The valleys of Mars were created by runoff: study

LONDON: The contours observed on Mars today may have been created by runoff, say scientists who found that the ramification angles of the valleys on the red planet were very similar to those found in the arid landscapes on Earth.

The surface of Mars bears imprints of structures that resemble fluvial steam systems on Earth.

Scientists badume, therefore, that there must have been enough water on the red planet to feed the streams that have their way into the ground.

For years, however, scientists have been debating the source from which this water must come from.

A study, published in Science Advances, suggests that the ramified structure of ancient river systems on Mars has striking similarities with arid landscapes.

Using statistics from all river valleys mapped on Mars, the researchers conclude that the contours still visible today must have been created by a superficial runoff of rainwater.

Therefore, the influence of groundwater seepage from the ground can be ruled out as a dominant process for shaping these features.

The distribution of ramification angles of valleys on Mars is very similar to those found in arid landscapes on Earth.

This implies that there must have been a similar hydrologic environment with sporadic rain events on Mars for a prolonged period of time and that this rainwater could have run rapidly over the surface shaping the water networks. valley.

This is how river valleys develop in the arid regions of the Earth. For example, in Arizona, researchers observed the same valley network patterns in a landscape where astronauts train for future Martian missions. The valleys of arid regions form a narrow-angle fork.

The ramification angles on Mars are relatively low. Seybold therefore excludes the influence of groundwater shoots as a major channel-forming process on Mars.

Hydrographic networks formed by re-emerging groundwater, such as those found, for example, in Florida, tend to have much wider branching angles between the two tributaries and do not correspond to narrow angles. water courses in arid areas.

Conditions such as those found today in arid and terrestrial landscapes have probably prevailed on Mars for a relatively short period of time, there are about 3.6 to 3.8 billion years.
During this period, the atmosphere on Mars could be much denser than today.

"Recent research shows that there must have been much more water on Mars than previously supposed," said Hansjorg Seybold, a professor at ETH Zurich.

One hypothesis suggests that the northern third of Mars was covered by an ocean at that time. Water evaporated, condensed around high upland volcanoes south of the ocean and resulted in heavy rainfall.

As a result, the rivers formed, leaving traces that can still be seen on Mars today. The big question is where the water is gone over time.

"It is likely that most of it has evaporated in space, but it could still be found in the vicinity of Mars, it is a question for a future space mission", said Seybold.