Mars is called the red planet. But once, it was actually blue and covered in water, bringing us closer to finding out if Mars had ever harboured life.
Most researchers agree that there has been water on Mars, but just how much water is still debated.
Now a study from the University of Copenhagen shows that some 4.5 billion years ago, there was enough water for the entire planet to be covered in a 300-metre-deep ocean.
"At this time, Mars was bombarded with asteroids filled with ice. It happened in the first 100 million years of the planet's evolution. Another interesting angle is that the asteroids also carried organic molecules that are biologically important for life," says Professor Martin Bizzarro from the Centre for Star and Planet Formation.
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