Evidence of liquid oceans on Saturn's moon Enceladus increases chances of finding alien life in our Solar System

 

Science Editor

One of the moons of Saturn has turned out to be another possible habitat for extraterrestrial microbes after scientists have discovered that it possesses a large ocean of water beneath its icy surface.

Measurements of gravity fluctuations around Enceladus taken by Nasa’s Cassini spacecraft indicate that there is an underground ocean of melted water at the moon’s south pole which may be the source of dramatic vapour plumes seen at its surface.

The existence of liquid water is widely assumed to be a vital precondition for life so its presence suggests that Enceladus may be another habitable part of the Solar System, along with Titan, the biggest moon of Saturn, and Europa, an ice-covered moon of Jupiter.

A study led by Luciano Iess of Sapienza University in Rome, published in the journal Science, shows that during three flybys of Enceladus between 2010 and 2012, which brought Cassini within 100km (62 miles) of its surface, the spacecraft’s velocity changed slightly in response to fluctuations in the moon’s gravity field, which could only be readily explained by the presence of a large body of liquid water at its south pole.

“Using geophysical measurements, we have been able to confirm that there is a large ocean beneath the surface of Enceladus’s south-polar region. This provides a possible source for the water that Cassini has seen spewing from the geysers in this region,” said Professor David Stevenson, a co-investigator at the California Institute of Technology in Pasadena.

“This water ocean may extend halfway or more towards the equator [of Enceladus] in every direction. This means that it is as large, or larger, than Lake Superior [the largest of the Great Lakes],” Professor Stevenson said.

The Cassini spacecraft observed the water plumes on Enceladus in 2005 to the surprise of astronomers given that the surface temperatures on the moon, which is barely 500km wide, hover around minus 180C and the lunarscape is covered in a thick crust of solid ice.

Calculations suggest that the liquid ocean is located at a depth of between 30km and 40km beneath the surface and is prevented from freezing up completely by the geophysical heat generated by the tidal forces on the moon as it completes its elliptical orbit around Saturn.

“Enceladus shows some similarity to Europa, a much larger moon of Jupiter, which, like Enceladus has an ocean that is in contact with underlying rock. In this respect these two bodies are of particular interest for understanding the presence and nature of habitable environments in our Solar System,” Professor Stevenson said.

“The data suggest that indeed there is a large, possibly regional ocean about 50km below the surface of the south pole. This then provides one possible story to explain why water is gushing out of these fractures we see at the south pole,” he said.

Liquid water is denser than ice – which is why ice floats on water – and this difference in density deep under the frozen surface causes fluctuations in the moon’s gravity field, which resulted in Cassini slowing down by a few millimetres per second as it flew past Enceladus. Calculations suggest the ocean is 10km deep.

Although there is no direct evidence connecting the underground ocean to the surface plumes of salty water vapour, the astronomers believe the two are connected via a network of “tiger stripes” or fractures in the ice that can be seen from space.

“Material from Enceladus’s south polar jets contains salty water and organic molecules, the basic chemical ingredients for life,” said Linda Spilker, the Cassini project scientist at Nasa’s Jet Propulsion Laboratory in Pasadena.

“Their discovery expanded our view of the ‘habitable zone’ within our solar system and in planetary systems of other stars. This new validation that an ocean of water underlies the jets furthers understanding about this intriguing environment,” Dr Spilker said.

Start your day with The Independent, sign up for daily news emails
News
Keith Fraser says we should give Isis sympathises free flights to join Isis (AFP)
news
Life and Style
A picture taken on February 11, 2014 at people walking at sunrise on the Trocadero Esplanade, also known as the Parvis des droits de l'homme (Parvis of Human Rights), in front of the Eiffel Tower in Paris.
techGoogle celebrates Paris's iconic landmark, which opened to the public 126 years ago today
News
Cleopatra the tortoise suffers from a painful disease that causes her shell to disintegrate; her new prosthetic one has been custom-made for her using 3D printing technology
newsCleopatra had been suffering from 'pyramiding'
News
people
Arts and Entertainment
Coachella and Lollapalooza festivals have both listed the selfie stick devices as “prohibited items”
music
Sport
Nigel Owens was targeted on Twitter because of his sexuality during the Six Nations finale between England and France earlier this month
rugbyReferee Nigel Owens on coming out, and homophobic Twitter abuse
ebooks
ebooksA special investigation by Andy McSmith
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Senior Web Designer / Front End Developer

£28000 - £32000 per annum: Recruitment Genius: This fast expanding web managem...

Ashdown Group: Trainee Consultant - Surrey / South West London

£22000 per annum + pension,bonus,career progression: Ashdown Group: An establi...

Ashdown Group: Trainee Consultant - Surrey/ South West London

£22000 per annum + pension,bonus,career progression: Ashdown Group: An establi...

Ashdown Group: Recruitment Consultant / Account Manager - Surrey / SW London

£40000 per annum + realistic targets: Ashdown Group: A thriving recruitment co...

Day In a Page

No postcode? No vote

Floating voters

How living on a houseboat meant I didn't officially 'exist'
Louis Theroux's affable Englishman routine begins to wear thin

By Reason of Insanity

Louis Theroux's affable Englishman routine begins to wear thin
Power dressing is back – but no shoulderpads!

Power dressing is back

But banish all thoughts of Eighties shoulderpads
Spanish stone-age cave paintings 'under threat' after being re-opened to the public

Spanish stone-age cave paintings in Altamira 'under threat'

Caves were re-opened to the public
'I was the bookies’ favourite to be first to leave the Cabinet'

Vince Cable interview

'I was the bookies’ favourite to be first to leave the Cabinet'
Election 2015: How many of the Government's coalition agreement promises have been kept?

Promises, promises

But how many coalition agreement pledges have been kept?
The Gaza fisherman who built his own reef - and was shot dead there by an Israeli gunboat

The death of a Gaza fisherman

He built his own reef, and was fatally shot there by an Israeli gunboat
Saudi Arabia's airstrikes in Yemen are fuelling the Gulf's fire

Saudi airstrikes are fuelling the Gulf's fire

Arab intervention in Yemen risks entrenching Sunni-Shia divide and handing a victory to Isis, says Patrick Cockburn
Zayn Malik's departure from One Direction shows the perils of fame in the age of social media

The only direction Zayn could go

We wince at the anguish of One Direction's fans, but Malik's departure shows the perils of fame in the age of social media
Young Magician of the Year 2015: Meet the schoolgirl from Newcastle who has her heart set on being the competition's first female winner

Spells like teen spirit

A 16-year-old from Newcastle has set her heart on being the first female to win Young Magician of the Year. Jonathan Owen meets her
Jonathan Anderson: If fashion is a cycle, this young man knows just how to ride it

If fashion is a cycle, this young man knows just how to ride it

British designer Jonathan Anderson is putting his stamp on venerable house Loewe
Number plates scheme could provide a licence to offend in the land of the free

Licence to offend in the land of the free

Cash-strapped states have hit on a way of making money out of drivers that may be in collision with the First Amendment, says Rupert Cornwell
From farm to fork: Meet the Cornish fishermen, vegetable-growers and butchers causing a stir in London's top restaurants

From farm to fork in Cornwall

One man is bringing together Cornwall's most accomplished growers, fishermen and butchers with London's best chefs to put the finest, freshest produce on the plates of some of the country’s best restaurants
Robert Parker interview: The world's top wine critic on tasting 10,000 bottles a year, absurd drinking notes and New World wannabes

Robert Parker interview

The world's top wine critic on tasting 10,000 bottles a year, absurd drinking notes and New World wannabes
Don't believe the stereotype - or should you?

Don't believe the stereotype - or should you?

We exaggerate regional traits and turn them into jokes - and those on the receiving end are in on it too, says DJ Taylor