Evrim Yazgin
Cosmos science journalist
Sedimentary mineral deposits analysed by the Chinese Zhurong Mars rover appear to have been left by an ancient sea 3.5 billion years ago.
Evidence is piling up that ancient Mars was a wet world – at least temporarily.
Zhurong’s findings supporting this theory are published in the journal Scientific Reports.
The rover landed on Mars in May 2021. Since then, it has been analysing deposits on the surface of the Red Planet in the Vastitas Borealis – a low-lying plain in the northern hemisphere.
Previous research suggested that the materials in the region originated from flooding and marine sediments.
The researchers used a mix of elevation data from the Mars Orbiter Laser Altimeter and geochemical analysis from Zhurong. They estimated the surface ages at locations in the southern Utopia Planitia.
Utopia Planitia is the largest impact crater in the whole solar system at about 3,300km in diameter – nearly the size of Australia from east coast to west coast. This means it covers about 6% of the Mars’s total surface area. The crater formed 4.3–4.1 billion years ago.
The researchers found features such as troughs and sediment channels consistent with a nearshore zone. This suggests flooding about 3.68 billion years ago. In this scenario, a short-lived frozen ocean formed a coastline, with the ocean surface likely freezing and disappearing approximately 3.42 billion years ago.
They say that the Zhurong rover won’t be able to travel north to verify these hypotheses. But future missions may be able to confirm the existence of the ancient Martian ocean.
