Bad news about life on Mars?

Mars today is just a dry desert. However, much geological evidence shows that water flowed across the surface of the Red Planet billions of years ago.

This water could then provide an environment favorable to life as we know it.

How did Mars lose all its water?

Compared to Earth, Mars is smaller and lighter, and as a result the Red Planet has developed a limited gravitational field. This characteristic causes a large part of the nitrogen gas in the atmosphere to escape quickly.

View of Mars taken in 2022. (Photo: NASA).

This causes the planet to quickly cool, the Martian core hardens, leading to loss of magnetic field.

Without a protective magnetic field, Mars is exposed to solar wind, gradually eroding its atmosphere. At the same time, volcanic activity decreased, preventing the release of gases, especially carbon dioxide, needed to maintain a dense atmosphere.

The lack of nitrogen and carbon dioxide has hindered the renewal of the Martian atmosphere. The remaining gases eventually dissolve in liquid water, leading to a decrease in atmospheric pressure.

But low atmospheric pressure makes it difficult to maintain water in a liquid state. So, Martian water gradually turns into steam. Solar radiation then contributes to the breakdown of these water molecules in the upper atmosphere.

Scientists believe that liquid water has been flowing on the surface of Mars for a long time, possibly even millions of years.

This idea is based on various geological observations, such as the presence of valley networks, fossil rivers and dry lake beds, as well as evidence of minerals formed in the presence of water. They bode well for life.

However, a new study challenges this notion.

A wet past that was shorter than expected

Recent data obtained from laboratory simulations and field observations suggest that canyons on Mars may result from the evaporation of carbon dioxide ice , not water activity. liquid for long periods of time.

Ravines on Mars have carbon dioxide ice at their edges. (Photo: HiRISE).

This hypothesis is based on the idea that during the Martian winter, carbon dioxide present in the atmosphere will solidify and form carbon dioxide ice. When temperatures rise in spring, this ice can sublimate directly into a gas without going through a liquid state.

This process occurs especially quickly due to the low atmospheric pressure on Mars.

Researchers simulated these conditions in the laboratory to better understand carbon dioxide ice sublimation in the Martian environment.

The results suggest that this process could shape the Martian landscape in ways similar to the effects of water. This raises questions about the origin of some of the ravines observed on the Red Planet.

This research has important implications for the search for life on the planet. It suggests that the period of time during which Mars had favorable conditions for life, at least on the surface, may be shorter than previously expected.

Of course, this doesn't mean that Mars is completely devoid of water, just that its role in shaping the landscape may be less important than expected.