Scientists have discovered complex organic molecules in ice grains ejected from Saturn’s moon Enceladus. The findings suggest that the moon’s subsurface ocean hosts chemical reactions that could lead to the formation of life. The discovery was made by analyzing data from NASA’s Cassini spacecraft.
Cassini flew through the icy spray from Enceladus in 2008, collecting samples of freshly ejected ice grains. “Cassini was detecting samples from Enceladus all the time as it flew through Saturn’s E ring,” said lead author Nozair Khawaja. “We had already found complex organic molecules in these ice grains.”
The team focused on the freshest and fastest ice grains that hit Cassini’s Cosmic Dust Analyzer instrument.
At high impact speeds, the organic molecules were not hidden, allowing the scientists to detect previously unseen signals. They identified new molecules that had never been found before in Enceladus’s ice grains. These included nitrogen- and oxygen-bearing compounds, ethers, and esters.
Signs of life on Enceladus
On Earth, such molecules are involved in chemical reactions that can lead to the formation of life. “There are many possible pathways from the organic molecules we found to potentially biologically relevant compounds, which enhances the likelihood that the moon is habitable,” Khawaja explained.
The findings confirm that the complex organic molecules are readily available in Enceladus’s ocean and not just a result of long exposure to space. This makes Enceladus a promising candidate for future missions searching for signs of life. “Even not finding life on Enceladus would be a huge discovery,” Khawaja said, “because it raises serious questions about why life is not present in such an environment when the right conditions are there.”
The European Space Agency is already considering dedicated missions to Enceladus.
The plan is to fly through the moon’s icy jets and even land on its surface to collect samples. The latest results from Cassini will help guide decisions on the scientific instruments to be used. Enceladus meets all the criteria for a potentially habitable environment.
It has liquid water, a source of energy, key chemical elements, and complex organic molecules. Studying this intriguing moon could significantly advance our understanding of habitable environments beyond Earth.
