Author: Aaron J. Cavosie, Senior lecturer, School of Earth and Planetary Sciences, Curtin University

In the 1970s, images from the NASA Mariner 9 orbiter revealed water-sculpted surfaces on Mars. This settled the once-controversial question of whether water ever rippled over the red planet. Since then, more and more evidence has emerged that water once played a large role on our planetary neighbour. For example, Martian meteorites record evidence for water back to 4.5 billion years ago. On the young side of the timescale, impact craters formed over the past few years show the presence of ice under the surface today. Today the hot topics focus on when water appeared, how much was there, and…

Water is ubiquitous on Earth – about 70% of Earth’s surface is covered by the stuff. Water is in the air, on the surface and inside rocks. Geologic evidence suggests water has been stable on Earth since about 4.3 billion years ago. The history of water on early Mars is less certain. Determining when water first appeared, where and for how long, are all burning questions that drive Mars exploration. If Mars was once habitable, some amount of water was required. We studied the mineral zircon in a meteorite from Mars and found evidence that water was present when the…