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鈥檚 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鈥檚 conference will be held June 24-28 at the Hyatt Regency Hotel in Bellevue. It鈥檚 the biggest meeting of astrobiologists in the world and dozens of 91探花 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 91探花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 , 91探花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 91探花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 91探花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 91探花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 鈥� 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 91探花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鈥檚 focus and scientific benefit is about more than simply hunting for life, though that is the key motivator.

“It鈥檚 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 鈥� fundamental, I would say 鈥� interdisciplinary science that thrives independently of the existence of extraterrestrial life.鈥�

The subsurface ocean of Saturn’s moon probably has higher than previously known concentrations of carbon dioxide and hydrogen and a more Earthlike pH level, possibly providing conditions favorable to life, according to new research from planetary scientists at the 91探花.

The presence of such high concentrations could provide fuel 鈥� a sort of chemical 鈥渇ree lunch鈥� 鈥� for living microbes, said lead researcher a 91探花doctoral student in Earth and space sciences. Or, it could mean 鈥渢hat there is hardly anyone around to eat it.鈥�

The new information about the composition of Enceladus鈥� ocean gives planetary scientists a better understanding of the ocean world鈥檚 capacity to host life. Fifer said.

Enceladus is a small moon, an ocean world about 310 miles (500 kilometers) across. Its salty subsurface ocean is of interest because of the similarity in pH, salinity and temperature to Earth’s oceans. Plumes of water vapor and ice particles 鈥� spotted and studied by the spacecraft 鈥� erupting hundreds of miles into space from the ocean through cracks in Enceladus’s ice-encased surface provide a tantalizing glimpse into what the moon鈥檚 subsurface ocean might contain.

But Fifer and colleagues found that the plumes aren鈥檛 chemically the same as the ocean from which they erupt at 800 miles an hour; the eruption process itself changes their composition. He is working with ESS faculty members and . They will present their work June 24 at the .

Fifer and colleagues say the plumes provide an “imperfect window” to the composition of Enceladus鈥檚 global subsurface ocean and that the plume composition and ocean composition could be much different. That, they find, is due to plume , or the separation of gases, which preferentially allows some components of the plume to erupt while others are left behind.

This in mind, the team returned to data from the Cassini mission with a computer simulation that accounts for the effects of fractionation, to get a clearer idea of the composition of Enceladus鈥檚 inner ocean鈥檚. They found 鈥渟ignificant differences鈥� between Enceladus鈥檚 plume and ocean chemistry. Previous interpretations, they found, underestimate the presence of hydrogen, methane and carbon dioxide in the ocean.

鈥淚t鈥檚 better to find high gas concentrations than none at all,鈥� said Fifer. 鈥淚t seems unlikely that life would evolve to consume this chemical free lunch if the gases were not abundant in the ocean.鈥�

Those high levels of carbon dioxide also imply a lower and more Earthlike pH level in the ocean of Enceladus than previous studies have shown. This bodes well for possible life, too, Fifer said.

“Although there are exceptions, most life on Earth functions best living in or consuming water with near-neutral pH, so similar conditions on Enceladus could be encouraging,” he said. “And they make it much easier to compare this strange ocean world to an environment that is more familiar.”

There could be high concentrations of ammonium as well, which is also a potential fuel for life. And though the high concentrations of gases might indicate a lack of living organisms to consume it all, Fifer said, that does not necessarily mean Enceladus is devoid of life. It might mean microbes just aren鈥檛 abundant enough to consume all the available chemical energy.

The researchers can use the gas concentrations to determine an upper limit for certain types of possible life that could exist in the icy ocean of Enceladus.

In other words, he said: “Given that there’s so much free lunch available, what’s the greatest amount that life could be eating to still leave behind the amount we see? How much life would that support?”

Thanks to Cassini, he said, we know about Enceladus’ ocean and the types of gases, salts and organic compounds that are present there. Studying how the plume composition changes can teach us yet more about this ocean and everything in it.

“Future spacecraft missions will sample the plumes looking for signs of life, many of which will be affected just by the eruption process,” Fifer said. “So, understanding the difference between the ocean and the plume now will be a huge help down the road.”

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For more information, contact Fifer at lufifer@uw.edu.