Space scientists have now revealed much more about the ancient climate of Mars. And it appears huge amounts of rainfall and snowmelt once filled lake beds and river valleys as recently as 3.5 billion years ago.
This news boosts expectations evidence of alien life will one day be found on Earth’s neighbour planet.
We’re trying to understand how much water was there and where did it all go
Dr Gaia Stucky de Quay
The study represents the first time scientists have quantified the rain once present across the planet.
The research conveniently coincides with NASA’s Mars 2020 Perseverance rover making its way to Mars.
The space agency’s probe will in February next year land in one of the lake beds crucial to this new research.
Mars’ ancient climate and surface conditions remain an enigma to scientists.
To geologists, the existence of riverbeds and ancient lake basins suggests a planet with significant rainfall or snowmelt.
However, experts in modelling climate remain unable to account for the observed geology.
Dr Gaia Stucky de Quay, a postdoctoral fellow at the University of Texas and lead author, said: “This is extremely important because 3.5 to four billion years ago Mars was covered with water.
“It had lots of rain or snowmelt to fill those channels and lakes.
“Now it’s completely dry. We’re trying to understand how much water was there and where did it all go.”
Although scientists have discovered huge reserves of frozen water on Mars, no significant amount of liquid water has been found.
Experts now know between 13ft and 520ft (4m to 159m) of rain must have fallen in a single episode to fill the Martian lakes.
In some cases, these will have provided enough water to overflow and breach the lake basins.
Dr Stucky de Quay added this research can improve Martian climate models, despite the wide range of the estimates.
She said: ”It’s a huge cognitive dissonance. Climate models have trouble accounting for that amount of liquid water at that time.
“It’s like, liquid water is not possible, but it happened. This is the knowledge gap that our work is trying to fill in.”
Space agency NASA launched its Mars 2020 Perseverance Rover in June.
The probe will early next year begin to explore the Jezero crater, which contains one of the open lake beds used in the study.
According to co-author Tim Goudge, an assistant professor at the University of Texas, and the lead scientific advocate for the landing site, the data collected by the crater could be significant for determining how much water was on Mars and whether there are signs of ancient alien life.
He said: ”Gaia’s study takes previously identified closed and open lake basins, but applies a clever new approach to constrain how much precipitation these lakes experienced.
“Not only do these results help us to refine our understanding of the ancient Mars climate, but they also will be a great resource for putting results from the Mars 2020 Perseverance Rover into a more global context.”
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