Life may be detected in a single ice grain containing one bacterial cell or portions of a cell which means it could be found in the frozen sea spray from the moons orbiting Saturn or Jupiter.

Finding that will take is a mass spectrometer onboard a spacecraft, and that will happen when the Europa Clipper mission launches in October with the The SUrface Dust Analyzer.

The authors couldn't simulate grains of ice flying through space at 2 to 3 miles per second to hit an observational instrument so they used an experimental setup that sent a thin beam of liquid water into a vacuum, where it disintegrates into droplets. They then used a laser beam to excite the droplets and mass spectral analysis to mimic what instruments on the space probe will detect.

Graphical representation of Saturn’s moon Enceladus depicts hydrothermal activity on the seafloor and cracks in the moon’s icy crust that allow material from the watery interior to be ejected into space. Credit: NASA/JPL-Caltech

The study focused on Sphingopyxis alaskensis, a common bacterium in waters off Alaska. While many studies use the bacterium Escherichia coli as a model organism, this single-celled organism is much smaller, lives in cold environments, and can survive with few nutrients. All these things make it a better candidate for potential life on the icy moons of Saturn or Jupiter.

Results show that the instruments can detect this bacterium, or portions of it, in a single ice grain. Different molecules end up in different ice grains. The new research shows that analyzing single ice grains, where biomaterial may be concentrated, is more successful than averaging across a larger sample containing billions of individual grains.

A recent study led by the same researchers showed evidence of phosphate on Enceladus. This planetary body now appears to contain energy, water, phosphate, other salts and carbon-based organic material, making it increasingly likely to support lifeforms similar to those found on Earth.

The authors hypothesize that if bacterial cells are encased in a lipid membrane, like those on Earth, then they would also form a skin on the ocean’s surface. On Earth, ocean scum is a key part of sea spray that contributes to the smell of the ocean. On an icy moon where the ocean is connected to the surface (e.g., through cracks in the ice shell), the vacuum of outer space would cause this subsurface ocean to boil. Gas bubbles rise through the ocean and burst at the surface, where cellular material gets incorporated into ice grains within the plume.

They believe they can can detect cellular material in one out of hundreds of thousands of ice grains.