This article was originally published on Conversation. (Opens in a new tab) Post contributed this article to Space.com Expert Voices: Editorial and Insights.
Katharina Milikovic (Opens in a new tab)،, ARC Future Fellow, School of Earth and Planetary Sciences, Curtin University
Since 2018, NASA’s InSight mission to Mars has recorded seismic waves from more than 1300 swamp (Opens in a new tab) In her quest to explore the inner structure of the red planet. The solar panels of a car-sized robotic lander are now covered in Martian dust and NASA scientists anticipation (Opens in a new tab) It will be completely decommissioned by the end of 2022.
But our planetary neighbor’s internal vibrations aren’t the only things InSight’s seismographs are detecting: They also pick up on the impact of space rocks crashing into Martian soil.
In a new search (Opens in a new tab) Publishing in Nature Geoscience, we used data from InSight to detect and identify four high-speed meteor impacts, then tracked the resulting craters in satellite images from NASA’s Mars Reconnaissance Orbiter.
Related: NASA’s Mars Insight probe takes dusty ‘final selfie’ as power dwindles
rocks from space
The solar system is filled with relatively small rocks called meteorites, and it is common for them to collide with planets. When a meteorite hits a planet with an atmosphere, it heats up due to friction – and may burn up completely before reaching Earth.
On Earth, we know these incoming meteors as meteors, or meteors: beautiful events that we observe in the night sky. The meteor sometimes explodes when it reaches the thick atmosphere closest to Earth, resulting in a stunning atmospheric explosion.
Read more: Where do meteorites come from? We tracked down hundreds of fireballs slithering across the sky to find out (Opens in a new tab)
Occasionally, a space rock escapes its fiery path through the air and falls to Earth, where it is known as a meteorite.
A few of these meteorites hit the surface so quickly that they made a hole in the ground called an impact crater. Compared to human lifespan, such events are very rare on Earth.
Recording traces of space rocks
Scientists have detected vibrations from meteor air eruptions using seismic detectors several times, including recent study (Opens in a new tab) Of the bright meteors over Australia.
However, only once has a high-speed space rock been observed crashing into Earth optically and by modern seismic equipment. This was the effect of the crater that Founded in 2007 (Opens in a new tab) Near the village of Carancas in Peru.
Several impacts on the Moon were detected by a network of seismic sensors created during the American Apollo missions in the 1960s and 1970s. However, there was no recording of the natural impact associated with the visual detection of a new crater.
Read more: The study indicates that the moon is still geologically active (Opens in a new tab)
The closest things to such an observation were synthetic effects: the booster rocket landings of the ascent units that drove the Apollo astronauts off the moon.
These man-made impacts on the Moon have been recorded in both seismic data and visual images from orbit. This data was Newly used (Opens in a new tab) To test simulating how impacts produce seismic waves.
Incoming meteors make waves in the atmosphere as well as the Earth. The atmosphere of Mars is equal to 1% of the Earth’s, and it has a different chemical composition. This means that meteorite events on Mars take a different shape.
For meteor events large enough to drop a meteorite, the fate of the meteorite and any resulting crater is Different (Opens in a new tab) than we expected on our planet.
Here on Earth, or on the Moon, individual craters are the norm. However, on Mars, about half the time a high-velocity space rock explodes in the atmosphere shortly before impact, resulting in a tight pool of craters.
The separation of these individual parts remains close to ground level, forming a A set of small effects (Opens in a new tab).
From vibrations to pits
Recently, the InSight mission observed sound and seismic waves from four meteor impact events. These waves travel at different speeds, and a comparison of their different arrival times and other properties has allowed us to estimate the location of the impacts.
These impact sites were then confirmed by satellite imaging from the Mars Reconnaissance Orbiter.
Knowing the exact size and location of these impact craters helps us calculate the size and velocity of the incoming space rock and the amount of energy released from the impact.
Once we are confident that we know something about the impact that caused the seismic waves we detected, we can use the waves to learn about the interior of Mars. Moreover, when we compare seismic observations on Mars with observations from Earth and the Moon, we can learn more about how planets formed and how the solar system evolved.
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