Scientists use deep planetary scan to confirm Martian core — ScienceDaily

Seismologists from the Australian National University (ANU) have developed a new method to scan the deep interior of planets in our solar system to confirm whether they have a core at the heart of their existence.

The scanning method, which works in a similar way to an ultrasound scan that uses sound waves to generate images of the patient’s body, requires only one seismometer on the planet’s surface to operate. It can also be used to confirm the size of a planet’s core. The study was published in Natural astronomy.

Using the ANU model to scan the entire interior of Mars, researchers confirmed that the Red Planet has a large core at its center – a theory first confirmed by a team of scientists in 2021.

Study co-author Professor Hrvoje Tkalcic from ANU said that based on data collected using the ANU technique, the researchers found that Mars’ core, which is smaller than Earth’s, is about 3620 kilometers.

“Our study presents an innovative method using a single instrument to scan the interior of each planet in a way that has never been done before,” he said.

Confirming the existence of a planetary core, which researchers call the “engine room” of all planets, could help scientists learn more about the planet’s past and evolution. It can also help scientists determine at what point in the planet’s history a magnetic field formed and ceased to exist.

The core plays an active role in maintaining the planet’s magnetic field. In the case of Mars, this may help explain why, unlike Earth, the Red Planet no longer has a magnetic field – something that is crucial to sustaining all forms of life.

“The modeling suggests that the Martian core is liquid, and while it is composed primarily of iron and nickel, it may also contain traces of lighter elements such as hydrogen and sulfur. These elements can alter the core’s ability to transport heat,” lead author Dr Sheng Wang, who is also from ANU, said.

“The magnetic field is important because it shields us from cosmic radiation, which is why life on Earth is possible.”

Using a seismometer on the surface of Mars, the ANU team measured specific types of seismic waves. Seismic waves, which are triggered by earthquakes, emit a spectrum of signals, or “echoes,” that change over time as they reverberate through the Martian interior.

These seismic waves pierce and bounce off the core of Mars.

Professor Tkalcic said the researchers were interested in the “late” and “weaker” signals that can survive hours after being emitted by earthquakes, meteor strikes and other sources.

“Although these late signals appear noisy and not useful, the similarity between these weak signals recorded at different places on Mars emerges as a new signal that reveals the presence of a large core at the heart of the Red Planet,” said Professor Tkalcic .

“We can determine how far these seismic waves travel to reach the core of Mars, but also the speed at which they travel through the interior of Mars. This data helps us make estimates of the size of Mars’ core.”

The researchers say their method of using a single seismometer to confirm the presence of a planetary core is also a “cost-effective solution.”

‚ÄúThere is only one seismic station on Mars. There were four of them on the Moon in 1970. The situation with a limited number of instruments is unlikely to change in the coming decades or even this century because of the high cost,” Dr. Wang said.

“We need an approach right now to use just one seismometer to study planetary interiors.”

Researchers hope this new ANU-developed technique, involving a single seismometer, can be used to help scientists learn more about our other planetary neighbours, including the Moon.

“The US and China plan to send seismometers to the Moon, and Australia also has ambitions to take part in future missions, so there is potential for further research using new and more sophisticated instruments,” Professor Tkalcic said.

Dr Wang said: “Although there is a lot of research on planetary cores, the images we have of planetary interiors are still very blurry. But with new tools and methods like ours, we’ll be able to get clearer images that will help us answer questions like how big nuclei are and whether they take solid or liquid form.

“Our method can even be used to analyze the moons of Jupiter and the planets of the outer solar system, which are solid.”

To carry out their research, the ANU scientists used data collected by a seismometer attached to NASA’s InSight lander, which has been collecting information on earthquakes, Martian weather and the planet’s interior since it touched down on Mars in 2018.

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