Soil analysis carried out by scientists at Imperial College London indicates that Mars has been in a drought for as long as 600 million years and that liquid water may have been present for only 5000 years of the planets entire history of more than a billion years. Those 5000 years would not be enough to represent a foundation for life on Mars, the researchers concluded.
In their study, which is published in the journal Geophysical Research Letters, the researchers describe their approach of searching for clay particles that are formed when rock is broken down by water. "Such particles are an important marker of contact between liquid water and the soil, forming a distinct population in the soil," the group said. However, there was no such marker. Even if the few particles they saw were clay, they accounted for less than 0.1 percent of the soil composition in their samples. The scientists noted that clays account for up to 50 percent of the soil content on Earth, which led the researchers to conclude that mars has been dry for a long time.
Even if only a small portion of soil was analyzed the group at Imperial College London believes that it applies to all of Mars since satellite images have shown that the Mars surface is uniform across the planet. However, while life on the Mars surface is unlikely, the research group noted that future Mars missions should focus on digging deeper into the ground as life could be "taking refuge underground." At the time Mars had liquid water on its surface, the planet may have had warmer weather periods that potentially supported life.