Charles Darwin proposed that life could have emerged in a “” with the right cocktail of chemicals and energy. A from the 91̽��, published this month in Communications Earth & Environment, reports that a shallow “soda lake” in western Canada shows promise for matching those requirements. The findings provide new support that life could have emerged from lakes on the early Earth, roughly 4 billion years ago.

Scientists have known that under the right conditions, the complex molecules of life can emerge spontaneously. As recently fictionalized in the blockbuster hit “Lessons in Chemistry,” biological molecules can be coaxed to form from inorganic molecules. In fact, long after made amino acids, the building blocks of proteins, has made the building blocks of RNA. But this next step requires extremely high phosphate concentrations.

Phosphate forms the “backbone” of RNA and DNA and is also a key component of cell membranes. The concentrations of phosphate required to form these biomolecules in the lab are hundreds to 1 million times higher than the levels normally found in rivers, lakes or in the ocean. This has been called the “phosphate problem” for the emergence of life — a problem that soda lakes may have solved.

“I think these soda lakes provide an answer to the phosphate problem,” said senior author , a 91̽��professor of Earth and space sciences. “Our answer is hopeful: This environment should occur on the early Earth, and probably on other planets, because it’s just a natural outcome of the way that planetary surfaces are made and how water chemistry works.”

Soda lakes get their name from having high levels of dissolved sodium and carbonate, similar to dissolved baking soda. This occurs from the reactions between water and volcanic rocks beneath. Soda lakes can also have high levels of dissolved phosphate.

Previous 91̽��research in 2019 found that chemical conditions for life to emerge could theoretically occur in soda lakes. The researchers combined chemical models with laboratory experiments to show that natural processes can theoretically concentrate phosphate in these lakes to levels up to 1 million times higher than in typical waters.

For the new study, the team set out to study such an environment on Earth. By coincidence, the most promising candidate was within driving distance. Tucked away at the end of a from the 1990s was the highest known natural phosphate level in the scientific literature at in inland British Columbia, Canada, about seven hours’ drive from Seattle.

The lake is about 1 foot deep and has murky water with fluctuating levels. It sits on federal land at the end of a dusty dirt road on the Cariboo Plateau, in British Columbia ranching country. The shallow lake meets the requirements for a soda lake: a lake above volcanic rock (in this case, basalt) combined with a dry, windy atmosphere that evaporates incoming water to keep water levels low and concentrates dissolved compounds within the lake.

Analysis published in the new paper suggests soda lakes are a strong candidate for the emergence of life on Earth. They also could be a candidate for life on other planets.

“We studied a natural environment that should be common throughout the solar system. Volcanic rocks are prevalent on the surfaces of planets, so this same water chemistry could have occurred not just on early Earth, but also on early Mars and early Venus, if liquid water was present,” said lead author , a postdoctoral researcher in Earth and space sciences at the UW.

The 91̽��team visited Last Chance Lake three times from 2021 to 2022. They collected observations in early winter, when the lake was covered in ice; in early summer, when rain-fed springs and snowmelt-fed streams put water at its highest; and in late summer when the lake had almost completely dried up.

“You have this seemingly dry salt flat, but there are nooks and crannies. And between the salt and the sediment there are little pockets of water that are really high in dissolved phosphate,” Haas said. “What we wanted to understand was why and when could this happen on the ancient Earth, in order to provide a cradle for the origin of life.”

On all three visits the team collected samples of water, lake sediment and salt crust to understand the lake’s chemistry.

In most lakes the dissolved phosphate quickly combines with calcium to form calcium phosphate, the insoluble material that makes up our tooth enamel. This removes phosphate from the water. But in Last Chance Lake, calcium combines with plentiful carbonate as well as magnesium to form dolomite, the same mineral that forms picturesque mountain ranges. This reaction was predicted by the previous modeling work and confirmed when dolomite was plentiful in Last Chance Lake’s sediments. When calcium turns into dolomite and does not remain in the water, the phosphate lacks a bonding partner — and so its concentration rises.

“This study adds to growing evidence that evaporative soda lakes are environments meeting the requirements for origin-of-life chemistry by accumulating key ingredients at high concentrations,” Catling said.

The study also compared Last Chance Lake with Goodenough Lake, a roughly 3-foot-deep lake with clearer water and different chemistry just a two-minute walk away, to learn what makes Last Chance Lake unique. The researchers wondered why life, present in all modern lakes at some level, was not using up the phosphate in Last Chance Lake.

Goodenough Lake has mats of cyanobacteria that extract or “fix” nitrogen gas from the air. Cyanobacteria, like all other lifeforms, also require phosphate — and its growing population consumes some of that lake water’s phosphate supply. But Last Chance Lake is so salty that it inhibits living things that do the energy-intensive work of fixing atmospheric nitrogen. Last Chance Lake harbors some algae but has insufficient available nitrogen to host more life, allowing phosphate to accumulate. This also makes it a better analog for a lifeless Earth.

“These new findings will help inform origin-of-life researchers who are either replicating these reactions in the lab or are looking for potentially habitable environments on other planets,” Catling said.

The research was funded by the Simons Foundation. The other co-author is , a 91̽��graduate student in Earth and space sciences. Graduate students with the 91̽��Astrobiology Program also assisted with sample collection.

For more information, contact Haas at sb704989@uw.edu or Catling at dcatling@uw.edu.

An international team including a 91̽�� scientist has found that the water on one of Saturn’s moons harbors phosphates, a key building block of life. The team led by the Freie Universität Berlin used data from ��������’s Cassini space mission to detect evidence of phosphates in particles ejected from the ice-covered global ocean of Saturn’s moon Enceladus.

Phosphorus, in the form of phosphates, is vital for all life on Earth. It forms the backbone of DNA and is part of cell membranes and bones. The new , published June 14 in Nature, is the first to report direct evidence of phosphorus on an extraterrestrial ocean world.

The team found that phosphate is present in Enceladus’ ocean at levels at least 100 times higher — and perhaps a thousand times higher — than in Earth’s oceans.

“By determining such high phosphate concentrations readily available in Enceladus’ ocean, we have now satisfied what is generally considered one of the strictest requirements in establishing whether celestial bodies are habitable,” said third author , a 91̽��postdoctoral researcher in Earth and space sciences. While at Freie Universität Berlin, Klenner did experiments that revealed the high phosphate concentrations present in Enceladus’ ocean.

One of the most profound discoveries in planetary science over the past 25 years is that worlds with oceans beneath a surface layer of ice are common in our solar system. These ice-covered celestial bodies include the icy moons of Jupiter and Saturn — including Ganymede, Titan and Enceladus — as well as even more distant celestial bodies, like Pluto.

��������’s explored Saturn, its rings and its moons from 2004 to 2017. It first discovered that Enceladus’ harbors an ice-covered watery ocean, and analyzed material that erupted through cracks in the region of the moon’s south pole.

The spacecraft was equipped with the . which analyzed individual ice grains emitted from Enceladus and sent those measurements back to Earth. To determine the chemical composition of the grains, Klenner used a specialized setup in Berlin that mimicked the data generated by an ice grain hitting the instrument. He tried different chemical compositions and concentrations for his samples to try to match the unknown signatures in the spacecraft’s observations.

“I prepared different phosphate solutions, and did the measurements, and we hit the bullseye. This was in perfect match with the data from space,” Klenner said. “This is the first finding of phosphorus on an extraterrestrial ocean world.”

Planets with surface oceans, like Earth, must reside within a narrow range of distances from their host stars (in what is known as the “habitable zone”) to maintain temperatures at which water neither evaporates nor freezes. Worlds with an interior ocean like Enceladus, however, can occur over a much wider range of distances, greatly expanding the number of habitable worlds likely to exist across the galaxy.

In previous studies, the team at the Freie Universität Berlin determined that Enceladus harbors a “soda ocean,” rich in dissolved carbonates, that also contains a vast variety of reactive and sometimes complex carbon-containing compounds. The team also found indications of hydrothermal environments on the seafloor.�� The new study now shows the unmistakable signatures of dissolved phosphates.

“Previous geochemical models were divided on the question of whether Enceladus’ ocean contains significant quantities of phosphates at all,” said lead author at Freie Universität Berlin. “These measurements leave no doubt that substantial quantities of this essential substance are present in the ocean water.”

To investigate how the ocean on Enceladus can maintain such high concentrations of phosphate, geochemical lab experiments and modeling included in the new paper were conducted by a Japan-based team led by second author at the Tokyo Institute of Technology and a U.S.-based team led by fourth author at the Southwest Research Institute in San Antonio, Texas. Other authors are from Germany, the U.S., Japan and Finland.

For more information, contact Klenner at fklenner@uw.edu and Postberg at frank.postberg@fu-berlin.de.

Adapted from a Freie Universität Berlin .

A new analysis of 2.5-billion-year-old rocks from Australia finds that volcanic eruptions may have stimulated population surges of marine microorganisms, creating the first puffs of oxygen into the atmosphere. This would change existing stories of Earth’s early atmosphere, which assumed that most changes in the early atmosphere were controlled by geologic or chemical processes.

Though focused on Earth’s early history, the research also has implications for extraterrestrial life and even climate change. The led by the 91̽��, the University of Michigan and other institutions was published in August in the Proceedings of the National Academy of Sciences.

“What has started to become obvious in the past few decades is there actually are quite a number of connections between the solid, nonliving Earth and the evolution of life,” said first author , a 91̽��doctoral student in Earth and space sciences. “But what are the specific connections that facilitated the evolution of life on Earth as we know it?”

In its earliest days, Earth had no oxygen in its atmosphere and few, if any, oxygen-breathing lifeforms. Earth’s atmosphere became permanently oxygen-rich about 2.4 billion years ago, likely after an explosion of lifeforms that photosynthesize, transforming carbon dioxide and water into oxygen.

But in 2007, co-author at Arizona State University analyzed rocks from the Mount McRae Shale in Western Australia, reporting a of oxygen about 50 to 100 million years before it became a permanent fixture in the atmosphere. More recent research has confirmed other, earlier short-term oxygen spikes, but hasn’t explained their rise and fall.

In the new study, researchers at the University of Michigan, led by co-corresponding author , analyzed the same ancient rocks for the concentration and number of neutrons in the element mercury, emitted by volcanic eruptions. Large volcanic eruptions blast mercury gas into the upper atmosphere, where today it circulates for a year or two before raining out onto Earth’s surface. The new analysis shows a spike in mercury a few million years before the temporary rise in oxygen.

“Sure enough, in the rock below the transient spike in oxygen we found evidence of mercury, both in its abundance and isotopes, that would most reasonably be explained by volcanic eruptions into the atmosphere,” said co-author , a 91̽��professor of Earth and Space Sciences.

Where there were volcanic emissions, the authors reason, there must have been lava and volcanic ash fields. And those nutrient-rich rocks would have weathered in the wind and rain, releasing phosphorus into rivers that could fertilize nearby coastal areas, allowing oxygen-producing cyanobacteria and other single-celled lifeforms to flourish.

“There are other nutrients that modulate biological activity on short timescales, but phosphorus is the one that is most important on long timescales,” Meixnerová said.

Today, phosphorus is plentiful in biological material and in agricultural fertilizer. But in very ancient times, weathering of volcanic rocks would have been the main source for this scarce resource.

“During weathering under the Archaean atmosphere, the fresh basaltic rock would have slowly dissolved, releasing the essential macro-nutrient phosphorus into the rivers. That would have fed microbes that were living in the shallow coastal zones and triggered increased biological productivity that would have created, as a byproduct, an oxygen spike,” Meixnerová said.

The precise location of those volcanoes and lava fields is unknown, but large lava fields of about the right age exist in modern-day India, Canada and elsewhere, Buick said.

“Our study suggests that for these transient whiffs of oxygen, the immediate trigger was an increase in oxygen production, rather than a decrease in oxygen consumption by rocks or other nonliving processes,” Buick said. “It’s important because the presence of oxygen in the atmosphere is fundamental – it’s the biggest driver for the evolution of large, complex life.”

Ultimately, researchers say the study suggests how a planet’s geology might affect any life evolving on its surface, an understanding that aids in identifying habitable exoplanets, or planets outside our solar system, in the search for life in the universe.

Other authors of the paper are co-corresponding author , a former 91̽��astrobiology graduate student now at the University of St. Andrews in Scotland; , a former 91̽��graduate student now at the California Institute of Technology; and at the University of Michigan. The study was funded by NASA, the NASA-funded 91̽�� team and the MacArthur Professorship to Blum at the University of Michigan.

For more information contact Meixnerová at janameix@uw.edu or Buick at buick@uw.edu. Note: Meixnerová is on European Time; Buick is on Pacific Time.

NASA: NNX16AI37G, 80NSSC18K0829

In September, a team led by astronomers in the United Kingdom that they had detected the chemical phosphine in the thick clouds of Venus. The team’s reported detection, based on observations by two Earth-based radio telescopes, surprised many Venus experts. Earth’s atmosphere contains small amounts of phosphine, which may be produced by life. Phosphine on Venus generated buzz that the planet, often succinctly touted as a “,” could somehow harbor life within its acidic clouds.

Since that initial claim, other science teams have on the reliability of the phosphine detection. Now, a team led by researchers at the 91̽�� has used a robust model of the conditions within the atmosphere of Venus to revisit and comprehensively reinterpret the radio telescope observations underlying the initial phosphine claim. As they report in a accepted to the Astrophysical Journal and posted Jan. 25 to the preprint site arXiv, the U.K.-led group likely wasn’t detecting phosphine at all.

“Instead of phosphine in the clouds of Venus, the data are consistent with an alternative hypothesis: They were detecting sulfur dioxide,” said co-author , a 91̽��professor of astronomy. “Sulfur dioxide is the third-most-common chemical compound in Venus’ atmosphere, and it is not considered a sign of life.”

The team behind the new study also includes scientists at ��������’s Caltech-based Jet Propulsion Laboratory, the NASA Goddard Space Flight Center, the Georgia Institute of Technology, the NASA Ames Research Center and the University of California, Riverside.

The UW-led team shows that sulfur dioxide, at levels plausible for Venus, can not only explain the observations but is also more consistent with what astronomers know of the planet’s atmosphere and its punishing chemical environment, which includes clouds of sulfuric acid. In addition, the researchers show that the initial signal originated not in the planet’s cloud layer, but far above it, in an upper layer of Venus’ atmosphere where phosphine molecules would be destroyed within seconds. This lends more support to the hypothesis that sulfur dioxide produced the signal.

Both the purported phosphine signal and this new interpretation of the data center on radio astronomy. Every chemical compound absorbs unique wavelengths of the , which includes radio waves, X-rays and visible light. Astronomers use radio waves, light and other emissions from planets to learn about their chemical composition, among other properties.

In 2017 using the , or JCMT, the U.K.-led team discovered a feature in the radio emissions from Venus at 266.94 gigahertz. Both phosphine and sulfur dioxide absorb radio waves near that frequency. To differentiate between the two, in 2019 the same team obtained follow-up observations of Venus using the , or ALMA. Their analysis of ALMA observations at frequencies where only sulfur dioxide absorbs led the team to conclude that sulfur dioxide levels in Venus were too low to account for the signal at 266.94 gigahertz, and that it must instead be coming from phosphine.

In this new study by the UW-led group, the researchers started by modeling conditions within Venus’ atmosphere, and using that as a basis to comprehensively interpret the features that were seen — and not seen — in the JCMT and ALMA datasets.

“This is what’s known as a radiative transfer model, and it incorporates data from several decades’ worth of observations of Venus from multiple sources, including observatories here on Earth and spacecraft missions like ,” said lead author Andrew Lincowski, a researcher with the 91̽��Department of Astronomy.

The team used that model to simulate signals from phosphine and sulfur dioxide for different levels of Venus’ atmosphere, and how those signals would be picked up by the JCMT and ALMA in their 2017 and 2019 configurations. Based on the shape of the 266.94-gigahertz signal picked up by the JCMT, the absorption was not coming from Venus’ cloud layer, the team reports. Instead, most of the observed signal originated some 50 or more miles above the surface, in Venus’ mesosphere. At that altitude, harsh chemicals and ultraviolet radiation would shred phosphine molecules within seconds.

“Phosphine in the mesosphere is even more fragile than phosphine in Venus’ clouds,” said Meadows. “If the JCMT signal were from phosphine in the mesosphere, then to account for the strength of the signal and the compound’s sub-second lifetime at that altitude, phosphine would have to be delivered to the mesosphere at about 100 times the rate that oxygen is pumped into Earth’s atmosphere by photosynthesis.”

The researchers also discovered that the ALMA data likely significantly underestimated the amount of sulfur dioxide in Venus’ atmosphere, an observation that the U.K.-led team had used to assert that the bulk of the 266.94-gigahertz signal was from phosphine.

“The antenna configuration of ALMA at the time of the 2019 observations has an undesirable side effect: The signals from gases that can be found nearly everywhere in Venus’ atmosphere — like sulfur dioxide — give off weaker signals than gases distributed over a smaller scale,” said co-author Alex Akins, a researcher at the Jet Propulsion Laboratory.

This phenomenon, known as spectral line dilution, would not have affected the JCMT observations, leading to an underestimate of how much sulfur dioxide was being seen by JCMT.

“They inferred a low detection of sulfur dioxide because of that artificially weak signal from ALMA,” said Lincowski. “But our modeling suggests that the line-diluted ALMA data would have still been consistent with typical or even large amounts of Venus sulfur dioxide, which could fully explain the observed JCMT signal.”

“When this new discovery was announced, the reported low sulfur dioxide abundance was at odds with what we already know about Venus and its clouds,” said Meadows. “Our new work provides a complete framework that shows how typical amounts of sulfur dioxide in the Venus mesosphere can explain both the signal detections, and non-detections, in the JCMT and ALMA data, without the need for phosphine.”

With science teams around the world following up with fresh observations of Earth’s cloud-shrouded neighbor, this new study provides an alternative explanation to the claim that something geologically, chemically or biologically must be generating phosphine in the clouds. But though this signal appears to have a more straightforward explanation — with a toxic atmosphere, bone-crushing pressure and some of our solar system’s hottest temperatures outside of the sun — Venus remains a world of mysteries, with much left for us to explore.

Additional co-authors are at the JPL, at UC Riverside, and at the Goddard Space Flight Center, 91̽��researcher , at Georgia Tech and at NASA Ames. The research was funded by the NASA Astrobiology Program and performed at the NExSS Virtual Planetary Laboratory.

For more information, contact Meadows at meadows@uw.edu, Akins at alexander.akins@jpl.nasa.gov and Lincowski at alinc@uw.edu.

Many of these online opportunities are streamed through Zoom. All 91̽��faculty, staff, and students have access to��.��

Film Screening: “Blind Bombing, Filmed by a Bat” with Kota Takeuchi

April 28, 3:30 – 5:00 PM��| Zoom Event

�����پ�������Kota Takeuchi��will screen and talk about his short film “Blind Bombing, Filmed by a Bat” (32 min., 2019) which explores how balloon bombs were created, propagandised, and used in Japan during World War II. The film combines interviews and historical data, while developing a loose relationship between an animal (the bat) and the fictional Japanese monster Te no Me.

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Astrobiology Spring Colloquium Series – Juan Perez Mercader (Harvard University)

April 28,�� 3:00 – 4:00 PM | Zoom��Lecture

Join the Astrobiology Department in continuing their biannual colloquium series featuring key speaker Juan Perez Mercader from Harvard’s Department of Earth & Planetary Sciences. Mercader will present a lecture titled Mimicking simple life without biochemistry. Synthesis and boot-up from a homogeneous mixture of functional polymer vesicles: birth, growth, self-replication, extinction and competition cycles.

Please be aware that the talks in this colloquium series are scientific presentations geared towards the Astrobiology Community and will contain theories and terminology common to the field.

Free, please email��astrobio@uw.edu for password��|

Labor On-line: Virtual seminar Series, Spring 2020

Tuesdays at 1:15 PM and Wednesdays at 6:00 PM

This Spring,��Harry Bridges Center for Labor Studies��hosts two weekly online seminars with a wide range of labor scholars and activists. These sessions are free and open to the public.

������������

This week’s ��seminar:
Hosted by Labor Studies faculty at 91̽��Bothell

April 28 –��Japanese Teacher Unions
1:30 PM | Zoom:��
Presented by:��Keith Nitta, Professor 91̽��Bothell ��& Jordan Woljter, Law, Economics and Public Policy

This week’s����seminar:
Hosted by the 91̽��Tacoma Labor Solidarity Project

April 29 – “Rebooting Big Tech”
6:00 PM | Zoom:��
Presented by: Professor Rob Larson, Economics, Tacoma Community College

Quick Talk:��Chagall, Modigliani, & Jewish Painters from the Russian “Pale of Settlement”

April 28, 4:00 PM | Zoom

The Stroum Center for Jewish Studies invites Dr.��Galya Diment, professor of Slavic Languages and Literatures at the 91̽��, for a 20-minute “quick talk” on how early 20th-century painters Marc Chagall and Amedeo Modigliani related to Jewishness in their lives and art — and how their work contrasts with that of other Jewish painters from the Russian “Pale of Settlement.”

The talk will be followed by a Q&A session, with questions submitted via www.slido.com and moderated by a staff member.

Free, please register for access��|

Re/frame: The Built Environment

April 30, 12:00 – 1:00 PM | Zoom

The Henry’s current exhibition,��In Plain Sight, includes multiple works by artists who are exploring the concept of the built environment. These human-made spaces in which we live, work, and recreate, heavily influence many facets of our lives. Join us to see how artists have grappled with the built environment in a variety of works from our permanent collection.

Re/frame is a recurring program that delves into the Henry’s extensive collection, highlighting a different group of objects each month. Join us for group discussions and the opportunity to see art rarely on public view.

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Reading Recommendation: Helen Sword’s Air & Light & Time & Space: How Successful Academics Write

Looking for a good excuse to look away from your screens? Caitlin Palo, Program and Events Manager with the��Simpson Center for the Humanities, suggests Helen Sword’s Air & Light & Time & Space: How Successful Academics Write.

In the midst of overwhelming pressure to stay productive during a global pandemic (with nothing less than a dissertation to complete), Palo reflects on��Sword’s suggestions for making space to write.

“Air & Light & Space & Time��is not an instructional book. It is an orchestration of voices, an ethnography of writers. It is a picture of the rich diversity of writing practices at the heart of intellectual endeavors in the sciences as well as in the humanities, and an invitation to think more broadly about one’s own practices in the company of other successful writers.”

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#BurkeFromHome Trivia Night: Now starting at 7pm

Every Friday, 7:00 PM������Virtual Event

Join the Burke Museum online on Fridays at 7 PM for #BurkeFromHome Trivia. The popular Burke Trivia Night is back—this time online to practice social distancing while having loads of fun! Get your nerd on with natural history and culture-themed trivia.

BYOB, snacks, and slippers!

Free, please register for access��|

Staying home? Here’s what to watch

Ongoing | Your favorite streaming service

Looking for ways to stay entertained while staying at home?��If you’ve already binged all the shows in your Netflix queue, fear not. Faculty in the Department of Cinema & Media Studies��have gathered television and film recommendations to fit every mood.

Looking for more?

Check out UWAA’s Stronger Together web page for��more digital engagement opportunities.

Scientists have discovered thousands of , including dozens of terrestrial — or rocky — worlds in the around their parent stars. A promising approach to search for signs of life on these worlds is to probe exoplanet atmospheres for “biosignatures” — quirks in chemical composition that are telltale signs of life. For example, thanks to photosynthesis, our atmosphere is nearly 21% oxygen, a much higher level than expected given Earth’s composition, orbit and parent star.

Finding biosignatures is no straightforward task. Scientists use data about how exoplanet atmospheres interact with light from their parent star to learn about their atmospheres. But the information, or spectra, that they can gather using today’s ground- and space-based telescopes is too limited to measure atmospheres directly or detect biosignatures.

Exoplanet researchers such as , a professor of astronomy at the 91̽��, are focused on what forthcoming observatories, like the , or JWST, could measure in exoplanet atmospheres. On Feb. 15 at the in Seattle, Meadows, a principal investigator of the UW’s , will deliver a talk to summarize what kind of data these new observatories can collect and what they can reveal about the atmospheres of terrestrial, Earth-like exoplanets. Meadows sat down with 91̽��News to discuss the promise of these new missions to help us view exoplanets in a new light.

What changes are coming to the field of exoplanet research?

In the next five to 10 years, we’ll potentially get our first chance to observe the atmospheres of terrestrial exoplanets. This is because new observatories are set to come online, including the James Webb Space Telescope and ground-based observatories like the . A lot of our recent work at the Virtual Planetary Laboratory, as well as by colleagues at other institutions, has focused on simulating what Earth-like exoplanets will “look” like to the JWST and ground-based telescopes. That allows us to understand the spectra that these telescopes will pick up, and what those data will and won’t tell us about those exoplanet atmospheres.

What types of exoplanet atmospheres will the JWST and other missions be able to characterize?

Our targets are actually a select group of exoplanets that are nearby — within 40 light years — and orbit very small, cool stars. For reference, the Kepler mission identified exoplanets around stars that are more than 1,000 light years away. The smaller host stars also help us get better signals on what the planetary atmospheres are made of because the thin layer of planetary atmosphere can block more of a smaller star’s light.

So there are a handful of exoplanets we’re focusing on to look for signs of habitability and life. All were identified by ground-based surveys like and its successor, — both run by the University of Liège — as well as the run by Harvard. The most well-known exoplanets in this group are probably the seven terrestrial planets orbiting . TRAPPIST-1 is an M-dwarf star — one of the smallest you can have and still be a star — and its seven exoplanets span interior to and beyond the habitable zone, with three in the habitable zone.

We’ve identified TRAPPIST-1 as the best system to study because this star is so small that we can get fairly large and informative signals off of the atmospheres of these worlds. These are all cousins to Earth, but with a very different parent star, so it will be very interesting to see what their atmospheres are like.

What have you learned so far about the atmospheres of the TRAPPIST-1 exoplanets?

The astronomy community has taken observations of the TRAPPIST-1 system, but we haven’t seen anything but “non-detections.” That can still tell us a lot. For example, observations and models suggest that these exoplanet atmospheres are less likely to be dominated by hydrogen, the lightest element. That means they either don’t have atmospheres at all, or they have relatively high-density atmospheres like Earth.

No atmospheres at all? What would cause that?

M-dwarf stars have a very different history than our own sun. After their infancy, sun-like stars brighten over time as they undergo fusion.

M-dwarfs start out big and bright, as they gravitationally collapse to the size they will then have for most of their lifetimes. So, M-dwarf planets could be subjected to long periods of time — perhaps as along as a billion years — of high-intensity luminosity. That could strip a planet of its atmosphere, but volcanic activity can also replenish atmospheres. Based on their densities, we know that many of the TRAPPIST-1 worlds are likely to have reservoirs of compounds — at much higher levels than Earth, actually — that could replenish the atmosphere. The first significant JWST results for TRAPPIST-1 will be: Which worlds retained atmospheres? And what types of atmospheres are they?

I’m quietly optimistic that they do have atmospheres because of those reservoirs, which we’re still detecting. But I’m willing to be surprised by the data.

What types of signals will the JWST and other observatories look for in the atmospheres of TRAPPIST-1 exoplanets?

Probably the easiest signal to look for will be the presence of carbon dioxide.

Is CO2 a biosignature?

Not on its own, and not just from a single signal. I always tell my students — look right, look left. Both Venus and Mars have atmospheres with high levels of CO2, but no life.

In Earth’s atmosphere, CO2 levels adjust with our seasons. In spring, levels draw down as plants grow and take CO2 out of the atmosphere. In autumn, plants break down and CO2 rises. So if you see seasonal cycling, that might be a biosignature. But seasonal observations are very unlikely with JWST.

Instead, JWST can look for another potential biosignature, methane gas in the presence of CO2. Methane should normally have a short lifetime with CO2. So if we detect both together, something is probably actively producing methane. On Earth, most of the methane in our atmosphere is produced by life.

What about detecting oxygen?

Oxygen alone is not a biosignature. It depends on its levels and what else is in the atmosphere. You could have an oxygen-rich atmosphere from the loss of an ocean, for example: Light splits water molecules into hydrogen and oxygen. Hydrogen escapes into space, and oxygen builds up into the atmosphere.

The JWST likely won’t directly pick up oxygen from — the biosphere we’re used to now. The Extremely Large Telescope and related observatories might be able to, because they’ll be looking at a different wavelength than the JWST, where they will have a better chance of seeing oxygen. The JWST will be better for detecting biospheres similar to what we had on Earth billions of years ago, and for differentiating between different types of atmospheres.

What are some of the different types of atmospheres that TRAPPIST-1 exoplanets might possess?

The M-dwarf’s high-luminosity phase might drive a planet toward an atmosphere with a runaway greenhouse effect, like Venus. As I said earlier, you could lose an ocean and have an oxygen-rich atmosphere. A third possibility is to have something more Earth-like.

Let’s talk about that second possibility. How could JWST reveal an oxygen-rich atmosphere if it can’t detect oxygen directly?

The beauty of the JWST is that it can pick up processes happening in an exoplanet’s atmosphere. It will pick up the signatures of collisions between oxygen molecules, which will happen more often in an oxygen-rich atmosphere. So we likely can’t see oxygen amounts associated with a photosynthetic biosphere. But if a much larger amount of oxygen was left behind from ocean loss, we can probably see the collisions of oxygen in the spectrum, and that’s probably a sign that the exoplanet has lost an ocean.

So, JWST is unlikely to give us conclusive proof of biosignatures but may provide some tantalizing hints, which require further follow-up and — moving forward — thinking about new missions beyond the JWST. NASA is already considering new missions. What would we like their capabilities to be?

That also brings me to a very important point: Exoplanet science is massively interdisciplinary. Understanding the environment of these worlds requires considering orbit, composition, history and host star — and requires the input of astronomers, geologists, atmospheric scientists, stellar scientists. It really takes a village to understand a planet.

For more information, contact Meadows at meadows@uw.edu.

91̽�� astrobiologist has created software that simulates multiple aspects of planetary evolution across billions of years, with an eye toward finding and studying potentially habitable worlds.

Barnes, a 91̽��assistant professor of astrobiology, astronomy and data science, released the first version of VPLanet, his virtual planet simulator, in August. He and his co-authors described it in a accepted for publication in the Publications of the Astronomical Society of the Pacific.

“It links different physical processes together in a coherent manner,” he said, “so that effects or phenomena that occur in some part of a planetary system are tracked throughout the entire system. And ultimately the hope is, of course, to determine if a planet is able to support life or not.”

VPLanet’s mission is three-fold, Barnes and co-authors write. The software can:

• simulate newly discovered exoplanets to assess their potential to possess surface liquid water, which is a key to life on Earth and indicates the world is a viable target in the search for life beyond Earth
• model diverse planetary and star systems regardless of potential habitability, to learn about their properties and history, and
• enable transparent and open science that contributes to the search for life in the universe

The first version includes modules for the internal and magnetic evolution of terrestrial planets, climate, atmospheric escape, tidal forces, orbital evolution, rotational effects, stellar evolution, planets orbiting binary stars and the gravitational perturbations from passing stars.

It’s designed for easy growth. Fellow researchers can write new physical modules “and almost plug and play them right in,” Barnes said. VPLanet can also be used to complement more sophisticated tools such as machine learning algorithms.

An important part of the process, he said, is validation, or checking physics models against actual previous observations or past results, to confirm that they are working properly as the system expands.

“Then we basically connect the modules in a central area in the code that can model all members of a planetary system for its entire history,” Barnes said.

And though the search for potentially habitable planets is of central importance, VPLanet can be used for more general inquiries about planetary systems.

“We observe planets today, but they are billions of years old,” he said. This is a tool that allows us to ask: ‘How do various properties of a planetary system evolve over time?’”

The project’s history dates back almost a decade to a Seattle meeting of astronomers called “Revisiting the Habitable Zone” convened by , principal investigator of the UW-based , with Barnes. The habitable zone is the swath of space around a star that allows for orbiting rocky planets to be temperate enough to have liquid water at their surface, giving life a chance.

They recognized at the time, Barnes said, that knowing if a planet is within its star’s habitable zone simply isn’t enough information: “So from this meeting we identified a whole host of physical processes that can impact a planet’s ability to support and retain water.”

Barnes discussed VPLanet and presented a tutorial on its use at the recent AbSciCon19 worldwide astrobiology conference, held in Seattle.

The research was done through the Virtual Planetary Laboratory and the source code is available .

Barnes’s other faculty co-authors are astronomy professor ; , professor of atmospheric sciences; and research scientist . Other 91̽��co-authors are doctoral students , , and ; and undergraduate researchers Caitlyn Wilhelm, Benjamin Guyer and Diego McDonald.

Other co-authors are of the Carnegie Institution for Science; of the Flatiron Institute, of the Max Planck Institute for Astronomy in Heidelberg, Germany, of the University of Bern, of the NASA Goddard Space Flight Center and of Weber State University.

The research was funded by a grant from the NASA Astrobiology Program’s Virtual Planetary Laboratory team, as part of the research coordination network, or NExSS.

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For more information, contact Barnes at 206-543-8979 or rkb9@uw.edu.

Grant numbers

VPL under cooperative agreement #NNA13AA93A

NASA grants #NNX15AN35G, #13-13-NA17 0024, and #80NSSC18K0829

NASA Earth and Space Science Fellowship Program grant #80NSSC17K0482

In recent years, the idea of life on other planets has become less far-fetched. NASA announced June 27 that it will send a vehicle to , a celestial body known to harbor surface lakes of methane and an ice-covered ocean of water, boosting its chance for supporting life.

On Earth, scientists are studying the most extreme environments to learn how life might exist under completely different settings, like on other planets. A 91̽�� team has been studying the microbes found in “,” trapped layers of sediment with water so salty that it remains liquid at below-freezing temperatures, which may be similar to environments on Mars or other planetary bodies farther from the sun.

At the recent meeting in Bellevue, Washington, researchers presented DNA sequencing and related results to show that brine samples from an Alaskan cryopeg isolated for tens of thousands of years contain thriving bacterial communities. The lifeforms are similar to those found in floating sea ice and in saltwater that flows from glaciers, but display some unique patterns.

“We study really old seawater trapped inside of permafrost for up to 50,000 years, to see how those bacterial communities have evolved over time,” said lead author , a 91̽��doctoral student in oceanography.

Cryopegs were first discovered by geologists in Northern Alaska decades ago. This field site in Utqiaġvik, formerly known as Barrow, was excavated in the 1960s by the U.S. Army’s Cold Regions Research and Engineering Laboratory to explore large wedges of freshwater ice that occur in the permafrost there. Subsurface brine was eventually collected from the site in the 2000s.

“The extreme conditions here are not just the below-zero temperatures, but also the very high salt concentrations,” said , a 91̽��professor of oceanography who studies microbial life in the Arctic Ocean. “One hundred and forty parts per thousand — 14% — is a lot of salt. In canned goods that would stop microbes from doing anything. So there can be a preconceived notion that very high salt should not enable active life.”

It’s not fully known how cryopegs form. Scientists believe the layers might be former coastal lagoons stranded during the last ice age, when rain turned to snow and the ocean receded. Moisture evaporated from the abandoned seabed was then covered by permafrost, so the remaining briny water became trapped below a layer of frozen soil.

To access the subsurface liquids, researchers climb about 12 feet down a ladder and then move carefully along a tunnel within the ice. The opening is just a single person wide and is not high enough to stand in, so researchers must crouch and work together to drill during the 4- to 8-hour shifts.

Deming describes it as “exhilarating” because of the possibility for discovery.

Samples collected in the spring of 2017 and 2018, geologically isolated for what researchers believe to be roughly 50,000 years, contain genes from healthy communities of bacteria along with their viruses.

“We’re just discovering that there’s a very robust microbial community, coevolving with viruses, in these ancient buried brines,” Cooper said. “We were quite startled at how dense the bacterial communities are.”

The extreme environments on Earth may be similar to the oceans and ice of other planets, scientist believe.

“The dominant bacterium is Marinobacter,” Deming said. “The name alone tells us that it came from the ocean – even though it has been in the dark, buried in frozen permafrost for a very long time, it originally came from the marine environment.”

Mars harbored an ocean of water in the past, and our solar system contains at least a half-dozen oceans on other planets and icy moons. Titan, the moon of Saturn that NASA will explore, is rich in various forms of ice. Studying life on Earth in frozen settings that may have similarities can prepare explorers for what kind of life to expect, and how to detect it.

The research was funded by the Gordon and Betty Moore Foundation to learn how bacteria and viruses coevolve in different marine environments. Other collaborators at 91̽��are , a postdoctoral researcher in Oceanography, Max Showalter, a doctoral student in Oceanography, and , a research scientist in Oceanography.

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For more information, contact Cooper at zcooper@uw.edu or Deming at jdeming@uw.edu.

inflated a big black fabric tent in the lobby of the Hyatt Regency Hotel on Wednesday and stood outside it inviting passers-by: “Come on in and watch the show — we’re talking about astrobiology.”

Barnes, a 91̽�� research assistant professor of astronomy, was showing off the department’s to colleagues at , the national conference on astrobiology, . The conference is happening all week at the Hyatt, and dozens of 91̽��faculty and students are involved.

The tent is about 10 feet tall and 20 feet across and stays upright with the help of a high-powered fan. Its graphics come via Microsoft’s World Wide Telescope. 91̽��astronomy faculty and students to conduct outreach about astronomy to area schools, and have been educating (and entertaining) thousands of students about the cosmos since.

But recently, Barnes and graduate students have been using the Mobile Planetarium to tell K-12 students about astrobiology. It’s a hit with middle school students especially, he said.

“They get excited about it. It’s a very visceral experience, very immersive, and there’s often a lot of screaming as they move through the universe,” Barnes said, smiling. “You can see they’re engaged.”

Astrobiology graduate students were conducting the shows inside the tent on Wednesday, starting a new presentation every so often as people filed by and stepped — climbed, really — through a fabric doorway into the dark interior.

There mid-Wednesday, astronomy doctoral students David Graham, then , gave engaging, illustrated lectures to visitors huddled in the darkness inside. Aided by graphics displayed in color against the rounded tent ceiling, they in turn took their audience from scenes of “extremophile” creatures living on Earth out through the solar system and into deep space — so far out, whole galaxies appear as mere dots.

Garcia talked of the “big questions” astrobiologists want to answer, leading with the most basic: “Are we alone in the universe?”

He added: “Personally I think this also tells me that life is precious. Even if planets are common we haven’t seen life on them yet, so the life on our own planet is really precious as well.

“So, it’s not just a scientific pursuit — astrobiology — but it’s also, how do we relate to our environment? And I think it’s really beautiful in that way.”

Barnes does assessments before and after his school visits and said they show the students enjoy the presentation, even if a little part of that might be just being away from class.

“But it’s all just about getting them to remember this experience. They remember they had a good experience — that’s still a win.”

He said one thing he definitely sees is that “people from all over, whatever their background, they do ‘get’ this — they go, ‘Whoa, there’s no life out there that we know, but that’s interesting and maybe I can think about this.’

“And the best, of course, is every time you go you get two or three kids who say, ‘This is really cool — maybe I want to study planets.'”

Barnes also reported on the 91̽��Mobile Planetarium to the conference in a separate session Thursday. He hopes to keep it going and is looking for further funding for the project.

Soon he was back out front, looking for the next audience.

“We’re talking astrobiology. Want to come in and see the show?”

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For more information, contact Barnes at rkb9@uw.edu.

is the study of life in the universe and of the terrestrial environments and planetary and stellar processes that support it. To study astrobiology is to ask questions that cut across multiple disciplines and could take lifetimes to answer. The field gathers expertise from a host of other disciplines including biology, chemistry, geology, oceanography, atmospheric and Earth science, aeronautical engineering and of course astronomy itself.

These questions also include: What can Earth’s own species, and its chemical past, tell us about how to spot life elsewhere? How did the first cells arise? Can we map the surfaces of exoplanets? How can we motivate students to be curious about space?

Every two years, researchers gather from around the world to share and discuss their latest findings in a weeklong conference. Called for short, this year’s conference will be held June 24-28 at the Hyatt Regency Hotel in Bellevue. It’s the biggest meeting of astrobiologists in the world and dozens of 91̽�� researchers will attend and participate.

Public attitudes have warmed greatly toward astrobiology in the 21^st century, prompted by exoplanet discoveries and exploration of other worlds in the solar system. Study of extraterrestrial life remains a hopeful science wryly aware that, as an old joke goes, it has yet to prove that its very subject matter exists.

The 91̽��founded its own program in 1999, involving roughly 30 faculty and about as many students a year. “The program is a leader in both training the next generation of astrobiologists and in fundamental astrobiology research,” said , 91̽��professor of astronomy and principal investigator for the UW-based , which explores computer models of planetary environments and will be the subject of a .

“The Astrobiology Science Conference is the biggest meeting of astrobiologists in the world, and this year, members of the 91̽��Astrobiology Program are playing a major role in conference organization, as well as presenting our research at the meeting,” said Meadows, who chaired the science committee for AcSciCon2019.

Here are several 91̽��presentations and papers scheduled for the weeklong conference. Though the lead presenter is listed here only, most projects involve the work of several colleagues.

• A study of water vapor and ice particles emitting from the plume on Saturn’s moon Enceladus, leading to a better understanding of the moon’s subsurface ocean. With Earth and space sciences doctoral student and colleagues. ()
• An examination of whether the coming James Webb Space Telescope will be able to detect atmospheres for all worlds in the intriguing, seven-planet system TRAPPIST-1, and finding that clouds and water vapor in the planets’ atmospheres might make such study more challenging. With astronomy and astrobiology doctoral student and colleagues. ()
• Description of a new open-source computer software package called VPLanet that simulates a wide range of planetary systems across billions of years, simulating atmospheres, orbits and stellar phenomena that can affect a planet’s ability to sustain liquid water on its surface, which is key to life. With Rory Barnes and colleagues. ()
• An exploration of how viruses and hosts co-evolved, enabling microbial life in extremely cold brines. With oceanography professor ().
• Modeling Earth’s atmosphere 2.7 billion years ago and the effect of iron-rich micrometeorites that rained down, melted and interacted with the surrounding gases, leading to a better understanding of carbon dioxide levels at that time. With Earth and space sciences graduate student and colleagues. ()
• A presentation on the 91̽��Astronomy Department’s successful outreach to students through its that visits K-12 schools, enabling them to create shows of their own. With astronomy research assistant professor and several colleagues. and .)
• An exploration of how to determine if oxygen detected on an exoplanet is really produced by life, using high-resolution planetary spectra from ground-based telescopes. With , an astronomy doctoral student, and colleagues. ()
• A discussion of how studying a giant Pacific Octopus might help us learn more about different forms of cognition and better know and understand life beyond Earth — if we ever find it. With , a doctoral student in psychology. ()
• A study of microbial life in extremely cold brines within unfrozen subsurface areas of permafrost, and their possible relevance to similar environments on Mars or icy moons in the solar system. With , a doctoral student in biological oceanography, and colleagues. (.)

Many other 91̽��faculty members will participate, either with reports on their own research or in support of colleagues or graduate students. These include ESS professors , , , , , astronomy professors , and , among others.

Astrobiologists such as Sullivan point out that the field’s focus and scientific benefit is about more than simply hunting for life, though that is the key motivator.

“It’s about thinking about life in a cosmic context. And about the origin and evolution of life,” Sullivan said.

“Even if you only care about Earth life, astrobiology is a viable — fundamental, I would say — interdisciplinary science that thrives independently of the existence of extraterrestrial life.”