What Can We Learn Flying Through the Plumes at Enceladus?

The Cassini spacecraft captured this image of cryovolcanic plumes erupting from Enceladus' ice-capped ocean. Image Credit: NASA/JPL/CalTech

In the next decade, space agencies will expand the search for extraterrestrial life beyond Mars, where all of our astrobiology efforts are currently focused. This includes the ESA’s JUpiter ICy moon’s Explorer (JUICE) and NASA’s Europa Clipper, which will fly past Europa and Ganymede repeatedly to study their surfaces and interiors. There’s also NASA’s proposed Dragonfly mission that will fly to Titan and study its atmosphere, methane lakes, and the rich organic chemistry happening on its surface. But perhaps the most compelling destination is Enceladus and the lovely plumes emanating from its southern polar region.

Since the Cassini mission got a close-up look at these plumes, scientists have been aching to send a robotic mission there to sample them – which appear to have all the ingredients for life in them. This is not as easy as it sounds, and there’s no indication flying through plumes will yield intact samples. In a recent paper, researchers from the University of Kent examined how the velocity of a passing spacecraft (and the resulting shock of impact) could significantly affect its ability to sample water and ice within the plumes.

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How Warm Are the Oceans on the Icy Moons? The Ice Thickness Provides a Clue.

Jupiter's moon Ganymede is the largest moon in the Solar System and may have an ocean sandwiched between two layers of ice. But how warm is that ocean? Image Credit: By National Oceanic and Atmospheric Administration Public Domain, https://commons.wikimedia.org/w/index.php?curid=8070396

Scientists are discovering that more and more Solar System objects have warm oceans under icy shells. The moons Enceladus and Europa are the two most well-known, and others like Ganymede and Callisto probably have them too. Even the dwarf planet Ceres might have an ocean. But can any of them support life? That partly depends on the water temperature, which strongly influences the chemistry.

We’re likely to visit Europa in the coming years and find out for ourselves how warm its ocean is. Others on the list we may never visit. But we may not have to.

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Fly Slowly Through Enceladus' Plumes to Detect Life

The plumes of Enceladus have phosphate-rich ice grains entrained. Credit: NASA
A NASA illustrations of Cassini flying through the plumes of Enceladus. Credit: NASA.

Enceladus is blasting water into space from the jets at its southern pole. This makes it the ideal place to send a dedicated mission, flying the spacecraft through the plumes with life-detection instruments s. A new study suggests that a spacecraft must proceed carefully through the plumes, keeping its speed below 4.2 km/second (2,236 miles per hour). Using a specialized, custom-built aerosol impact spectrometer at these speeds will allow fragile amino acids to be captured by the spacecraft’s sample collector. Any faster, they’ll shatter, providing inclusive results.

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Europa and Enceladus are the Perfect Targets for a Lightsail Mission

Saturn's moon Enceladus isn't just bright and beautiful. It has an ocean under all that ice that has chemicals necessary for life. Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team

There’s always a need for new technologies or for novel uses of existing technologies to lower the cost of space exploration and extend our reach. Lightsails are a novel type of spacecraft that could eventually be our first visitors to nearby stars like the Alpha Centauri system. But they could be put to productive use right here in our Solar System.

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Mini-Subs Could One Day Ply the Seas Under Europa’s Ice

This is a model of the miniature underwater vehicle being developed at MARUM with partners from industry. It will have a diameter of around ten cm and a length of about 50 cm. The tiny submarines will be placed inside a melt probe then released in the subglacial lakes under Antarctica. Image Credit: MARUM – Center for Marine Environmental Sciences, University of Bremen.

The most promising places to look for life in the Solar System are in the ocean moons Europa and Enceladus. But all that warm, salty, potentially life-supporting water is under thick sheets of ice: up to 30 km thick on Europa and up to 40 km thick for Enceladus.

The main obstacles to exploring all that water are the thick ice barriers. Assuming a spacecraft can be designed and built to melt its way through all that ice, what then?

Submarines can do the actual exploring, and they needn’t be large.

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Whether Saturn's Rings are Young or Old, its Moons are as Ancient as the Planet Itself

The moons of Saturn, from left to right: Mimas, Enceladus, Tethys, Dione, Rhea; Titan in the background; Iapetus (top) and irregularly shaped Hyperion (bottom). Some small moons are also shown. All to scale. Credit: NASA/JPL/Space Science Institute

Saturn is best known for two things: its iconic ring structures and its large system of natural satellites. Currently, 146 moons and moonlets have been discovered orbiting the ringed giant, 24 of which are regular satellites. These include the seven largest moons, Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, and Mimas, which are icy bodies believed to have interior oceans. In addition, there are unresolved questions about the age of these satellites, with some suspecting that they formed more recently (like Saturn’s rings, which are a few hundred million years old).

To address these questions, an international team of astronomers created a series of high-resolution simulations coupled with improved estimates of Trans-Neptunian Object (TNO) populations. This allowed them to construct a chronology of impacts for Saturn’s most heavily cratered regular satellites – Mimas, Enceladus, Tethys, Dione, and Rhea. This established age limits of 4.1 and 4.4 billion years for all five, with the two innermost moons appearing more youthful than the outer three. These results could have significant implications for our understanding of the formation and tidal evolution of moons in the outer Solar System.

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We've Got to Go Back to Enceladus. Here's a Mission That Could Get the Science

Four key objectives of the proposed AXE mission. Credit: NASA/JPL-Caltech

In our search for life on other worlds, the one we’ve most explored is Mars. But while Mars has the makings for possible life, it isn’t the best candidate in our solar system. Much better are the icy moons of Jupiter and Saturn, which we know have liquid water. And of those, perhaps the best candidate is Saturn’s moon Enceladus.

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JWST Spies a Gigantic Water Plume at Enceladus

Images from the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) show a water vapour plume jetting from the south pole of Saturn’s moon Enceladus, extending out 40 times the size of the moon itself. The inset, an image from the Cassini orbiter, emphasises how small Enceladus appears in the JWST image compared to the water plume. Credit: NASA, ESA, CSA, STScI, G. Villanueva (NASA’s Goddard Space Flight Center), A. Pagan (STScI).

The James Webb Space Telescope has observed a huge water vapor plume emanating from Saturn’s moon Enceladus. Astronomers say the plume reaches nearly 10,000 kilometers (6,200 miles) into space, which is about the equivalent distance as going from Ireland to Japan. This is the largest plume ever detected at Enceladus.

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One Spacecraft Could Visit All of Saturn's Inner Large Moons

Saturn's largest moons. Credit: NASA / JPL-Caltech / Montage by Emily Lakdawalla / Processing by Processing by Ted Stryk, Gordan Ugarkovic, Emily Lakdawalla, and Jason Perry.

If you’ve ever played Kerbal Space Program, you know how difficult it can be to get your spacecraft into the orbit you want. It’s even more difficult in real life. This is why it’s pretty impressive to see a proposal to study all of Saturn’s large inner moons in one go.

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We Could Soon See Landslides on Europa and Ganymede

Image of potential flat, smooth terrain on Ganymede imaged by NASA's Galileo spacecraft in 2000 that could be indicative of landslides. (Credit: NASA/JPL/Brown University)

The European Space Agency’s (ESA) recently launched Jupiter Icy Moons Explorer (JUICE) mission and NASA’s upcoming Europa Clipper mission could allow scientists to image landslides on the icy moons of Europa and Ganymede due to potential moonquakes on these small worlds. This comes after a recent study examined fault scarps on Europa and Ganymede orbiting Jupiter and Enceladus and Dione orbiting Saturn with the goal of drawing a connection between tectonic activity (quakes) and observed mass wasting (landslides) on these surfaces. The researchers “consider whether such smooth material can be generated by mass wasting triggered from local seismic shaking”, according to the study.

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