IT’S said to be a discovery beyond everyone’s wildest imagination.

A team of Italian researchers have poked at the polar ice caps on Mars with a radar and uncovered a lake that stretches about 20km across and 1.5km deep.

Previous discoveries have only been around temporary trickles of water and so to have found a massive reservoir of liquid hidden underground has been hailed a stunningly amazing result.

The researchers say the lake was likely able to stay liquid because of salts from Martian rocks dissolving into the water, coupled with the incredible pressure of the ice above.

The all-Italian team led by the National Institute of Astrophysics made the discovery using MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding), a radar installed on board the European Mars Express probe and developed under the control of the Italian Space Agency.

“We discovered water on Mars,” said lead researcher Roberto Orosei at the National Institute of Astrophysics in Bologna, Italy. He added that any other explanation for the bright reflections the scientists saw in the radar data was “untenable”.

The findings were published overnight in the journal Science and have excited the scientific community.

“There is no reason to conclude that the presence of subsurface water on Mars is limited to a single location,” the researchers wrote.

The underground lake found by @esa is near the Martian South Pole but there’s nothing special about the location meaning these reservoirs could be anywhere (and hence possibly everywhere!) on Mars pic.twitter.com/gmjuT6VLS2 — Alan Duffy (@astroduff) July 25, 2018

Australian experts have applauded the find, saying the discovery of liquid and frozen water resources is key because of their ability to produce fuel and provide life support for astronauts during deep space missions, allowing lower cost launches and space operations.

“Why is this so exciting? Well, we know Mars was once warm and wet — and likely stayed that way for a very long time,” said Dr Jonti Horner of the University of Southern Queensland.

“The shift from ‘warm and wet’ to ‘frozen wasteland’ would have occurred very, very slowly, giving any life that got started on Mars plenty of time to adapt and to move with the water.

“This lake, if it really is there, would be a prime place to look for life — after all, we have similar things on Earth, like the lakes buried beneath Antarctica, and life has been found to exist and thrive down there.

“That doesn’t mean that there will be life there — but it does suggest that a lake on Mars would be a perfect place to look.”

Associate Professor Alan Duffy, lead scientist of Australia’s Science Channel, said the ending of Total Recall where Arnold Schwarzenegger melted vast ice reserves just became less science fiction and more science fact.

“This is a stunning result that suggests water on Mars is not a temporary trickle like previous discoveries but a persistent body of water that provides the conditions for life for extended periods of time,” he said.

The radar from @esa Mars Express strongly reflects from a feature 20km nearly 1.5km under the surface. Liquid water is highly reflective unlike rock/ice allowing this reservoir to be spotted from space pic.twitter.com/Wa12SOsTEC — Alan Duffy (@astroduff) July 25, 2018

“The liquid water is not a lake that you would want to swim in, locked away 1.5km beneath the surface of the Martian South Pole, the water would be a brine mixed with perchlorate salts,” he said.

“It’s those salts that keep the water from freezing, familiar to anyone who can drive on ice-free roads in winter after the salt gritters have been at work.

“The underground water might exist as a lake trapped beneath rock layers or mixed in with Martian soil to create a salty sludge, but either way at 20km across there is a lot of it.”

The concentration of salts needed to keep the water liquid could be fatal for any microbial life similar to Earth’s, which means caution needs to be taken, with no immediate means of sampling the water.

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Professor Andrew Dempster, director of the Australian Centre for Space Engineering Research, said the discovery reinforced work over the past few years that had identified water as the first resource to be “mined” in space.

“Since United Launch Alliance put a price on delivering water in space in 2016, researchers, agencies and companies have focused on water, for support of life and chemical processes, and for conversion to hydrogen and oxygen for rocket fuel,” he said.

“That water could be sourced from asteroids, the moon, or Mars. Discovery of a large water supply on Mars confirms we’re heading in the right direction.”

Professor Dempster said Australia had taken a leadership position on the matter, with University of New South Wales researchers examining business cases, mining methods, earth analogues, asteroid selection, asteroid navigation and other resources such as platinum.

They will be hosting the fourth Off-Earth Mining Forum in Sydney in 2019.