Space News from SpaceDaily.com
Life on 'Death Star'? Saturn moon Mimas has hidden ocean
ADVERTISEMENT

Paris, Feb 7 (AFP) Feb 07, 2024
Saturn's small moon Mimas seems an unlikely suspect in the hunt for life in Earth's backyard -- it is probably best known for looking like the "Death Star" in the Star Wars films.

But scientists said on Wednesday that underneath the unassuming moon's icy shell is a vast hidden ocean that has many of the ingredients necessary to host primitive alien life.

Mimas is the latest to join a growing family of icy moons thought to harbour inner oceans in our Solar System which also includes fellow Saturn satellites Enceladus and Titan as well as Jupiter's Europa and Ganymede.

But the inclusion of Mimas in this list has come as a surprise.

"If there is one place in the universe where we did not expect to find conditions favourable to life, it is Mimas," said Paris Observatory astronomer Valery Lainey, the lead author of a new study in the journal Nature.

Mimas, which is only 400 kilometres (250 miles) in diameter, was "not at all suitable for the job", Lainey told a press conference.

Discovered by English astronomer William Herschel in 1789, the moon has the nickname "Death Star" because one particularly huge crater makes it look eerily similar to the space station used by Darth Vader and the villainous Empire in Star Wars.

Its craggy, crater-riddled surface is inert, showing no sign of underlying geologic activity that would suggest a hidden ocean.


- 'Something happening inside' -


Other water worlds such as Mimas' big sibling Enceladus have smooth surfaces due to their rumbling internal oceans and many geysers.

These geysers, which shoot out material from the surface, also demonstrate that there is enough heat below to keep the water in a liquid state.

Despite its seemingly desolate exterior, Lainey said the researchers suspected that "something was happening inside" Mimas.

They studied how the moon's rotation is affected by its interior structure, first publishing research in 2014 which was not strong enough to prove the presence of a hidden ocean.

Most scientists remained convinced by the other main hypothesis: that Mimas has a solid core of rock.

"We could have left it there," Lainey said, adding that they were "frustrated".

For the new study, the team carefully analysed the moon's rotation and orbit in dozens of images taken by NASA's Cassini spacecraft, which orbited Saturn from 2004 to 2017.

They detected tiny oscillations -- rotations of just a few hundred metres -- which could not have occurred if the moon had a solid rock interior.

"The only viable conclusion is that Mimas has a subsurface ocean," said two US-based scientists not involved in the study.

"The finding calls for a fresh take on what constitutes an ocean moon," Matija Cuk of the Search for Extraterrestrial Intelligence (SETI) and planetary scientist Alyssa Rose Rhoden wrote in a comment article in Nature.


- The right stuff for life -


Mimas' ice-covered shell is between 20 and 30 kilometres thick, similar to Enceladus, the study estimated.

The researchers believe the ocean formed relatively recently -- between five to 15 million years ago -- which could explain why signs of its existence have yet to rise and smooth the moon's surface.

The ocean likely exists due to the influence of Saturn's many other moons, whose tidal effects shook Mimas and created the necessary heat, they said.

Mimas "brings together all the conditions necessary for habitability: water maintained by a heat source that is in contact with rocks so that chemical exchanges develop," said study co-author Nicolas Rambaux, also of the Paris Observatory.

So could this nearby water world harbour primitive forms of life such as bacteria?

"That question will be addressed by future space missions over the coming decades," Lainey said.

"One thing is certain: if you are looking for the most recent conditions of habitability to have formed in the Solar System, Mimas is the place to look."

juc-dl/imm

EMPIRE COMPANY


ADVERTISEMENT




Space News from SpaceDaily.com
NASA Ends $2 Billion Satellite Refueling Project Amid Challenges
Japan Moon lander put to sleep after surviving lunar night
NASA, SpaceX postpone Crew-8 mission to Sunday

24/7 Energy News Coverage
The role of history in how efficient color names evolve
AI outperforms humans in standardized tests of creative potential
Building bionic jellyfish for ocean exploration

Military Space News, Nuclear Weapons, Missile Defense
Military Leaders Say Maintaining U.S. Strategic Edge Requires Continued Investment
As Russian Threats Grow, King Warns U.S. Space Command of American Vulnerabilities
South Korea's Yoon slams 'truly deplorable' North Korean remarks, calls for unification

24/7 News Coverage
Mercury rising: Study sheds new light on ancient volcanoes' environmental impact
Glacier shrinkage is causing a "green transition"
UMaine researchers use GPS-tracked icebergs in novel study to improve climate models


All rights reserved. Copyright Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.