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Wednesday's feature: Reach for the stars

One of the best things about being an Earth scientist is the opportunity to study some amazing places. And that doesn’t just mean our own planet. Traditionally a subject rooted in the Earth, geology is increasingly reaching out to the stars.

Planetary geology is a growing field, thanks to the insight geologists have about our own planet, which can be applied to others – in particular, the closest planet to us in the solar system, Mars. 

‘We’ve only got the Earth to go by, as an analogue for Mars’ says Dr Matt Balme, a planetary geologist at the Open University. ‘In terms of geology, it’s very hard to start from the ground up and imagine all sorts of new geological processes.’

‘I look at the shape of the land, the landforms and the processes that shape them. Just from the surface appearance, Mars and Earth are very similar. And of course, the physics is the same throughout the Universe. So if you have sand grains, volcanoes and lava, it acts the same way, plus or minus a bit for different gravity or air pressure.’

Increasingly, geologists don’t have to rely on remote studies of Mars, with the success of rovers like Curiosity, which is currently carrying out geological experiments on the planet’s surface.

One of Curiosity’s primary goals is the search for evidence of past life on Mars. It’s currently at a site called Glenelg, where it will look strictly for extrinsic evidence for life on Mars, not actual living or fossilised life-forms themselves. This means testing for habitable environments, by looking for evidence of a liquid water phase, potential sources of energy, organics, and other chemical constituents required for life to begin, evolve, and flourish.

Until this mission, most of us have an idea of Mars developed from films. And when we did see pictures of the real thing, they were often from a distance, or grainy, half lit hints at a shadowy landscape. What Curiosity has given us is arguably as important as the science itself – we now have exquisite, high definition panoramas of the landing site, delivered to us via a twitter account as they are taken. We have direct access to information which, although it’s not coming directly from Curiosity, is updated by NASA in real time. It’s still 570 million kilometres away, but Mars has never seemed so close to us.

Curiosity may not have enough time to explore distances that great, but it has already uncovered some intriguing details about the local geology. Landing in the 155km-wide Gale Crater, it began snapping the local terrain, and found what appears to be an angular unconformity in the layers of Mount Sharp (Aeolis Mons). Geologists are speculating from these early photographs that this horizon represents the interface between hydrated and non-hydrated rocks, or some form of hydraulic interaction. From photographs, the horizon certainly resembles erosional surfaces such as pediments, gently inclined surfaces truncating underlying bedrock. These typically form due to the action of free-flowing water. The geological history of these structures requires further investigation, and is one of the targets on Curiosity’s hit-list.

Curiosity is also breaking new ground in the communication of science to the public. Since landing, the rover has documented every aspect of its journey to its followers on Twitter. Often, the images include the rover itself – a kind of ‘self portrait’. These images don’t just give us a sense of scale. They remind us of the enormousness of Curiosity’s task, carrying out scientific experiments alone in a barren landscape.

The world of science – and social media – moves fast. Already, Curiosity’s successor, InSight, has been announced. Who knows what means of communication with the public NASA will have developed by then?

Geologists are at the forefront of this amazing project, demonstrating not only how far the subject can take you, but how studying Earth science can change our view of our planet, and ourselves.