Scientists have detected poison in molecular droplets emitted by Saturn’s small moon. It adds to the existing conspiracy about the possibility of life there.
The poison is hydrogen cyanide, a colorless gas that is deadly to many life forms on Earth. But it may have played an important role in the chemical reactions that produced the ingredients that set the stage for the birth of life.
“This is the starting point for most theories about the origin of life,” says Jonah Peter, a biophysics graduate student at Harvard University. “This is like the Swiss Army knife of prebiotic chemistry.”
So Peter was excited when he discovered hydrogen cyanide on Saturn’s icy moon Enceladus, which is about 510 miles across. It has an underground ocean, making it one of the most promising places to search for life elsewhere in the solar system.
Peter and his collaborators Tom Nordheim and Kevin Hand of NASA’s Jet Propulsion Laboratory in California reported their findings in a paper published Thursday in the journal Nature Astronomy.
They also discovered organic molecules such as acetylene, propene, and ethane that can accelerate chemical reactions to provide energy to the microorganisms that live in Enceladus’ ocean. The data also indicated the presence of alcohols such as methanol, but the researchers were unable to definitively identify which ones.
Chemical experiments have shown that hydrogen cyanide may be an important precursor for molecules necessary for the development of life. “By combining them in different ways, they can produce amino acids, which are precursors to proteins, as well as the nucleobases and sugars needed to make RNA and DNA,” Peter said.
Twenty years ago, Enceladus was considered a mostly bland ice ball.
But in 2005, planetary scientists were stunned when NASA’s Cassini spacecraft discovered steam and ice crystals spewing out of a crack near the moon’s south pole. Saturn’s tidal forces pull and compress Enceladus’ interior, and the friction generates enough heat to melt the ice.
Initial analyzes showed not only water but also carbon dioxide, methane, hydrogen, and ammonia. The eruption was indicative of a subsurface hydrothermal reaction, where hot rock meets liquid water.
Subsequent scrutiny of the data from the Cassini mission, which ended in 2017, has further increased curiosity about what lies beneath. Scientists now believe that Enceladus not only has a pool of liquid water beneath its south pole, but also a global saltwater ocean beneath its outer icy shell.
Earlier this year, another team of scientists reported that ice particles in Enceladus’ plumes contain phosphates, which also points to geochemical interactions between the ocean and rock beds. ing. Phosphorus is another important element considered essential to life.
“In fact, the prospects for the development of life on Enceladus are getting better and better,” said Frank Postberg, a professor of planetary science at the Free University of Berlin who led the phosphate research.
In the latest study, Peter and his collaborators once again dug into data from Cassini’s flybys. The amount of hydrogen cyanide is so small that it cannot be immediately observed. Instead, the researchers started by creating a list of his 50 compounds that they thought could be present on Enceladus. He then built models for 10 to 15 of those compounds and tested which model best fit Cassini’s observations.
“This is a great analysis to learn more about what we see in plumes,” said Kathleen Craft, a planetary scientist at the Johns Hopkins Applied Physics Laboratory in Maryland. ” he said.
For Dr. Kraft, Enceladus is an interesting place, but not the only one. Other moons like Europa, which orbits Jupiter, also have oceans beneath their ice. NASA’s next mission, Europa Clipper, will carry instruments similar to Cassini’s and could make similar discoveries.
“The ocean world is all very exciting,” Dr. Kraft said. “They’re all a little different from each other, but they have a lot of similarities.”
Alfonso Dávila, a researcher in the Extraterrestrial Biology Division at NASA’s Ames Research Center in California, said the presence of hydrogen cyanide and other newly reported organic compounds in Enceladus’ plumes is a sign of “the complexity of the ocean.” “It does not reveal the origin of organic matter.”
“But it brings us a little closer to the answer,” he said.
