An artist’s impression of Europa Clipper near the moon it is named after
NASA
An instrument on a NASA spacecraft due to blast off to Europa later this year may be able to directly detect cellular material ejected from the icy moon of Jupiter, raising the prospects for finding life.
Europa has garnered scientific interest because researchers believe it contains a vast, saltwater ocean under its thick icy shell. It is also surrounded by an orbiting blanket of ice grains and dust, believed to be remnants of material thrown up following bombardments by meteorites.
NASA’s Europa Clipper spacecraft, due to launch in October and arrive at its destination in 2030, will fly near the moon, but won’t land on it. It will carry 10 experiments with the aim of studying Europa’s internal structure, including the chemistry of its ocean and its potential habitability for life beyond Earth.
One of these is the SUrface Dust Analyser (SUDA), which is a type of instrument known as a mass spectrometer. It will collect material ejected from the moon to reveal its chemical composition, including potential organic molecules and salts.
SUDA hasn’t been designed to look for signs of existing life on Europa, but now Frank Postberg at the Free University of Berlin, Germany, who works on the instrument, and his colleagues have shown that it could detect fragments of cellular material, potentially providing evidence of current life.
“If life forms on Europa follow the same principle of having a membrane and DNA made from amino acids… then detecting [those chemicals] would be a smoking gun for life there,” he says.
“It’s a fascinating result because these ice grains hit your instrument in space with speeds of 4 to 6 kilometres per second,” says team member Fabian Klenner at the University of Washington. “We showed that, even then, you are still able to identify cell material.”
These extreme speeds will see particles hit SUDA with high kinetic energy, breaking large molecular structures up into smaller constituent parts for analysis. To simulate this kinetic energy, the team blasted water droplets with lasers. Inside the water, they placed samples of Sphingopyxis alaskensis, a bacterium known to survive in extremely cold marine environments, to take the place of potential life on Europa.
When the lasers hit the droplets they disintegrated into a smaller spray that hit the SUDA detector. The researchers found they could distinguish the fragmented cellular material, including fatty acids, which cell membranes are rich in, and amino acids.
“We’ve now simulated having a cell in a single ice grain without any pre-treatment, which may be a plausible case for what we’d see in Europa,” says Klenner. The next step will be to repeat the experiment with many different types of cell cultures, he says.
Murthy Gudipati at NASA’s Jet Propulsion Laboratory in Pasadena, California, who works on SUDA but wasn’t involved with the research, says that even with the differences between lab conditions and those that Europa Clipper is expected to encounter, the results should reflect what the spacecraft might see during its mission.
However, he says its ability to unambiguously distinguish cellular material from other organic molecules and salts will depend on the specific composition of ice grains ejected from Europa. If SUDA picks up many other complex organic molecules and salts mixed in the ice grain, it may be harder for researchers to detect cellular material for certain, says Gudipati.
Currently, NASA says that “Europa Clipper is not a life detection mission – its main science goal is to determine whether there are places below Europa’s surface that could support life”. When asked by New Scientist if this new research will change the goals of the mission, the agency wasn’t able to provide a response before publication.
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