Recent findings from the InSight mission reveal that Mars experiences 280 to 360 major meteorite impacts annually, far exceeding previous estimates based on satellite images. This seismic approach offers a new way to date the surfaces of Mars and other planets. Credit: NASA/JPL–Caltech
Seismic signals signal Mars approximately 300 basketball-sized meteorites strike each year, providing a new tool for dating planetary surfaces.
Scientists involved in NASAThe InSight mission revealed that Mars is subject to a much greater number of meteorite impacts than previously thought, with annual rates ranging from 280 to 360 significant impacts. This new understanding is based on seismic data captured by the InSight seismometer, which suggests a more efficient method for dating planetary surfaces throughout the Solar System.
New research led by scientists at Imperial College London and ETH Zurich, working as part of NASA’s InSight mission, shed light on how often “marsquakes” caused by meteorite impacts occur on Mars.
Scientists have found that Mars experiences approximately 280 to 360 meteorite impacts each year, creating craters larger than eight meters in diameter and shaking the red planet’s surface.
The rate of these tremors, which were detected by InSight’s “seismometer” — an instrument capable of measuring the tiniest movements of the earth — exceeded previous estimates based on satellite images of the Martian surface.
These craters were created on September 5, 2021 by a meteorite impact on Mars, first captured by NASA InSight. This enhanced color image taken by NASA’s Mars Reconnaissance Orbiter highlights dust and soil disturbed by the impact in blue to make details more visible to the human eye. Credit: NASA/JPL-Caltech/University of Arizona
Seismic data and planetary dating
The researchers say that this seismic data could be a better and more direct way of measuring meteorite impact rates and could help scientists more accurately date planetary surfaces in the Solar System.
Study co-author Dr. Natalia Wojcicka, a researcher at Imperial College London’s Department of Earth Science and Engineering, said: “Using seismic data to better understand how often meteorites hit Mars and how these impacts change its surface, we can start machining. together the timeline of the red planet’s geological history and development.
“You can think of it as a kind of ‘cosmic clock’ that will help us date the surfaces of Mars and perhaps, beyond, other planets in the Solar System.”
The study is published in the journal today (June 28). Astronomy of nature.
A collage showing three meteoroid impacts first detected by a seismometer on NASA’s InSight lander and later captured by the agency’s Mars Reconnaissance Orbiter using the HiRISE camera. Credit: NASA/JPL-Caltech/University of Arizona
Impact craters like cosmic clocks
For years, scientists have used the number of craters on the surface of Mars and other planets as a “cosmic clock” to estimate planetary age — with older surfaces on more cratered planets than younger ones.
To calculate planetary age in this way, scientists have traditionally used models based on lunar craters to predict the impact rate of meteorites of various sizes over time. In order to apply these models to Mars, they need to be adjusted for how the atmosphere might prevent the smallest impactors from hitting the surface, and for the varying size and position of Mars in the solar system.
For small craters less than 60 meters wide, 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 operating on the surface of Mars. InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a lander designed to provide Mars with its first thorough inspection since its formation 4.5 billion years ago. Credit: NASA/JPL-Caltech
Observations from the InSight seismometer
In this new research, part of the InSight mission to understand the seismic activity and internal structure of Mars, researchers have identified a previously unrecognized pattern of seismic signals as produced by meteorite impacts. These signals featured an unusually higher proportion of high-frequency waves compared to typical seismic signals, as well as other characteristics, and are known as “very high-frequency” marsquakes.
The researchers found that the rate of meteoroid impacts is higher than previously estimated when they looked at freshly formed craters captured by satellite images and consistent with extrapolating data from craters on the lunar surface.
This highlighted the limitations of previous models and estimates, as well as the need for better models to understand cratering and meteorite impacts on Mars.
The power of seismic data in planetary science
To solve this problem, a team of scientists used NASA’s InSight lander and its extremely sensitive seismometer, SEIS, to record seismic events that can be caused by meteorite impacts.
SEIS detected seismic signatures characteristic of these very high-frequency seismic tremors, which the researchers found to be indicative of meteoroid impacts and distinct from other seismic activity.
Using this new method of detecting impacts, the researchers found many more impact events than predicted by satellite imaging, especially for small impacts that create craters only a few meters in diameter.
Study co-author Professor Gareth Collins, from Imperial College London’s Department of Earth Science and Engineering, said: “The SEIS tool has proven to be incredibly successful at detecting impacts – listening for impacts seems to be more effective than looking for them if we want to understand them. how often they occur.”
Improving our understanding of the solar system
The researchers believe that deploying smaller, more affordable seismometers on future landers could further improve our understanding of Mars’ impact rate and internal structure. These instruments would help researchers detect more seismic signals and provide a more comprehensive data set for understanding meteorite impacts on Mars and other planets, as well as their internal structures.
Dr. Wojcicka said: “We use seismology to understand the internal structure of planets. This is because as seismic waves pass through or bounce off the material in the planets crust, mantle and core, they change. By studying these changes, seismologists can determine what these layers are made of and how deep they are.
“On Earth, you can more easily understand the internal structure of our planet by looking at data from seismometers located around the globe. However, there was only one on Mars – SEIS. To better understand the internal structure of Mars, we need more seismometers spread across the planet.”
Like new research published in Astronomy of naturethe team also participates in another study published in Scientific advances today, which used images and atmospheric signals recorded by InSight to estimate how often impacts occur on Mars. Despite using different methods, both studies reached similar conclusions, strengthening the overall findings.
Reference: “Estimating Martian Impact Rates from Very High Frequency Marsquakes Statistics” 28 Jun 2024, Astronomy of nature.
DOI: 10.1038/s41550-024-02301-z