Soil on Mars is very different to soil on Earth. As there is no vegetation on Mars and little or no organics at the surface, martian soil has not formed from organic processes such as the decaying of plant matter and the action of microorganisms. The martian soil has formed simply from the erosion and weathering of rock- large crustal rocks being ground into smaller and smaller pieces- through physical and chemical processes. What we know about martian soil comes mainly from the six successful missions that have landed on the surface. The outer layers of the martian crust are primarily basalt, like the oceanic crust of Earth, and the soil is composed mainly of iron oxides, iron rich smectite clays, and salts. I am interested in the search for life on other planets, and so I am fascinated by the question of whether the martian soil could support any Earth-like life. Low availability of liquid water is the strongest challenge for any life at or near the martian surface. Let’s assume for a minute though that the martian soil is in contact with frequent liquid water. Then would it be hospitable for some forms of life?
Curiosity Touching Down, Artist's Concept via NASA Goddard Photo and Video on Flickr
There is so much still to learn about soil on Mars. We hope to learn more about the soil when the Mars Science Laboratory lands in August, but there is always more to learn from the multitude of imagery and spectra that we have of the martian surface. You can also learn about martian soil by looking at soils on Earth such as in the photo below – where I examined the salty dry soil around gullies (we see similar features on Mars) near Arkaroola. Mars is such an exciting place, and every day we draw closer to finding environments that are hospitable to life, have the potential to support microorganisms, and can help us answer the question of ‘is there life on Mars?’. The best way to learn though, would be to visit and dig up that soil ourselves!