NASA’s Mariner 9 orbiter sent back images that showed surfaces on Mars shaped by water, putting to rest the debate about whether the red planet ever had flowing water. Since that discovery, we’ve seen a growing pile of evidence indicating that water was a significant factor in Mars’ history. For instance, some Martian meteorites suggest that water existed as far back as 4.5 billion years ago. More recently, impact craters formed in the last few years have revealed ice lurking beneath the Martian surface. Now, researchers are diving into questions about when water first appeared, how abundant it was, and how long it remained. A fresh study published in PNAS has stirred up excitement, led by Jianhui Li from Guangzhou University, with contributions from both Chinese and American scientists. This research utilized data from the Zhurong rover, which has provided a unique glimpse into rocks that are thought to be near an ancient shoreline. The team believes they’ve uncovered beach deposits from a long-lost Martian ocean, painting a picture of Mars 3.6 billion years ago when it might have been covered by a vast ocean, with the Zhurong landing site marked by an orange star and NASA’s Perseverance rover’s site indicated by a yellow star.
There is a scarcity of evidence supporting the presence of surface water during the Hesperian period, which spans from 3.7 to 3 billion years ago. Remarkable orbital imagery reveals extensive outflow channels within Hesperian landforms, including a region characterized by canyons known as Kasei Valles. These formations are thought to have resulted from sudden discharges of groundwater rather than from the existence of standing water.From this perspective, it appears that Mars underwent a cooling and drying process by the time of the Hesperian period. Nevertheless, the discoveries made by the Zhurong rover, which include coastal deposits indicative of an ocean, suggest that surface water may have remained stable on Mars for a longer duration than previously acknowledged. It is possible that this stability extended into the Late Hesperian period.This finding could imply that habitable environments, particularly those surrounding an ocean, persisted into more recent geological times.
