How NASA's InSight Data Is Rewriting Mars' History

Seismic signals indicate Mars Our planet is struck annually by about 300 basketball-sized meteorites, providing a new tool for determining the age of planetary surfaces.

Scientists participating in NASANASA’s InSight mission has revealed that Mars is hit by far more meteorite impacts than previously thought, with rates ranging from 280 to 360 major impacts per year. This new understanding stems from seismic data captured by InSight’s seismometer, which suggests a more efficient way to date the surfaces of planets across the solar system.

New research led by scientists in Imperial College London A recent study by researchers at the University of Zurich in Switzerland in collaboration with the Federal Institute of Technology Zurich, working as part of NASA's InSight mission, has revealed how frequently “Marsquakes” caused by meteorite impacts occur on Mars.

Researchers found that Mars is exposed to about 280 to 360 meteorite collisions annually, which result in craters with a diameter of more than eight meters, shaking the surface of the red planet.

The rate of these Marsquakes, detected by InSight's seismometer — an instrument capable of measuring the slightest ground movements — exceeds previous estimates based on satellite images of the Martian surface.

These craters were formed as a result of a meteorite colliding with Mars on September 5, 2021, and are the first craters to be observed by NASA's InSight probe. Taken by NASA's Mars Reconnaissance Orbiter, this color image highlights dust and soil disturbed by the impact in blue to make details more visible to the human eye. Copyright: NASA/JPL-Caltech/University of Arizona

Seismic data and planetary dating

The researchers say this seismic data could be a better, more direct way to measure meteorite impact rates, and could help scientists more accurately date the surfaces of planets across the solar system.

“By using seismic data to understand how often meteorites hit Mars and how these impacts change its surface, we can start to better piece together,” said Dr. Natalia Wojcicka, co-author of the first study and a research associate in the Department of Earth Sciences and Engineering at Imperial College London. Together a timeline of the geological history and evolution of the Red Planet.

“You can think of it as a kind of ‘cosmic clock’ to help us determine the age of the surfaces of Mars and, perhaps later, other planets in the solar system.”

The study was published today (June 28) in the journal Natural astronomy.

A composite image shows three meteorite impacts first detected by the seismometer on NASA's InSight lander and later captured by the agency's Mars Reconnaissance Orbiter using its HiRISE camera. Image credit: NASA/JPL-Caltech/University of Arizona

Impact craters as cosmic clocks

For years, scientists have used the number of craters on Mars and other planetary surfaces as “cosmic clocks” to estimate the age of planets — with older surfaces on planets having more craters than younger ones.

To calculate the planet’s age this way, scientists used models based on craters on the moon’s surface to predict the rate at which meteorites of different sizes would strike over time. To apply those models to Mars, they would have to be modified to account for how the atmosphere prevents the smallest objects from hitting the surface, and for Mars’ different size and location in the solar system.

For small craters less than 60 meters across, Mars scientists have also been able to observe how often new craters form using satellite images — but the number of craters found this way is much lower than expected.

An artist's rendering of the InSight lander working on the surface of Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport, is a lander designed to give Mars its first comprehensive examination since it formed 4.5 billion years ago. Image credit: NASA/JPL-Caltech

Insights from InSight's seismometer

In this new research, which is part of InSight's mission to understand seismic activity and the internal structure of Mars, researchers have identified a previously unknown pattern of seismic signals produced by meteorite impacts. These signals were characterized by an unusually larger proportion of high-frequency waves compared to typical seismic signals, as well as other characteristics, and are known as “very high-frequency” Martian earthquakes.

The researchers found that the rate of meteorite impacts is higher than previously estimated by looking at newly formed craters captured by satellite images and in agreement with extrapolation of data from craters on the moon's surface.

This highlights the limitations of previous models and estimates, as well as the need for better models for understanding crater formation and meteorite impacts on Mars.

The Power of Seismic Data in Planetary Science

To address this problem, the team of scientists used NASA's InSight probe and its highly sensitive seismometer, SEIS, to record seismic events that may have been caused by meteorite impacts.

SEIS detected distinct seismic signatures of these high-frequency Martian earthquakes, which researchers found were indicative of meteorite impacts and distinct from other seismic activity.

Using this new method of impact detection, researchers found many more impact events than predicted by satellite imaging, especially for small impacts that produce craters only a few meters across.

Professor Gareth Collins, co-author of the study at the Department of Earth Sciences and Engineering at Imperial College London, said: “SEIS has proven incredibly successful at detecting impacts – it seems that listening to impacts is more effective than looking for them if we want to understand them.” How many times does it happen?”

Improve our understanding of the solar system

Researchers believe that deploying smaller, more affordable seismometers on future landers could further advance our understanding of Mars’ impact rates and internal structure. These instruments could help researchers detect more seismic signals, providing a more comprehensive dataset for understanding meteorite impacts on Mars and other planets, as well as their internal structure.

“To understand the internal structure of planets, we use seismology,” Dr. Wojcica said. “This is because seismic waves change when they travel through or reflect off materials in a planet’s crust, mantle, and core. By studying these changes, seismologists can determine what these layers are made of and how deep they are.”

“On Earth, you can understand the internal structure of our planet most easily by looking at data from seismometers located around the world. However, on Mars there was only one – SEIS. In order to better understand the internal structure of Mars, we need To more seismometers distributed throughout the planet.

As well as new research published in Natural astronomyThe team is also participating in another study to be published in Advancement of science Today, the study used images and aerial signals recorded by the InSight lander to estimate how often impacts occur on Mars. Despite using different methods, the two studies reached similar conclusions, strengthening the overall results.

Reference: “Estimation of impact rate on Mars from statistics of very high-frequency Martian earthquakes” 28 June 2024, Natural astronomy.
DOI: 10.1038/s41550-024-02301-z