Though Mars is currently a lifeless desert planet, that wasn’t always the case. Scientists have long suspected that Mars used to have an atmosphere thick enough to sustain vast liquid water oceans billions of years ago. NASA’s Curiosity rover has discovered some of the best evidence yet that supports the theory of Mars sustaining water for long periods of time. Because liquid water is an important precursor to life as we know it, this has some pretty impressive implications for the possibility of ancient life on Mars. The results span six papers, all of which appear in the December 9 issue of Science.
In the Yellowknife Bay in the Gale crater, Curiosity has been analyzing soil samples, collecting data about the geology and geochemistry of the area, in hopes of better understanding the past environment. This data will help researchers decide if ancient Martian life was plausible or not. After analyzing the chemical composition of the rocks, researchers were able to deduce that some of them had traveled great distances before experiencing erosion until much later. The mineral-rich clay that could have supported life was not localized near volcanoes, as there were not large amounts of trademark water soluble elements like calcium and sodium concentrated in those regions. The data suggests that these minerals were present and shuffled around for quite a while, but eventually did succumb to the drying environment and the increasingly hostile water conditions.
Based on what researchers have learned, Yellowknife Bay may have been in a good position to support life. The pH of the water was not acidic and the salt content was likely quite low. There were other elements and minerals available that would have readily supported microbial life. It is likely that these conditions were similar to those experienced by the earliest life forms on Earth. The sedimentary rocks have been shown to have elements like hydrogen, oxygen, carbon, nitrogen, sulfur and phosphorus within them; all of which are critical to the existence of life.
Curiosity has completed about 2/3 of its two-year-long primary science mission of exploring the Gale crater on Mars. It is responsible for analyzing geological samples in order to characterize the environment, find clues surrounding Mars’ liquid water past, and help determine if Martian life was ever a possibility. Based on these latest findings, there is much more evidence in support of ancient life on Mars.
On Earth, sedimentary rocks don’t usually last very long. They are easily weathered, and it becomes incredibly difficult to locate ancient rocks for study. Because the atmosphere on Mars is all but gone and the surface doesn’t really experience much extreme weather, the rocks are incredibly well preserved and are really quite abundant. Studying the elements these rocks can provide valuable information about the environment on Mars billions of years ago and how it might have related to the earliest life on Earth.