SATURN’S largest moon, Titan, boasts vast seas of sand reminiscent of the science fiction desert planet of Frank Herbert’s Dune novels, scientists have discovered.

Radar images from the Cassini spacecraft, which is surveying Saturn, its rings and its satellites, have revealed that dark patches around Titan’s equator, once thought to be liquid oceans, are in fact vast expanses of sand dunes.

Titan’s dunes rise up to 330ft (100m) high, and run parallel to one another for hundreds of miles, resembling the great waves of dunes found on Earth in the Arabian and Namibian deserts, researchers said.

The longest of the dune fields observed from Cassini stretches for more than 930 miles (1,500km).

Ralph Lorenz, of the University of Arizona, who led the study team, said: “It’s bizarre. These images from a moon of Saturn look just like radar images of Namibia or Arabia. Titan’s atmosphere is thicker than Earth’s, its gravity is lower, its sand is certainly different — everything is different except for the physical process that forms the dunes.”

The dunes appear to be made up of small particles of icy sand about the size of coffee grounds that are piled into heaps by winds created by the tidal effect that Saturn’s vast gravity has on Titan.

Astronomers had thought it unlikely that the moon, the only satellite in the solar system with an atmosphere, could have dunes because its winds did not appear to be sufficiently powerful to sculpt them.

It is now clear that at Titan’s surface, the tidal effect from Saturn, which is 400 times greater than the Moon’s effect on Earth, drives winds that can whip up dunes. Details of the research are published today in the journal Science.

“Tides apparently dominate the near-surface winds because they’re so strong throughout the atmosphere,” Dr Lorenz said. “Solar-driven winds are strong only high up.

“When we saw these dunes in radar it started to make sense. If you look at the dunes, you see tidal winds might be blowing sand around the moon several times and working it into dunes at the equator. It’s possible that tidal winds are carrying dark sediments from higher latitudes to the equator, forming Titan’s dark belt.”

The researchers’ model of Titan suggests that tides can create surface winds that reach about 1mph. “Even though this is a very gentle wind, this is enough to blow grains along the ground,” Dr Lorenz said. “It’s exciting that the radar, which is mainly to study the surface of Titan, is telling us so much about how winds on Titan work. This will be important information for when we return to Titan.”

The dark patches on Titan’s surface had been thought to be lakes and seas of liquid hydrocarbons, though the moon’s thick smog has made this impossible to confirm by observation from Earth.

The revelation that the equatorial patches are dunes suggests that the moon may have something in common with the fictional world of Arakis, the desert planet created by Herbert.

• While Titan is thought unlikely to harbour life, two other papers in Science have shed light on how life might have originated in the solar system.

  Work by the Carnegie Institution of Washington has shown that meteorites are capable of carrying organic molecules, suggesting they could have spread the precursors of life through the early solar system.

  Another team, from the University of Southern California, has suggested that organic nitrogen could be one of the most reliable markers for life on other worlds.

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