Marsquakes Were Simulated On A Laboratory Analog Of The Planet's Core
Japanese scientists have created a laboratory analog of the matter that supposedly makes up the core of Mars, and measured the speed at which acoustic waves pass through it. This will help you interpret the earthquake data that the InSight landing platform collects. A description of the scientists' work was published in the scientific journal Nature Communications.
"The results of our experiments will help scientists who work with seismic data from Mars to understand whether the core of this planet consists mainly of iron and sulfur. If this is not the case, then we will discover something new. For example, if there are oxygen and silicon in the core of the red planet, this will indicate that Mars, like Earth, experienced a collision with another "germ" of the planet," said one of the authors of the study, associate Professor Keisuke Nishida of the University of Tokyo.
Now, most planetary scientists assume that at the beginning of its existence, Mars was very similar to Earth. At that time, it had a dense atmosphere, water oceans, and a fairly mild climate. Thanks to this, life could appear on Mars.
However, these conditions existed on the planet for a relatively short time, only about a billion years after its formation. At the beginning of the so-called Hesperian era, about 3.6 billion years ago, it turned into a lifeless desert. Almost all of its atmosphere and water reserves have escaped into space or turned into ice reserves.
One of the driving factors in this process, as many planetary scientists suggest, was that Mars, unlike Earth, does not have its own magnetic field. Our planet has it due to the flows of molten iron that move inside the earth's core. Therefore, geologists have long been interested in how the core of Mars is arranged, what it consists of, and why it did not become the source of the red planet's magnetic "shield."
The first such data, as Nishida notes, scientists will receive in the near future, when the InSight platform, which landed on the surface of Mars in the late fall of 2019, will accumulate enough data on Marsquakes. By analyzing them, scientists will be able to measure the size and mass of the Martian core, as well as understand what state it is now.
Nishida and his colleagues took the first step towards successfully interpreting this data. In their laboratory, they recreated different versions of the rocks of the core of Mars, varying the amount of two components – iron and sulfur. Scientists suggest that they are mainly made up of the core of the red planet.
By compressing a mixture of these elements in special diamond anvils, scientists passed acoustic vibrations through them that mimicked Marsquakes, and measured how these waves changed as they passed through the miniature counterparts of the Martian core.
To do this, scientists connected a diamond anvil to a particle accelerator and a Spring-8 x-ray source. By irradiating a replica of the Martian core with high-energy light particles, geologists were able to accurately measure the speed at which seismic waves moved through its thickness, as well as assess how the proportion of sulfur in its matter affected these acoustic vibrations.
"Due to technical difficulties, it took more than three years before we were able to record all the ultrasonic signals that are needed to study the properties of analogs of the Martian core. The volume of this data is not as large as it might be assumed, but it is critical to find out the properties of the real red planet," Nishida concluded.