Careful reanalysis of data from more than a decade ago indicates that Saturn’s biggest moon, Titan, does not have a vast ocean beneath its icy surface, . Instead, a journey below the frozen exterior likely involves more ice giving way to slushy tunnels and pockets of meltwater near the rocky core.

Data from NASA’s to Saturn initially led researchers to suspect a large ocean composed of liquid water under the ice on Titan. However, when they modeled the moon with an ocean, the results didn’t match the physical properties described by the data. A fresh look yielded new — slushier — results. The findings could spark similar inquiries into other worlds in the solar system and help narrow the search for life on Titan.

“Instead of an open ocean like we have here on Earth, we’re probably looking at something more like Arctic sea ice or aquifers, which has implications for what type of life we might find, but also the availability of nutrients, energy and so on,” said , a ����Ӱ�Ӵ�ý assistant professor of Earth and space sciences.

The study, , was led by NASA with collaboration from Journaux and , a UW graduate student of Earth and space sciences in his lab.

The Cassini mission, which began in 1997 and lasted nearly 20 years, produced volumes of data about Saturn and its 274 moons. — shrouded by a hazy atmosphere — is the only world, apart from Earth, known to have liquid on its surface. Temperatures hover around -297 degrees Fahrenheit. Instead of water, liquid methane forms lakes and falls as rain.

As Titan circled Saturn in an elliptical orbit, the researchers observed the moon stretching and smushing depending on where it was in relation to Saturn. In 2008, they proposed that Titan must possess a huge ocean beneath the surface to allow such significant deformation.

“The degree of deformation depends on Titan’s interior structure. A deep ocean would permit the crust to flex more under Saturn’s gravitational pull, but if Titan were entirely frozen, it wouldn’t deform as much,” Journaux said. “The deformation we detected during the initial analysis of the Cassini mission data could have been compatible with a global ocean, but now we know that isn’t the full story.”

In this study, the researchers introduce a new level of subtlety: timing. Titan’s shape shifting lags about 15 hours behind the peak of Saturn’s gravitational pull. Like a spoon stirring honey, it takes more energy to move a thick, viscous substance than liquid water. Measuring the delay told scientists how much energy it takes to change Titan’s shape, allowing them to make inferences about the viscosity of the interior.

The amount of energy lost, or dissipated, in Titan was much greater than the researchers expected to see in the global ocean scenario.

“Nobody was expecting very strong energy dissipation inside Titan. That was the smoking gun indicating that Titan’s interior is different from what was inferred from previous analyses,” said , a postdoctoral fellow at NASA’s Jet Propulsion Laboratory, who led the study.

The model they propose instead features more slush and quite a bit less liquid water. Slush is thick enough to explain the lag but still contains water, enabling Titan to morph when tugged.

Petricca arrived at this conclusion by measuring the frequency of radio waves coming from the Cassini spacecraft during Titan fly-bys, and Journaux helped ground the results with thermodynamics. Journaux studies water and minerals under extreme pressure to gauge the potential for life on other planets.

“The watery layer on Titan is so thick, the pressure is so immense, that the physics of water changes. Water and ice behave in a different way than sea water here on Earth,” Journaux said.

His has spent years developing the methods to simulate extraterrestrial environments in the lab. He was able to provide Petricca and colleagues with a dataset describing the anticipated physical properties of water and ice deep inside Titan.

“We could help them determine what gravitational signal they should expect to see based on the experiments made here at UW,” Journaux said. “It was very rewarding.”

“The discovery of a slushy layer on Titan also has exciting implications for the search for life beyond our solar system,” Jones said. “It expands the range of environments we might consider habitable.”

Although the notion of an ocean on Titan invigorated the search for life there, the researchers believe the new findings might improve the odds of finding it. Analyses indicate that the pockets of freshwater on Titan could reach 68 degrees Fahrenheit. Any available nutrients would be more concentrated in a small volume of water, compared to an open ocean, which could facilitate the growth of simple organisms.

While it is unlikely that the researchers discover fish wriggling through slushy channels, if life is found on Titan, it may resemble polar ecosystems on Earth.

Journaux is on the team for to Titan, scheduled for launch in 2028. The data collected here will guide the mission and Journaux hopes to return with some evidence of life on the planet and a definitive answer about the ocean.

Co-authors include , , , , , and from NASA; at Southwest Research Institute; and from the University of Nantes; from the University of Bologna; from the California Institute of Technology and from Sapienza University of Rome.

This research was funded by NASA, the Swiss National Science Foundation and the Italian Space Agency.��

For more information, contact Journaux at bjournau@uw.edu or Petricca at flavio.petricca@jpl.nasa.gov.����

This story was adapted from .

On Monday, large parts of the United States will experience a . This eclipse is expected to be a more significant event than the one in 2017, and the next one visible from the U.S. won’t happen until 2044. The sky will darken in Uvalde, Texas, just seconds before 2:30 p.m. Eastern Time (1:30 p.m. local time in Texas) on April 8. The will then arc up through Arkansas, Missouri, Illinois, Ohio and New York state before exiting the U.S. over Maine at 3:30 p.m. Eastern Time. Seattle is on the outer edge of the eclipse’s effects, with skies expected to darken here just 20% below regular levels.��

Among the many people travelling to witness the total eclipse firsthand will be , a ����Ӱ�Ӵ�ý research assistant professor of Earth and space sciences, along with four UW graduate students. This effort is funded in part by the .

Journaux’s research combines results from experiments and space missions to understand Earth as well as other planets and moons within our solar system. For this trip he will bring a special telescope to capture the unique view of the sun and surrounding skies that becomes possible during a solar eclipse. ��

UW News asked Baptiste about the upcoming trip as part of an occasional series, “In the Field,” highlighting UW field efforts.��

Where are you going, and when?����

Baptiste Journaux: We are currently aiming for somewhere along the border between Arkansas and Oklahoma. We will be there Sunday and Monday. The final location on Monday will depend on last-minute weather assessments to make sure we have the best chances of low cloud coverage. The choice of that general area is guided by flight prices and low population density to avoid traffic.����

Have you visited this site before?��

BP: No — it will be quite exploratory! ��

What do you and your students hope to see?��

BP: First, we are hoping to be able to observe the eclipse in the totality zone without too much cloud cover for near the longest eclipse time possible (more than 4 minutes). This will be significantly longer than the 2017 eclipse. During the totality, we will be able to see the sun’s corona with the naked eye. This is the farthest-extending feature of the sun’s atmosphere and is only visible during total eclipses.����

As the sun is currently approaching its — or the peak in the roughly 11-year cycle of solar activity — we are expecting to see quite a few more solar features than in 2017. One feature we hope to see is large plasma bridges, called , that are suspended over the surface of the sun by its strong magnetic field.����

During totality, the sky will get dark, and we should be able to see Mercury, Venus, Mars, Jupiter and Saturn appear on both sides of the sun. There is also a comet, , that should be visible just next to Jupiter. Overall, it promises to be quite an incredible and unique spectacle.��

Who will be participating in this field effort?��

BP: We will be going with four Earth and space sciences graduate students — , , and — as well as Sarah Smith with the College of the Environment, who will help to document the effort.��

What is the telescope that you will be bringing? What do you hope to learn?��

BP: We are bringing a special telescope that allows us to observe the sun in a single wavelength of hydrogen, the main constituent of the sun, to capture images of the sun’s surface features during the progression of the eclipse. We have been taking images of the sun from the UW campus to practice the use of this type of telescope, known as an H-alpha telescope.��

What’s something you enjoy about going into the field?��

BP: The main thing is experiencing a unique cosmic event that really gives perspective on the size and force of the universe. This is, honestly, one of the most incredible things that one can experience. Sharing that with our students will be a privilege. ��

Can people follow your efforts?��

BP: I will post on my X account, , and we will have full coverage through the UW Environment channels on and .��

Anything you’d like to add?��

BP: Wish us luck with the weather! ��

����

For more information, contact Journaux at bjournau@uw.edu.��

The American Geophysical Union Sept. 13 that five ����Ӱ�Ӵ�ý faculty members have been elected as new fellows, representing the departments of astronomy, Earth and space sciences, oceanography, global health, and environmental and occupational health sciences.

The Fellows program recognizes AGU members who have made exceptional contributions to Earth and space sciences through a breakthrough, discovery or innovation in their field. The five UW honorees are among 54 people from around the world in the 2023 Class of Fellows. AGU, the world’s largest Earth and space sciences association, annually recognizes a select number of individuals nominated by their peers for its highest honors. Since 1962, the AGU Union Fellows Committee has selected less than 0.1% of members as new fellows.

Also honored by AGU this year are three UW faculty members, from the departments of Earth and space sciences and atmospheric sciences, who have received other awards.

Here are the UW’s five new AGU Fellows:

, professor of Earth and space sciences, studies which characteristics of Earth help this planet support life, and whether life might be found on other planets. His work spans astronomy, biology and geology, on planetary environments including Earth, Mars, Venus and icy moons, as well as planets outside this solar system. He is the author of “Astrobiology: A Very Short Introduction” for the layperson and “Atmospheric Evolution on Inhabited and Lifeless Worlds” for researchers.

, who holds the Karl M. Banse Endowed Professorship in oceanography, explores the limits and ecological contributions of microbial life in deep ocean and polar regions, focusing in recent years on how microbes adapt to the extreme conditions of Arctic sea ice. In addition to a research and teaching career, Deming founded what is now the UW Center for Environmental Genomics and helped establish the nation’s first graduate training program in astrobiology.

, professor of global health and of environmental and occupational health sciences, has been conducting research on the health risks of climate variability and change for nearly 30 years. She focuses on estimating current and future health risks of climate change, designing adaptation policies and measures to reduce risks in multi-stressor environments, and estimating the health co-benefits of mitigation policies. Ebi is also founding director of the UW , or CHanGE.

, professor of astronomy, is an astrobiologist and planetary astronomer whose research focuses on��predicting, acquiring and analyzing observations of planetary atmospheres and surfaces. In addition to studying planets within our solar system, she is interested in exoplanets — those outside the solar system — and��how they might reveal the presence of life. With the UW’s Virtual Planetary Laboratory, she uses models of planets and planet-star interactions to generate plausible planetary environments and spectra for extrasolar terrestrial planets and the early Earth.

, professor and chair of Earth and space sciences, is a geochemist and glaciologist whose research focuses on polar climate and ice sheets in the Arctic and in Antarctica. He is best known for his analyses of Antarctic ice cores using measurements of oxygen and hydrogen in the ice to better understand how climate has varied in the past, over hundreds to thousands of years.

In addition to the newly elected fellows, UW faculty members are also recognized in several subject-specific awards and lectures:

, professor of atmospheric sciences, will deliver the in December at the AGU’s fall meeting. Alexander studies the relationship between climate change and the chemical composition of the atmosphere. She looks at the pathways by which atmospheric pollutants form, how those chemical pathways can vary, and what that means both for present-day air quality and for the future of climate change.

, research assistant professor of Earth and space sciences, has received the for his research modeling natural disasters using geodesy, or the shape of the Earth’s surface, and seismology. Crowell pioneered ways to use GPS and related data in earthquake and tsunami early warning systems. He is currently using this data to better understand natural disasters as they unfold and develop a risk-mitigation framework for coastal hazards such as tsunamis.

, research assistant professor of Earth and space sciences, has received the . Journaux uses modeling and experiments to explore the conditions in extreme environments on other planets, and how that might affect their ability to harbor life. He is a member of the science team for NASA’s upcoming Dragonfly mission, which will characterize the chemistry and habitability of Saturn’s largest moon, Titan.

, a researcher at the Pacific Northwest National Laboratory with an affiliate UW faculty position in oceanography, has received the .

All honorees will be recognized in December at the AGU’s fall meeting in San Francisco.

The red streaks crisscrossing the surface of Europa, one of Jupiter’s moons, are striking. Scientists suspect it is a frozen mixture of water and salts, but its chemical signature is mysterious because it matches no known substance on Earth.

An international team led by the ����Ӱ�Ӵ�ý may have solved the puzzle with the discovery of a new type of solid crystal that forms when water and table salt combine in cold and high-pressure conditions. Researchers believe the new substance created in a lab on Earth could form at the surface and bottom of these worlds’ deep oceans.

The , published the week of Feb. 20 in the Proceedings of the National Academy of Sciences, announces a new combination for two of Earth’s most common substances: water and sodium chloride, or table salt.

“It’s rare nowadays to have fundamental discoveries in science,” said lead author , a UW acting assistant professor of Earth and space sciences. “Salt and water are very well known at Earth conditions. But beyond that, we’re totally in the dark. And now we have these planetary objects that probably have compounds that are very familiar to us, but at very exotic conditions. We have to redo all the fundamental mineralogical science that people did in the 1800s, but at high pressure and low temperature. It is an exciting time.”

At cold temperatures water and salts combine to form a rigid salted icy lattice, known as a hydrate, held in place by hydrogen bonds. The only for sodium chloride was a simple structure with one salt molecule for every two water molecules.

But the two new hydrates, found at moderate pressures and low temperatures, are strikingly different. One has two sodium chlorides for every 17 water molecules; the other has one sodium chloride for every 13 water molecules. This would explain why the signatures from the surface of Jupiter’s moons are more “watery” than expected.

“It has the structure that planetary scientists have been waiting for,” Journaux said.

The discovery of new types of salty ice has importance not just for planetary science, but for physical chemistry and even energy research, which uses hydrates for energy storage, Journaux said.

The experiment involved compressing a tiny bit of salty water at synchrotron facilities in France, Germany and the U.S. between two diamonds about the size of a grain of sand, squeezing the liquid up to 25,000 times the standard atmospheric pressure. The transparent diamonds allowed the team to watch the process through a microscope.

“We were trying to measure how adding salt would change the amount of ice we could get, since salt acts as an antifreeze,” Baptiste said. “Surprisingly, when we put the pressure on, what we saw is that these crystals that we were not expecting started growing. It was a very serendipitous discovery.”

Such cold, high-pressure conditions created in the lab would be common on Jupiter’s moons, where scientists think 5 to 10 kilometers of ice would cover oceans up to several hundred kilometers thick, with even denser forms of ice possible at the bottom.

“Pressure just gets the molecules closer together, so their interaction changes — that is the main engine for diversity in the crystal structures we found,” Journaux said.

Once the newly discovered hydrates had formed, one of the two structures remained stable even after the pressure was released.

“We determined that it remains stable at standard pressure up to about minus 50 C. So if you have a very briny lake, for example in Antarctica, that could be exposed to these temperatures, this newly discovered hydrate could be present there,” Journaux said.

The team hopes to either make or collect a larger sample to allow more thorough analysis and verify whether the signatures from icy moons match the signatures from the newly discovered hydrates.

Two upcoming missions will explore Jupiter’s icy moons: The European Space Agency’s mission, launching in April, and NASA’s mission, launching for October 2024. NASA’s launches to Saturn’s moon Titan in 2026. Knowing what chemicals these missions will encounter will help to better target their search for signatures of life.

“These are the only planetary bodies, other than Earth, where liquid water is stable at geological timescales, which is crucial for the emergence and development of life,” Journaux said. “They are, in my opinion, the best place in our solar system to discover extraterrestrial life, so we need to study their exotic oceans and interiors to better understand how they formed, evolved and can retain liquid water in cold regions of the solar system, so far away from the sun.”

This research was funded by NASA. Co-authors are professor and graduate student at the UW. Additional co-authors were at the German Electron Synchrotron in Hamburg; the European Synchrotron Facility in France; the Institute of Geochemistry and Petrology in Switzerland, the Bavarian Geoinstitute for Experimental Geochemistry and Geophysics in Germany; NASA’s Jet Propulsion Laboratory; and the University of Chicago.

For more information, contact Journaux at bjournau@uw.edu.

Researchers from the ����Ӱ�Ӵ�ý and the University of California, Berkeley have conducted experiments that measured the physical limits for the existence of liquid water in icy extraterrestrial worlds. ��This blend of geoscience and engineering was done to aid in the search for extraterrestrial life and the upcoming robotic exploration of oceans on moons of other planets.

The were recently published in Cell Reports Physical Sciences.

“The more a liquid is stable, the more promising it is for habitability,” said co-corresponding author , an acting assistant professor of Earth and space sciences at the UW.���� “Our results show that the cold, salty, high-pressure liquids found in the deep ocean of other planets’ moons can remain liquid to much cooler temperature than they would at lower pressures. This extends the range of possible habitats on icy moons, and will allow us to pinpoint where we should look for biosignatures, or signs of life.”

Jupiter and Saturn’s icy moons — including Europa, Ganymede and Titan — are leading candidates within our solar system for hosting extraterrestrial life. These ice-encrusted moons are thought to harbor enormous liquid oceans, up to several dozen times the volume of oceans on Earth.

“Despite its designation as the ‘blue marble,’ Earth is remarkably dry when compared to these worlds,“ Journaux said.

The oceans on these moons may contain various types of salts and are expected to range from about 100 miles deep, on Europa, to more than 400 miles deep, on Titan.

“We know that water supports life, but the major part of the oceans on these moons are likely below zero degrees Celsius and at pressures higher than anything experienced on Earth,” Journaux said. “We needed to know how cold an ocean can get before entirely freezing, including in its deepest abyss.”

The study focused on eutectics, or the lowest temperature that a salty solution can remain liquid before entirely freezing. Salt and water are one example — salty water remains liquid below the freezing temperature of pure water, one of the reasons people sprinkle salt on roads in winter to avoid the formation of ice.

The experiments used UC Berkeley equipment originally designed for the future cryopreservation of organs for medical applications and for food storage. For this research, however, the authors used it to simulate the conditions thought to exist on other planets’ moons.

Journaux, a planetary scientist and expert on the physics of water and minerals, worked with UC Berkeley engineers to test solutions of five different salts at pressures up to 3,000 times atmospheric pressure, or 300 megapascals — about three times the pressure in Earth’s deepest ocean trench.

“Knowing the lowest temperature possible for salty water to remain a liquid at high pressures is integral to understanding how extraterrestrial life could exist and thrive in the deep oceans of these icy ocean worlds,” said co-corresponding author Matthew Powell-Palm, who did the work as a postdoctoral researcher at UC Berkeley, also co-founder and CEO of the cryopreservation company BioChoric, Inc.

Journaux recently started working with , which will send a rotorcraft in 2027 to Saturn’s largest moon, Titan. NASA also is leading the mission in 2024 to explore Europa, one of the many moons orbiting Jupiter. Meanwhile, the European Space Agency in 2023 will send its JUICE spacecraft, or , to explore three of Jupiter’s largest moons: Ganymede, Callisto and Europa.

“The new data obtained from this study may help further researchers’ understanding of the complex geological processes observed in these icy ocean worlds,” Journaux said.

Other authors are Boris Rubinsky, Brooke Chang, Anthony Consiglio, Drew Lilley and Ravi Prasher, all at UC Berkeley. The study was funded by the National Science Foundation and NASA.

For more information, contact Journaux at bjournau@uw.edu or Powell-Palm at mpowellp@berkeley.edu. ������