Astro Blog

By Dennis Normile , Science.  Excerpt: Over decades, lunar orbiters have amassed evidence that the Moon’s polar craters hold stores of water, locked up as ice. But no mission has directly sampled these frozen deposits to determine how much ice is there, how it is distributed, or how it got there in the first place. As early as next week, China will launch Chang’e-7, a robotic mission designed to address those questions by sending a thruster-powered “hopping” probe into a crater near the lunar south pole, among the coldest, darkest places in the Solar System. ...with the Chang’e missions, named after a Chinese Moon goddess, China “grew its capabilities step by step,” he says, progressing from orbiters to landers, rovers, and, most recently, the first sample return from the Moon’s far side . ...Rocks returned by the Apollo missions of the 1960s and ’70s have long suggested sunlit regions of the Moon are nearly bone dry. But in the 1990s, NASA’s Clementine and Lunar Prospector orbiter...

By Science Advisor.  Excerpt: If the space community had to place bets on the most promising candidate for life in the solar system, Enceladus would probably win...a salty liquid ocean, as well as compounds like phosphorus and complex hydrocarbons, all necessary for life as we know it on Earth. But the world had been missing one crucial factor: stability. Since life takes a long time to evolve, a good candidate world should remain stable over many millions or billions of years. Stability is often determined through a world’s heat balance, where the amount of energy it receives from its star equals the amount of energy it radiates outward. Though scientists knew that Enceladus’s southern pole leaked out heat from the forces of Saturn’s gravity stretching and squashing the world, its heat balance was still off. But when researchers used data from NASA’s Cassini mission to study Enceladus’s north pole, they found that  the surface was around 7ºC warmer than the models predicted ....

By Robert Sanders , UC Berkeley News.  Excerpt: Mars today is a cold, dry, dusty planet with its only obvious water locked up in frozen polar ice caps. But billions of years ago, it appears to have had sandy beaches lapped by waves along the shoreline of a vast ocean. The evidence for beaches on Mars comes from a Chinese rover, called Zhurong, that landed on the planet in 2021. During its short life it detected evidence of underground beach deposits in an area thought to have once been the site of an ancient sea, bolstering the idea that the planet long ago had large bodies of water. ...between May 2021 and May 2022, Zhurong traveled 1.9 kilometers (1.2 miles) roughly perpendicular to escarpments thought to be an ancient shoreline from a time — 4 billion years ago — when Mars had a thicker atmosphere and a warmer climate. Along its path, the rover used ground penetrating radar (GPR) to probe up to 80 meters (260 feet) beneath the surface. ...“The structures don’t look like sand du...

By Sarah Stanley , Eos/AGU.  Excerpt: A closer look at previously disregarded observations reveals stronger evidence that a deep ocean lies beneath Callisto’s icy surface. ... Cochrane et al.  have revisited the Galileo data in more detail. Unlike in prior studies, this team incorporated all available magnetic measurements from Galileo’s eight close flybys of Callisto. Their expanded analysis much more strongly suggests that Callisto hosts a subsurface ocean....  Full article at https://eos.org/research-spotlights/jupiters-moon-callisto-is-very-likely-an-ocean-world . 

By Katherine Kornei , Eos/AGU.  Excerpt: In 2011, a striking black rock about the size of an apple was discovered in the Sahara desert. ...that meteorite, which has come to be known as NWA 7034, or “Black Beauty,” is different from most other meteorites: It’s a chunk of Mars. ...Tiny grains of zircon from NWA 7034 have now revealed that hydrothermal activity likely persisted in Mars’s crust 4.45 billion years ago. That’s the earliest indirect evidence of water on the Red Planet....  Full article at https://eos.org/articles/martian-meteorite-points-to-ancient-hydrothermal-activity . 

By Saima May Sidik , Eos/AGU.  Excerpt: Geological evidence on Mars indicates that 3.6 billion years ago, an intense pulse of water carved rivers and lakes across the planet, an abrupt shift from the preceding 500-million-year era of much gentler fluvial activity. Researchers have long  puzzled over  the cause. A new study by  Buhler  shows, paradoxically, that the collapse of the Martian atmosphere and entry into a  colder  climate may have melted the polar ice cap and triggered global-scale flooding. ...In total, about 4% to 40% of the water ice could have melted, an amount of water equivalent to between 20% and 200% of the  water currently found near the surface on Mars ....  Full article at https://eos.org/research-spotlights/how-an-ocean-sized-lake-may-have-formed-on-ancient-mars . 

By Kimberly M. S. Cartier , Eos/AGU.  Excerpt: Europa Clipper launched at 12:06 pm EDT on 14 October from NASA’s Kennedy Space Center in Florida. Clipper successfully deployed its solar panels and communicated with mission control once in space. ...NASA’s Europa Clipper spacecraft...will head to Jupiter’s icy moon Europa and determine whether it’s a hospitable place for life. ...There will be 49 flybys of Europa to study the moon from pole to pole ...The craft is set to  arrive  at Jupiter in April 2030. ...Europa is one of Jupiter’s four Galilean moons. Past missions to the Jovian system discovered that Europa, along with fellow icy moons Ganymede and Callisto, have vast liquid water oceans sloshing around beneath icy shells. “ Ocean worlds  have been considered potentially habitable environments for a while,” said  Monica Vidaurri , a doctoral student in planetary modeling at Stanford University in California. “This is the first time we’re really dedicating a...

By Vashan Wright ,  Matthias Morzfeld , and  Michael Manga , PNAS - Proceedings of the National Academy of Sciences.  Abstract: Large volumes of liquid water transiently existed on the surface of Mars more than 3 billion years ago. Much of this water is hypothesized to have been sequestered in the subsurface or lost to space. We use rock physics models and Bayesian inversion to identify combinations of lithology, liquid water saturation, porosity, and pore shape consistent with the constrained mid-crust (∼11.5 to 20 km depths) seismic velocities and gravity near the InSight lander. A mid-crust composed of fractured igneous rocks saturated with liquid water best explains the existing data. Our results have implications for understanding Mars’ water cycle, determining the fates of past surface water, searching for past or extant life, and assessing in situ resource utilization for future missions.  Full article at https://www.pnas.org/doi/10.1073/pnas.24...

By EMILY LAKDAWALLA  , Sky & Telescope.  Excerpt: Martian gullies have been the center of a debate about whether Mars ever has flowing water. Now, a comprehensive study examines the question. Lots of Mars’s hillslopes have gullies, steep ravines that grow when we’re not looking. They look so much like Earth’s own gullies, formed when water and debris carve into steep slopes, that it’s easy to think that water must be involved on Mars, too. But physics says water shouldn’t ever be liquid anywhere on the Martian surface today. Many scientists therefore think gully formation must be triggered by some kind of dry process, involving ice (either water ice or carbon dioxide ice) that  sublimates  directly from solid to gas. In a new study, published in the August 2024 issue of  Icarus , Axel Noblet (University of Western Ontario, Canada) and colleagues amass data on nearly 8,000 gullied slopes and come up with an answer to the “wet or dry” question: It’s both, and ...

By Damond Benningfield , Eos/AGU.  Excerpt: The  Winchcombe meteorite  splashed into headlines on 28 February 2021, when it streaked above Gloucestershire, England, and broke apart in the atmosphere. Its largest chunk hit a driveway in the village of Winchcombe and splattered into thousands of pieces. ... Analysis of the meteorite  and video of its descent revealed that its parent meteoroid was probably 20–30 centimeters in diameter when it hit the atmosphere, with a mass of about 13 kilograms. ...The research team’s analyses revealed that the meteorite contains eight rock types, all of which show evidence of having been altered by water. ...In addition to revealing the asteroid’s history, the lab work also supported the suggestion that CM and other carbonaceous chondrites supplied young Earth with water and organic compounds....  Full article at https://eos.org/articles/a-splashy-meteorite-was-forged-in-multiple-collisions . 

By JONATHAN O’CALLAGHAN , Science.  Excerpt: With surface temperatures hot enough to melt lead, Venus today is a veritable hellhole, despite being similar in size to Earth and orbiting in the habitable zone of the Sun. Yet studies suggest the planet may have once hosted oceans and even conditions suitable for life. Explaining how all that water disappeared has been a problem. A study  published today  in Nature offers a solution, identifying a new water-loss mechanism operating high in Venus’s atmosphere that could have doubled the rate of water loss. Speedier drying could have allowed oceans to exist until later in Venus’s history—implying the planet might have been habitable for longer. ...At 96% carbon dioxide, its atmosphere traps so much heat that surface temperatures reach more than 450°C. Yet spacecraft and telescopes have seen faint hints of water vapor in the atmosphere, and in the late 1970s, NASA’s Pioneer Venus orbiter detected a sign of long-vanishe...

https://eos.org/agu-news/oceans-of-opportunity By Caryl-Sue Micalizio , Eos/AGU.   Our solar system’s ocean worlds—planets and moons covered in ice-crusted oceans—are weird, wonderful, and ripe for exploration. [Here are a series of articles] Uranus: A Time to Boldly Go by Kimberly Cartier; Marine Science Goes to Space by Damond Benningfield on how ocean worlds are redefining what constitutes a habitable zone and how missions in development, like JUICE and Europa Clipper, are relying on terrestrial deep-sea scientific advances to look for oceanic activity that’s out of this world. ...older missions are still contributing to the discourse, as archival  Cassini data helped scientists identify phosphorus —the rarest element necessary for life as we know it—on Enceladus. ...Erik Klemetti explores Cryovolcanism’s Song of Ice and Fire .... 

https://www.nasa.gov/feature/goddard/2023/webb-detects-water-vapor-in-rocky-planet-forming-zone By NASA.  Excerpt: Water is essential for life as we know it. However, scientists debate how it reached the Earth and whether the same processes could seed rocky exoplanets orbiting distant stars. New insights may come from the planetary system PDS 70, located 370 light-years away. The star hosts both an inner disk and outer disk of gas and dust, separated by a 5 billion-mile-wide (8 billion kilometer) gap, and within that gap are two known gas-giant planets. New measurements by NASA’s James Webb Space Telescope’s MIRI (Mid-Infrared Instrument) have detected water vapor in the system’s inner disk, at distances of less than 100 million miles (160 million kilometers) from the star – the region where rocky, terrestrial planets may be forming. (The Earth orbits 93 million miles from our Sun.) This is the first detection of water in the terrestrial region of a disk already known to host two o...

https://skyandtelescope.org/astronomy-news/four-of-uranuss-moons-might-contain-briny-oceans/ By Emily Lakdawala, Sky & Telescope.  Excerpt: A  new paper re-analyzing Voyager observations  suggests that four of Uranus’ five icy satellites also host oceans: Ariel, Umbriel, Titania, and Oberon. (Only small Miranda, intermediate in size between Saturn’s Mimas and Enceladus, appears not to.) The oceans are desperately thin: less than 30 kilometers (20 miles) thick inside Ariel and Umbriel (both of which are about 1,000 kilometers across, similar in size to Saturn’s Tethys and Dione), and less than 50 kilometers thick within Titania and Oberon (which are larger at about 1,500 kilometers, similar to Saturn’s Rhea and Iapetus). If the oceans exist, they would be left over from much larger liquid layers that formed when the moons first formed. ...They’d be extremely briny, hyper-concentrated with whatever dissolved materials helped to lower the temperature at which water would...

https://eos.org/features/marine-science-goes-to-space By Damond Benningfield , Eos/AGU.  Excerpt: Cassini  discoveries added  Enceladus to a growing list of possible ocean worlds in our own solar system—bodies with large amounts of liquid water hidden from view. Some of them could contain more water than all of Earth’s oceans combined. And in addition to Enceladus, planetary scientists have counted at least one other member of the list, Jupiter’s moon  Europa , among the ranks of the “possibly habitable.” “There could be life in our own solar system, and we may already have flown past it,” said  Christopher German , a senior scientist at  Woods Hole Oceanographic Institution and a coleader of  Network for Ocean Worlds  (NOW), a NASA-funded effort to advance research on these intriguing bodies. “Instead of just a sci-fi thing, suddenly we have grounds for wondering if there’s life on these nearby worlds—places we have the technology to reach.” ......

https://eos.org/research-spotlights/long-lived-lakes-reveal-a-history-of-water-on-mars By  Sarah Derouin , Eos/AGU.  Excerpt: The northern hemisphere of Mars is divided into two broadly distinctive areas: the smooth northern lowlands and the pockmarked southern highlands. The region of  Arabia Terra  ...is thought to contain some of the planet’s oldest rocks, at more than 3.7 billion years old. Among the craters in the southern highlands, valleys and paleolakes abound, exposing sedimentary and geomorphologic evidence of liquid water. However, relatively few paleolakes have been identified in Arabia Terra.  Dickeson et al.  ...describe seven new paleolakes in the region. The researchers focused on paleolake features including lake levels, drainage catchments, fans, and lake outlets. ...There was evidence of surface water inflows that filled the lakes as well as outlet streams that drained them, forming a cascading chain of lakes. The team also observed multi...

https://www.theguardian.com/science/2022/nov/16/meteorite-that-landed-in-cotswolds-may-solve-mystery-of-earths-water By  Hannah Devlin , The Guardian.  Excerpt: Water covers three-quarters of the Earth’s surface and was crucial for the emergence of life, but its origins have remained a subject of active debate among scientists. Now, a 4.6bn-year-old rock that crashed on to a  driveway in Gloucestershire last year  has provided some of the most compelling evidence to date that water arrived on Earth from asteroids in the outer solar system.... 

https://www.nytimes.com/2021/03/19/science/mars-water-missing.html Source:  By  Kenneth Chang , The New York Times.  Excerpt: Mars once had rivers, lakes and seas. Although the planet is now desert dry, scientists say most of the water is still there, just locked up in rocks. ...most of the water, a new study concludes, went down, sucked into the red planet’s rocks. And there it remains, trapped within minerals and salts. Indeed, as much as 99 percent of the water that once flowed on Mars could still be there, the researchers estimated in  a paper published this week in the journal Science.  Data from the past two decades of robotic missions to Mars, including NASA’s Curiosity rover and the Mars Reconnaissance Orbiter, showed a wide distribution of what geologists call hydrated minerals.... 

https://eos.org/research-spotlights/moon-may-hold-billions-of-tons-of-subterranean-ice-at-its-poles Source:  By Jerald Pinson, Eos/AGU.  Excerpt: New research indicates that if even a moderate amount of the water delivered by asteroids to the Moon was sequestered, the lunar poles would contain gigaton deposits (1 billion metric tons) of ice in sheltered craters and beneath its surface. ...“We looked at the entire time history of ice deposition on the Moon,” said   Kevin Cannon , a planetary scientist at the Colorado School of Mines in Golden and lead author of the   new study   in the AGU journal Geophysical Research Letters. Cannon and his team used conservative estimates for the amount of water that asteroids were likely to contain upon impact with the Moon and how much of it was likely to be retained once the dust had settled. ...“If the very oldest regions have been stable and accumulating ice for billions of years, then some could have very substantial de...

https://www.sciencemag.org/news/2020/11/famed-meteorite-reveals-early-water-mars-and-early-outer-space-bombardment Source:  By   Paul Voosen .  Excerpt: With just 15 grams of the 4.4-billion-year-old   “Black Beauty” meteorite   [from Mars] discovered in 2011 in the western Sahara, [Martin Bizzarro’s] team has revealed a record of asteroid impacts and volcanic eruptions spanning nearly all of martian history. One of the most surprising findings: After Mars underwent a pummeling early in its life, all went quiet—even during a time, nearly 4 billion years ago, when our Solar System was thought to have suffered a cataclysmic assault... .