An international team of researchers, led by ETH Zurich and Imperial College London, have calculated the initial assessment of the global meteorite strikes on Mars by analyzing seismic data. Their results suggest that the planet experiences between 280 to 360 meteorite impacts annually, resulting in impact craters larger than 8 meters (about 26 feet) in diameter.
Géraldine Zenhäusern, ETH Zurich, who co-led the study, commented, “This rate was about five times higher than the number estimated from orbital imagery alone. Aligned with orbital imagery, our findings demonstrate that seismology is an excellent tool for measuring impact rates.”
Using data from the seismometer deployed during the NASA InSight Mission to Mars, researchers found that 6 seismic events recorded in the vicinity of the station had previously been identified as meteoric impacts—a process enabled by the recording of a specific acoustic atmospheric signal generated when meteorites enter the Martian atmosphere.
Recently, Zenhäusern from ETH Zurich and Natalia Wójcicka from Imperial College London, along with a research team, discovered that six seismic events on Mars are part of a larger group of marsquakes called very high frequency (VF) events. These quakes are generated by impacts and occur much faster than tectonic marsquakes of similar size, with the process lasting only 0.2 seconds or less.
By analyzing marsquake spectra, the team identified a further 80 marsquakes believed to be caused by meteoroid strikes. This research began in December 2021, prior to the end of the InSight mission, and resulted in the identification of fresh craters associated with the seismic events. The team’s collaboration with the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) confirmed the presence of these fresh craters, providing insights into the frequency of meteorite strikes on Mars.
Approximately 17,000 meteorites fall to Earth each year, but on Mars, the thinner atmosphere exposes its surface to larger and more frequent meteorite strikes.
While scientists have traditionally relied on orbital images and Moon-based models to estimate meteorite impact rates, estimating these rates on Mars presents unique challenges due to its stronger gravitational pull, proximity to the asteroid belt, and less well-preserved impact craters caused by regular sandstorms.
However, recent advancements in measuring Mars’ impact rate have leveraged the detection of seismic waves from meteorite impacts using seismometers, providing valuable new insights into the frequency of meteorite strikes on the red planet.
“We estimated crater diameters from the magnitude of all the VF-marsquakes and their distances, then used it to calculate how many craters formed around the InSight lander over the course of a year. We then extrapolated this data to estimate the number of impacts that happen annually on the whole surface of Mars,” Wójcicka explains.
Zenhäusern adds, “While new craters can best be seen on flat and dusty terrain where they really stand out, this type of terrain covers less than half of the surface of Mars. However, The sensitive InSight seismometer could hear every impact within the landers’ range.”
The density and size of craters caused by meteorite strikes provide valuable information about the age of different planetary regions. For instance, Venus, with its thick atmosphere and volcanic activity, shows very few craters, indicating a relatively young surface. On the other hand, Mercury and the Moon have heavily cratered surfaces, suggesting great age. Mars, with a mix of old and young regions, can be differentiated by the number of craters present.
Recent data reveals that Mars is impacted by an 8-meter crater nearly every day and a 30-meter crater about once a month. Understanding the frequency of these impacts is crucial for the safety of robotic and future human missions to the red planet.
“This is the first paper of its kind to determine how often meteorites impact the surface of Mars from seismological data – which was a level one mission goal of the Mars InSight Mission,” says Domenico Giardini, Professor of Seismology and Geodynamics at ETH Zurich and co-Principal Investigator for the NASA Mars InSight Mission. “Such data factors into the planning for future missions to Mars.”
Zenhäusern and Wójcicka suggest that the next phase of this research will involve utilizing machine learning technologies to assist researchers in detecting additional craters in satellite images and recognizing seismic events in the data.
Journal reference:
- Zenhäusern, G, Wójcicka, N, Stähler, SC, Collins, GS, Daubar, IJ, Knapmeyer, M, Ceylan, S, Clinton, JF, Giardini, D. An estimate of the impact rate on Mars from statistics of very-high-frequency marsquakes. Nature Astronomy, 2024; DOI: 10.1038/s41550-024-02301-z
- Daubar, IJ, Garcia, RF, Stott, AE, Fernando, B, Collins, GS, Dundas, CM, Wójcicka, N, Zenhäusern, G, McEwen, AS, Stähler, SC, Golombek, M, Charalambous, C, Giardini, D, Lognonné, P, Banerdt, WB. Seismically Detected Cratering on Mars: Enhanced Recent Impact Flux? Science Advances, 2024; DOI: 10.1126/sciadv.adk7615
- Posiolova, L.V., et al. Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation. Science 378, 412–417, 2022; DOI: 10.1126/science.abq7704
- Garcia, R.F., et al. Newly formed craters on Mars located using seismic and acoustic wave data from InSight. Nature Geoscience 1–7, 2022; DOI: 10.1038/s41561-022-01014-0