China’s Zhu Rong robotic rover has found evidence that points to water being present on Mars for longer than previously thought. Scientists have long believed that Mars had a thicker, warmer atmosphere and liquid water on its surface billions of years ago, but that the planet cooled down as it lost its protective magnetic field about 4 billion years ago. The current geological age known as the Amazonian epoch – thought to have begun 3.5 to 1.8 billion years ago – has been seen as a time when Mars was cold and dry, with no surface water. But according to Chinese scientists, there is evidence of water in mineral samples – dating back 700 million years – collected by the Zhu Rong rover that suggests a more active surface hydrosphere in the Amazonian period than was thought. The rover landed in a large plain in the northern lowlands of Mars called Utopia Planitia in May last year. Its main objectives are to investigate the morphology, mineralogy, space environment, surface structure and water or ice distribution of the southern part of the plain. Scientists from the Chinese Academy of Sciences analysed the data on sediments and minerals from the plain that was gathered by the rover over its first 92 Martian days of exploration. Their findings were published in the peer-reviewed journal Science Advances on Wednesday. “We identified a distinct class of hydrated minerals using the spectrometer over a few bright-toned rocks, which has not been identified previously using orbital data,” said Liu Yang, lead author of the study and a researcher at the National Space Science Centre under the Chinese Academy of Sciences. Liu told state newspaper People’s Daily that the rocks had “absorption features” and were believed to be “hydrated silica or hydrated sulphates”. In the paper, the researchers said the bright-toned rocks were similar to the fractured layer of duricrust observed at Chryse Planitia, a lowland region in the northern hemisphere of the planet where Nasa’s Viking 1 lander touched down in 1976. But the scientists said the thin and brittle duricrust – or the soil’s hard crust – at the Viking 1 site was likely formed by salt cementation via water vapour diffusion from the atmosphere. China’s Tianwen-1 orbiter uses ‘selfie stick’ to capture ice caps on Mars In contrast, duricrusts at the Zhu Rong landing site appeared to be more resistant to erosion and had formed cliffs in the surroundings, which would require a substantial amount of liquid water rather than water vapour, they said. “The Zhu Rong landing site (and the northern lowlands) may contain a considerable amount of accessible water in the form of hydrated minerals and possibly ground ice for in situ resource utilisation for future human Mars exploration,” the scientists said.