Curiosities about Enceladus, the brightest moon in the solar system

This frozen moon contains most of the chemical ingredients necessary for life, and likely has hydrothermal vents that spew hot, mineral-rich water into its subterranean ocean.

Enceladus is the brightest moon of Saturn -and of the entire solar system- and adorns the ringed planet as one more jewel of the 82 moons that this gas giant possesses, the planet that has the most natural satellites.

The study of Enceladus, discovered in 1789 by the British astronomer William Herschel, intensified from the year 2005 based on the information sent by the Cassini probe. After 20 years in activity, 13 of them studying the gaseous bodies of our solar system and its moons, Cassini disintegrated in the dense atmosphere of Saturn in 2017, when it was at the limit of its fuel, in a planned destruction from known Earth as ‘The Grand Finale’.

But Cassini, before he ‘died’, bequeathed us exciting information about Enceladus. Today we know that this frozen world apparently has a liquid ocean inside. For this reason, Enceladus has become a strong candidate to host extraterrestrial life. And we are not only talking about microorganisms that can survive in the most extreme conditions, but about life that is somewhat more complex, aquatic, living under the ice. The water of the inner ocean of Enceladus would be warm, a circumstance promoted by the gravitational forces of the enormous planet it orbits. That is, Saturn would be stirring the inner ocean of Enceladus causing it to heat up, and even hydrothermal waters exist.

The most recent information about Enceladus was released recently, in September: information obtained from the Cassini mission resulted in the most detailed collection of infrared images to date, which revealed the presence of fresh ice at both poles of Enceladus caused by recent geological activity.

Water geysers, a temperate ocean, hydrothermal waters, warm regions at the poles… In this gallery, we review the most important discoveries that have taken place around Enceladus, one of the most interesting moons in our solar system , the brightest moon, and a frozen world with the potential to harbor life.

The discovery of Enceladus
British astronomer William Herschel observed Enceladus orbiting Saturn on August 28, 1789. In addition, Herschel discovered the planet Uranus, hypothesized that nebulae are composed of stars, and developed a theory of stellar evolution.

First images of Enceladus
The first time we obtained images of this moon by a space probe was in 1981, thanks to Voyager 2, on its way to the outer limits of the solar system. The spacecraft returned images that revealed that Enceladus is geologically complex, its surface having gone through five different evolutionary periods.

Characteristics of Enceladus
It measures about 500 kilometers in diameter, can reach -198 °C at noon, and is the brightest satellite of Saturn because it is covered in ice, reflecting all light.

To get an idea, Enceladus is one tenth the size of Titan, Saturn’s largest moon; and it is much smaller than our Moon, which is about 3,500 kilometers across.

The discovery of geological activity on Enceladus
The Cassini mission in 2005 revealed a big surprise: a huge cloud of water vapor and ice particles at the south pole, which was being emitted through relatively warm fractures in the crust. That is, Enceladus has geological activity.

liquid water below the surface
In 2006, at last, Cassini mission scientists announced that they had found liquid water below the surface of Enceladus, spewing outward in the form of geysers. In turn, they found evidence that the jets could be coming out of pockets of liquid water near the surface.

The ‘tiger stripes’, tempered fractures on the surface of Enceladus
A year later, Cassini provided conclusive evidence that the jets originated near the hottest spots in the moon’s fractures, which we know as ‘tiger stripes’, and that they straddle the south polar region of Enceladus.

Presence of salty ice
In 2009, the Cassini mission detected sodium salts in ice grains in Saturn’s outer ring. The detection of salty ice indicated that Saturn’s moon Enceladus, which covers the ring with this material from the discharge of geysers, could harbor a reservoir of liquid water, perhaps an ocean, below its surface.

An electrical circuit links Enceladus with Saturn
This artist’s illustration shows a bright patch of ultraviolet light near Saturn’s north pole, the source of the magnetic connection between Saturn and its moon Enceladus. It was detected by the ultraviolet imaging spectrograph and particle and field instruments on NASA’s Cassini spacecraft in 2011.

Signs of an underground ocean
In 2014 scientists identify 101 different geysers of liquid water on Enceladus. Their analysis suggests that liquid water may have reached its surface from an underground sea, under the ice cap.

Presence of hot springs
In 2015, Cassini provided scientists with the first clear evidence that Enceladus exhibits signs of recent hydrothermal activity, similar to that occurring in Earth’s deep oceans. The mission found silicon-rich rock particles. And the scientists concluded that these tiny grains most likely formed when hot water, containing dissolved minerals from the moon’s rocky interior, traveled upwards, coming into contact with cooler water.

Could Enceladus harbor life?
Scientists announced in 2017 the detection of significant amounts of hydrogen on Enceladus. Of the geysers, it was determined that 98%, and the rest is a mixture of other molecules, including carbon dioxide, methane and ammonia. The detection of a large amount of hydrogen strongly suggests a continuing hydrothermal process, in which Enceladus’s groundwater would interact with rocks and organic compounds.

Examples on Earth
This detected chemistry is similar to that created by hydrothermal vents in Earth’s oceans, and could be used as an energy source for life forms, if they live in Enceladus’ ocean.

The most detailed infrared images of Enceladus
The latest exciting discovery around Enceladus was announced in September 2020, and it’s the most detailed infrared images yet from Cassini data, ahead of its Grand Finale.