WASHINGTON: Mars, by virtue of its tenuous atmosphere and proximity to our solar system's asteroid belt, is far more vulnerable than Earth to being struck by space rocks - one of the many differences between the two planetary neighbours.
Scientists are now gaining a fuller understanding of this Martian trait, with help from Nasa's robotic InSight lander. Researchers on Monday described how InSight detected seismic and acoustic waves from the impact of four meteorites and then calculated the location of the craters they left - the first such measurements anywhere other than Earth.
The researchers used observations from Nasa's Mars Reconnaissance Orbiter in space to confirm the crater locations.
"These seismic measurements give us a completely new tool for investigating Mars, or any other planet we can land a seismometer on," said planetary geophysicist Bruce Banerdt of Nasa's Jet Propulsion Laboratory, the InSight mission's principal investigator.
The space rocks InSight tracked - one landing in 2020 and the other three in 2021 - were relatively modest in size, estimated to weigh up to about 440 pounds, with diameters of up to about 50 cm and leaving craters of up to about 24 feet wide. They landed between 85 km and 290 km from InSight's location. One exploded into at least three pieces that each gouged their own craters.
"We can connect a known source type, location and size to what the seismic signal looks like. We can apply this information to better understand InSight's entire catalogue of seismic events, and use the results on other planets and moons, too," said Brown University planetary scientist Ingrid Daubar, a co-author of the study published in the journal Nature Geoscience.
The researchers believe that now the seismic signature of such impacts has been discovered they expect to find more contained in InSight's data, going back to 2018.
The three-legged InSight - its name is short for Interior Exploration Using Seismic Investigations, Geodesy and Heat Transport - landed in 2018 in a vast and relatively flat plain just north of the Martian equator called Elysium Planitia.
"The moon is also a target for future meteor impact detection," said planetary scientist and study lead author Raphael Garcia of the University of Toulouse's ISAE-SUPAERO institute of aeronautics and space.
"And it may be the same sensors will do it, because the spare sensors of InSight are currently integrated in the Farside Seismic Suite instrument for a flight to the moon in 2025," Garcia added, referring to an instrument due to be placed near the lunar south pole on the side of the moon permanently facing away from Earth. -- Reuters
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