The ice-encrusted oceans of among the moons orbiting Saturn and Jupiter are leading candidates within the seek for extraterrestrial life. A brand new lab-based study led by the University of Washington in Seattle and the Freie Universität Berlin shows that individual ice grains ejected from these planetary bodies may contain enough material for instruments headed there in the autumn to detect signs of life, if such life exists.
“For the primary time we’ve shown that even a tiny fraction of cellular material could possibly be identified by a mass spectrometer onboard a spacecraft,” said lead writer Fabian Klenner, a UW postdoctoral researcher in Earth and space sciences. “Our results give us more confidence that using upcoming instruments, we are going to have the opportunity to detect lifeforms much like those on Earth, which we increasingly consider could possibly be present on ocean-bearing moons.”
The open-access study was published March 22 in Science Advances. Other authors within the international team are from The Open University within the U.K.; NASA’s Jet Propulsion Laboratory; the University of Colorado, Boulder; and the University of Leipzig.
The Cassini mission that resulted in 2017 discovered parallel cracks near the south pole of Saturn’s moon Enceladus. Emanating from these cracks are plumes containing gas and ice grains. NASA’s Europa Clipper mission, scheduled to launch in October, will carry more instruments to explore in much more detail an icy moon of Jupiter, Europa.
To arrange for that mission, researchers are studying what this latest generation of instruments might find. It’s technically prohibitive to directly simulate grains of ice flying through space at 4 to six kilometers per second to hit an observational instrument, because the actual collision speed might be. As a substitute, the authors used an experimental setup that sends a skinny beam of liquid water right into a vacuum, where it disintegrates into droplets. They then used a laser beam to excite the droplets and mass spectral evaluation to mimic what instruments on the space probe will detect.
Newly published results show that instruments slated to go on future missions, just like the SUrface Dust Analyzer onboard Europa Clipper, can detect cellular material in a single out of lots of of hundreds of ice grains.
The study focused on Sphingopyxis alaskensis, a typical bacterium in waters off Alaska. While many studies use the bacterium Escherichia coli as a model organism, this single-celled organism is way smaller, lives in cold environments, and might survive with few nutrients. All these items make it a greater candidate for potential life on the icy moons of Saturn or Jupiter.
“They’re extremely small, in order that they are in theory able to fitting into ice grains which are emitted from an ocean world like Enceladus or Europa,” Klenner said.
Results show that the instruments can detect this bacterium, or portions of it, in a single ice grain. Different molecules find yourself in several ice grains. The brand new research shows that analyzing single ice grains, where biomaterial could also be concentrated, is more successful than averaging across a bigger sample containing billions of individual grains.
A recent study led by the identical 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 prone to support lifeforms much like those found on Earth.
The authors hypothesize that if bacterial cells are encased in a lipid membrane, like those on Earth, then they’d also form a skin on the ocean’s surface. On Earth, ocean scum is a key a 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 within the ice shell), the vacuum of outer space would cause this subsurface ocean to boil. Gas bubbles rise through the ocean and burst on the surface, where cellular material gets incorporated into ice grains throughout the plume.
“We here describe a plausible scenario for the way bacterial cells can, in theory, be incorporated into icy material that’s formed from liquid water on Enceladus or Europa after which gets emitted into space,” Klenner said.
The SUrface Dust Analyzer onboard Europa Clipper might be higher-powered than instruments on past missions. This and future instruments also will for the primary time have the opportunity to detect ions with negative charges, making them higher suited to detecting fatty acids and lipids.
“For me, it’s much more exciting to search for lipids, or for fatty acids, than to search for constructing blocks of DNA, and the rationale is because fatty acids look like more stable,” Klenner said.
“With suitable instrumentation, resembling the SUrface Dust Analyzer on NASA’s Europa Clipper space probe, it could be easier than we thought to search out life, or traces of it, on icy moons,” said senior writer Frank Postberg, a professor of planetary sciences on the Freie Universität Berlin. “If life is present there, in fact, and cares to be enclosed in ice grains originating from an environment resembling a subsurface water reservoir.”
The study was funded by the European Research Council, NASA and the German Research Foundation (DFG). Other co-authors are Janine Bönigk, Maryse Napoleoni, Jon Hillier and Nozair Khawaja on the Freie Universität Berlin; Karen Olsson-Francis at The Open University within the U.K.; Morgan Cable and Michael Malaska on the NASA Jet Propulsion Laboratory; Sascha Kempf on the University of Colorado, Boulder; and Bernd Abel on the University of Leipzig.
