It has long been believed that the dunes on Saturn’s largest moon formed from rainfall – but new evidence suggests otherwise.
Experts now claim that the mounds were shaped through a chemical reaction when cosmic rays hit ice on Titan’s surface.
The team recreated the process in a lab and found it created the same organic molecules found in dunes, and could explain similar formations on other planets or moons with no atmosphere.
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It has long been believed that the dunes on Saturn’s largest moon formed from rainfall – but new evidence suggests otherwise (artist impression)
The study was conducted by a trio of researchers at the University of Hawaii who analyzed the theory that Titan’s atmosphere consisted of some organic molecules, made up of long chains of carbon atoms.
The data was captured by the Cassini space probe and sparked the idea that the molecules had to have fallen from the atmosphere and formed the dunes.
However, the trio of researchers believed otherwise – that the dunes covering part of the equatorial region of Titan’s surface formed from a chemical reaction.
To test this theory, the team made batches of acetylene ice, the ice found on Titan, in a lab and then attacked it with radiation similar to that experienced by Titan.
It has long been believed that the dunes on Saturn’s largest moon formed from rainfall – but new evidence suggests otherwise. Experts now claim that the mounds were shaped through a chemical reaction when cosmic rays hit ice on Titan’s surface
They then heated the ice until it sublimated, leaving behind material made of organic molecules similar to those believed to form the dunes on Titan.
In so doing, they found that the process could produce phenanthrene in as little as 100 years –other molecules would take longer.
The team recreated the process in a lab and found it created the same organic molecules found in dunes, and could explain similar formations on other planets or moons with no atmosphere (pictured is Saturn with its moon Titan orbiting it)
WHAT DID CASSINI DISCOVER DURING ITS 20-YEAR MISSION TO SATURN?
Cassini launched from Cape Canaveral, Florida in 1997, then spent seven years in transit followed by 13 years orbiting Saturn.
An artist’s impression of the Cassini spacecraft studying Saturn
In 2000 it spent six months studying Jupiter before reaching Saturn in 2004.
In that time, it discovered six more moons around Saturn, three-dimensional structures towering above Saturn’s rings, and a giant storm that raged across the planet for nearly a year.
On 13 December 2004 it made its first flyby of Saturn’s moons Titan and Dione.
On 24 December it released the European Space Agency-built Huygens probe on Saturn’s moon Titan to study its atmosphere and surface composition.
There it discovered eerie hydrocarbon lakes made from ethane and methane.
In 2008, Cassini completed its primary mission to explore the Saturn system and began its mission extension (the Cassini Equinox Mission).
In 2010 it began its second mission (Cassini Solstice Mission) which lasted until it exploded in Saturn’s atmosphere.
In December 2011, Cassini obtained the highest resolution images of Saturn’s moon Enceladus.
In December of the following year it tracked the transit of Venus to test the feasibility of observing planets outside our solar system.
In March 2013 Cassini made the last flyby of Saturn’s moon Rhea and measured its internal structure and gravitational pull.
Cassini didn’t just study Saturn – it also captured incredible views of its many moons. In the image above, Saturn’s moon Enceladus can be seen drifting before the rings and the tiny moon Pandora. It was captured on Nov. 1, 2009, with the entire scene is backlit by the Sun
In July of that year Cassini captured a black-lit Saturn to examine the rings in fine detail and also captured an image of Earth.
In April of this year it completed its closest flyby of Titan and started its Grande Finale orbit which finished on September 15.
‘The mission has changed the way we think of where life may have developed beyond our Earth,’ said Andrew Coates, head of the Planetary Science Group at Mullard Space Science Laboratory at University College London.
‘As well as Mars, outer planet moons like Enceladus, Europa and even Titan are now top contenders for life elsewhere,’ he added. ‘We’ve completely rewritten the textbooks about Saturn.’
The team is hopeful about this new theory, as it could explain why other planets and moons without atmosphere have similar dunes.
This includes Makemake and Pluto, both of which have shown indications of organic ice on their surface.
The researchers acknowledge that both theories that seek to explain the means by which the dunes on Titan form are still unproven.
But they hope that will change, as NASA plans to send a probe called Dragonfly to Titan, which is set to land near the dunes in 2026.
NASA made an announcement in June during a media teleconference, detailing its vision of a robotic rotorcraft dubbed Dragonfly that will collect samples and measure soil composition in search for signs of habitability.
The enormous, icy moon is said to be the most Earth-like world in the solar system, and previous findings by the Cassini mission suggest it holds some of the ingredients necessary for the emergence of life.
Dragonfly is a bold, game-changing way to explore the solar system,’ said APL Director Ralph Semmel.
‘This mission is a visionary combination of creativity and technical risk-taking that will help us unravel some of the most critical mysteries of the universe — including, possibly, the keys to our origins.’
NASA plans to send a probe called Dragonfly to Titan, which is set to land near the dunes in 2026 (artist impressions)
Initially, Dragonfly will carry out a 2.7-year mission to explore different sites across Titan, including dunes and impact craters.
Observations from the Cassini mission indicate these areas once held liquid water and complex organic materials.
The dual quadcopter will sample these organic surface materials and measure their composition in effort to characterize the large moon’s habitability.
Dragonfly will first touchdown in an equatorial area known as the ‘Shangri-La’ dune fields, which have been compared to the Namibian dunes in southern Africa.
It will then complete ‘leapfrog’ flights of around 5 miles (8km) each to hop to other areas, stopping to take samples from each site.
Eventually, Dragonfly will make its way to the Selk impact crater, where scientists have spotted evidence of last liquid water, organic (carbon-containing) molecules, and energy.
These, together, are said to be the building blocks for life.
