NASA probe Insight: peek beneath the surface of Mars with ambient noise

Since the unmanned NASA probe “Insight” landed on Mars in November 2018, the probe has been using a seismograph – the Marsquake Service – to evaluate the earthquake activities of the planet in order to draw conclusions about the internal structure of the planet.

In July, the ETH Zurich team, in collaboration with the Swiss Seismological Service (SED), provided rough insights into, for example, the thickness of the Martian crust, the Martian mantle and the diameter of the liquid core.

However, structures close to the surface could not be determined in this way, except by drilling. In the meantime, the researchers at ETH Zurich have taken a step further: They used the ambient noise on Mars (“ambient noise”) to determine the local geology. This technique is used on Earth, for example, to find out whether the subsurface is weakening or amplifying seismic waves. From this, the seismic hazard of a location can be determined and unstable landslide zones on mountains or in lakes can be analyzed.

While there are numerous sources of noise available on earth, The only remaining source of ambient noise for the researchers on Mars was the wind.

Your geological results They have now published the history of Mars at depths of a few dozen to two hundred meters in Nature Communications.

Unlike on Earth, there was never any active plate tectonics on Mars. It was formed by phases of active volcanism. Large areas were covered with basaltic lava plateaus. The analyzes by ETH Zurich provide a detailed picture of the subsurface at the Insight landing site. The top layer consists of three meters of sand (regolith) and loose rock about 20 meters thick, which has been fissured by meteorite impacts. Below are layers of lava flows that, according to the publication, covered the planet 1.7 to 3.6 billion years ago.

These layers of lava are divided by sediments that lie at a depth of 30 to 75 meters. The seismic image of the geological stratification enabled researchers for the first time to understand the most important geological events that have occurred at the Insight landing site on Mars over the past three billion years.


(mack)

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