‘Mars’… What’s the first thing that comes to your mind when you hear this? Yeah, a reddish dusty neighbor of ours. Do you know how Mars got its name? Well, it’s from the Roman God of War due to its red color. The iron minerals in the Martian soil oxidize, or rust, causing the soil and atmosphere to look red. Like Earth, It’s a terrestrial planet that has seasons, polar ice caps, volcanoes, canyons, and weather. It is also smaller than Earth and thus has less gravity which means it now retains a thin atmosphere made of carbon dioxide, nitrogen, and argon.
Mars is one of the most explored planets or bodies in our solar system. It’s the only planet where rovers were sent. As we know, Mars’ surface cannot support life at this time. Current mars missions are collecting shreds of evidence about Mars’ past and future potential for life. There are also signs of ancient floods on Mars, but now water mostly exists in ice dirt, thin clouds and as hydrated minerals in the crust, etc.
Let’s look at how Mars became a frigid desert while its neighbor, Earth, stayed a biological paradise by retaining water.
Mars was once wet!
The red planet was once far bluer. It had enough water to cover the whole planet in roughly 100 to 1,500 meters of ocean. Residues of dried-up riverbeds, deltas, lake basins, and inland seas make it clear. It may have even had one or more different oceans in its northern hemisphere. But eventually, the planet lost its magnetic field and as a result, the atmosphere was gradually stripped away. It was assumed this was how Mars lost its water.
But a new study funded by NASA says that while some of the water did disappear, the majority remained. It says there exists a combination of two mechanisms that caused liquid water depletion on Mars:
- the trapping of water in minerals in the planet’s crust as well as
- the loss of water to the atmosphere.
According to the teams’ simulations, the planet lost most of its water between 4 to 3.7 billion years ago.
“We’re saying that the crust forms with hydrated minerals and that minerals have water in their crystal structure, and anywhere between 30 – 99 percent of the initial water remains trapped inside these minerals,” says Eva Scheller, a lead author of the new paper in Science.
Anytime when a rock is interacting with water, there will be a series of very complex reactions that form a hydrated mineral. This process, called “chemical weathering”, takes place on Earth also. But on our planet, volcanoes will recycle the water back into the atmosphere. However, this process doesn’t take place on Mars due to the absence of tectonic plates there which makes the changes permanent.
Using observations made by Mars rovers such as the Perseverance, Curiosity, etc, as well as of meteorites from the planet, the team focused on the key component of water- Hydrogen.
There are different kinds of hydrogen atoms. Most have only a single proton in their nucleus, but a tiny fraction has both a proton and a neutron which make them heavy. These are known as deuterium or “heavy” hydrogen. The lighter kind escapes the planet’s atmosphere at a faster rate and thus the loss of most of the water to space left relatively more deuterium behind.
The theory also says that once Mars had a stronger magnetic field. Eventually, this field weakened because of the planet’s core cooling, and the Martian atmosphere was stripped away due to heavy radiation from the Sun. This caused low pressure which leads to water vaporizing. This theory suggests that the water vapor then leaked into space over the following billions of years. Also, huge dust storms play a major role in Mars’ liquid water depletion.
Releasing the water trapped in minerals requires heating them to high temperatures. Elon Musk, the founder of SpaceX who dreams of sending colonists to Mars in the future, has planned about detonating nuclear bombs on Mars to melt the ice caps and warm the planet to make it hospitable. Those explosions would also release some of the water in the hydrated minerals, although Ms. Scheller declined to speculate how much.
Why water on Mars is so important?
Understanding how Mars lost its water ties directly into the biggest questions in planetary science. The question of habitability! How did Earth become habitable while others in the solar system did not?! Among them, Mars is the most similar planet to Earth. So, revisiting Mars’ history also allows us to look back in time into the history of our planet. This will help planetary scientists to reconstruct the timeline and thereby understand how Mars and other terrestrial planets evolve through the ages and also, future manned Mars missions will get advantaged.
“There is absolutely no way we’re gonna learn about this on Earth because the first billion years of evolution on Earth has disappeared off the record,” Rapin, a researcher, says. “And so we can gain an idea about what happened on a habitable world that is similar to Earth.”
You may also be interested in reading more about water on mars: Water on Mars…The New Discovery For NASA
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