Why do astronomers find Saturn’s moon Enceladus particularly fascinating? » ABC of science

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Beneath its thick surface of ice, Enceladus contains an ocean that could potentially harbor a habitable environment, making it fascinating to scientists.

Enceladus is Saturn’s sixth largest moon (out of 83 moons), measuring just 500 kilometers in diameter. William Herschel discovered it in 1789, and despite brief flybys during NASA’s Voyager missions, little was still known about the moon in the 1980s. However, images taken during the flyby indicated that Enceladus harbors many secrets, which has aroused the interest of scientists, even though the small moon is already near the most captivating planet in our solar system.

Saturn’s major moons (Photo credit: Kevin Gill/Wikimedia Commons)

Just like the first six discovered moons of Saturn, Herschel’s son named it after a Greek giant, since “Saturn” in Greek mythology is “Cronus”, the leader of the Titans (Cronus is also the name of one of Saturn’s moons). Additionally, the geological features of Enceladus are named after people, characters, or places, such as Aladdin, Alibaba, and Samarkand Sulci.

Fast forward to 2005, when the Cassini spacecraft was sent on a mission to investigate Saturn and its system of multiple moons. Fortunately, Cassini was able to provide scientists with the data they wanted on Enceladus. Magnetometers aboard the spacecraft detected what appeared to be an atmosphere pushing against Saturn’s magnetic field, implying that the moon is releasing gases.

This sparked the interest of the scientific community, as they had discovered something they had never seen before; the secrets of icy Enceladus.

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Enceladus and its icy surface (Photo credit: elRoce/Shutterstock)

Inside Enceladus

Enceladus has mostly cool, incredibly clean ice covering its surface. It has five distinct terrains spread across its surface, including one of the smoothest surfaces ever seen in our solar system!

Some regions have an abundance of craters, indicating an older surface, while others have rilles that appear to be uncraterd, suggesting more recent formation. Consequently, it must have a “volcanism of water”, which allows the continuous renewal of damaged surfaces. It’s like the Moon is constantly repairing itself! Therefore, it is believed to be geologically active, with an entirely salty ocean world hidden beneath its ice cover.

Due to its thick layer of ice, Enceladus is also the most reflective body in the solar system, therefore the brightest body (after the sun, of course). Because it reflects so much sunlight, that means the midday temperature is -198 degrees Celsius, making it Saturn’s coldest Moon.

Cosmic behavior and internal activity (Feathers)

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Illustration of the layers of Enceladus, with plumes released from the South Pole (Photo credit: jenikirbyhistory)

Enceladus orbits Saturn in an elliptical orbit and engages in a cosmic dance with Saturn’s other moon, Dione. As a result, it is subject to the gravitational pull of Dione and, of course, Saturn itself. These abrupt interactions cause a phenomenon known as tidal warping, which causes the South Pole’s “Tiger Stripe” fissures to constantly contract and expand as they move toward and away from Saturn. Muscular movement of these cracks causes chemicals and gases to be ejected from the moon’s thick icy surface at around 1300 km/h.

These plumes drawn from Enceladus are eventually pulled by Saturn’s gravity, to become part of its E ring. Cassini was able to collect samples of plume particles as they are constantly thrown off by Enceladus. Data from the spacecraft revealed a striking resemblance to chemicals found around hydrothermal vents on Earth, which are located deep in the ocean where sunlight does not reach.

Infrared eyes on Enceladus

Infrared view of Enceladus and its “tiger cracks” (Photo credit: Flickr)

Potential Habitability

On Earth, these vents generate massive amounts of heat energy and organic chemicals, allowing a rich and diverse ecosystem to thrive. Some theories even suggest that it could be the first place where life developed on Earth! This is what makes Enceladus so fascinating. After 4 years of research, more and more evidence of a potentially habitable environment beneath the frozen surface of Enceladus has been uncovered.

Silica crystals, carbon dioxide, large volumes of methane, and molecular hydrogen (H2) have all contributed to the hypothesis that something similar to hydrothermal vents exists inside the buried global ocean. and subterranean of the tiny moon.

Additionally, scientists have attempted to develop alternative explanations for why these chemicals exist on Enceladus, but none of these hypotheses fit. Hydrothermal vents were the only plausible explanation for the chemicals discovered in the Enceladus plumes.

Note: This does not imply that life exists on Enceladus, rather that life MAY have the POTENTIAL to evolve or thrive in the environment it contains.

Conclusion and further investigation

Cross section of Enceladus

Illustration of hypothetical cross-section of Enceladus and its layers, if hydrothermal vents exist (Photo credit: Flickr)

If something like these vents exist on Enceladus, there is a greater possibility that life could exist/thrive on this tiny, icy cold moon full of magnificent mysteries. This makes Enceladus one of the most promising candidates for hosting extraterrestrial life. The next step, according to NASA, is to launch missions solely dedicated to searching for bio-signatures on Enceladus.

As a result, Cassini has given humanity the green light to search for life on this enigmatic little moon. What is hiding under the thick layer of ice?

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