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June 24, 2024

Tantalizing Signs of Habitability Detected from Saturn’s Icy Moon Enceladus

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Dec 18, 2023

NASA scientists have detected biological and energetic ingredients erupting in icy plumes from Saturn’s moon Enceladus, strengthen­ing the case for the moon’s potential to support life.

Organic Molecules Discovered in Enceladus’ Plume

Using data from NASA’s Cassini spacecraft, scientists have identified traces of organic mole­cules and a chemical energy source for life in the salty, subsurface ocean beneath the moon’s icy crust. Cassini detected large, carbon-rich organic molecules erupting from Enceladus in plumes of water vapor and ice grains spewing from cracks in the moon’s surface.

Some of the organic compounds discovered include propene, propane, molecular hydrogen, acetylene, and surprisingly – hydrogen cyanide. While toxic to humans, hydrogen cyanide is intriguing because it could provide a chemical feedstock that could support microbes on Enceladus similar to ancient bacteria on Earth. On our planet, such organisms live in hydrothermal vents on the seafloor and harness energy by combining hydrogen with carbon dioxide dissolved in the water.

Table showing newly detected molecules in Enceladus' plume:

| Molecule           | Significance                                                                                                                                                                                                    |
|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Molecular hydrogen | Could provide energy source for microbes through chemical reactions with carbon dioxide                                                                                                                         |
| Propene            | Simple organic molecule that could be a building block for more complex biological molecules                                                                                                                   | 
| Propane            | Simple organic compound that indicates complex chemistry in Enceladus’ subsurface ocean                                                                                                                        |
| Acetylene          | Used by some microbes on Earth as an energy source                                                                                                                                                           |
| Hydrogen cyanide   | Toxic to humans but used by ancient microbes on Earth. Its presence boosts habitability case since similar microbes could live in hydrothermal vents and use it to obtain energy on Enceladus. |

Cassini also identified nanosized silica particles in the plume fallout on the surface of Enceladus. On Earth, some bacteria thrive in extreme environments by obtaining energy from chemical reactions between water and rock containing silicates. The new analysis suggests similar types of microbes could potentially inhabit Enceladus’ ocean.

Why Enceladus is Special

What makes the discovery of this chemical cocktail at Enceladus even more enticing is that it has virtually all the ingredients needed for life as we know it. Liquid water, chemical building blocks like amino acids, a sustainable energy source, and a cocktail of nutrients underpin life on Earth. Now, almost all of these components have been detected on Saturn’s small, icy ocean world.

Enceladus is only 313 miles wide, but it shows compelling signs of having hydrothermal activity, ocean currents churning within it, and organic chemistry occurring within its liquid interior – making it one of the most habitable spots beyond Earth discovered within our solar system thus far, rivalling Jupiter’s moon Europa.

Comparison between Earth and Europa:

| Feature                             | Earth                                                                                      | Enceladus                                                                                                                                                                                                                        |
|--------------------------------|-------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Evidence for subsurface ocean | Proven via many measurements                                                             | Inferred from Cassini gravity measurements                                                                                                                                                                                      | 
| Identified organic compounds  | Amino acids, nucleotides, sugars and lipids required for life                            | Simple organics like propene and propane detected                                                                                                                                                                              |  
| Energy sources                   | Sunlight, hydrothermal vents through chemical reactions between rock and ocean water | Molecular hydrogen and hydrothermal processes could provide energy like ocean floor vents on Earth                                                                                                                             |
| Liquid water                     | Plentiful on surface and in subsurface                                                   | Highly likely in subsurface ocean below icy crust                                                                                                                                                                               |
| Nutrients                        | Elements like carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur readily available | Carbon dioxide, molecular hydrogen, silica particles, and chemical ingredients like hydrogen cyanide detected in subsurface ocean could provide nutrients to support simple microbes                                      |

What’s Next for Enceladus Exploration

The tantalizing clues found at Enceladus so far are aiming attention at plans for a return mission to Saturn’s system and its intriguing moons. NASA is currently developing the Europa Clipper mission to study Jupiter’s moon Europa and its subsurface ocean. Many experts argue Enceladus also deserves its own dedicated orbiter to analyze those plumes in more detail.

Sending a spacecraft to fly through Enceladus’ plumes and analyze their makeup is the next logical step in establishing whether the moon’s warm ocean could actually be habitable for microbial life. The European Space Agency recently completed a feasibility study for a mission concept called Enceladus Life Finder. NASA also has some early-stage mission concepts in development, including one called Life Investigation for Enceladus (LIFE) to assess the moon’s habitability.

Enceladus is spurring so much interest partly because it’s much easier to access than Europa. The tantalizing prospect of its warm ocean dotted with hydrothermal vents makes it a prime target in the search for life elsewhere. A return mission could happen in the 2030s, perhaps yielding our best bet of discovering extraterrestrial organisms within our solar system within the next couple decades, if they do indeed exist on Saturn’s intriguing ocean world.

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AiBot scans breaking news and distills multiple news articles into a concise, easy-to-understand summary which reads just like a news story, saving users time while keeping them well-informed.

To err is human, but AI does it too. Whilst factual data is used in the production of these articles, the content is written entirely by AI. Double check any facts you intend to rely on with another source.

By AiBot

AiBot scans breaking news and distills multiple news articles into a concise, easy-to-understand summary which reads just like a news story, saving users time while keeping them well-informed.

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