Researchers doubt water as the originator of the mighty Mars canyons

Zurich (Switzerland) – An eye-catching network of deep gorges known as Labyrinthus Noctis flows into another gigantic Mars Canyon, the Valles Marineris. 4000 kilometers long, 200 kilometers wide and seven kilometers deep, this structure is the largest canyon in our solar system. So far, scientists have mainly believed that these gorges were once created by massive amounts of water. A Swiss volcanologist now announces doubts about this idea: “The eroding power of once immense lava flows alone could have dug the mighty gorges.” Thus, at least according to the researcher’s theory, the likelihood of life on the red planet disappearing.

As the Italian geologist and specialist in volcanism on planets, Giovanni Leone , who works in the research group of Professor Paul Tackley at the Institute of Geophysics at the ETH Zurich , currently in the journal “Journal of Volcanology and Geothermal Research” (DOI: 10.1016 / j .jvolgeores.2014.01.011), is the result of his several-year study of thousands of high-resolution surface images taken by several Marssonds.

So far, the majority of Mars scientists believed that the canyons were once dug by huge streams of water because they look like orbiting earthly canyons that were actually created by water. As a further possibility tectonic processes were assumed, which could have led to the largest rift fracture of a planet of our solar system.

However, Leone now concludes from his observations that only lava flows had the power and mass to dig these mighty gorges into the Martian surface.

Der Forscher hat sich in den vergangenen Jahren intensiv mit den Strukturen dieser Canyons und ihrer Ausflüsse in das Ares Valles und die Chryse planitia eine riesige Tiefebene in der Nordhemisphäre des Mars, befasst. Sein Fazit dieser Studie fällt eindeutig aus: “Alles, was ich darauf erkannte, waren Strukturen von Lava, wie wir sie von der Erde her kennen. Die typischen Anzeichen von durch Wasser verursachten Erosion konnte ich auf keinem der Bilder sehen.”

To be sure, he does not want to be able to completely exclude water as the ultimate creative force. However, traces of it – such as salt deposits in places where water evaporated from the ground, or erosion traces on the rubble pockets of the landslides – he found only very rarely. “So you have to seriously ask why water should have formed the Valles Marineris, if no massive and widespread traces of it can be seen.” Also, the volcanologist can not explain where the gigantic masses of water that could form these canyons should have come from.

His own explanatory model, on the other hand, shows a different genesis from the source to the mouth of the canyon system. Accordingly, the researcher locates the source of lava flows in the volcanic region of Tharsis. From there lava tunnels extend to the beginning of the Labyrinthus Noctis. If the pressure of an eruption eased, the tunnel ceilings partially collapsed. Thus chains of almost circular holes formed the funnel chains called “pit chains” on Tharsis.

As lava flowed through these tunnels again, she tore the blankets completely, creating deep V-shaped trenches. Through the melting of ground and edge material, but also by purely mechanical erosion, the lava masses made a deeper and wider bed, forming canyons whose edges had become unstable. Subsequent lava carried or covered the debris from the landslide. “The more lava flowed, the wider the canyon became,” says Leone .

His explanatory model has highlighted the planetary researchers with height and surface measurements of various Marssonde. Indeed, the valleys of the Labyrinthus noctis actually show the typical V-shape of young lava valleys whose tunnel roofs have completely collapsed. “The upper edges of these valleys, however, are at the same height, and if there were tectonic influences, the upper edges would not be at the same level.”

“On Mars, there are neither migratory plates nor subduction zones,” says the researcher. “Against water as a formative force speaks the fact that it would have taken tens of millions of cubic kilometers of it to create such deep ditches and canyons – almost all of the atmospheric water in Mars’ history would have had to be concentrated in Labyrinthus noctis.”

In addition, the atmosphere on Mars is too thin, the temperatures are too cold. Water, which would come to the surface, would not remain fluid, he says: “How should a river of sufficient size and strength be formed under such conditions?”

Also for the hopes of former or even today still active life on Mars, Leone’s study could have far-reaching consequences: “If one assumes that Lava formed the Labyrinthus Noctis and the Valles Marineris, then there was probably always much less water on Mars when the research community accepted. “

In the past, only very little rain had fallen on Mars. That would never have been enough to dig such deep and great gorges. The shallow ocean north of the Martian equator was probably much smaller than expected – or hoped. He only existed around the North Pole. The likelihood that life existed on Mars would also be much smaller.

However, Leone can imagine as living place for living beings the still existing lava tubes. These would provide protection against the strong UV radiation on Mars. He therefore proposes to conduct a mission to Mars with the aim of exploring lava tunnels. He considers it feasible to use a rover through a hole in the roof of a tunnel and there to look for traces of life: “For this purpose could be determined based on my data.”

With his study, Leone floats against the tide and possibly overturns a dogma. Most of the work over the past 20 years has dealt with the question of water on Mars and how it could have eroded these canyons. Although in 1977, a researcher expressed the idea that Valles Marineris could be created by lava – but could not prevail with it.

Leone himself explains this with a tunnel view of the red planet and the prevailing mainstream in Martian research. For decades, people have always told the same story and purposefully researched it without achieving a breakthrough. Perhaps he is wrong, but science can only move forward if other models of thinking are considered. “I now expect a heated debate,” says Leone , showing himself prepared for this, “but my evidence is strong.”