Spacecraft traversing through ice plumes in space could aid scientists in detecting extraterrestrial life — even if it involves minuscule traces of a cell within a few ice grains, laboratory experiments have unveiled for the first time.
If alien life exists on Saturn’s moon Enceladus or Jupiter’s Europa, the most feasible method to uncover evidence of it currently lies in the massive geysers erupting from these moons into space. These potent plumes, originating from the extensive subsurface oceans of each moon, burst into space through crevices in their icy exteriors, carrying ice particles believed to potentially harbor bacterial cells and other organic compounds. The latest research indicates that scientists can discern signs of life possibly embedded in the ice.
The ability to identify a bacterial cell within these grains is described as “astonishing” by a researcher at the University of Washington in Seattle and the lead author of the study. Even if present in a minute fraction within a handful of grains, these instruments can pinpoint it effectively.
By examining and analyzing Enceladus’ plumes, scientists can determine the existence of life-friendly molecules in their subsurface oceans. However, among the hundreds of thousands of ice grains ejected into space by these icy moons, bacterial cells may be concentrated in only a small fraction of them.
Cells Encased in Ice
To replicate such a scenario in a laboratory setting, Klenner and his team combined freeze-dried bacterial cells known as Sphingopyxis alaskensis in liquid water, ensuring an average of one bacterium cell per droplet. S. alaskensis, commonly found in Alaskan sea waters, thrives in cold conditions and sustains itself on minimal nutrients, making it a suitable analog for organisms in extreme environments on Earth.
“They are extremely small, capable of fitting into ice grains emitted from ocean worlds like Enceladus or Europa,” as stated in the study.
In an experiment detailed in a study published in the journal on Friday (March 22), researchers injected water containing these bacteria into a small vacuum chamber using a very thin tube. The water droplets, measuring 15 micrometers in diameter, slightly larger than ice grains in space, were then charged by a laser beam to analyze the particles’ spectra through mass spectroscopy. This technique revealed various compounds like amino acids and fatty acids, indicating the presence of a bacterial cell within the water sample.
The findings suggest that even if a mere 1% of a cell is embedded on a tiny ice grain, its chemical characteristics will be detectable.
“Our results provide confidence that upcoming instruments could detect life forms similar to those on Earth, possibly present on ocean-bearing moons,” mentioned Klenner.
During a mission lasting three to four years, spacecraft can examine numerous grains during multiple flybys of a target. Even if a few grains exhibit spectra akin to the researchers’ findings, the likelihood of identifying a bacterial cell or its fragment increases significantly.
The dust analyzer aboard NASA’s spacecraft, launched in 2005, could only record 30 to 300 particles per flyby, indicating its limitations in detecting bacterial cells if present. Conversely, the Europa Clipper mission by NASA, designed to explore Jupiter’s moon Europa, can analyze 10,000 to 100,000 individual ice grains per flyby, enhancing the chances of spotting bacterial cells if they exist on the moon.
With the aid of such instruments, the search for life or its remnants on icy moons may be more achievable than previously thought, as suggested by a study co-author, a professor of planetary sciences at the Free University of Berlin.