Category: Featured (page 1 of 13)

This artist’s concept shows what exoplanet K2-18 b could look like based on new observation. The exoplanet, of a size between Earth and Neptune, orbits the cool dwarf star K2-18. A new investigation of the planet with the James Webb Space Telescope has revealed the presence of carbon-bearing molecules in the atmosphere, including methane and carbon dioxide. (NASA, CSA, ESA, J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)

Beware easy answers to the question of whether life exists beyond Earth.

Be they “alien” skeletons in Mexico City, interstellar probes that briefly pass through our solar system, UFOs of all sorts and claims to have found “biosignature” chemical byproducts of life around planets where many other factors say that life cannot exist — their chances of being meaningful are vanishingly small.

But they make good copy, can bring quick attention and even fame to researchers and sidekicks, and they often cannot be proven 100 percent wrong.   Data from planets close and distant, solar systems like ours and stunningly different and faraway galaxies we have only begun to understand are often way too complex to completely dismiss possibilities.

Unless, of course, they can be shown to be entirely different than claimed, as were the two “non-human corpses” put on display this month in Mexico City by a well-known ufologist and debunked as a mash-up of human and animal bones or ancient mummies from Peru.

The real recent astrobiology news came instead from new results featuring the James Webb Space Telescope and its reading of the atmosphere of a large planet (8.6 times more massive than Earth) 120 light-years away.  Researchers found methane and carbon dioxide in its atmosphere and possibly a hydrogen-rich atmosphere that surrounds an ocean-covered surface.

The findings, by a team at the University of Cambridge, do not claim to have detected signs of life, although they also reported the possible presence of a molecule called dimethyl sulfide (DMS). On Earth, this is only produced by life, with the bulk of the compound in Earth’s atmosphere coming from phytoplankton in watery environments.

But instead of focusing on a single molecule, Nikku Madhusudhan, an astronomer at the University of Cambridge and lead author of the paper, point elsewhere to the importance of their work — that the planet is large and not necessarily rocky yet it has that interesting suite of chemicals in its atmosphere.

“Our findings,” he said in a release, “underscore the importance of considering diverse habitable environments in the search for life elsewhere.”… Read more

The Familiar, Yet So Different, Hydrocarbon Rivers of Titan

Images from the Cassini mission show river networks draining into lakes in Titan’s north polar region. False color was used to make the features more visible. (NASA/JPL/USGS

There are three planets or moons in our solar system known to now have, or once had, surface rivers, lakes, deltas and a hydrologic system.  There’s Earth, of course, Mars long ago when it was warmer and wetter, and the so different yet so similar rivers of hydrocarbons on Saturn’s moon, Titan.

Understanding the dynamics of rivers in particular is crucial to understanding the workings of a planet or moon.  That is why so much time is spent studying the flow and spread and slopes of rivers on Earth, and why the Mars rovers Curiosity and Perseverance have spent year delving into the fossil riverbeds and fossil lakes and fossil deltas of Mars.

And that’s also why researchers have begun to focus on most unusual rivers and lakes and even seas of Titan.  Yes, the liquids are a mix of methane, ethane, water ice and nitrogen, so they are very different from our liquid worlds.

But they apparently have rapids, whirlpools and waterfalls, just like rivers on Earth.

And using research done two decades ago into the predictable behavior of Earth’s flowing water, a team of geologists and planetary scientists at the Massachusetts Institute of Technology and elsewhere has made progress in understanding some basics about the flow of Titan’s surface liquids.

A new Proceedings of the National Academy of Sciences paper describes some of what has been learned, and the flow of methane and ethane rivers seems to have many of the characteristics of flowing water on Earth and that long-ago flow of water on Mars.

But there are also some differences that could be windows into greater, and intriguing disparities.  A finding highlighted in the PNAS paper is that almost all Titan rivers flow into lakes and seas without ever creating fan-shaped deltas.

On Earth — and long ago on Mars — almost all major rivers ended the with these distinctive transitions into larger bodies of water.

So what could explain the difference?

This artist’s concept envisions what hydrocarbon ice forming on a liquid hydrocarbon sea of Saturn’s moon Titan might look like. This model from scientists on NASA’s Cassini mission suggests that clumps of methane-and-ethane-rich ice — shown here as the lighter-colored clusters — could float under some conditions. (NASA/JPL-Caltech/USGS)

We’ll get back to the delta question, but first some background on the characteristics of Titan.… Read more

The Mars Water Story Takes an Important New Turn in Jezero Crater

A mosiac made of 203 individual images taken by Perseverance showing the fossilized remains of what was  likely once a strong and wild river in Jezero Crater.  Named Skrinkle Haven after a site in Wales, this river is the most powerful identified so far by Mars rovers.  (NASA/JPL

The central and ever-surprising story of water on ancient Mars took a new turn recently when NASA announced that the Perseverance rover had found the fossil remains of a once-powerful river in Jezero Crater.

From the nature and patterns of the riverbed turned to stone, to the ways that grains of sand and rocks been moved, textured and deposited and to the features of the surrounding landscape,  the rover science team came go a speedy conclusion:  This was a Mars river of substance.  It carried substantial tonnages of sediment and rocks of some size, and laid down deep layers of sediment.

“We’re seeing what looks like the result of sudden, abrupt, high-energy inflow of water, carrying a lot of debris,” said Libby Ives, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory (JPL). “This was no tiny stream; it was a pretty big channel.”

But there’s more.  The river was not only powerful it was also deep — especially where it apparently emptied into a large lake.  This was a very different kind of water environment at ancient Jezero than what the previous NASA rover, Curiosity, found in Gale Crater.

“At Gale, you could wade through the water we found evidence for,” said Kathryn Stack Morgan, deputy science lead for Perseverance and formerly a member of the Curiosity science team.

“Here, we’re talking about scuba diving. This was really surprisingly deep.”

Jezero crater once held a large lake, fed by wide and deep channels. Those large channels then spread and distributary channels (rivers) were carved.  The strong and fast-moving river recently identified by the Perseverance team is near the crater hole in the center of the image.  The wide fossil waterway going from left to upper right is called Nerevta Vallis. (NASA/JPL/JHUAPL/MSSS/Brown University)

Mars scientists have long observed via orbiting satellites what they concluded were deep rivers on Mars.  The area around the recently discovered riverbed actually had features that were interpreted from orbit to form a likely riverbed — part of a network of waterways that flowed into Jezero.

But Stack said that having the rover directly on the ancient riverbed, to have it observing and analyzing a substantial river that once existed, is a very different experience.… Read more

Destination: Europa

An artist rendering of Europa Clipper over Europa. The spacecraft is scheduled to launch in fall 2024.  (NASA/JPL)


These are the words broadcast by the computer HAL as recounted in Arthur C. Clarke’s book “2010: Odyssey Two,” the sequel to the iconic “2001: A Space Odyssey.”

The message had been delivered to the computer by the non-corporeal David Bowman (the focus of the “2001”), but more accurately from the energy-based aliens who control the fate of Bowman, the famous monoliths and much more.  The aliens had concluded that Europa, with its subsurface ocean, could support life with the potential to evolve, and so they wanted the Jovian moon to be protected from meddling by humans or anyone else.

Clarke’s “Odyssey Two” was released in 1982, when Europa was not exactly a front-burner destination for NASA or anyone else.

But much has changed, and Clarke’s early focus on Europa as the most potentially habitable object in the solar system has been embraced by NASA and others for some time.

Surface features of Jupiter’s icy moon Europa are revealed in an image obtained by Juno’s Stellar Reference Unit (SRU) during the spacecraft’s flyby in 2022.  The spacecraft came within 219 miles of the moon.

While the fictional admonition not to land on Europa is (for now, a least) being respected,  the pull of Europa has become enormously strong.


The NASA spaceship Juno recently performed a flyby of the moon and took some revealing new photos. (See above.)

Just last month, the European Space Agency launched the Jupiter Icy Moons Explorer (JUICE)  spacecraft that is headed to Jupiter and three Jovian moons, including Europa.

And now all the parts and instruments of NASA’s Europa Clipper are in a Jet Propulsion Lab clean room for assembly in preparation for an October, 2024 launch. The Clipper will not land on Europa, but it will get closer than any other spacecraft has come.

So while it won’t be until the early 2030s that JUICE and the Clipper have their close encounters with Europa, the moon is very much on the front burner now for astrobiologists, planetary scientists and space (and science fiction) aficionados of all kinds.

This composite includes the four largest moons of Jupiter which are known as the Galilean satellites. These moons were first identified by the Italian astronomer Galileo Galilei in 1610.

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A New Model For How Earth Acquired Its Water

One of the best known photographs of Earth, this image was taken by the crew of the final Apollo mission as the crew made its way to the Moon.  Named the “Blue Marble,” the image highlights how much of the planet is covered by water — 71 percent of the surface.  How this came to be remains an open scientific question.

Theories abound on how Earth got its water.

Most widely embraced is that asteroids, and maybe comets, crashed into our planet and released the water they held — in the form of ice or hydrated minerals in their crystal structures — and over time water became our oceans.  The inflow was especially intense during what is called “the Late Heavy Bombardment,” some 4 billion years ago.

The isotopic composition of our water is comparable to water in asteroids in the outer asteroid belt, and so it makes sense that they could have delivered the water to Earth,

But there is also the view Earth formed with the components of water inside the planet and the H₂O was formed and came to the surface over time.  Several hydrous minerals in our mantle store the necessary elements to create water and in this theory the pressure from hot magma rising up and cooler magma sinking down crushes this hydrous material and wrings them like a sponge.  Water would then find its way to the surface through volcanoes and underwater vents.

Now a new model has been proposed and it has a novel interest because it originates in the discovery of thousands of exoplanets in the past quarter century.

This new approach, described by Anat Shahar of the Carnegie Institution for Science and colleagues from UCLA in the journal Nature, says that Earth’s water could have come from the interactions between of a very early and primarily hydrogen atmosphere and the scalding ocean of magma that covered the planet.

That the planet could have had a thick hydrogen atmosphere that wasn’t quickly destroyed is a new idea and it comes from the finding that many so-called “super-Earth” exoplanets have, or had, such an atmosphere.  While super-Earths are larger and more massive than Earth, many are rocky, terrestrial planets and so share characteristics with our planet.

“Exoplanet discoveries have given us a much greater appreciation of how common it is for just-formed planets to be surrounded by atmospheres that are rich in molecular hydrogen, H2, during their first several million years of growth,” Shahar said.… Read more

Pam Conrad: The NASA Astrobiologist Who Also Became a Minister

Pan Conrad on her last Sunday as rector of St. Albans Episcopal Church in Glen Burnie, Maryland. (Julian Lahdelma)

Science and religion so often seem to be in conflict, with the chasm between them widening all the time.

For many, the grounding of their religion is in faith and belief in powers beyond our understanding.  For people of science, the grounding is in empirical facts and measurements that can be tested to help explain our world.

The conflicts between science and religion have been many,  perhaps most intensely on issues including evolution, how life on Earth began and how our universe came to be.

The era of pioneering scientists being punished or hounded by religious leaders — think of Galileo, astrobiologist-before-his-time Giordano Bruno, Charles Darwin — is largely in the past.  But so too is the era when the most prominent natural scientists were profoundly religious people, such as Sir Isaac Newton, James Maxwell (who correctly theorized the nature of electromagnetism) and one of the 19th century physicist and scientific titan, Lord Kelvin.

The field of astrobiology presents innumerable issues where a scientific and religious focus certainly could clash.  Astrobiology is focused on the search for life beyond Earth which, if detected, could raise significant issues for some religious people.

The astrobiology effort is grounded in our scientific theories of how the universe began and evolved over its 13.6 billion years, so spiritual and religious views that once dominated thinking about these questions play little role.

And then there is the origin-of-life issue, which is also part of astrobiology and is, of course, an arena where scientific and religious views are often in conflict.

With so many divides between a scientific and a religious approach to astrobiological questions, it might seem that there is little room for overlap.

Conrad has worked on the characterization of biosignatures and the habitability of Mars, first at JPL and now at the Earth and Planets Laboratory at the Carnegie Institution of Science. She worked on the science team of the Curiosity rover on Mars and now she works with three instruments on the Perseverance rover at Jezero Crater, Mars. (NASA)

But then I spoke with the Rev. Pamela Conrad, who I knew from some years ago when we often talked about astrobiology and even took a trip to Death Valley together, where she helped me understand some of the science of life surviving in extreme environments and how to find it.… Read more

The Strange Interstellar Object Oumuamua Was a Comet and Not The Space Probe Some Had Proposed

New research concludes that the interstellar object that entered our solar system and then rocketed out was a small comet and not a spacecraft, as some had speculated. (JPL/NASA)

In 2017, an  unusual small object flew into our solar system from afar,  approached the inner solar system and the Sun and then sped back out to interstellar space.  In all, it was detected and followed for 11 days.

The object was puzzling because such interstellar visitors had not been observed before, and most mysterious because it accelerated in a most unusual way out of the solar system.  This was not the normal behavior of any object in the solar system.

The object, a few hundred meters in length, was first identified as an asteroid because it had not of the sparkle of a comet, and a “dark comet” was proposed, and  then  something perhaps sent by aliens to explore the solar system.  After all, the shape of the object known as ‘Oumuamua — Hawaiian for “Scout”– was described as reddish and sometimes shaped like a pancake and sometimes like a cigar.

‘Oumuamua became an object of great fascination among space scientists and even became the subject a popular book by a Harvard astronomer who argued that it was clearly an alien lightsail. That is, a probe that is propelled by the propulsive radiation of starlight itself.

Now, a paper offers a very different, and apparently quite compelling, explanation.,

In Nature, University of California, Berkeley astrochemist Jennifer Bregner and Cornell University astronomer Darryl propose that the comet’s mysterious deviations from a typical object’s path around the Sun can be explained by a simple physical mechanism likely common among many icy comets: outgassing of hydrogen as the comet warmed up in the sunlight.

What made ‘Oumuamua different from every other well-studied comet in our solar system was its size. It was so small that the gravitational nudge it received around the Sun was slightly altered by the tiny push created when hydrogen gas spurted out of the ice.

And that’s what caused the acceleration, the scientists say.

An artist rendering of ‘Oumuamua, the first known alien object to enter our solar system. It was identified by the Pan-STARRS 1 telescope in Hawaii. It was later followed by observatories around the world and astronomers generally concluded that it had been traveling for millions of years before its chance encounter with our solar system.

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A Scientific Bonanza From Asteroid Ryugu and Hayabusa2

Optical microscope images of six particle samples that were selected from what Hayabusa2 brought back to Earth from asteroid Ryugu. {Japan Aerospace Expedition Agency (JAXA), Science.}

Collecting and transporting back to Earth samples of other planets, moons, asteroids and comets is extremely difficult, costly and time-consuming.  But as just-released papers based on Japan’s Hayabusa2 sample return mission to the asteroid Ryugu make abundantly clear, the results can be fabulous.

In a series of articles in the journal Science, scientists who studied the samples (which were returned to Earth in late 2020) and commentators marvel at the opportunity to study material that was formed as the solar system itself formed — more than 4.5 billion years ago.

The sample contains thousands of different organic (carbon-based) molecules of different kinds, including amino acids and a range of aromatic hydrocarbons.  There are also many minerals formed in the presence of water.

This composition was not a big surprise based on other similar carbon-based meteorites that have fallen to Earth. But they were totally clean samples that were in no way contaminated by life and  physical conditions on our planet. They also had not made the fiery passage through our atmosphere before landing and becoming a meteorite that someone may chance to find.

What they are, then, are pristine examples of the early solar system — solar system baby pictures — with the chemistry and physical thumbprints of the solar nebula and interstellar space from which our Sun and solar system were formed.

The asteroid Ryugu at 30 miles, as photographed by Hayabusa2.  Ryugu is a near-Earth asteroid, far from the main asteroid belt between Mars and Jupiter.   (JAXA, University of Tokyo and collaborators)

The return capsule brought back about 10 grams of the asteroid.  That might not seem like a lot, but it was more than enough to learn a great deal about an important asteroid from an ancient asteroid family.

As Hiroshi Naraoka of Kyushu University and his colleagues conclude in their Ryugu paper, “Meteorites made of material similar to Ryugu may have delivered amino acids and other prebiotic organic molecules to the early Earth and other rocky planets — providing the building blocks of life.”

Ryugu provides the best chance to date to study what precisely could have been delivered.

Hayabusa2 touchdown on asteroid Ryugu in 2019. (JAXA)

The studies together tell the history of Ryugu, its history and its composition. Read more

Many Complex Organic Compounds –Evolved Building Blocks of Life — Are Formed Where Stars Are Being Born

The Taurus Molecular Cloud is an active site for star formation.  It is also filled with complex organic molecules, including the kind that are building blocks for life.  The Cloud is 450 light years away, but similar star-forming regions with complex organics are found thoughout the galaxy. (Adapted, ESA/Herschel/NASA/JPL-Caltech)

Recent reports about the detection of carbon-based organic molecules on Mars by the instruments of the Perseverance rover included suggestions that some of the organics may well have fallen from space over the eons, and were then preserved on the Martian surface.

Given the cruciality of organics as building blocks of life –or even as biosignatures of past life — it seems surely important to understand more about how and where the organics might form in interstellar space, and how they might get to Mars, Earth and elsewhere.

After all, “follow the organics” has replaced the NASA rallying cry to “follow the water” in the search for extraterrestrial life in the solar system and cosmos.

And it turns out that seeking out and identifying organics in space is a growing field of its own that has produced many surprising discoveries.  That was made clear during a recent NASA webinar featuring Samantha Scibelli of the University of Arizona, a doctoral student in astronomy and astrophysics who has spent long hours looking for these organics in space and finding them.

She and associate professor of astronomy Yancy Shirley have been studying the presence and nature of complex organics in particular in a rich star-forming region, the Taurus Molecular Cloud.

Using the nearby radio observatory at Kitt Peak outside of Tucson, she has found a range of complex organics in starless or pre-stellar cores with the Cloud.  The campaign is unique in that some 700 hours of observing time were given to them, allowing for perhaps the most thorough observations of its kind.

The results have been surprising and intriguing.

In this mosaic image stretching 340 light-years across, the James Webb’s Near-Infrared Camera (NIRCam) displays the Tarantula Nebula star-forming region in a new light, including tens of thousands of never-before-seen young stars that were previously shrouded in cosmic dust. The most active region appears to sparkle with massive young stars, appearing pale blue. (NASA/STScI)

A first take-away (surprising to those unfamiliar with the field) is that complex organics are often detected in these star-forming regions throughout the galaxy and cosmos — just as they were found in many regions of the Taurus cloud.… Read more

The Cosmos, As Viewed By The James Webb Space Telescope

The iconic “Pillars of Creation” image, on left, was taken in visible light by the Hubble Space Telescope in 2014. A new, near-infrared-light view from NASA’s James Webb Space Telescope, at right, helps us peer through more of the dust in this star-forming region. The thick, dusty brown pillars are no longer as opaque and many more red stars that are still forming come into view.  The pillars of gas and dust seem darker and less penetrable in Hubble’s view, and they appear more permeable in Webb’s. (NASA)

The James Webb Space Telescope was developed to allow us to see the cosmos in a new way — with much greater precision, using infrared wavelengths to piece through dust around galaxies, stars and planets, and to look further back into time and space.

In the less than four months since the first Webb images were released,  the pioneering telescope has certainly shown us a remarkable range of abilities.  And as a result, we’ve been treated to some dazzling new views of the solar system, the galaxy and beyond.  This is just the beginning and we thankfully have years to come of new images and the scientific insights that come with them.

Just as the Hubble Space Telescope, with its 32 years of service and counting, ushered in a new era of space imagining and understanding, so too is the Webb telescope revolutionizing how we see and understand our world writ large.  Very large.

Neptune as seen by Voyager 2 during a flyby more than three decades ago, the Hubble Space Telescope last year, and the JWST this summer. ( NASA/ESA/CSA))

The differences between the Webb’s image and previous images of Neptune are certainly dramatic, in terms of color, precision and what they tell us about the planet.

Surely most striking in Webb’s new image is the crisp view of the planet’s rings, some of which have not been seen since NASA’s Voyager 2 became the first spacecraft to observe Neptune during its flyby in 1989. In addition to several bright, narrow rings, the Webb image clearly shows Neptune’s fainter, never-seen dust bands as well.

Neptune is an ice giant planet. Unlike Jupiter and Saturn, which consist primarily of hydrogen and helium, Neptune has an interior that is much richer in heavier elements (“heavier is the sense of not hydrogen or helium.) One of the most abundant heavy molecules is methane, which appears blue in Hubble’s visible wavelengths but largely white in the Webb’s near-infrared camera.… Read more

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