Skip to main content

4 of Uranus’s icy moons could have liquid water oceans

When it comes to exploring planets in our solar system, most of the attention gets placed on those nearest to Earth which are easier to visit, and with powerful telescopes, we often observe the gas giants Jupiter and Saturn too. The more distant planets like Uranus and Neptune, however, are often overlooked and there’s growing support among planetary scientists for sending a mission there. Now, new evidence gives even more impetus for a mission to Uranus, with a recent study showing that four of the planet’s moons could host water.

Researchers from NASA’s Jet Propulsion Laboratory reanalyzed data from the Voyager 2 mission which passed Uranus in the 1980s to look at the five largest of its 27 moons: Ariel, Umbriel, Titania, Oberon, and Miranda. Using computer modeling of how porous the surfaces are, they found that four of these moons likely have liquid water oceans beneath icy crusts.

Uranus is surrounded by its four major rings and 10 of its 27 known moons in this color-added view that uses data taken by the Hubble Space Telescope in 1998. A study featuring new modeling shows that four of Uranus’ large moons likely contain internal oceans.
Uranus is surrounded by its four major rings and 10 of its 27 known moons in this color-added view that uses data taken by the Hubble Space Telescope in 1998. A study featuring new modeling shows that four of Uranus’ large moons likely contain internal oceans. NASA/JPL/STScI

The diagram below shows what the interiors of the five largest moons are thought to be composed of, with layers of ice, rock, and water. Even though Uranus and its moons are very far from the sun and therefore have very cold surface temperatures, there could be salty oceans present because they are insulated by a thick layer of ice and seem to have ammonia in them, which acts like an antifreeze. And in some cases, the moons could be warmed by internal heat mechanisms from their rocky mantles.

New modeling shows that there likely is an ocean layer in four of Uranus’ major moons: Ariel, Umbriel, Titania, and Oberon. Salty – or briny – oceans lie under the ice and atop layers of water-rich rock and dry rock. Miranda is too small to retain enough heat for an ocean layer.
New modeling shows that there likely is an ocean layer in four of Uranus’ major moons: Ariel, Umbriel, Titania, and Oberon. Salty – or briny – oceans lie under the ice and atop layers of water-rich rock and dry rock. Miranda is too small to retain enough heat for an ocean layer. NASA/JPL-Caltech

The insulating effect is similar to what is seen at the icy moons around Jupiter and Saturn, which are also thought to host oceans and are targets for studying habitability. There seem to be a wide range of places that could host water oceans, even if they are outside the habitable zone.

“When it comes to small bodies – dwarf planets and moons – planetary scientists previously have found evidence of oceans in several unlikely places, including the dwarf planets Ceres and Pluto, and Saturn’s moon Mimas,” said lead author Julie Castillo-Rogez of NASA’s Jet Propulsion Laboratory in a statement. “So there are mechanisms at play that we don’t fully understand. This paper investigates what those could be and how they are relevant to the many bodies in the solar system that could be rich in water but have limited internal heat.”

The research is published in the Journal of Geophysical Research.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Astronomers spot cyclones at Uranus’ pole for the first time
NASA scientists used microwave observations to spot the first polar cyclone on Uranus, seen here as a light-colored dot to the right of center in each image of the planet. The images use wavelength bands K, Ka, and Q, from left. To highlight cyclone features, a different color map was used for each.

Even at almost 2 billion miles away from the sun, Uranus is still affected by changing seasons and weather just like Earth. On Uranus, though, each season is an epic 21 years long because of its distance from the sun. That makes it an intriguing place to study weather conditions, and recent research by NASA has observed a polar cyclone there.

As the planet is tipped over on its side, its poles aren't always facing in the right direction to be seen from Earth. But since 2015, astronomers have been able to observe the poles, and to peer into the atmosphere to see what is happening there.

Read more
How to watch JUICE mission launch to Jupiter’s icy moons
The European Space Agency's JUICE spacecraft.

[UPDATE: The original target launch date of Thursday, April 13, was called off due to poor weather conditions at the launch site. The JUICE mission is now targeting the morning of Friday, April 14. Full details below.]

Juice launch to Jupiter

Read more
Launch of Europe’s Jupiter Icy Moons Explorer delayed by 24 hours
An Ariane 5 rocket containing the Juice spacecraft on the launchpad at Europe’s Spaceport in Kourou, French Guiana, on Thursday April 13 2023.

The launch of the European Space Agency (ESA)'s JUICE mission to the icy moons of Jupiter has been delayed by 24 hours due to weather conditions. Risk of lightning near the launch pad at Europe’s Spaceport in Kourou, French Guiana meant that the launch was scrubbed around 10 minutes prior to the scheduled liftoff today, Thursday, April 13.

Juice launch to Jupiter

Read more