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

What the JWST is Learning About Exoplanet Atmospheres

We are now well into the era of exoplanet atmospheres, of measurements made possible by the James Webb Space Telescope.  While prior observatories could detect some chemicals in exoplanet atmospheres,  the limits were substantial. This is an artist’s impression of a hot Jupiter with a thick atmosphere transiting its host star. (NASA, ESA, and G. Bacon (STScI)

The James Webb Space Telescope is beginning to reveal previously unknowable facts about the composition of exoplanets — about the presence or absence of atmospheres around the exoplanets and the makeup of any atmospheres that are detected.

The results have been coming in for some months and they are a delight to scientists.  And as with most things about exoplanets, the results are not always what were expected.

For instance, gas giant planets  orbiting our Sun show a clear pattern; the more massive the planet, the lower the percentage of “heavy” elements (anything other than hydrogen and helium) in the planet’s atmosphere.

The James Webb Space Telescope is returning insights into the atmospheres of exoplanets that scientists have long dreamed about obtaining. Some are predicting a new era in exoplanet research. (NASA)

But out in the galaxy, the atmospheric compositions of giant planets do not fit the solar system trend, an international team of astronomers has found.

Researchers discovered that the atmosphere of exoplanet HD149026b, a “hot jupiter” given the name “Smertrios” that orbits a Sun-like star, is super-abundant in the heavier elements carbon and oxygen – far above what scientists would expect for a planet of its mass.

In its “early release” program for exoplanet results, JWST also observed WASP-39 b, a “hot Saturn” (a planet about as massive as Saturn but in an orbit tighter than Mercury) orbiting a star some 700 light-years away.

The atmosphere around the planet provided the first detection in an exoplanet atmosphere of sulfur dioxide (SO2), a molecule produced from chemical reactions triggered by high-energy light from the planet’s parent star.

The Trappist-1 system –seven Earth-sized planets orbiting a red dwarf star only 40 light-years away — is another subject of great interest and JWST has provided some exciting results there too.

While the first Trappist-1 planet studied — the one nearest to the star — apparently has no atmosphere, JWST was able to in effect take the planet’s temperature.  The telescope captured thermal signatures from the planet, which is another first.

When starlight passes through a planet’s atmosphere, certain parts of the light are absorbed by the atmosphere’s elements.

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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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What Would Happen If Our Solar System Had a Super-Earth Like Many Others? Chaos.

Our solar system’s rocky planets are tiny compared with the larger gas and ice giants. Exoplanet research has found, however, that the most common planets in the galaxy appear to be super-Earths and sub-Neptunes, types of planets not found in our system. Size comparison of the planets. (Alexaldo/iStock/Getty)

Before astronomers began to find planets — many, many planets — orbiting Suns other than ours,  the scientific consensus was that if other solar systems were ever found they would probably look much like ours.  That would mean small, rocky planets closest to the Sun and large gaseous planets further out.

That assumption crash and burned with the discovery of the first discovery of an exoplanet orbiting a star — 51 Peg.  It was a hot, Jupiter-sized planet that circled its Sun in four days.

That planetary rude awakening was followed by many others, including the discovery of many rocky planets much larger than those in our system which came to be called  super-Earths.  And equally common are gaseous planets quite a bit smaller than any near us, given the name sub-Neptunes.

Many papers have been written theorizing why there are no super-Earth or sub-Neptunes in our solar system.  And now astrophysicist Stephen Kane of the University of California, Riverside has taken the debate another direction by asking this question:  What would happen to our solar system planets if a super-Earth or sub-Neptune was present?

The results of his dynamic computer simulations are not pretty: the orbits of many of our planets would change substantially and that would ultimately result in some being kicked out of the solar system forever.  The forces of orbit-transforming gravity set loose by the addition of a super-Earth are strong indeed.

The term super-Earth is a reference only to an exoplanet’s size – larger than Earth and smaller than Neptune – but not suggesting they are necessarily similar to our home planet. The true nature of these planets, such as Gliese 832c, above, remains ambiguous because we have nothing like it in our own solar system. Super-Earths they are common among planets found so far in our galaxy. (Planetary Habitability Laboratory/University of Puerto Rico at Arecibo)

Let’s go back to our actual solar system for some context.

The gap in size between the size of our terrestrial planets and giant gas planets is great. The largest terrestrial planet is Earth, and the smallest gas giant is Neptune, which is four times wider and 17 times more massive than Earth.… Read more

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

New Martian Surprise From The Curiosity Rover

NASA researchers found that waves on the surface of a shallow lake in Gale Crater stirred up sediment billions of years ago. That sediment eventually creating rippled textures left in rock. (NASA/JPLVCaltech/MSSS)

In its more than a decade of exploring Gale Crater on Mars, the rover Curiosity has found innumerable signs of the presence of long-ago water.

There have been fossil streams, alluvial fans, lakes shallow and deep, deltas and countless examples of rocks infiltrated and chemically transformed in the presence of water.  The picture of the crater as a watery environment in the warmer and wetter days of Martian history — 4 billion to 3 billion years ago — is well established.

Nonetheless. it still came as a wonder that the rover came across the entirely unexpected remains of fossilized ripples in a shallow lake bed.  What was even more surprising is that it was found in an area previously determined to have little likelihood of having ever been wet.

“Billions of years ago, waves on the surface of a shallow lake stirred up sediment at the lake bottom, over time creating rippled textures left in rock,” NASA said in a statement last week.

It was the first time such a feature has been discovered in Gale Crater, although the rover has passed through numerous fossil lake beds.

The Marker Band is a continuous dark, thin and hard layer running from left to right (but thinning out on the left) setting off the region of the rippled rock bed.   Both its composition and origins are not well understood. (NASA/JPL-Caltech)

One of the mission’s main goals has been to find out if this area in the southern highlands of Mars might have once been habitable for microbial life.

It was determined within the first two years of the rover’s time in Gale Crater that the crater was indeed once habitable based on the past presence of significant amounts of water and chemicals left behind by that long-departed water. Understanding the crater’s history of water has been a central goal of the mission.

The Curiosity team was thrilled by their new find.

“This is the best evidence of water and waves that we’ve seen in the entire mission,” said Curiosity project scientist Ashwin Vasavada. “We climbed through thousands of feet of lake deposits and never saw evidence like this.”

The rippled fossils are in an area set off by a black, hard-rock line called the “Marker Band.”… Read more

A New Twist On Planet Formation

This image of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are being formed in this protoplanetary disk. {ESO, Atacama Large Millimeter/submillimeter Array (ALMA)}

Before the first exoplanets were discovered in the 1990s,  our own solar system served as the model for what solar systems looked like.  The physical and chemical dynamics that formed our system were also seen as the default model for what might have occurred in solar systems yet to be found.

As the number of exoplanets identified ballooned via the Kepler Space Telescope and others, and  it became clear that exoplanets were everywhere and orbiting most every star, the model of our own solar system became obviously flawed.  The first exoplanet identified, after all, was a “hot Jupiter” orbiting very close to its star — a planetary placement previously thought to be impossible.

With the growing number of known exoplanets and their most unusual placements, the field of planet formation — focused earlier on understanding on how the planets of our system came into being and what they were made of — expanded to take in the completely re-arranged planetary and solar system menagerie being found.

This was basic science seeking to understand these newfound worlds, but it also became part of the fast-growing field of astrobiology, the search for planets that might be habitable like our own.

In this context, planet formation became associated with the effort to learn more about the dynamics that actually make a planet habitable — the needed composition of a planet, the nature of its Sun, its placement in a solar system and how exactly it was formed.

So the logic of planet formation became the subject of myriad efforts to understand what might happen when a star is born, surrounded by a ring of gas and dust that will in time include larger and larger collections of solids that can evolve into meteors, planetesimals and if all goes a particular way, into planets.

A thin section of primitive meteorite under a microscope. The various colors suggest different minerals that comprise meteorites. The round-shaped mineral aggregates are called chondrules, which are among the oldest known materials in our solar system. (Science)

As part of this very broad effort to understand better how planets form, meteorites have been widely used to learn about what the early solar system was like. Meteorites are from asteroids that formed within the first several million years of planetary accretion.… Read more

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