Key findings about volcanic activity on Mars
- Volcanic activity on Mars has existed in the past. The most recent one probably occurred 50,000 years ago.
- Olympus Mons, the largest volcano on Mars, has shown no signs of activity for 25 million years.
- Volcanic activity on Mars and Earth likely contributed elements such as oxygen and hydrogen, which are key ingredients for life, to the atmosphere.
Mars is and always has been a very volcanic planet. In the modern era, volcanism on Mars was concentrated in certain areas, namely the Elysium and Tharsis regions, but at one time it was widespread throughout the planet. Ground-based data shows that Mars has had volcanism for a long time and from the very beginning, and some researchers argue that it may continue.
“Some of the largest volcanoes in our solar system exist on Mars. In fact, the largest mountain in our solar system, Olympus Mons, is a giant volcano,” says geologist and planetary scientist Corey M. Hughes.
For comparison, Mount Olympus is approximately 2.5 times larger than Mount Everest. But while this monster mountain might put on a volcanic show, it hasn't erupted in 25 million years. However, we know that it is possible, and that it once was.
Read more: First evidence of a recently active volcano on Mars
Volcanic activity on Mars
According to some reports, there may have been volcanism on Mars just 50,000 years ago, which, from a geological perspective, is like the blink of an eye.
Researchers typically use something called crater density counting to determine the age of volcanism on rocky planets. Using rocks from the surface of the Moon, scientists can measure how many craters there were at different points in the history of our solar system. By counting the number of craters, their density and size on Mars, researchers can determine the age of that surface based on what we know about our moon, Hughes says.
Additionally, researchers are using spectroscopy (light bouncing off a planet) to identify materials found on Mars.
“The way light reflects off a surface, as well as specific wavelengths and unique absorption rates, can help researchers identify volcanic signatures,” Hughes says.
By combining these two methods, crater density counting and spectroscopy, scientists can age lava to a certain period of time to find out when the last eruptions occurred.
Why volcanic activity matters on Earth and Mars
Early volcanism matters because we know that on Earth it could have provided the atmosphere with essential elements such as oxygen and hydrogen, which almost all living things need to survive.
“Volcanoes eject a lot of rock, but they also emit a lot of gas,” says Hughes. “Volcanism is a mechanism that allows volatile substances to be taken from the depths of the planet and released into the atmosphere.”
In some cases, this can make a planet uninhabitable, as has happened on Venus, a planet where runaway greenhouse gases are causing temperatures to be the hottest in the solar system at 700 degrees Celsius, according to the European Planetary Society. But in other cases, volcanism can become the building material for life on Earth. This means that volcanism provides clues to the search for life on other planets.
Volcanic activity on Mars could help life thrive
In addition, the Earth's core and Mars are also very similar, indicating that Mars was once home to life. The difference between Earth and Mars is that Earth has plate tectonics that move around causing earthquakes and eruptions that recycle rock from the core to the surface. But this is not the case on Mars.
This is why there is granite on the surface of the Earth, but not on Mars: to get granite, you need subduction. However, both planets are covered in basalt, a type of slow-moving lava that is also a sign of ancient volcanism.
Researchers have long been looking for life on Mars, or more precisely, signs of water that exists or has ever existed. According to NASA, in the planet's early history, 3.7 billion years ago, Mars had plenty of water, and precipitation cycles included snow, rain, large lakes, rivers and possibly an ocean in the planet's northern hemisphere. All life on Earth requires water, so when it comes to Mars, we always “follow the water.”
For geologists, volcanism provides elements that may signify life on other planets.
“We have compelling evidence that Mars was once habitable, but whether the planet had life is another story,” says Hughes.
Read more: Wavy ripples prove the existence of ice-free lakes on ancient Mars
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