This icy moon orbiting Saturn is more alive than we thought

When NASA’s Cassini spacecraft visited Enceladus, Saturn’s sixth moon, in 2005, its observations led to a startling discovery.

The icy moon, 310 miles across, is not just another cold rock. He’s active – a real chemistry lab in space. The salty ocean sloshes under its icy crust. Holes in the ice, centered along the moon’s south pole, pump powerful chemicals hundreds of miles into space.

All this active chemistry has brought Enceladus near the top of the list of planets and moons in the solar system that may have the right conditions for simple life. But some key ingredients in microbial evolution seemed to be missing. Chief among them was hydrogen cyanide, sometimes called prussic acid, which is highly flammable, extremely poisonous, but also very useful on Earth as an ingredient in many industrial chemicals and pharmaceuticals.

More than 15 years after the spacecraft reached Enceladus, a team of scientists from Caltech and Harvard took a closer look at the piles of data collected by the spacecraft during its 10-year mission and concluded that initial readings were wrong. Enceladus if have hydrogen cyanide, claimed astrobiologists Jonah Peter and Kevin Hand and planetary scientist Tom Nordheim. And that bodes well for hope that the icy moon is home to alien life.

Is this icy moon our best chance of finding alien life?

“Our results indicate the presence of a rich, chemically diverse environment that may support complex organic synthesis and possibly even the origin of life,” Peter, Hand and Nordheim wrote in a new, yet to be peer-reviewed study that appeared online on page 12. January. All three scientists are affiliated with Caltech and NASA’s Jet Propulsion Laboratory. Peter also works for Harvard.

The team’s findings may force scientists to continue to prioritize Enceladus as they intensify their search for alien life. It may even be given a higher priority than Mars, Venus and even Europa, a moon of Jupiter that has much in common with Enceladus and is a favored target for alien hunters.

Continuation of the story

This does not mean that first contact is imminent. At the moment, what scientists hope to confirm on Enceladus is clear conditions for life, somewhere beneath the moon’s cool crust. Checking all these chemical and environmental boxes could warrant new missions to the moon in the coming decades.

And it is these probes that can find very simple life forms: bacteria or other microbes. “I believe the prospects for microbial life beneath the surface of Enceladus or Europa are high,” Avi Loeb, a Harvard physicist who wasn’t involved in the Cassini reanalysis, told The Daily Beast.

Although Loeb warned, “I doubt if there are any dead fish on the icy surface.”

Biologists generally agree that simple organisms as we understand them require certain ingredients in certain combinations to evolve: carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus to begin with. There must be enough variability in the surrounding environment – basically elements move and mix – to provide energy for chemical reactions that mix, match and remix these elements until they produce something capable of eating, metabolizing, excreting, breathing, moving, growing, reproducing and react to external stimuli. That’s life.

There are important intermediate steps in this evolutionary process. And hydrogen cyanide—a compound of hydrogen, carbon, and ammonia with the chemical formula HCN—allows you to do one of these steps. “With HCN, biochemically important molecules such as amino acids can be built,” Dirk Schulze-Makuch, an astronomer at the Technical University Berlin, told The Daily Beast. Amino acids, in turn, can form the proteins that living cells need to function and reproduce.

Analyzing data from Cassini’s first flyby of Enceladus’s southern plumes, scientists quickly found traces of carbon, hydrogen, nitrogen, oxygen and sulfur. The plumes indicated variability—so among the basic ingredients of life, the moon lacked only a few things to evolve. One of them was hydrogen cyanide or something like that.

View of Enceladus captured by NASA’s Cassini spacecraft.

NASA/JPL/Institute of Space Sciences

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View of Enceladus captured by NASA’s Cassini spacecraft.

NASA/JPL/Institute of Space Sciences