Nasa's InSight reveals Mars hit by meteorites nearly daily

Seismic recordings from Nasa's InSight spacecraft have revealed that Mars is bombarded by basketball-sized meteorites almost daily, at a rate five times higher than previously estimated. The study, published on Friday, indicates that Mars is hit by 280 to 360 meteorites each year, all creating craters larger than eight meters wide.
Previous estimates of meteorite impacts on Mars were based on images from orbiting spacecraft or models derived from craters observed on the Moon.However, the InSight probe, which landed on Mars' Elysium Planitia in 2018, has provided a new method for scientists to study these impacts by listening to the planet's internal rumblings.
Mars's proximity to the solar system's main asteroid belt and its thin atmosphere make it a prime target for meteorites. While Earth's atmosphere often breaks apart incoming meteorites, Mars's atmosphere, being 100 times thinner, offers much less protection.
Rather than relying on distant images, the international research team utilized the data collected by InSight's seismometer to monitor meteorite impacts on Mars.
"Listening for impacts seems to be more effective than looking for them if we want to understand how often they occur," said study co-author Gareth Collins from Imperial College London.
The researchers identified a particular acoustic signal produced when meteorites strike Mars, which allowed them to estimate the diameter of the craters and their distance from InSight. This data was then used to calculate how many craters are formed each year near the lander, and this figure was extrapolated to estimate the total number of impacts on the planet.
"This rate was about five times higher than the number estimated from orbital imagery alone," noted study co-author Geraldine Zenhaeusern from the ETH Zurich University.
Observing meteorite impacts on Mars through imagery is challenging due to the frequent and intense dust storms that obscure visibility. Identifying new craters is easiest in flat, dusty areas, which make up less than half of Mars's surface.
"The sensitive InSight seismometer, however, could hear every single impact within the landers' range," Zenhaeusern added.
This study marks the first time that scientists have determined the frequency of meteorite impacts on Mars using seismological data.
"This is the first paper of its kind to determine how often meteorites impact the surface of Mars from seismological data," said Domenico Giardini, a participant in the InSight mission.
This information is critical for future Mars missions, as researchers estimated that a significant meteorite strike, creating a 30-meter crater, occurs on Mars about once a month. This finding could be significant for astronauts planning to walk on the Martian surface in the future.
Understanding the frequency of these impacts is vital for the safety and planning of human missions to Mars. The new method of "listening" for meteorite impacts rather than solely relying on visual data offers a more accurate and comprehensive understanding of the risks posed by these cosmic collisions.