Was there water on early Mars?

Since the Viking missions of the 1970s, planetary scientists have changed their perception of water on Mars several times, passing from the picture of a dry planet to that of a warmer and wetter one. Mars Express's data are now shedding a new light on the complex issue of the evolution of water on the Red Planet.

All seven of Mars Express' instruments are helping us unravel Mars' watery history – answering questions such as: where was the liquid water on Mars? where did it go? how much still exists? Whilst MARSIS, OMEGA and HRSC have been particularly useful in understanding the history of water on the surface, ASPERA and SPICAM are revealing how water has been lost to space over its history.

MARSIS has probed beneath the surface of Mars to depths of thousands of metres to detect abundant water ice in the polar regions. It has completely changed our understanding of the subsurface, including finding a buried crater that may contain a thick layer of water-rich ice.

OMEGA detects minerals on the surface of Mars, which helps reveal the history of Martian water, demonstrating, for example, that water could have been stable on Mars' surface but not for very long.

HRSC images Mars' surface in high resolution, revealing valleys that have been carved out by glaciers and flowing liquid water, rough surfaces that are footprints of floods, and signs of buried glaciers.

Studies using SPICAM data revealed that the process by which water moves through and leaves Mars’ atmosphere is shaped by seasons and storms. Another study using ASPERA data showed that the Sun’s radiation may play a surprising role in the escape of Mars' atmosphere, including the water within.

At the end of this article are links to just some of our previous stories detailing Mars Express' revelations regarding the history of water on Mars. Discover even more past articles here.