Mars was wet more recently than we thought, according to Chinese rover

There may have been liquid water on Mars much more recently than we thought, according to an analysis of rocks by China’s Zhurong rover

By Alex Wilkins

The Zhurong rover looking back at its lander

China National Space Administration

Mars may have had liquid water hundreds of millions of years more recently than we thought, according to data gathered by China’s Zhurong rover.

While evidence of liquid water on Mars has been found before, it was generally thought that the planet was wet until only about 3 billion years ago, which is when a period of its history known as the Amazonian began and which continues today.

China’s Zhurong rover has been exploring Utopia Planitia, a relatively unexplored impact crater in northern Mars, since May 2021. Yang Liu at the National Space Science Center in Beijing, China, and his colleagues used the rover’s spectrometers to analyse rocks on the surface of the crater and found minerals containing water.

“The discovery of hydrated minerals has significant implications on the geological history of the region and the climate evolution of Mars,” says Liu.

The researchers used a laser on the rover to obtain a sample from rocks, which was then analysed using two on-board spectrometers. They then compared the recorded signatures with those of known hydrated minerals in rocks on Earth.

The evidence suggests to Liu and his colleagues that there may have been liquid water well into the late Amazonian, says Liu – although the team weren’t able to say exactly how recently it was present.

Understanding how recently Mars had liquid water could help us assess how much water remains locked up there today in ice or mineral form. This information will be useful in the search for a potential source of water for future missions there.

“If you’ve got hydrated minerals on the surface of these relatively young rocks, that kind of implies you must have had liquid water on the surface [of Mars] at those relatively [recent times],” says Jon Wade at the University of Oxford.

The equipment on the Zhurong rover doesn’t currently have the capability to identify exactly what kind of minerals are present in the samples, so future work should focus on identifying them in detail, says Wade.

Journal reference: Science Advances, DOI: 10.1126/sciadv.abn8555

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