Titan is one of Saturn’s most remarkable moons. Unlike many of the gas giant’s 62 satellites, it isn’t merely a rocky object captured by the planet’s immense gravitational pull, nor is it an icy sphere. It’s actually a muddy world, with oceans, lakes and seas of methane moved by hydrocarbon winds.
This enigmatic, fascinating moon – which some consider to be a future candidate for extraterrestrial life – along with the rest of the Saturnian system is currently being visited by NASA Cassini’s spacecraft. This distant probe is still sending back data to Earth, and a new radar imagery, presented this week at the 47th annual Lunar and Planetary Science Conference in Texas, reveals that it’s spotted what is probably the highest peak on Titan.
There’s a collection of mountainous ridges on Titan called Mithrim Montes; as per convention, these mountains have been named after a location in the Lord of the Rings novels. The highest peaks on Titan are all around 3,000 meters (10,000 feet high), but the tallest, nestled within these specific ridges, beats them all: At a height of 3,337 meters (10,948 feet), it is indubitably Titan’s highest mountain.
The misty moon of Titan. The bright spots are near-infrared radiation reflecting off a hydrocarbon sea. NASA/JPL-Caltech/University of Arizona/University of Idaho
Although Titan has a considerably thick atmosphere, Cassini’s radar instrumentation was able to peer through the surface and spy the impressive peak. “It's not only the highest point we've found so far on Titan, but we think it's the highest point we're likely to find,” said Stephen Wall, deputy leader of the Cassini radar team at NASA's Jet Propulsion Laboratory in Pasadena, California, in a statement.
The primary purpose of Cassini’s radar is to look for segments of the moon’s surface that are showing dynamic activity, including mountain building. The fact that most of the tallest mountains on Titan appear to be along its equatorial region – Mithrim Montes’ mountains being no exception to this – suggests that the equator is, or has been, quite active, geologically speaking.
Mountains on Earth are built when two tectonic plates collide into each other and force gargantuan pieces of rock up into the sky. Over time, these mountains have to compete against two things: their own mass, which if high enough causes them to sink back into the crust from whence they came, and the weather, which slowly chips away at their peaks and erodes them.
The mountain ranges identified by the International Astronomical Union. NASA/JPL-Caltech/University of Arizona/USGS
On Titan, despite the fact that it has rain and rivers that erode its landscape, this process is far less effective on it as on Earth. Being about 10 times further away from the Sun, Titan receives far less incoming solar radiation, which ultimately drives weather and climate; therefore, there’s less energy to power erosional activity.
However, the mountains are betrayed by their own mass. The icy crust of Titan from which these mountains grow skywards sits on a deep ocean of liquid water. In addition, the crust itself is relatively soft, especially compared to its Earthly equivalent. Both of these layers are prone to compression, and when the mountains become too massive, they begin to sink back into the depths.
This is why scientists are unlikely to find mountains much taller than the current record holder on Titan – they’d just be too heavy.