Mars was once much more interesting. Today, dust storms rage there and streams of liquid salt water flow here and there, but billions of years ago, the planet could boast of giant volcanoes, a system of canyons and river valleys. Not so long ago, scientists found volcanoes on the Red Planet, which were formed quite recently, by geological standards. Remarkably, they may have had exactly the right conditions for microbial life to thrive.
Mount Olympus on Mars - the largest volcano in the solar system - is 22 kilometers high and its base is more than 500 kilometers across. It began to grow about 3 billion years ago, but some lava flows on its high slopes may be as old as 2 million years, judging by the absence of overlapping impact craters. The craters that form as a result of an asteroid impact show how old the surface of a body in our solar system can be - the more craters, the older the surface. However, fresh lava from a volcano can cover old craters, resetting the clock.
This is exactly what happened to Mount Olympus and several of its neighbors. It is unlikely that they have gone out completely. They may still be able to squeeze out lava in the future, although this will have to wait a couple of million years.
Looking for small volcanoes
Are volcanoes still forming on Mars? Where are the youngest who have appeared recently? Scientists have previously noticed various clusters of small and apparently very young "cones" - symmetrical hills with craters on top - but their origin was controversial. They could be really places of volcanic eruptions, but at the same time, "mud volcanoes" formed by the release of dirt from the ground, or "rootless cones" formed by explosions of lava falling on wet or icy ground.
A study by a Czech-German-American group of scientists led by Petr Broz provided compelling new evidence that at least some of them are indeed volcanoes. Brose and his team explored the cones of Coprates Chasma, the deepest part of the canyon system of Martian Valles Marynerys. This is far from the main volcanic provinces of Mars and suggests that magma erupted from the bowels through ancient rifts in the canyon system.
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Scientists firmly believe that these are real volcanic cones, similar to the common volcanoes on Earth known as cinder cones and tuff cones. They confirm this by thin layers visible on the inner wall of the crater in HiRISE images and other facts. The image resolution is sufficient to see that the cone is composed of layers, just like tuff cones on Earth.
The analysis showed that the area surrounding the craters is 200-400 million years old - about this time, giant amphibians and the first dinosaurs roamed the Earth.
The cones were to be built by explosive eruptions of lava clumps ranging in size from a pea to a brick, layering gradually until they reached their final height. The surface of each cone must be "reinforced" because the lumps, when reaching the ground, were hot enough to fuse and protect it. This may explain their fresh appearance, in contrast to mud volcanoes, which should be more vulnerable to erosion.
The scientists' findings are interesting for many reasons. Such a young volcanism on Mars indicates that volcanic processes are still taking place on the planet - and volcanoes are still forming.
Astrobiological interest
So far, a team of scientists has obtained information on the composition of only one of the cones using the CRISM tool on the MRO. This revealed the presence of a mineral, opal silica, and mineral sulfates, which indicate that hot rocks, before or after eruption, interacted with Martian groundwater.
If this is the case, then even for a short time each volcano could have formed a mixture of water, heat and chemical energy to support microbial life, such as that inhabits hot springs on Earth. Given that the cones in this study are at least 200 million years old, they are unlikely to be able to support life today, but would be a good place to look for fossilized microbes with minimal risk of contaminating an active ecosystem.
Ilya Khel