy in Heidelberg, Germany. “Or, the star clusters toward the center are so bright that they have saturated that area of the image.”

The diffraction spike in the center of NGC 1365 is a telescope artifact caused by an enormous amount of light in a compact region. It’s caused by either the active supermassive black hole or tightly grouped stars in the galactic centre. NGC 1365 is a double-barred spiral galaxy about 74 million light-years away. Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team

Stars near a galaxy’s center are typically much older than stars in the arms. The further a star is from the galactic center, the younger it typically is. The younger stars appear blue and have blown away the cocoon of gas and dust that they spawned in.

This is NGC 2835, a spiral galaxy about 35 million light-years away that has four or five spiral arms. Blue dots are very young stars that have blown away nearby gas and dust with their powerful UV light. Orange/red clumps are where even younger stars reside. They’re still surrounded by gas and dust. Several background galaxies are visible in the image. Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team

Orange clumps indicate even younger stars. They’re still wrapped in their blanket of gas and dust and are still actively accreting material and forming. “These are where we can find the newest, most massive stars in the galaxies,” said Erik Rosolowsky, a professor of physics at the University of Alberta in Edmonton, Canada.

The new images were released alongside some of the Hubble’s views of the same galaxies. These highlight how observing different wavelengths of light reveals or obscures different details in the galaxies. In the PHANGS observing program, different telescopes have observed galaxies in visible light, infrared light, UV light, and radio.

A Hubble Space Telescope image of NGC 628 (left) and the same galaxy as imaged by the JWST (right.) Both images are grand and inspiring and full of information, but the JWST image provides more detail. Large bubble-shaped gaps between concentrations of gas and dust are visible. In some of the images, those could be caused by supernovae. Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team

Since the human eye can’t see infrared, different visible colours are assigned to different wavelengths of light in order to make the images meaningful. In the JWST image of NGC 628 above, the galaxy’s center is filled with old stars that emit some of the shortest wavelengths of light the telescope can detect. They’ve been given a blue colour to make them visible. In the Hubble image, the same region is more yellow and washed out. The region emits the longest wavelengths of light that the Hubble can sense, so it has different colour assignments than the JWST.

Janice Lee is a project scientist at the Space Telescope Science Institute in Baltimore. She spoke for all of us when she said, “Webb’s new images are extraordinary. They’re mind-blowing even for researchers who have studied these same galaxies for decades. Bubbles and filaments are resolved down to the smallest scales ever observed and tell a story about the star formation cycle.”

This is NGC 1672, a spiral galaxy about 60 million light-years away. It may be a type II Seyfert galaxy, though astronomers aren’t totally certain. It has both a bright nucleus and a surrounding starburst region. Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), PHANGS Team

These galaxies are all spiral galaxies like the Milky Way, meaning their massive arms define them. The spiral arms are more like waves that travel through space rather than individual stars moving collectively. Astronomers study the arms because they can provide key insights into how galaxies build, maintain, and shut off star formation. “These structures tend to follow the same pattern in certain parts of the galaxies,” Rosolowsky added. “We think of these like waves, and their spacing tells us a lot about how a galaxy distributes its gas and dust.”

The spiral galaxy NGC 1566 is about 60 million light-years away in the constellation Dorado. NGC is interacting with smaller member galaxies in its neighbourhood. It’s an active galaxy, meaning its nucleus emits a lot of light that doesn’t come from stars. Instead, it probably comes from the supermassive black hole at the center. NGC 1566 is extensively studied due to its proximity, orientation, its strong spiral arms and its active galactic nucleus. Image Credit: NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

Ever since it began science operations, the JWST has given astronomers an overwhelming flow of data that will fuel research for years and decades to come. These beautiful images are just a part of a larger data release that includes a catalogue of about 100,000 star clusters. “The amount of analysis that can be done with these images is vastly larger than anything our team could possibly handle,” said the University of Alberta’s Erik Rosolowsky. “We’re excited to support the community so all researchers can contribute.”

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Within the next fifteen years, NASA, China, and SpaceX plan to send the first crewed missions to Mars. In all three cases, these missions are meant to culminate in the creation of surface habitats that will allow for many returns and – quite possibly – permanent human settlements. This presents numerous challenges, one of the greatest of which is the need for plenty of breathable air and propellant. Both can be manufactured through electrolysis, where electromagnetic fields are applied to water (H2O) to create oxygen gas (O2) and liquid hydrogen (LH2).

While Mars has ample deposits of water ice on its surface that make this feasible, existing technological solutions fall short of the reliability and efficiency levels required for space exploration. Fortunately, a team of researchers from Georgia Tech has proposed a “Magnetohydrodynamic Drive for Hydrogen and Oxygen Production in Mars Transfer” that combines multiple functionalities into a system with no moving parts. This system could revolutionize spacecraft propulsion and was selected by NASA’s Innovative Advanced Concepts (NIAC) program for Phase I development.

The proposal comes from Alvaro Romero-Calvo, an assistant professor at the Georgia Institute of Technology, and his colleagues from the Georgia Tech Research Corporation (GTRC). The system employs a magnetohydrodynamic (MHD) electrolytic cell, which relies on electromagnetic fields to accelerate electrically conductive fluid (in this case, water) without any moving parts. This allows the system to extract and separate oxygen and hydrogen gas in microgravity, removing the need for forced water recirculation and the associated equipment (i.e., pumps or centrifuges).

As a specialist in low-gravity science, fluid mechanics, and magnetohydrodynamics, Romero-Calvo and his team have spent many years investigating the applications of MHD systems for spaceflight. The need for a dedicated study to assess the concept’s feasibility and integration into a suitable oxygen production architecture ultimately motivated their proposal. In a previous study, Romero-Calvo and co-author Dr. Katharina Brinkert (a professor of Chemistry at the University of Warwick) noted how water harvested in situ would reduce vehicle launch masses.

However, they also noted that operating this kind of machinery in microgravity presented many unknowns, most of which are not addressed by current research. In particular, they stressed how the absence of buoyancy in microgravity results in major technical challenges, like the need to detach and collect oxygen and hydrogen bubbles, which was traditionally addressed using forced water recirculation loops. However, they argued, this leads to liquid management devices composed of multiple elements and moving parts, which are complex, inefficient, and unreliable in space. As Romero-Calvo explained in a recent Georgia Tech news release:

“The idea of using MHD forces for liquid pumping is explored in the 1990 thriller The Hunt for Red October, where a stealth soviet submarine powered by an MHD drive defects to the United States. Although it’s fun to see Sean Connery playing the role of a Soviet submarine commander, the truth is that submarine MHD propulsion is very inefficient. Our concept, on the contrary, works in the microgravity environment, where the weak MHD force becomes dominant and can lead to mission-enabling capabilities.”

Instead of traditional recirculation loops, the proposed MHD system relies on two distinct mechanisms to separate oxygen and hydrogen from water. The first comes from diamagnetic forces, which arise in the presence of strong magnetic fields and result in a magnetic buoyancy effect. Second, there are Lorentz forces, which are a consequence of the imposition of a magnetic field on the current generated between two electrodes. As Romero-Calvo noted in their proposal paper:

“Both approaches can potentially lead to a new generation of electrolytic cells with minimum or no moving parts, hence enabling human deep space operations with minimum mass and power penalties. Preliminary estimations indicate that the integration of functionalities leads to up to 50% mass budget reductions with respect to the Oxygen Generation Assembly architecture for a 99% reliability level. These values apply to a standard four-crew Mars transfer with 3.36 kg oxygen consumption per day.”

Two CubeSats communicated and then maneuvered toward one another in a recent technology demonstration. Credit: NASA

If successful, this HMD system would enable the recycling of water and oxygen gas in long-term space travel. Romero-Calvo and other colleagues at the Daniel Guggenheim School of Aerospace Engineering at Georgia Tech demonstrated in another paper that this technology could also have applications for water-based SmallSat propulsion and other mission profiles where ISRU is a must. At present, Romero-Calvo and his colleagues have formulated the concept and have developed analytical and numeral models.

The next step will involve the team and their partners at Giner Labs (a Massachusetts-based electrochemical R&D firm) conducting feasibility studies. Over the next nine months, they will receive $175,000 to explore the system’s overall viability and technology readiness level. These will consist primarily of computational studies but will include prototypes testing key technologies here on Earth. As a Phase I proposal, they will also be eligible to compete for Phase II funding worth $600,000 for a two-year study.

An early demonstrator of this technology was tested aboard the 24th flight of the New Sheperd (NS-24), an uncrewed mission that launched on December 19th, 2023. With support from Blue Origin and the American Society for Gravitation and Space Research (ASGSR), Romero-Calvo’s team tested how magnets electrolyzer water in microgravity conditions. The data from this flight and the forthcoming tests will inform an HMD electrolyzer prototype and could lead to a system integrated aboard future space missions. Said Romero-Calvo:

“We were studying the fundamental magnetohydrodynamic flow regimes that arise when we apply a magnetic field to water electrolyzers in spaceflight conditions,” Romero-Calvo explained. “The Blue Origin experiment, in combination with our current collaboration with Prof. Katharina Brinkert’s group at the University of Warwick, will help us predict the movement of oxygen bubbles in microgravity and it hints at how we can build a future water electrolyzer for humans.”

Further Reading: NASA, Georgia Tech

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The number of near misses, false starts, and legitimate disasters that have befallen our species since the day we took our first upright steps all those generations ago is too large to count and could honestly take up this entire book. I’ll give us humans this much, though: we’re survivors, through and through.

We are, to put it bluntly, remarkable. There is nothing in this cosmos that even begins to approach anything resembling the complexity of the human brain. There is no other world that we have discovered, within our solar system or without, that can support the dizzying array of chemical reactions that we call life, let alone consciousness.

Sure, with enough planets around enough stars within enough galaxies, life is probably bound to happen one way or another, but it appears that life only happened here, once, billions of years ago, when it didn’t appear – or was snuffed out – even in our own solar backyard.

Even our planet is special. Take a look at the other planets of the solar system. If doesn’t matter if you’re using a backyard telescope or the latest NASA robotic gear, the answer is always the same. While every planet looks and acts (and probably smells) different from all the rest, they all share one thing in common: they’re dead.

Lifeless. Uninhabitable. Inhospitable. Barren balls of cold rock. Barren balls of molten rock. Barren balls of exceedingly hot rock buried under thick layers of atmosphere. Barren.

There are a million tales that the universe has been spinning for over 13 billion years to make life possible. Life could not have arisen too early in our cosmological history, for there was not yet enough generations of stars born and dead to spread their ash, their byproduct of oxygen and carbon, into the wider galactic mix. And, alas, there will come a time in the distant future, trillions of years from now but yet countable with finite numbers, when the universe will be too old, too cold, and too exhausted to fashion new stars at all.

Life as we know it was given only a narrow window of possibility in time, dictated by the cold laws of physics and the chance byproduct of the great machinations foreign, alien, and unthinking that churn in our universe, each one stretching so achingly slowly for millions, if not billions, of years. Each one governed by forces both comprehensible and mysterious, each one leading to the lucky chance of an Earth.

Some argue that the way the universe is constructed is a little too particular. That if any one small thing were to change, from the speed of light to the amount of atomic matter assembled during the big bang, life as we know it would be outright impossible. Perhaps some other form of intelligence could rise up in that strange cosmos, shuddering at the impossible thought of creatures anchored to a planet and swimming in its water oceans. Perhaps not. Either way, it appears that our universe is especially tuned for the appearance of life as we know it, indicating either divine intervention or some conspiracy of physics too far beyond our comprehension to grasp.

To that line of thinking I have this response. We have but one universe for us to study; it is all we’ve had and all that ever will be. As peculiar as this universe of ours appears, we cannot access or interrogate other possibilities. We do not know how special or generic this cosmos is, the same way you could not measure the probability of the Queen of Diamonds appearing in your hand if you did not know the contents of the full deck. That stark reality does not rule out divinity or exotic physics, but it also does not demand them. If you wish to believe in either of those, I will not begrudge you.

No matter how you count the probabilities and odds and chance encounters, here we are, alive and abundant on some planet whose name is given only by ourselves, for there’s no one else to speak of it, the glimmer of thinking, watchful eyes looking out into the void and daring to call it home.

The post The Seeming Impossibility of Life appeared first on Universe Today.

A recent study published in The Astrophysucal Journal Letters discusses the detection of water within the atmosphere of GJ 9827 d, which is a Neptune-like exoplanet located approximately 97 light-years from Earth, using NASA’s Hubble Space Telescope (HST), and is the smallest exoplanet to date where water has been detected in its atmosphere. This study was conducted by an international team of researchers and holds the potential to identify exoplanets throughout the Milky Way Galaxy which possess water within their atmospheres, along with highlighting the most accurate methods to identify the water, as well.

For the study, the researchers analyzed data using Hubble’s Wide Field Camera 3 (WFC3), which is a fourth-generation ultraviolet imaging spectrograph (UVIS)/Infrared (IR) imager that replaced the Wide Field Planetary Camera 2 during Servicing Mission 4, which was conducted by STS-125 in May 2009 and was the fifth and final servicing mission for Hubble. The researchers used WFC3 to observe 11 transits of GJ 9827 d, which orbits its star in 6.2 days, over a period of three years and identified what they hypothesize to be water within the exoplanet’s atmosphere. While the team stops short at confirming the existence of water, they eliminated the likelihood that the results were from starspots after analyzing data from NASA’s Kepler/K2 mission.

Image of NASA’s Hubble Space Telescope, which is about the size of a school bus, obtained by the STS-125 crew on May 19, 2009, after completion of Servicing Mission 4. (Credit: NASA)

“This would be the first time that we can directly show through an atmospheric detection that these planets with water-rich atmospheres can actually exist around other stars,” said Dr. Björn Benneke, who is an Associate Professor and the Head of the Astronomy Group within the Department of Physics at Université de Montréal and lead author of the study. “This is an important step toward determining the prevalence and diversity of atmospheres on rocky planets.”

While the team does not definitively confirm the existence of water within GJ 9827 d’s atmosphere, they do have a series of competing hypotheses pertaining to how and why water could exist: the atmosphere is rich in hydrogen like most gaseous planets but with traces of water, which the team was fortunate enough to detect; or GJ 9827 d is a rocky planet surrounded by a water vapor envelope. However, the team notes that recent studies of GJ 9827 d have suggested it could lose more than half of its atmosphere over the course of one billion years, meaning GJ 9827 d isn’t likely to possess an atmosphere dominated by hydrogen.

“The planet GJ 9827 d could be half water, half rock. And there would be a lot of water vapor on top of some smaller rocky body,” said Dr. Benneke.

GJ 9827 d’s temperature is estimated to be approximately 425 degrees Celsius (800 degrees Fahrenheit), or about as hot as the surface of Venus. Therefore, the water vapors the astronomers have potentially detected could be steam resulting from the parent star’s intense heat. Either GJ 9827 d is a rocky exoplanet with a watery envelope currently being boiled off, or the same could be happening to its all-gaseous atmosphere, as well. Discovered using the transit method in 2017 by NASA’s Kepler/K2 mission, GJ 9827 d’s radius is approximately 3.5 times larger than the Earth and slightly over twice the mass, possibly further strengthening the argument that it’s a rocky exoplanet, but that has yet to be confirmed.

Artist’s impression of GJ 9827 d, which is the smallest exoplanet ever found to potentially possess water in its atmosphere. (Credit: NASA, ESA, Leah Hustak and Ralf Crawford (STScI))

The researchers note that GJ 9827 d could be a future observational target by NASA’s James Webb Space Telescope (JWST), as JWST has conducted atmospheric observations on a myriad of exoplanets, including WASP-80 b, WASP-39 b, and K2-18 b, just to name a few.

What new discoveries will astronomers make about GJ 9827 d and other watery exoplanets in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

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The science of studying gravitational waves just got a big boost thanks to the European Space Agency. Its science program committee just approved the Laser Interferometer Space Antenna—affectionately known as LISA—for official planning and building. That means gravitational wave astronomers will take their next steps to capture information about gravity waves from space.

LISA—or something like it—has been on the drawing boards since the 1980s. The current LISA observatory was proposed about a decade later and scientists flew a “pathfinder mission” to test out its principal design. Now, it’s going to be a full-fledged set of three spacecraft set to launch in 2035 and should revolutionize gravitational wave studies.

This graphic shows how LISA will work. Courtesy ESA.

The spacecraft constellation will maneuver into three separate positions in an Earth-like heliocentric orbit. Essentially, they’ll form a triangle, joined together by laser beams that will each shoot across 2.5 million kilometers of space. Those beams will be the prime gravitational wave detectors. When a wave passes by, it will change the length of each laser “arm”. Sophisticated instruments onboard will record the changes and send that data back to Earth for analysis. The differential changes in the length of each arm will tell scientists crucial information about the objects that collided to create the waves. If all goes well, LISA will become the first space-based observatory dedicated solely to these ripples in the fabric of spacetime.

The Next Steps

The decision to forge ahead with LISA is a formal step called “adoption”. It basically says that the technology for the mission and the concept and timeline are good to go. That allows the agency to go ahead with building the spacecraft and its instrumentation. From this point, the agency is now free to solicit and select contractors for fabrication. The design and assembly process could begin as early as January 2025.

LISA’s development won’t be easy, according to lead project scientist Nora Lützgendorf. “LISA is an endeavor that has never been tried before,” she said. “Using laser beams over distances of several kilometers, ground-based instrumentation can detect gravitational waves coming from events involving star-sized objects – such as supernova explosions or merging of hyper-dense stars and stellar-mass black holes. To expand the frontier of gravitational studies we must go to space. Thanks to the huge distance traveled by the laser signals on LISA, and the superb stability of its instrumentation, we will probe gravitational waves of lower frequencies than is possible on Earth, uncovering events of a different scale, all the way back to the dawn of time.”

Protecting LISA from Outside Influences in Space

Of course, space presents unique challenges to the spacecraft’s mission. In that regard, LISA faces some similar types of issues that LIGO and others meet on the ground. For example, the ground rumbles from heavy trucks driving by disturb the LIGO instruments. That means its scientists have to filter out any non-gravitational-wave disturbances.

There aren’t trucks in space, thankfully, but LISA will face some non-gravitational-wave forces such as light pressure and the solar wind. Scientists will get around those with some very clever spacecraft designs. Each of the three craft will be equipped with telescopes, lasers, and test masses made of gold-coated gold and platinum.

To protect the test masses from outside influences (which can “push around” the masses), they will float freely inside the spacecraft. The outer hulls of the craft will absorb the outside influences. Thrusters will adjust the spacecraft in position and keep the masses from experiencing anything except the target gravitational waves. The result should be a very “clean” capture of gravitational wave data from distant objects and events in the Universe.

LISA’s Gravitational Wave Targets

This intricate mission should be able to capture the ripples in spacetime produced when massive objects collide. That includes the mergers of supermassive black holes at the hearts of galaxies. In our own galaxy, LISA should be able to detect the mergers of white dwarfs or neutron stars. Its data should give astronomers precise information about the distances to these events and even their locations.

Sources of gravitational waves in the Universe that LISA will detect. Courtesy ESA.

“For centuries we have been studying our cosmos through capturing light. Coupling this with the detection of gravitational waves is bringing a totally new dimension to our perception of the Universe,” said LISA project scientist Oliver Jennrich. “If we imagine that, so far, with our astrophysics missions, we have been watching the cosmos like a silent movie, capturing the ripples of spacetime with LISA will be a real game-changer, like when sound was added to motion pictures.”

One very exciting possibility that LISA could enable is the detection of the very first seconds after the Big Bang occurred. That’s because gravitational waves from that seminal event will carry distance and intensity information. Not only that, but LISA data will also help astronomers measure the expansion rate of the Universe throughout time. If all this comes to pass, it will prove the usefulness of gravitational waves as a unique way of measuring things in the cosmos.

For More Information

Capturing the Ripples of Spacetime: LISA Gets Go-ahead
LISA Consortium

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The search for life on alien worlds has captivated us for hundreds of years. In some respect, the search for life has expanded to the search for water since it is not unreasonable to assume if there is water then there is a good chance there is life too. When NASA selected the landing site for Perseverance, they were looking for such a body of water and settled upon the Jezero Crater. Images from orbiters reveal a crater that looks like it has been filled with water in the past but further investigations were needed to confirm. Now it seems, Perseverance has risen to the challenge. 

Perseverance is a car sized rover that arrived on Mars on 18 February 2021 and carried with it the innovative Ingenuity helicopter, the first powered aircraft on another world. The main objective of the mission was to identify ancient Martian environments capable of supporting life and if possible, finding evidence of ancient microbial life through collecting rock and soil samples. Since its arrival in 2021, the rover has been travelling around the 50km wide crater studying the geology and atmosphere as it goes. 

Mars Perseverence rover sent back this image of its parking spot during Mars Solar Conjunction. Courtesy NASA/JPL-Caltech

A paper recently published in Science Advances journal declares that the crater was indeed filled at some point in its geological past, with water! More that it has deposited layers of sediments on the floor of the crater which have gone through periods of erosion as the lake shrank but are now visible in space images of the region. 

Although there have been nearly 3 years of operation on Mars, the really interesting stuff occurred between May and December 2022 when Perseverance drove from the crater floor onto the ancient river delta, a region believed to be 3 billion years old. During its journey, Perseverance used RIMFAX (the Radar Imager for Mars’ Subsurface Experiment) to shoot radar signals into the ground every 10cm. The pulses reflected from depths of about 20metres from below the surface showing that the base of the sediment was here and they had located the top of the buried crater. 

The Jezero Crater and delta. Credit NASA

The data from RIMFAX showed sediment from two distinct periods bordered by periods of erosion as the environmental factors affected the sediments. The team reported that the original crater floor was not completely flat and that erosion must have taken place prior to the deposition of the sediments in the lake. 

Despite the discovery of sediments, the team have yet to identify any fossilised remains or primitive life. The journey however has just begun. Over the last few decades we have found mounting evidence that water is common across the universe. It seems to that the processes we see on Earth are also common. Perhaps then we may be permitted to assume that other processes are replicated across the Cosmos, perhaps those that lead to the evolution of life! Time will tell if this latter assumption plays out. 

Source : Confirmation of ancient lake on Mars builds excitement for Perseverance rover’s samples

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The Moon is a bit of a hot bed for exploration of late.  The Japanese agency JAXA have been getting in on the act but their SLIM lander fell on its side with its solar panels pointing toward the ground. Until today, JAXA thought that was it but today it seems that they have managed to re-established contact again.

JAXA’s first lunar lander known as SLIM (Smart Lander for Investigating Moon) was designed to demonstrate the ability to land on the Moon. The mission was particularly wanting to show how precision can be applied to lunar landings. During the descent, craters were identified using technology developed for facial recognition and location pinpointed by the lunar orbiter SELENE. They hoped to land with an accuracy of 100m which, in comparison to the historic Apollo 11 mission accepted a 20km range. 

JAXA’s H-IIA Launch Vehicle taking off from the Tanegashima Space Center. Credit: Wikipedia Commons/NARITA Masahiro

On its arrival on January 20th one of the two engines lost power so with reduced power, the landing was compromised. On touchdown it somehow slid and tumbled down the side of a crater leaving its solar panels unable to generate electricity. Reacting swiftly the team immediately commanded the lander to transmit landing data before the power ran out.  As the lander sat there quietly out of power, the team waited, hoping that the batteries may recharge once other aspects of the Moon started to receive sunlight. 

Fortunately during the final stages of the descent the two probes on board were successfully deployed. One of them a tiny hoping robot and the other designed to roll about the surface. Thankfully they both seemed to be working well with one image having been beamed back to show the orientation of the spacecraft on its side. Not only did the probes function well but the on board navigation camera captured images during the descent showing the rocky terrain just before touch down. 

Even though the mission ended in a slightly unplanned way it still managed to land within its 100 metre target, hitting 55 metres from its identified spot.  A couple of hours after touchdown the team decided to switch off the power to conserve power for a possible power up when solar energy allowed. 

In a post on the company ‘X’ profile the team confirmed that sufficient sunlight had managed to trickle in to give the batteries enough power to boot up and operations resumed.

Source : JAXA ‘X’ feed

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Space exploration is a tricky and at times, dangerous business. The safety of the crews is of paramount importance and escape technology is always factored into spacecraft design. Whilst Artemis I did not require such provisions when it launched Artemis II with astronauts on board is being prepared with a ski-lift style escape system to take them far away from the launch pad. 

Artemis I was launched back in November 2022 after a total of four failed launches. at 6:47 UT the first of the Artemis series of spacecraft lifted off safely for a flight that lasting 25 days. Following an orbit around the Moon, it returned safely to Earth completing phase one of the Artemis program. 

NASA’s Space Launch System rocket carrying the Orion spacecraft launches on the Artemis I flight test, Wednesday, Nov. 16, 2022, from Launch Complex 39B at NASA’s Kennedy Space Center in Florida. Credit: NASA/Joel Kowsky.

The next phase, Artemis II will repeat the success of Artemis I but with crew on board. In this second phase to NASA establishing a long term presence on the Moon, the crew will experience a 10 day flight. The main aim to test the technology needed to support a human crew. Artemis II is currently slated to launch no sooner than September 2025. 

With the human inhabitants on board Artemis II NASA of course, have considered crew safety and escape methods at various stages of the flight. In a series of tests known as the Integrated System Verification and Validation Tests, NASA has a series of seven tests to complete. Test Five involves the test of the emergency egress procedures and technology. 

The emergency egress test demonstrates what will happen in the event of an emergency during the countdown that requires the astronauts to evacuate the Orion module. If an emergency event occurs the crew and support personnel will immediately head to the emergency egress baskets which are currently being installed. 

The baskets are like ski lift gondolas that are hung from overhead wires – known as a catenary system – suspended from the mobile launcher. The baskets would transport the personnel to the ground far from Orion where emergency transport vehicles would be waiting to take them further away. Overall, NASA plans to spend about a week practicing and operating the emergency drills both day and night. 

In the first few tests no-one will ride in the baskets, instead, the tests will be conducted with water tanks filled with different volumes of water to replicate different passenger weights.

Source : Artemis Teams Install Emergency Escape Baskets at NASA Kennedy

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Do exoplanets have exomoons? It would be extraordinary if they didn’t, but as with all things, we don’t know until we know. Astronomers thought they may have found exomoons several years ago around two exoplanets: Kepler-1625b and Kepler-1708b. Did they?

In 2017, researchers found evidence of moons around Kepler-1625b and Kepler-1708b. It was an exciting result, though the researchers warned their findings were inconclusive. They hoped that the Hubble would be able to confirm the exomoons. “Finally, we report evidence for an exomoon candidate Kepler-1625b I, which we briefly describe ahead of scheduled observations of the target with the Hubble Space Telescope,” wrote the authors (Teachey et al. 2017.)

More recently, Rene Heller and Michael Hippke wrote in Nature Astronomy that the data Teachey et al. relied on does not support exomoons. “The probability of a moon orbiting Kepler-1708b is clearly lower than previously reported,” said research co-author Michael Hippke from the Sonneberg Observatory. “The data do not suggest the existence of an exomoon around Kepler-1708b,” he added. Heller and Hippke said the same thing about Kepler-1625b.

Now, a group of researchers, including two of the authors of the original 2017 research that showed evidence of the exomoons, David Kipping and Alex Teachey, have responded to Heller and Hippke.

“Recently, Heller & Hippke argued that the exomoon candidates Kepler-1625 b-i and Kepler-1708 b-i were allegedly ‘refuted,'” Kipping and Teachey write. They claim that Heller and Hippke discarded too much useful data, eliminating the exomoon-supporting signal in the Hubble light curves for Kepler-1625 b-i. Their response is in a Matters Arising article under consideration by Nature Astronomy.

Detecting exomoons is extremely difficult. The only evidence is in light curves. The two exoplanets at issue, Kepler-1625 b and Kepler-1708b are 8,200 and 5,500 light-years away, respectively. Even though we often talk about galaxies that are several billions of light years away, these two planets are at an extreme distance. It’s easy to forget that and how difficult they are to observe.

An artist’s illustration of the Kepler 1625 system. The star in the distance is called Kepler 1625. The gas giant is Kepler 1625B, and the exomoon orbiting it is unnamed. Is the moon really there? Or is it noise in the signal? Image: NASA, ESA, and L. Hustak (STScI)

Kepler found the pair of exoplanets in this work with the transit method. The transit method measures the dip in light caused by a planet passing in front of its star. The transit produces a light curve, which astronomers analyze for the presence of a planet. An exomoon around a planet detected with the transit method produces its own dip in light, a sub-transit if you will.

But these light curves don’t jump out of the data. It takes detailed analysis to find them. Exomoon light curves are much fainter than exoplanet light curves. Since they’re so faint, noise in the signal can obscure them or even present false signals. Only structured analysis can reveal these faint exomoon light curves, and there are more ways than one to analyze this type of data. Different researchers employ different methods, models, and algorithms to analyze data, and sometimes they even exclude data that other researchers retain. It’s not simple.

In this case, Kipping and Teachey say that Heller and Hippke made errors in their analysis and also excluded critical information.

“We demonstrate that their Hubble light curve exhibits ~20% higher noise and discards 11% of the useful data, which compromises its ability to recover the subtle signal of Kepler-1625 b-i,” write Kipping and Teachey.

Something similar occurred with Kepler-1708 b-i, too. Kipping and Teacher write that Heller and Hippke mishandled some of the data, particularly the choices they made when detrending it. Detrending refers to removing a trend in data to allow cyclical and other patterns to emerge. Heller and Hippke’s analysis and detrending indicated no exomoon around Kepler-1708 b-i. But when Kipping and Teacher analyzed Heller and Hippke’s work, they said they could “… recover the original moon signal, to even higher confidence than before.”

Kipping and Teacher are very clear about one thing: “We begin by first clearly stating: both exomoon candidates may not be real. Our original and continued claim is modest: these objects are candidates for which the data exhibits substantial but not entirely conclusive evidence in favour of exomoons.”

Kepler-1708b.

Kipping and Teacher say that Heller and Hippke’s analysis is flawed. For Kepler-1708 b-i, the light curve still shows a potential exomoon, shown in all of the panels below as a dashed line.

This figure from Kipping and Teacher’s work explains some of the findings. The top panel shows the two epochs (left & right) of Kepler-1708 initially published. The solid lines are the best-fit planet+moon
model, and the dashed line is the isolated moon component. The middle panel represents the same light curve date but with the wotan filter that Heller and Hippke used. Kipping and Teacher used the same filter, but their results still showed the dashed line exomoon signal. The bottom panel shows a similar result. Where Heller and Hippke say there was no exomoon signal, Kipping and Teacher found one. Image Credit: Teacher et al. 2024.

In their 2023 paper contradicting the exomoon explanation, Heller and Hippke wrote that “The proposed exomoon transit signal is not distinct from other sources of variations in the light curve, which are probably of stellar or systematic origin.”However,t Kipping and Teacher’s work shows that the curve is still there in the data.

Kepler-1625 b-i

Kipping and Teacher also take exception to Heller and Hippke’s analysis of Kepler-1625 b-i. K & T again say that the other researchers made errors in their analysis. For one thing, Heller and Hippke removed the first exposure in each orbit. This means that there’s 11% less valuable data. K & T explain that removing this much data works against detecting such a faint exomoon signal.

K & T also point out that Heller and Hippke did not provide important data when requested, even by e-mail correspondence. That could be a red flag, or it could have a simple explanation. However, failing to share important data with other researchers is not a good look. “The authors also provide no description of their reduction of the Hubble data, a troubling omission given the notoriously large number of choices required to interpret an instrument with such strong systematics,” K & T write.

K & T assumed, for the purposes of this work, that Heller and Hippke used the data reduction that they used in previously published work. The results? K & T still found signals indicating a possible exomoon.

This figure shows light curves for Kepler-1625 b and its potential exomoon. A is from Heller et al.’s 2019 publication in which T & K were still able to find the exomoon signal despite H & H missing it. B is T & K’s fit to the same data, where the exomoon curve is clearly recovered. C compares H & H’s data from two papers, 2019 and 2023, showing that they’re identical. D is T & K’s analysis of H & H’s 2023 light curves, where, again, the exomoon signal is clear. Image Credit: Teacher et al. 2024.

“Heller & Hippke concluded that the exomoon candidates Kepler-1625 b-i and Kepler-1708 b-i are
unlikely, but we have shown that their arguments are fundamentally flawed, stemming from numerous choices and interpretations that do not hold up to scrutiny,” Kipping and Teacher write.

Barring any further response from Heller and Hippke, the last words go to Kipping and Teacher. “We conclude that both candidates remain viable but certainly demand further observations.”

The post Did We Find Exomoons or Not? The Question Lingers. appeared first on Universe Today.

One ongoing mystery on Mars is the sporadic detection of atmospheric methane. Since 1999 detections have been made by Earth-based observatories, orbital missions, and on the surface by the Curiosity Rover. However, other missions and observatories have not detected methane at all, and even when detected, the abundances appear to fluctuate seasonally or even daily.

So, where does this intermittent methane come from? A group of scientists have proposed an interesting theory: the methane is being sucked out of the ground by changes in pressure in the Martian atmosphere. The researchers simulated how methane moves underground on Mars through networks of underground fractures and found that seasonal changes can force the methane onto the surface for a short time.

In their paper, published in the Journal of Geophysical Research: Planets, the scientists say their simulations predict short-lived methane pulses prior to sunrise for Mars’ upcoming northern summer period, which is a candidate time frame for Curiosity’s next atmospheric sampling campaign.

“Our work suggests several key time windows for Curiosity to collect data,” said John Ortiz, a graduate student at Los Alamos National Laboratory who led the research team. “We think these offer the best chance of constraining the timing of methane fluctuations, and (hopefully) down the line bringing us closer to understanding where it comes from on Mars.”

The presence of methane (CH4) in the Martian atmosphere is of great interest to planetary scientists and exobiologists because it could indicate present or past microbial life. Or, it could also be related to nonbiological processes, such as volcanism or hydrothermal activity.

The problem with detecting methane is that it doesn’t last long. Once released into the atmosphere, it can be quickly destroyed by natural atmospheric processes. Therefore, any methane detected in Mars’ atmosphere means it must have been released recently, which only adds to the intrigue.

On Earth, most methane is produced by living creatures such as microorganisms in sedimentary strata, or in the guts of ruminants (cows, sheep, deer, etc.). For methane produced through abiotic or non-living processes, there is a high likelihood it could have been produced millions or even billions of years ago, lying trapped in underground rock formations.

But still, finding methane on Mars is a big deal because of the potential for biological sources, such as methanogenic microbes.

This graphic is the result of an analysis that gives a percentage chance of the methane originating in each grid square centered on Gale Crater. Image Credit: Giuranna et al. (2019)

In 2004, the Mars Express Orbiter (MEO) detected methane in the Martian atmosphere. In 2013 and 2014 Curiosity detected spikes in methane in the atmosphere at Gale Crater. Interestingly, MEO detected a methane spike again, at the same location that Curiosity did, only one day later.

Ortiz and his team wanted to better understand Mars’ methane levels, and used high-performance computing clusters to simulate how methane travels through networks of underground fractures, and then released into the atmosphere when driven by atmospheric pressure fluctuations. They also modeled how methane is adsorbed onto the pores of rocks, which is a temperature-dependent process that may contribute to the methane level fluctuations.

The team said their simulations predicted methane pulses from the ground surface into the atmosphere just before the Martian sunrise in the planet’s northern summer season, which just recently ended. This corroborates previous rover data suggesting that methane levels fluctuated not only seasonally, but also daily. With these insights, the Curiosity rover team can figure out when and where to look for methane, which could aid in the rover’s main goal, searching for signs of life.

“Understanding Mars’ methane variations has been highlighted by NASA’s Curiosity team as the next key step towards figuring out where it comes from,” Ortiz said. “There are several challenges associated with meeting that goal, and a big one is knowing what time of a given sol (Martian day) is best for Curiosity to perform an atmospheric sampling experiment.”

Paper: “Sub-diurnal methane variations on Mars driven by barometric pumping and planetary boundary layer evolution.” Journal of Geophysical Research: Planets. DOI: 10.1029/2023JE008043
LANL press release

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Exoplanet K2-18b is garnering a lot of attention. James Webb Space Telescope spectroscopy shows it has carbon and methane in its atmosphere. Those results, along with other observations, suggest the planet could be a long-hypothesized ‘Hycean World.’ But new research counters that.

Instead, the planet could be a gaseous mini-Neptune.

K2-18b is in the habitable zone of a red dwarf star about 134 light-years away. It’s about 2.6 Earth radii and about 8.6 Earth masses. Its orbital period is only 33 days, so it’s close to its star. But since the star is a dim red dwarf, K2-18b receives about the same amount of energy from its star as Earth does from the Sun.

Scientists are still puzzling over the planet’s density and composition. Its density is in between the densities of Earth and Neptune. Since it’s not predominantly rock like Earth or all gas like Neptune, that led to speculation that it’s a hycean (ocean) world. The only way scientists can determine what K2-18b is made of is to discover what’s in its atmosphere.

That’s what the JWST did, and its observations found a number of chemicals, including CO2 and methane. It also found a lack of ammonia.

Earlier this month, scientists presented some research (Shorttle et al. 2024) based on the JWST’s findings. By working with climate atmosphere models, those researchers concluded that K2-18b is most likely a magma ocean world. “The magma ocean model reproduces the present JWST spectrum of K2-18b,” they wrote, “… suggesting this is as credible an explanation for current observations as the planet hosting a liquid water ocean.”

But another group of researchers don’t agree with that. Those researchers don’t think the planet is a hycean world or a lava world. They’ve presented a paper titled “JWST observations of K2-18b can be explained by a gas-rich mini-Neptune with no habitable surface.” The lead author is Nicholas Wogan, a post-doctoral researcher in the Space Science Division at NASA’s Ames Research Center. Wogan studies the early Earth, as well as exoplanets and astrobiology.

The JWST found methane (CH4) and carbon dioxide (CO2) in K2-18b’s atmosphere, and it also detected no ammonia. Those results generally indicate a hycean world with a thick Hydrogen/Helium atmosphere. But Shorttle et al.’s analysis showed otherwise, saying that the results could also show a planet with a magma world.

The new paper from Wogan et al. comes to a different conclusion. “… we favour the mini-Neptune interpretation because of its relative simplicity and because it does not need a biosphere or other unknown source of methane to explain the data,” they write.

In their work, the researchers used photochemical and climate models to simulate different versions of K2-18b, including hycean worlds and a gas-rich mini-Neptune with no defined surface. Their work shows that the gas-rich mini-Neptune model fits the data best.

There’s an extraordinary amount of complexity in planetary atmospheres, and figuring out what’s going on from such a great distance is an enormous task. Not only do scientists need to know what chemicals are present (thanks, JWST), but they need to understand all the processes taking place. The temperature and pressure in an atmosphere play huge roles in what we can see and in what may remain hidden.

One aspect of K2-18b’s atmosphere is supercriticality. A supercritical fluid is one that’s above its critical point in temperature and pressure. Above this critical point, neither gas nor liquid phases exist. But the pressure isn’t high enough to force the material into a solid. Jupiter and Saturn have supercritical fluids deep in their atmosphere, and they behave very differently than liquids or gases. That adds another layer of complexity.

Researchers have climate models that embody the complexity as best they can, and the researchers compared the JWST’s findings to three modelled exoplanets: an uninhabitable hycean world, a habitable hycean world, and a gaseous mini-Neptune with no surface.

This figure from the research helps explain the findings. Each panel is a separate model compared to the JWST’s NIRSpec and Single Object Slitless Spectroscopy observations. JWST data rules out the lifeless hycean world model because it doesn’t have enough methane. The inhabited hycean model and the mini-Neptune model fit the JWST data better, but invoking a biotic source for the planet’s methane is too much of a reach for the authors. Instead, they’ve settled on the mini-Neptune model as the best fit. Image Credit: Wogan et al. 2024.

“Given the additional obstacles to maintaining a stable temperate climate on Hycean worlds due to H2 escape and potential supercriticality at depth, we favour the mini-Neptune interpretation because of its relative simplicity and because it does not need a biosphere or other unknown source of methane to explain the data,” the authors write.

The authors point out that for a hycean world to maintain its 1% atmospheric methane, there would need to be a biogenic source or some other unknown source. They also write that if K2-18b is a hycean world, it would be very difficult for it to avoid the runaway greenhouse effect and maintain a stable temperature. The authors discard the hycean hypothesis because it is full of challenges. According to them, a gaseous mini-Neptune scenario fits the data and models better.

They point to the planet’s deep atmosphere to explain the JWST’s findings. “Deep-atmosphere thermochemical quenching” can explain the methane and carbon dioxide that JWST found, and deep atmosphere kinetics like upwelling can explain the lack of ammonia and carbon monoxide.

This won’t be the last word on K2-18b. The data will be subjected to further analysis. As the effort to understand it continues, the results will also strengthen our existing atmospheric and climate models. One day in the future, scientists will know how to differentiate exoplanets.

But for now, they’re still figuring it out.

The post Another Explanation for K2-18b? A Gas-Rich Mini-Neptune with No Habitable Surface appeared first on Universe Today.

Black holes are powerful gravitational engines. So you might imagine that there must be a way to extract energy from them given the chance, and you’d be right. Certainly, we could tap into all the heat and kinetic energy of a black hole’s accretion disk and jets, but even if all you had was a black hole in empty space, you could still extract energy from a trick known as the Penrose process.

First proposed by Roger Penrose in 1971, it is a way to extract rotational energy from a black hole. It uses an effect known as frame dragging, where a rotating body twists nearby space in such a way that an object falling toward the body is dragged slightly along the path of rotation. We’ve observed the effect near Earth, though it is tiny. Near a rotating black hole, the effect can be huge. So strong that within a region known as the ergosphere objects can be dragged around the black hole at speeds greater than light in free space.

Trajectories of bodies in a Penrose process. Credit: Aleksandr Berdnikov, CC BY-SA 4.0

Roughly, the Penrose process is to fly into the ergosphere of a swiftly spinning black hole, and then release a bit of mass or radiation into the black hole. The resulting rotational kick sends you away from the black hole faster than you approached it. The extra energy you get is balanced by slowing down the black hole’s rotation. This process can in theory extract up to 20% of the black hole’s mass energy, which is huge. In comparison, fusing hydrogen into helium only yields about 1% of the mass energy.

Of course, theoretical physicists are never satisfied. If you can extract 20% of the mass energy from a black hole, why not more? This is the focus of a recent paper, though it should be noted that it focuses on a more abstract idea of a black hole than we see in the Universe.

Simple black holes can be characterized by three things: mass, rotation, and electric charge. The black holes we observe have the first two, but since matter is electrically neutral, not the third. This paper focuses on charged black holes. Our Universe is also expanding and can be roughly described by a solution to Einstein’s equations known as de Sitter space. It describes an empty universe with a positive cosmological constant. Anti-de Sitter space (AdS) would be a universe with a negative cosmological constant. Although AdS doesn’t describe our Universe, it allows for a few mathematical tricks theorists love, so it is often used to explore the limits of general relativity. This paper specifically looks at a charged black hole in anti-de Sitter space.

A visualization of anti-de Sitter space. Credit: Alex Dunkel

Although this study is entirely hypothetical, it’s interesting as a “what-if” scenario. Rather than extracting energy from a black hole’s rotation, the authors look at how to extract energy through particle decay using the Bañados-Silk-West (BSW) effect. Using some kind of electromagnetic or physical confinement mirrors, particles can be reflected back and forth near the event horizon, gaining energy from the black hole until they decay as usable energy. The problem with this idea, as the authors show, is that this can lead to a runaway effect where particle energy amplifies particle energy in a feedback look, leading to what’s known as a black hole bomb. So if you find yourself building a power plant near a charged black hole in an anti-de Sitter universe, tread carefully.

But more interesting is that the authors also looked at the case of a charged black hole in an otherwise empty anti-de Sitter universe. In this case, energy would also be extracted from the black hole. Instead of mirrors, the structure of spacetime itself would act as a kind of confinement chamber. So the charged black hole would release energy on its own. It would be similar to Hawking radiation, but in this case, it doesn’t rely upon quantum gravity. The authors also found that this case doesn’t lead to a black hole bomb.

As mentioned earlier, none of this applies to real black holes in our Universe. As far as we know, the Penrose process is the best we could really do. But studies like this are useful because of what they reveal about the fundamental nature of space and time. And now we know that even in a strange anti-universe we can only imagine, black holes can release energy over time.

Reference: Penrose, Roger, and R. M. Floyd. “Extraction of rotational energy from a black hole.” Nature Physical Science 229.6 (1971): 177-179.

Reference: Feiteira, Duarte, José PS Lemos, and Oleg B. Zaslavskii. “Penrose process in Reissner-Nordström-AdS black hole spacetimes: Black hole energy factories and black hole bombs.” arXiv preprint arXiv:2401.13039 (2024).

Reference: De Sitter, Willem. “On the relativity of inertia. Remarks concerning Einstein’s latest hypothesis.” Proc. Kon. Ned. Acad. Wet 19.2 (1917): 1217-1225.

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Going to Mars is a major step in space exploration. It’s not a quick jaunt nor will it be easy to accomplish. The trip is already in the planning stages, and there’s a good chance it’ll happen in the next decade or so. That’s why NASA and other agencies have detailed mission scenarios in place, starting with trips to the Moon. Recently, NASA updated its “Moon to Mars Architecture” documents, including a closer look at some key decisions about Mars exploration.

Those decisions cover a wide gamut of challenges to living and working on the Red Planet. NASA planners narrowed them down to these key areas: science priorities, number of crew members on the first trip, how many on each follow-up trip, number of crew members per Mars location, Mars surface power generation technologies, what kinds of missions will be sent (the “target state”), and establishing what they call a “loss of crew risk” posture. That last one involves making the right decisions about missions based on risk to the crew’s health and performance.

NASA Plans for the Moon and Mars

Why create a mission architecture for the Moon and Mars? Essentially, anybody going to these other worlds needs a mutually agreed-upon “roadmap” that plans the explorations and technologies needed. That’s why NASA created its first Moon to Mars objectives in 2022 and has been refining them ever since. The agency’s roadmap includes feedback from a wide swath of society. Members of academia, U.S. industry, international partners, and the NASA workforce all contributed to the project.

“Our new documents reflect the progress we’ve made to define a clear approach to exploration and lay out how we’ll incorporate new elements as technologies and capabilities in the U.S. and abroad mature,” said Catherine Koerner, associate administrator, Exploration Systems Development Mission Directorate at NASA Headquarters in Washington. “This process is ensuring that everything we are doing as an agency and together with our partners is focused on achieving our overarching exploration goals for the benefit of all.”

The Key Decisions Regarding Mars Exploration

In a white paper published along with the Moon to Mars Architecture document, NASA explains key areas of concern when it comes specifically to Mars exploration. The first is science. It’s the main reason for going the both the Moon and Mars, and its needs will drive almost all other considerations. It will determine the resources needed, including crew numbers, payloads, technology deliveries, and power and communications infrastructure, and contingencies for possible accidents or other challenges.

An artist’s concept of Mars explorers and their habitat on the Red Planet. Courtesy NASA.

Once the science is determined, planners can decide on crew needs for the first and subsequent missions. As the white paper states, “…a series of focused science exploration missions to different landing sites would favor one architecture. Establishing a permanent, fixed base from which astronauts could conduct many surface missions supporting diverse and evolving exploration activities would favor a very different architecture.”

From there, planners will figure out the “cadence” of the missions and crew deployments. How often do we send missions and how many people will go? Just as an example, let’s say that the first mission will land in Jezero Crater, near the Perseverance rover. NASA could use its data to determine further science exploration at the site. That will drive the best placement for habitats and other infrastructure, and the type of mission will dictate the number of crew members needed.

Those decisions will then drive the infrastructure and technology needed for each step. Science stations need power to do the science, but also to sustain the habitats for the science teams. If those teams travel across the surface, their rovers will need power, fuel, and possibly replacement parts. Crew members themselves will need to be able to grow food, use local resources to extract fuel and water, and otherwise maintain safe living conditions. And, these are just the first steps in the long-term exploration of Mars, enabled by what people learn about living and working on the Moon.

Why Does NASA Want a Moon to Mars Plan?

While it may seem sexy to send people directly to Mars without any intervening stops at the Moon, NASA and other agencies want a measured approach. The idea to use the Moon as a stepping stone to Mars is not new. The Moon makes a good “training base” of sorts where we can “practice” with the technologies and techniques of living on another world. In addition, it offers a unique environment for astronomy and planetary science exploration. Astronauts learn in an environment close to Earth and if something dire happens to them, rescue is not far away.

Artist’s impression of astronauts on the lunar surface, as part of the Artemis Program. Credit: NASA

These ideas underlie the planning for the upcoming Artemis missions to the lunar surface. There’s supposed to be a gateway orbiting the Moon, to which astronauts and equipment will fly. Then, from there, materials and people head to the Moon to explore various sites, and begin the complex tasks of exploration and habitat construction. That set of missions will establish the foundation for scientific exploration, and land a diverse set of people on the lunar surface, all in cooperation with international partners. Ultimately, everything they learn on the Moon will prepare people for the leap to Mars.

The Moon to Mars mission architectural plans unite both lunar and Mars exploration in one timeline, identifying technologies and capabilities needed to accomplish each step. They are living documents, updated every year to reflect changes in any aspect of mission planning and technology.

For More Information

NASA Shares Newest Results of Moon to Mars Architecture Concept Review
Moon to Mars Architecture
Key Mars Architecture Decisions (PDF)

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Science really does keep you on your toes. First there was matter and then there were galaxies. Then those galaxies had more stuff in the middle so stars further out were expected to move slowly, then there was dark matter as they actually seemed to move faster but now they seem to be moving slower in our Galaxy so perhaps there is less dark matter than we thought after all! 

Let’s start with dark matter.  It is a strange and mysterious form of matter that doesn’t really seem to behave in any way like normal matter. It doesn’t emit light, absorb or reflect it so is to all intents invisible, hence its name. It’s thought that about 27% of the Universe is made up of dark matter but the only way we can detect it is its gravitational effect on passing light and other matter. Despite mounting evidence for its existence, we have still yet to actually detect particles that make up dark matter, whatever they are. 

Physicists at MIT (the Massachusetts Institute of Technology) have measured the speed of stars in the Milky Way galaxy and found that those further out to the edge are moving slower than expected. This suggests, rather surprisingly that the core of the milky way may be lighter in mass than first thought and thus contain less dark matter. 

The team used data from Gaia and APOGEE (Apache Point Observatory Galactic Evolution Experiment) to plot the velocity of stars against their distance. This enabled them to generate a rotation curve that shows how fast matter rotates at a given distance from the centre of a galaxy. Interpreting graphs like these allow astronomers to estimate how much dark matter there is.

Artist impression of ESA’s Gaia satellite observing the Milky Way (Credit : ESA/ATG medialab; Milky Way: ESA/Gaia/DPAC)

This was quite in contrast to earlier observations since the 1970’s that revealed a hint of dark matter distribution. Measurements of previous galaxies showed that stars were moving around the centre at a fairly constant velocity with distance from centre. The only way this can be explained is dark matter. This work was pioneered by Vera Rubin from the Carnegie Institution in Washington and was supported by multiple observations from other astronomers in the following years. 

The efforts to measure galactic rotation have focussed on other galaxies rather than our own. It’s actually quite difficult to achieve the same in a galaxy that you live in but undaunted; Xiaowei Ou, Anna-Christina Eilers, and Anna Frebel set about the task. Their initial observations came from Gaia data but used APOGEE data to refine their results. They were able to measure distances of more than 33,000 stars out to a distance of 30 kiloparsecs (97,846 light years). The data was then incorporated into a model of circular velocity to estimate the velocity of stars given the location of all other stars in the galaxy. This gave them an updated and refined rotation curve. 

The curve their work revealed showed a more rapid decline over distance rather than the shallow decline they expected. Stars further out are moving slower than expected and so there is less matter in the centre of our galaxy. We can observe the ‘normal’ or baryonic matter but it requires less dark matter to account for the observations. Further research is now required to explore other galaxies like the Milky Way and perhaps, change our view of the amount of dark matter in the Universe. 

Source : Study: Stars travel more slowly at Milky Way’s edge

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I have spent the last few years thinking, perhaps assuming that astronauts live off dried food, prepackaged and sent from Earth. There certainly is an element of that but travellers to the International Space Station have over recent years been able to feast on fresh salad grown in special units on board. Unfortunately, recent research suggests that pathogenic bacteria and fungi can contaminate the ‘greens’ even in space.

It’s been at least three years that astronauts have been able to eat fresh lettuce and other leafy items along with tortillas and powdered coffee.. Specially designed chambers on board allow them to grown plants under carefully controlled temperature, water and lights to ensure a successful harvest.  There is however an issue that the ISS is a relatively closed environment and so it is easy for bacteria and fungi to spread and astronauts to get ill. 

The International Space Station stretches out in an image captured by astronauts aboard the SpaceX Crew Dragon Endeavour during a fly-around in November 2021. Credit: NASA

A paper just published in Scientific Reports and NPJ Microgravity and authored by a team led by Noah Totsline explores what happens with lettuce grown under ‘simulated’ weightless environments (the device known as a clinostat rotate them so that plants did not know which way was up or down). This was achieved by being gently rotated. Plants it seems though, are pretty good at sensing gravity using their roots. The team found that plants under these conditions were more prone to infection than those on Earth in particular Salmonella.

One of the main lines of defence for plants is their stomata. These are tiny pores in the leaves, much like the pores in our skin, that close to defend when an environmental stress is detected, such as bacteria.  The team exposed plants in their micro-gravitational environment to find the plants opened the stomata instead of closing them. 

The team went a step further and introduced a natural bacteria known as UD1022 which usually helps to protect plants. In the clinostat however, it failed to help the plant to protect itself from other more harmful bacteria.

The research was not just an interesting scientific problem but does solve real world problems. Space is slowly opening up with more and more non-astronauts becoming astronauts and travelling into space and this is only going to increase. As SpaceX and the like press ahead with the commercialisation of space travel we absolutely must find a way to grow and farm sustainable and healthy food instead of prepackaged snacks if we are to become a truly space fairing civilisation. 

We are some way away from that of course but this is step one in a long journey. Sadly it is not as simple a task as sterilising the seeds since their could easily be microbes in the environment on board the ISS (or other space craft that come in the future) and perhaps it is these that pose the greatest risk. The team are now looking at ways to genetically modify plants to help them cope in the microgravity of space.

Source : PROBLEMS WITH ROCKET SALAD

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The water that life knows and needs, the water that makes a world habitable, the water that acts as the universal solvent for all the myriad and fantastically complicated chemical reactions that make us different than the dirt and rocks, can only come in one form: liquid.

The vast, vast majority of the water in our universe is unsuitable for life. Some of it is frozen, locked in solid ice on the surface of a world too distant from its parent star or bound up in a lonely, wayward comet. The rest is vaporized, existing as a state of matter where molecules lose their electron companions, boundless and adrift through the great nebular seas that dot the galaxies, or ejected completely into the great voids between them. Either way, that water exists only one molecule at a time, at a temperature of over a million degrees yet its density so low that you could pass through it and mistake it for the cold, hard vacuum of space itself.

No, for water to be liquid it must exist in special place around a star, not too cold for it turn to ice, not too hot for it to turn to gas. It must lay within what astronomers call the habitable zone, or, if they’re feeling playful, the Goldilocks zone.

The habitable zone is different for every star throughout the galaxy, because no two stars are alike. The smallest red dwarfs are barely a tenth the mass of the Sun, with luminosities a thousand times weaker. The largest are great beasts, a hundred solar masses or more, so bright they can be seen from thousands of light-years away by the unaided eye. Around each star a simple iron law holds, the fact that the intensity of light, and all the warmth and comfort that light brings with it, diminishes with the square of the distance from the source. An object twice as far away will experience a quarter of the brightness; at a distance of four times that drops to a sixteenth, and so on. That is why Pluto, despite only sitting about 30 times further away from the Sun than the Earth, is forced to experience never-ending dim twilight, even at the height of its day.

Too far from a star and the radiant temperatures are too cold, and any water freezes. Too close, and the water slips its bonds, free to roam as a gas. In between, in a special band determined by the star’s mass, age, and brightness, sits the habitable zone, where a planet is capable – yes, merely capable – of hosting water in its liquid state on its surface.

For our own Sun, the habitable zone stretches from just within the orbit of Venus to just beyond the orbit of Mars. Three planets perfectly situated within the warm embrace of our Sun, and yet only one has life. What happened? What made our planet so special, or so lucky? It’s impossible to say for sure, because the potential of habitability is not a promise.

There is, however, one other place where we know liquid water can exist. Ironically, it’s in the frozen moons of the outer solar system. There, under surfaces of frozen ice a hundred kilometers thick sit globe-spanning liquid water oceans, with more liquid water than exists on the surface of the Earth. There the habitability isn’t given by the rays of the Sun, but from their molten cores emanating heat, driven by the gravitational warping of the giant planets they orbit. Life could certainly find a purchase there, in places of darkness that the Sun never can touch, even though there worlds are not, according to the traditional definition, habitable.

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As part of the Artemis Program, NASA intends to establish all the necessary infrastructure to create a “sustained program of lunar exploration and development.” This includes the Lunar Gateway, an orbiting habitat that will enable regular trips to and from the surface, and the Artemis Base Camp, which will permit astronauts to remain there for up to two months. Multiple space agencies are also planning on creating facilities that will take advantage of the “quiet nature” of the lunar environment, which includes high-resolution telescopes.

As part of this year’s NASA Innovative Advance Concepts (NIAC) Program, a team from NASA’s Goddard Space Flight Center has proposed a design for a lunar Long-Baseline Optical Imaging Interferometer (LBI) for imaging at visible and ultraviolet wavelengths. Known as the Artemis-enabled Stellar Imager (AeSI), this proposed array of multiple telescopes was selected for Phase I development. With a little luck, the AeSI array could be operating on the far side of the Moon, taking detailed images of stellar surfaces and their environments.

The proposal was made by Kenneth Carpenter and his colleagues at NASA Goddard Space Flight Center (GSFC). Carpenter is the Hubble Operations Project Scientist at GSFC and the ground system scientist for the Nancy Grace Roman Space Telescope (RST). As they note in their proposal, NASA’s return to the Moon offers several significant opportunities for him-impact scientific research. Not the least of these is the potential for creating observatories that take advantage of the “radio quiet” environment and extended periods of darkness on the far side of the Moon.

Artist’s illustration of a radio telescope inside a crater on the Moon. Credit: NASA/JPL-Caltech

Due to the tidally locked nature of its orbit, where one side of the Moon is always facing toward Earth, the Moon’s day/night cycle lasts for 14 days. This means a “lunar day” consists of two weeks of continuous sunlight, while a lunar night consists of two weeks of continuous darkness. At the same time, the Moon’s airless environment means that any observations by optical telescopes will not be subject to atmospheric interference. This makes the far side of the Moon a pristine environment for conducting high-resolution interferometric imaging, a method where multiple telescopes collect light to look for patterns of interference.

Astronomers extract data from these patterns to create a detailed picture of celestial objects that are difficult to resolve with conventional telescopes. This same technique allowed the Event Horizon Telescope (EHT), a global network of radio telescopes, to acquire the first image of a black hole ever taken. According to the team, a lunar interferometry array has immense scientific potential and could be built incrementally to limit construction costs:

“This can resolve the surfaces of stars, probe the inner accretion disks surrounding nascent stars and black holes, and begin the technical journey towards resolving surface features and weather patterns on the nearest exoplanets. A fully developed facility will be large and expensive, but it need not start that way. The technologies can be developed and tested with 2 or 3 small telescopes on short baselines. Once the technology is developed, baselines can be lengthened, larger telescopes can be inserted, and the number of telescopes can be increased. Each of these upgrades can be accomplished with minimal disruption to the rest of the system.”

Despite these advantages, the team notes how previous studies on interferometers in space concentrated on designs for free-flying arrays. This was largely due to the 2003-2005 NASA Vision Missions Studies that examined the trade-offs between free-flying space concepts and kilometer-sized interferometers built on the lunar surface. The study concluded that it was better to pursue space-based free-flyers, given the absence of pre-existing human infrastructure on the lunar surface that could provide power and regular maintenance.

Illustration of NASA astronauts on the lunar South Pole. Mission ideas we see today have at least some heritage from the early days of the Space Age. Credit: NASA

However, with the Artemis Program, Carpenter and his team argue that this situation is now changing. With the completion of surface habitats, transportation, drilling, and power facilities planned for the coming years, now is a good time to investigate the possibility of building interferometers on the lunar surface. “Our study of a lunar surface-based interferometer will be a huge step forward to larger arrays on both the moon and free-flying in space, over a wide variety of wavelengths and science topics,” they write. “It will determine, given the current and anticipated state of our space technology and human exploration plans, whether it is better to pursue designs for the lunar surface or for deep space.”

They further envision that a lunar interferometer will lead to advancements in astrophysics, like the study of stellar magnetic activity, the nuclei of active galaxies, and the dynamics of cosmological phenomena on many scales. The design and construction of such a facility will address key engineering concerns, like the best way to incorporate variable-length optical lines, the best configurations for the telescopes, and the optimal mirror size for meeting both technical and scientific goals. They also hope to create a plan for maintaining and expanding the facility over time using a mix of human and robotic support.

Beyond that, the anticipated benefits include technical advances that will enable a UV-optical interferometer and space-based missions capable of imaging black holes (similar to the EHT), searching for biosignatures, and directly imaging rocky exoplanets around other stars. Carpenter and his colleagues also anticipate that the creation of a major facility on the Moon, in conjunction with the Artemis Program’s human exploration goals, will generate tremendous public interest and engagement:

“Finally, this effort will make people dream again – and remember that we can do great things, even in [the] face of difficult times. Our study will help keep the focus on the grandeur of the Universe and what humans can do if they work hard together. Our project will excite generations of future Science, Technology, Engineering, Art, and Mathematics (STEAM) workers, who will be inspired by this bold vision.”

Further Reading: NASA

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In the early days of telescopic astronomy, you could only focus on one small region of the sky at a time. Careful observations had to be done by hand, and so much of the breakthrough work centered around a particular object in the sky. A nebula or galaxy, quasar or pulsar. But over the years we’ve been able to build telescopes capable of capturing a wide patch of sky all at once, and with automation, we can now map the entire sky. Early sky surveys took years to complete, but many modern sky surveys can look for changes on the order of weeks or days. This ability to watch for changes across the sky is changing the way we do astronomy, and it is beginning to yield some interesting results. As a case in point, an infrared sky survey is revealing hidden stars we hadn’t noticed before.

In a series of papers published in the Monthly Notices of the Royal Astronomical Society, the authors have analyzed data from a decade-long survey called the Visible and Infrared Survey Telescope (VISTA). VISTA allows astronomers to keep an eye on hundreds of millions of stars at infrared wavelengths. In these works, the team combed through the observations to focus on about 200 stars that showed the most dramatic shifts in brightness. These transient changes are important because they can reveal the subtle dynamics of stars.

Artist’s impression of an eruption in the disc of matter around a newborn star. Credit: Philip Lucas/University of Hertfordshire

One goal of the studies was to look for very young stars. Stars in the earliest moments of transition toward becoming true fusion-powered stars. And within their selected stars they found 32 erupting protostars. All of them experienced a rapid increase of at least a factor of 40, and some brightened as much as a factor of 300. The outbursts lasted for months or years, and they seem to occur within the disk of matter surrounding the young stars. Based on the dynamics, these bursts can accelerate the growth of young stars, but they could also make it more difficult for planets to form. They refer to these turbulent protostars as squalling newborns.

The team also found a surprise. Deep within the center of our galaxy, they found 21 red giant stars with dramatic brightness changes. They turned out to be a new type of red giant known as old smokers. The center of our galaxy is rich with heavy elements, so these red giants have a high metalicity. As they age, they can cast off clouds of dust that can obscure the star for a time. So the star temporarily fades from view and then re-brightens as the clouds disperse. This discovery could change our understanding of how heavy elements are released into the galaxy to be used by new stars.

Reference: Lucas, P W, et al. “The most variable VVV sources: eruptive protostars, dipping giants in the nuclear disc and others.” Monthly Notices of the Royal Astronomical Society 582.2 (2024): 1789–1822.

Reference: Guo, Zhen, et al. “Spectroscopic confirmation of high-amplitude eruptive YSOs and dipping giants from the VVV survey.” Monthly Notices of the Royal Astronomical Society 582.2 (2024): 1769–1788.

Reference: Peña, Carlos Conteras, et al. “On the incidence of episodic accretion in Class I YSOs from VVV.” Monthly Notices of the Royal Astronomical Society 582.2 (2024): 1823–1840.

Reference: Guo, Zhen, et al. “Multiwavelength detection of an ongoing FUOr-type outburst on a low-mass YSO.” Monthly Notices of the Royal Astronomical Society 582.2 (2024): L115–L122.

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