May 19, 2017 18:37 GMT by dailymail.co.uk

Titan's surface is more like MARS, not Earth, study finds

Scientists from the Massachusetts Institute of Technology found that the topographic history of Titan more closely resembles Mars, as neither has recently undergone plate tectonics.

With methane rivers and hydrocarbon lakes, Saturn’s largest moon is often referred to as Earth’s ‘toxic twin.’

But according to a new study, the topographic history of Titan more closely resembles Mars.

Unlike Earth, researchers found that neither Titan nor Mars have experienced active plate tectonics in the recent past, indicating that other processes are responsible for their surface features.

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While mountains on Earth, forged through plate tectonics, have altered the paths of rivers in our planet’s history, neither Mars nor Titan have experienced this phenomenon. An artisit's impression of Titan's surface is pictured, along with the landing of the Huygens probe 

While mountains on Earth, forged through plate tectonics, have altered the paths of rivers in our planet’s history, neither Mars nor Titan have experienced this phenomenon. An artisit's impression of Titan's surface is pictured, along with the landing of the Huygens probe 

TITAN: EARTH'S 'TOXIC TWIN'

Aside from Earth, Titan is the only place in the solar system known to have rivers, rainfall and seas - and possibly even waterfalls.

Of course, in the case of Titan these are liquid methane rather than water on Earth.

Regular Earth-water, H2O, would be frozen solid on Titan where the surface temperature is -180°C (-292°F).

With its thick atmosphere and organic-rich chemistry, Titan resembles a frozen version of Earth several billion years ago, before life began pumping oxygen into our atmosphere.

Because Titan is smaller than Earth, its gravity does not hold onto its gaseous envelope as tightly, so the atmosphere extends 370 miles (595km) into space.

With Titan's low gravity and dense atmosphere, methane raindrops could grow twice as large as Earth's raindrops. 

Scientists from the Massachusetts Institute of Technology (MIT) found that the origins of topography are very different across the three planets.

Titan is now the only planet aside from Earth with actively flowing rivers.

But, Mars once had a network of rivers as well.

While mountains on Earth, forged through plate tectonics, have altered the paths of rivers in our planet’s history, neither Mars nor Titan have experienced this phenomenon.

‘While the processes that created Titan’s topography are still enigmatic, this rules out some of the mechanisms we’re most familiar with on Earth,’ says lead author Benjamin Black, formerly an MIT graduate student and now an assistant professor at the City College of New York.

According to the researchers, Titan may owe its topography – or, the surface elevation – to processes such as the changes in the thickness of its icy crust as a result of Saturn’s tides.

And, the team found evidence that many of the features on Mars formed very early in the planet’s history.

This influenced the paths of young river systems early on, in addition to the effects of volcanic eruptions and asteroid impacts.

The researchers used maps of river networks and topography on Earth and Mars to help assess Titan’s history. While there are detailed maps for Earth and Mars, Titan’s hazy atmosphere (as seen above) means any maps of the massive moon can only show the broadest features

The researchers used maps of river networks and topography on Earth and Mars to help assess Titan’s history. While there are detailed maps for Earth and Mars, Titan’s hazy atmosphere (as seen above) means any maps of the massive moon can only show the broadest features

‘It’s remarkable that there are three worlds in the solar system where flowing rivers have carved into the landscape, either presently or in the past,’ says Taylor Perron, associate professor of geology in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS).

‘There’s this amazing opportunity to use the landforms the rivers have created to learn how the histories of these worlds are different.’

The researchers used maps of river networks and topography on Earth and Mars to help assess Titan’s topographic history.

While there are detailed maps for Earth and Mars, Titan’s hazy atmosphere means any maps of the massive moon can only show the broadest features.

Scientists from the Massachusetts Institute of Technology (MIT) found that the origins of topography are very different across the three planets. Titan is now the only planet aside from Earth with actively flowing rivers. But, Mars (shown) once had a network of rivers as well

Scientists from the Massachusetts Institute of Technology (MIT) found that the origins of topography are very different across the three planets. Titan is now the only planet aside from Earth with actively flowing rivers. But, Mars (shown) once had a network of rivers as well

With methane rivers and hydrocarbon lakes, Saturn’s largest moon is often referred to as Earth’s ‘toxic twin.’ But according to a new study, the topographic history of Titan more closely resembles Mars

With methane rivers and hydrocarbon lakes, Saturn’s largest moon is often referred to as Earth’s ‘toxic twin.’ But according to a new study, the topographic history of Titan more closely resembles Mars

To compensate for this disparity, the researchers reduced the resolution of the Earth and Mars maps, and superimposed maps of each world’s river networks.

The team marked the maps to show the direction each river appeared to flow.

And, while rivers only flow downhill, they also observed some that may appear to flow uphill based on the low resolution of the maps, which might fail to capture a mountain range or other elevated feature that would change their direction.

‘We know something about rivers, and something about topography, and we expect that rivers are interacting with topography as it evolves,’ Black says.

‘Our goal was to use those pieces to crack the code of what formed the topography in the first place.’

CASSINI'S 'GRAND FINALE'

Cassini has circled Saturn for 13 years since reaching its orbit in 2004, spearheading remarkable discoveries about the ringed planet and its icy moons – but now, it's running low on fuel.

On April 22 the spacecraft began to transition into its grand finale orbits, taking one last close flyby of Saturn's massive moon Titan.

Titan's gravity bent Cassini's flight path, causing the orbit to shrink until it was on course to pass between Saturn and the inner edges of its rings.

Cassini began the first of 22 dives through an unexplored gap on April 26.

The second of these dives began on Tuesday at 8:38pm BST (3:38pm ET).

Cassini's mission will officially terminate on September 15, after a planned plummet through Saturn's atmosphere.

And all the while it will transmit data from several instruments until the signal is finally lost.

After tallying the percentage of downhill rivers, the researchers found Titan more closely resembled Mars.

This phenomenon was also seen when they compared the ‘topographic conformity,’ or the degree of divergence between the topography’s slope and the direction of a river’s flow.

‘One prediction we can make is that, when we eventually get more refined topographic maps of Titan, we will see topography that looks more like Mars than Earth,’ Perron says.

‘Titan might have broad-scale highs and lows, which might have formed some time ago, and the rivers have been eroding into that topography ever since, as opposed to having new mountain ranges popping up all the time, with rivers constantly fighting against them.’

The researchers also investigated the effects of asteroid impacts on the topography of Mars, simulating river erosion and different impact cratering histories.

This revealed the pattern of river networks on Mars limits the extent that cratering has change the surface, suggesting the biggest impacts formed early on, and later events had much smaller effects.

With the Cassini spacecraft’s grand finale mission currently underway, the researchers say new data on Titan will soon pave the way for better understanding.

According to Perron, ‘Any way of filling in the details of what Titan’s surface is like, beyond what we can see directly in the images and topography Cassini has collected, will be valuable for planning a return.’

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