Mars used to be covered with rivers, lakes, and a shallow ocean that was similar to the ones on Earth.
However, between two billion and three billion years ago, severe climate change caused the waters to dry up.
The climate change was likely driven by the loss of Mars’ magnetic field. As a result, the solar wind gradually wore away at much of the planet’s atmosphere and led most liquid water to freeze or evaporate into space. As the last water vanished from Mars, the salty deposits were left behind.
The researchers think that as the water started to disappear on Mars, the remaining liquid became extremely salty.
Because of this, the water was able to stay in liquid form even though temperatures were as low as -40 degrees Fahrenheit, according to the ESA.
The last salty puddles could have kept surviving microbes alive. Their remains may have accumulated in the deposits as the water dried up completely.
The salt would act as a preservative, possibly safeguarding the evidence of these extinct lifeforms for billions of years.
Recent discoveries on Mars have also revealed that the planet may contain much more water than previously thought.
For example, in June, astronomers found at least 150,000 tons of water frost on some of the tallest volcanoes on Mars.
And in August, scientists discovered that a vast hidden ocean might be located beneath the planet’s surface.
The new study was published in the journal Scientific Data.
