Nullarbor Plain caves may guide search for life on Mars

Caves under the Nullarbor Plain could hold the answer to finding life on Mars, according to new research.

Hidden beneath the more than 200,000-square-kilometre Nullarbor Plain is a series of complex cave systems, which have eroded over millions of years.

Largely inaccessible from the surface, the cave systems have been relatively understudied.

Now, researchers have found a relationship between the vast trenches on the surface and the presence of underground caves.

"These trenches actually represent the surface footprint of caves that are much, much deeper and may not actually reach the surface just yet," researcher Milo Barham told ABC North and West Breakfast's Tom Mann.

An associate professor of Earth and planetary sciences at Curtin University, Dr Barham said satellite modelling and aerial photography had been vital in understanding the trenches, which were largely invisible to the naked eye.

"These [trenches] could be 20km long … they could be hundreds of metres wide, but they're only a couple of metres deep," Dr Barham said.

"When you're standing there, that just blends into the subtleties of the landscape. But when you actually then investigate a bit more, there's something more to it."

The previously unknown relationship between these shallow trenches and the caves underneath could shed light on cave systems in other environments, including on other planets.

Is there life on Mars?

The Nullarbor's cave system is an example of a karst terrain; a landscape formed when soluble rocks are dissolved.

These terrains make up about 15 per cent of Earth's ice-free land, and potentially similar landscapes have been identified on other planets, including Mars.

Dr Barham said the knowledge gained from the Nullarbor caves could be applied around the world.

"Twenty-five per cent of the world's population draws water from these karst aquifers. So, understanding where these kinds of empty spaces are in the subsurface is important for understanding where we're getting water," he said.

But the formula could come in handy in the hunt for extraterrestrial life as well.

"People have said that these cave systems on other planets actually represent the best place to go looking for life because of their more stable conditions, and essentially protection from that radiation bombardment," Dr Barham said.

"The same radiation protection is important for our astronauts, so potentially these cave systems are the sites that we should go to if we are looking for those bases off-world."

A special place for many

Across their Nullarbor studies, the researchers have regularly collaborated with Steve Milner, a field scientist and speleologist who has been exploring far-west South Australia and the Nullarbor for more than 30 years.

He said the surface trenches were the result of "the collapse of the deep systems below".

"Those voids underground are actually slowly working their way up to the surface, in geological time, not in our lifetimes, probably," Dr Milner said.

The new research is the latest in the expansive knowledge hidden inside the Nullarbor Plains, he said.

"There are so many hidden values of the Nullarbor Plain. It extends over 200,000 square kilometres, extends 850km by 450km, and there's so many interesting things there," Dr Milner said.

"There's the hidden evidence of climate change, there's bones of animals that are long extinct, telling the story of past habitats.

"It's just an amazing place, and of course, it's a place of culture and a special place for many."