Evidence is growing, showing that Mars, now cold and dry, had water flowing on its surface much more recently than previously thought.
Scientists have long believed that Mars was a wet planet about 3 billion years ago, during the Hesperian period. Then, the planet lost a lot of its water.
However, a new study presenting evidence of water activity from 700 million years ago, to the current Amazon period, poses new puzzles to solve about the Red Planet and its history.
The new study is based on data from China's Zhurong rover, which was part of the Tianwen-1 mission and landed on the surface of Mars in May 2021. In particular, scientists used data that collected by the rover during its first 92 days on Mars, or sols, at its landing site on Utopia Planitia.
Yang Liu, a researcher at the National Space Science Center (NSSC) under the Chinese Academy of Sciences (CAS) and colleagues, analyzed data from three different instruments at Zhurong: a laser-induced damage spectrometer (MarSCoDe), a telescopic micro-imaging camera and an infrared spectrometer. short wave.
The instruments studied minerals that, the team said, indicated the presence of large amounts of liquid water at the site some 700 million years ago, previously thought to be dry by scientists.
"This is a very exciting result," said Eva Scheller, a planetary scientist at the California Institute of Technology who was not involved in the latest research.
"We have very little documented evidence of 'young' liquid water systems on Mars. And for the ones we have, they are usually in the form of mineral salts," he said.
"But the Zhurong instrument sees water molecules locked in the rock, which is very interesting and different from other young liquid water environments that have been observed," said Scheller.
"This means that certain forms of water-carrying minerals would have formed over much longer time periods than had been previously considered in other scientific studies," he said.
NASA has sent a Mars rover to an ancient landing site that dates back to the Noachian epoch more than 3.7 billion years ago. Zhurong, along with a set of instruments, explored a new geologically young site to open a new window of opportunity for research on Mars.
"One of the main things we have to find and what I look forward to from the Zhurong explorers is how widespread these 'young' water-carrying minerals are. Are they common or unusual in these 'young' rocks?" said Scheller.
Zhurong has now covered about 2 kilometers in more than 350 days on Mars, and has analyzed various features on its journey, meaning more new Martian insights are likely still to come from the rover.
