Extract from ABC News
NASA's Perseverance rover takes a selfie with some of the sample collection tubes it deposited onto the surface of Mars. (Supplied: NASA/JPL-Caltech/MSSS)
Where there is water, there is life — or so the saying goes. Studies of the rippled surface of Mars show that some three billion years ago there were once rivers and lakes.
But what has puzzled scientists for decades was the search for more recent evidence of liquid.
Then on December 6, 2006 NASA released exciting images taken by its Mars Global Surveyor spacecraft.
In the wall of a crater on Mars you can see light-coloured deposits that appear to have been left by flowing water. The images might look like something seen under a microscope but scientists estimated the deposits were each several hundreds metres long.
Two photos taken six years apart of an unnamed crater in the Centauri Montes region show a material flow. (AFP)
"No-one expected what we found today," Kenneth Edgett, a scientist with Malin Space Science Systems in San Diego said at the time.
"We are talking about liquid water that is present on Mars right now."
The San Diego-based Malin Space Science Systems scientists who led led the study said at the time that the flow of water would have filled multiple swimming pools.
"If you were there and this was coming down the slope you'd kind of want to get out of the way," Dr Edgett said.
The water would have quickly boiled and evaporated, scientists said at the time, because of the low atmospheric pressure and temperatures.
Spacecraft had previously found evidence that liquid water was once present on the planet's surface, but the new photos sparked conversation about whether it still did.
Mars could have enough liquid water for a global ocean, researchers have found.
Little did scientists know that in November 2011 NASA's Curiosity Rover would take flight from Cape Canaveral and successfully in August 2012, helping to reveal that Mars could have supported ancient life.
Nor did they know that in 2024, deep in the Red Planet's outer crust, NASA's Insight lander would find a large underground reservoir of liquid water — enough to fill oceans on the planet's surface.
Then in September this year the Mars rover Perseverance uncovered rocks that hold the strongest signs yet of ancient life on the planet.
Perseverance, which has been living up to its name and roaming Mars since 2021, cannot directly detect life past or present, but it carries a drill to penetrate rocks and tubes to hold the samples gathered from places judged most suitable for having hosted life billions of years ago.
"All we can say is one of the possible explanations is microbial life, but there could be other ways to make this set of features that we see," lead researcher Joel Hurowitz of Stony Brook University told The Associated Press.
"It would be amazing to be able to demonstrate conclusively that these features were formed by something that was alive on another planet billions of years ago, right?"
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