3.7 billion years ago it still had lakes

The evidence that Mars once had rivers and seas that covered much of its surface with water continues to accumulate. These tests serve, however, more than just to demonstrate what we already know with some certainty, they also help us to know what these seas were like and, perhaps one day, they will tell us the story of their disappearance.

New tests. The images captured by the rover Curiosity have made it possible to identify in the Martian rock some geological structures undulating waves similar to those that can be found in the sandy beds of lakes and on beaches on our planet. These structures not only denote the presence of water, they also imply that it was on the surface, at the mercy of the winds of Mars.

The ripples. These geological marks were found in two places and, according to estimates, they were formed about 3.7 billion years ago. This detail is important since, as the team responsible for its discovery emphasizes, it implies that the surface water of the red planet lasted longer than some estimates calculate. That is, they extend the period in which Mars was partially covered by water.

The ripples observed by Curiosity are tiny: about six millimeters high, and separated by intervals of between four and five centimeters. From these data, the team estimates that these were formed on the floor of a shallow lake, about two meters deep.

Uncovered. Another important detail that these marks reveal to us is that the water in these lakes was liquid on the surface, that is, it was not covered by a layer of ice, since it would be the result of the action of the wind. This also contradicts some of the climate models applied to the Martian climate of the time.

“The shape of the waves could only have been formed under water open to the atmosphere and affected by the wind,” stated in a press release Claire Mondro, co-author of the study.

Modeling the undulations. The team analyzed the Curiosity observations and simulated through computer models the conditions that gave rise to these marks on the rock. Thus they were able to estimate an average wavelength of about 4.5 centimeters and the estimated depth of the body of water in which they formed.

Details of the analysis were published in an article in the magazine Science Advances.

Curiosity. He rover Curiosity has been 12 years of activity on the surface of Mars, where it has already traveled tens of kilometers. Perseverance’s older brother arrived in Gale Crater in mid-2012 as the spearhead of the Mars Science Laboratory mission.

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Image | NASA/JPL-Caltech