How Could We Detect Life Inside Enceladus?

Scientists recently determined that a certain strain of Earth bacteria could thrive under conditions found on Enceladus. Credit: NASA/JPL/Space Science Institute

For astrobiologists, the scientists dedicated to the search for life beyond Earth, the moons of Saturn are a virtual treasure trove of possibilities. Enceladus is especially compelling because of the active plumes of water emanating from its southern polar region. Not only are these vents thought to be connected directly to an ocean beneath the moon’s icy surface, but the Cassini mission detected traces of organic molecules and other chemicals associated with biological processes. Like Europa, Ganymede, and other “Ocean Worlds,” astrobiologists think this could indicate hydrothermal activity at the core-mantle boundary.

Both NASA and the ESA are hoping to send missions to Enceladus that could study its plumes in more detail. These include the Enceladus Orbitlander recommended in the Planetary Science and Astrobiology Decadal Survey 2023-2032 and the ESA’s Enceladus Moonraker, which could depart Earth in the next decade, taking advantage of a favorable alignment between the planets. In anticipation of what these missions could find, an international team of researchers used data from the Cassini mission to establish how samples of plume material could constrain how much biomass Enceladus has within it.

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ESA is Considering a Mission to Enceladus

There are plenty of exciting places in the solar system to explore. But few are more interesting than Saturn’s moon Enceladus. It’s one of the only planetary bodies known to have all six necessary components of Earth-based life. It has an active ocean and most likely hydrothermal vents, similar to those on Earth, where some species exist entirely separately from any solar-powered biosphere. All of this makes it one of the most likely candidates for life in the solar system – and the center of much astrobiological attention. Now a team from a variety of European countries and the US has proposed a mission to the moon that could profoundly impact our understanding of our place in the universe – if the European Space Agency (ESA) funds it.

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Will Enceladus finally answer, ‘Are we alone?’

We recently examined how and why the planet Mars could answer the longstanding question: Are we alone? There is evidence to suggest that it was once a much warmer and wetter world thanks to countless spacecraft, landers, and rovers having explored—and currently exploring—its atmosphere, surface, and interior. Here, we will examine another one of Saturn’s 83 moons, an icy world that spews geysers of water ice from giant fissures near its south pole, which is strong evidence for an interior ocean, and possibly life. Here, we will examine Enceladus.

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This is What a Robotic Explorer Might See When it Reaches Europa’s Oceans

Mounds of snow-like ice under an ice shelf. ©Helen Glazer, 2015 from the project Walking in Antarctica.

For decades, evidence has been mounting that beneath the icy crust of Jupiter’s moon Europa, a vast ocean exists that could possibly host microbial life. As scientists prepare to send the Europa Clipper mission to orbit the Jupiter system, they are trying to learn more about the subsurface ocean and the ice that encompasses the moon.

One way to study Europa is to look at similar environments here on Earth. Scientists say that conditions found under Earth’s Antarctic ice shelf provides an analog to Europa’s subsurface ocean and can help them determine how the moon’s ice shell accretes and grows.

A new study published in the journal Astrobiology looked at a unique phenomenon in the Antarctic ocean called underwater snow. This is where ice floats upwards onto the bottom of the ice shelf and attaches in fluffy-looking mounds. This helps to replenish the ice shelf. The study infers that the same phenomenon is likely true for Jupiter’s moon, and may play a role in building and replenishing its exterior ice shell.

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Solar System Tours: Plumes of Enceladus

“We’re coming up on the plumes!” The co-pilot announced over the intercom.

The other six passengers and I took our positions along the viewing cupola at the belly of the “Tour Bus”, and each grabbed on to the hand and foot restraints to keep ourselves in place in the weightlessness. We were traveling about 400 km (250 miles) above the south pole of Enceladus looking down at the highly reflective surface that was so bright it took about a minute for our eyes to adjust. We all remained silent, and my heart was pounding in anticipation. The Tour Bus silently coasted for a few more minutes as we took in the breathtaking view of Saturn’s sixth-largest moon.

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We Now Understand Why Enceladus has ‘Tiger Stripe’ Cracks at its Southern Pole

The "tiger stripes" of Enceladus - - as pictured by the Cassini space probe. Credit: NASA/JPL/ESA

One of the biggest surprises of the 13-year Cassini mission came in Enceladus, a tiny moon with active geysers at its south pole. At only about 504 kilometers (313 miles) in diameter, the bright and ice-covered Enceladus should be too small and too far from the Sun to be active. Instead, this little moon is one of the most geologically dynamic objects in the Solar System.

A new study has modeled how this activity could be taking place, and what mechanism might power the geysers spewing from ‘tiger stripe’ fissures. While previous studies have indicated some type of unknown internal heat source on Enceladus, the new study infers no heat source would be necessary.

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Cassini Saw Methane in Enceladus’ Plumes. Scientists Don’t Know How it Could be There Without Life

Icy water vapor geysers erupting from fissures on Enceladus. Credit: NASA/JPL

Even though the Cassini mission at Saturn ended nearly four years ago, data from the spacecraft still keeps scientists busy. And the latest research using Cassini’s wealth of data might be the most enticing yet.

Researchers say they’ve detected methane in the plumes of Saturn’s icy moon Enceladus. The process for how the methane is produced is not known at this time, but the study suggests that the surprisingly large amount of methane found are likely coming from activity at hydrothermal vents present on Enceladus’s interior seafloor. These vents could be very similar those found in Earth’s oceans, where microorganisms live, feed on the energy from the vents and produce methane in a process called methanogenesis.

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How Salty is Enceladus’ Ocean Under the ice?

An icy satellite of Saturn, Enceladus, has been a subject of increasing interest in recent years since Cassini captured jets of water and other material being ejected out of the south pole of the moon.  One particularly tantalizing hypothesis supported by the sample composition is that there might be life in the oceans under the ice shells of Enceladus. To evaluate Enceladus’ habitability and to figure out the best way to probe this icy moon, scientists need to better understand the chemical composition and dynamics of Enceladus’ ocean.

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