Lead author Fabian Klenner, a postdoctoral researcher at the University of Washington's Department of Earth and Space Sciences, expressed optimism about the potential for future spacecraft to identify lifeforms on ocean-bearing moons: "This is the first time we have evidence that even minimal amounts of cellular material in ice grains could be recognized by mass spectrometry equipment aboard a spacecraft," Klenner noted.

Published on March 22 in Science Advances, the study involved collaboration with researchers from The Open University in the U.K., NASA's Jet Propulsion Laboratory, the University of Colorado, Boulder, and the University of Leipzig. The research aims to simulate conditions that spacecraft instruments, such as those on the upcoming Europa Clipper mission, might encounter when analyzing space-ejected ice grains from moons like Europa and Enceladus.

Instead of simulating the actual high-speed collision of ice grains with a space probe, the team developed an experimental setup where a water jet is broken into droplets in a vacuum, excited with a laser, and then analyzed using mass spectrometry. This method successfully detected cellular material in a fraction of the ice grains, a significant finding for future extraterrestrial exploration missions.

The research specifically looked at Sphingopyxis alaskensis, a bacterium adapted to cold, nutrient-poor environments, making it an ideal model for potential life on icy moons. The study's innovative approach showed that detecting this bacterium or parts of it in individual ice grains is more effective than analyzing bulk samples, highlighting a new way to search for extraterrestrial life.

Further bolstering the case for life on these moons, the team previously found evidence of phosphate on Enceladus, adding to the list of ingredients necessary for life as we know it: energy, water, phosphate, other salts, and carbon-based organic materials.

The study also theorizes about the mechanics of how bacterial cells could be incorporated into ice grains emitted into space, drawing parallels with ocean scum on Earth and its role in sea spray. This mechanism suggests a plausible route for cellular material to be trapped in ice and ejected from moons like Enceladus and Europa.

The enhanced capabilities of instruments like the SUrface Dust Analyzer on the Europa Clipper mission, capable of detecting negatively charged ions, improve the prospects for identifying life-signature molecules such as fatty acids and lipids. "Detecting fatty acids might be simpler than searching for DNA components, as fatty acids tend to be more stable," said Klenner.

Frank Postberg, senior author and professor of planetary sciences at Freie Universitat Berlin, concluded, "With the right instruments, discovering life or its traces on icy moons might be easier than anticipated, provided life exists there and is encapsulated in ice grains from subsurface water reservoirs."

Research Report:How to identify cell material in a single ice grain emitted from Enceladus or Europa

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