Impact craters form on Mars almost every day

June 28 () –

Between 280 and 360 meteorites impact the surface of Mars each year, forming impact craters more than 8 meters in diameter, according to the first global estimate using seismic data.

The new data shows that such a crater occurs somewhere on the surface of Mars almost every day and a 30 meter crater occurs approximately once a monthSince hypervelocity impacts cause blast zones that are easily 100 times larger in diameter than the crater, knowing the exact number of impacts is important for the safety of robotic missions, but also for future human missions to the Red Planet.

Géraldine Zenhäusern of ETH Zurich, who co-led the study, commented it’s a statement“This rate was approximately five times greater than the amount estimated from orbital imagery alone. Consistent 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’s InSight mission to Mars, researchers discovered 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.

Now, new research has found that these 6 seismic events belong to a much larger group of Martian earthquakes, so-called very high frequency (VF) events. The origin process of these earthquakes occurs much faster than in the case of a similarly sized tectonic Martian earthquake. While a normal magnitude 3 earthquake on Mars takes several seconds, an event generated by an impact of the same size takes only 0.2 seconds or less, due to the hypervelocity of the collision. By analyzing the spectra of the Martian earthquakes, Another 80 Marsquakes have been identified that are now thought to be caused by meteorite impacts.

Their research quest began in December 2021, a year before dust on solar panels ended the InSight mission, when a large, distant earthquake recorded by the seismometer reverberated a broadband seismic signal across the planet. Remote sensing linked the earthquake to a 150-meter-wide crater.

To confirm this, the InSight team partnered with the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) to search for other recent craters that matched the timing and location of the seismic events detected by InSight. The teams’ research work paid off and they were lucky enough to find a second fresh crater more than 100 meters (320 feet) in diameter. However, smaller craters, formed when basketball-sized meteorites hit the planet and which should be much more common, remained elusive. Now, the number of meteorite impacts It is estimated again by the occurrence of these special high frequency earthquakes.

About 17,000 meteorites fall to Earth each year, but unless they streak across the night sky, they are rarely detected. Most meteorites disintegrate upon entering Earth’s atmosphere, but on Mars the atmosphere is 100 times thinner, leaving its surface exposed to larger and more frequent meteorite impacts.

Until now, planetary scientists have relied on images and orbital models inferred from well-preserved meteorite impact craters on the Moon, but extrapolating these estimates to Mars proved tricky. Scientists had to take into account Mars’ greater gravitational pull and its proximity to the asteroid belt, which means more meteorites hitting the red planet.

On the other hand, regular sandstorms result in craters that are much less well preserved than those on the Moon and are therefore not as easy to detect with orbital imaging. When a meteorite hits the planet, seismic waves from the impact travel through the crust and mantle and can be picked up by seismometers, providing a completely new way to measure Mars’ impact rate.

Study co-author Natalia Wójcicka of Imperial College London explains: “We estimated the diameters of the craters from the magnitude of all VF earthquakes and their distances, and then we used them 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 occur annually across the entire surface of Mars.”

Zenhäusern adds: “While the new craters can be seen best on flat, dusty terrain where they really stand out, this type of terrain covers less than half the surface of Mars. However, InSight’s sensitive seismometer could hear every impact within range of the landers.

Like the lines and wrinkles on our faces, the size and density of meteorite impact craters reveal clues about the age of different regions of a planetary body. The fewer craters, the younger the region of the planet. Venus, for example, has almost no visible craters because it is protected by a thick atmosphere and its surface is continually renewed by volcanism; the ancient surfaces of Mercury and the Moon are full of craters. Mars is among these examples, with some old and some young regions that can be distinguished by the number of craters.