New research suggests that NASA could find evidence of alien life by collecting ice grains from the geysers on icy moons like Enceladus and Europa. These moons shoot out icy plumes into space, which might contain signs of life.
Scientists believe that if alien life exists on moons like Enceladus and Europa, these geysers are the best places to look for it. Recent studies have found that these geysers come from underground oceans on the moons and shoot out ice grains into space through cracks in the icy surface. Scientists think these ice grains could contain tiny particles of bacterial cells and other organic molecules. By sending spacecraft through these plumes, scientists could spot signs of life stuck in the ice.
“It’s amazing how good we are at spotting a bacterial cell in these ice grains,” said Fabian Klenner, a researcher at the University of Washington in Seattle and the main author of the new study. “Even if there’s just a tiny bit in a few grains, we can detect it with these tools.”
Scientists can find out if there are molecules that support life in the underground oceans of Enceladus and possibly Europa by studying and testing the plumes. However, out of the many ice grains shot into space by these moons, only a few might have bacterial cells in them.
To mimic this situation in a lab, Klenner and his team combined freeze-dried bacteria called Sphingopyxis alaskensis with liquid water. They ensured that, on average, one bacteria cell was in each droplet. S. alaskensis is commonly found in the waters of Alaska. It survives in cold conditions and can live with low nutrients, making it a good match for environments like Enceladus or Europa.
“They are very small, so they could potentially fit into ice grains that come from an ocean world like Enceladus or Europa,” Klenner explained.
In the experiment, detailed in a study published in the journal Science Advances on Friday (March 22), the researchers used a thin tube to inject this water into a small vacuum chamber. The water droplets were about 15 micrometers in diameter, which is a bit larger than the ice grains in space but still extremely small.
Next, a laser beam energized the water droplets and the bacteria inside them. Using mass spectroscopy, a method that spacecraft can use, scientists collected the particles’ spectra, which measure different wavelengths of light emitted by the particles. These wavelengths can reveal their compositions. They discovered various amino acids and fatty acids, indicating the presence of a bacterial cell, which they already knew was in the water sample.
These findings demonstrate that even if only 1% of a cell is attached to a small ice grain, its chemical signature will still be detectable.
“Our findings make us more sure that with upcoming tools, we can spot life forms similar to those on Earth, which we think could exist on moons with oceans,” said Klenner.
During a mission lasting three to four years, spacecraft can collect hundreds of thousands or even billions of grains during multiple flybys of a target. If just a few of those grains show a similar composition to what the researchers discovered, then there’s a good chance it could contain a bacterial cell or fragment, according to Klenner. “The great thing is that you only need to find a cell in a few of these grains, and these instruments can confirm if there is a bacterial cell.”
The dust analyzer on NASA’s Cassini spacecraft, which detected the plumes coming from Saturn’s moon Enceladus in 2005, could only capture 30 to 300 particles during each flyby. So the probe “was definitely not equipped to find bacterial cells if they were present,” Klenner explained.
Another NASA mission, Europa Clipper, is set to launch this October. Its goal is to study Jupiter’s icy moon Europa. During each flyby, the spacecraft can collect 10,000 to 100,000 individual ice grains. This increases the chances of finding bacterial cells on the moon.
Frank Postberg, a professor of planetary sciences at the Free University of Berlin and co-author of the study, said, “Using such instruments, it might be easier than we thought to find life, or signs of it, on icy moons. This is, of course, if life exists there and is captured in ice grains from a place like a subsurface water reservoir.”
