NASA’s InSight lander has “heard” and detected the vibrations of four space rocks as they impacted Mars over the past two years.
Not only are these the first impacts recorded by the spacecraft’s seismometer since InSight landed on the Red Planet in 2018, they are also the first time seismic and acoustic waves from an impact have been detected on Mars.
The US space agency has released a recording of one of the Mars meteorite impacts, in which a distinctive “bloop” sound is heard three times as the space rock enters the atmosphere, explodes into pieces, and hits the surface.
The impacts ranged from 53 to 180 miles (85 to 290 kilometers) from the stationary lander’s position in a region of Mars called Elysium Planitia, a smooth plain north of the planet’s equator.
The first of the four meteoroids – the term used for space rocks before they hit the ground – made the most dramatic appearance.
NASA’s InSight lander has “heard” and detected the vibrations of four space rocks as they impacted Mars over the past two years (pictured).
Not only are these the first impacts recorded by the spacecraft’s seismometer since InSight landed on the Red Planet in 2018, they are also the first time seismic and acoustic waves from an impact have been detected on Mars
It entered the red planet’s atmosphere on September 5, 2021 and exploded into at least three fragments, each leaving a crater.
NASA’s Mars Reconnaissance Orbiter then flew over the estimated impact site to confirm the location.
It used its black and white context camera to reveal three dark spots on the surface.
After locating these spots, the orbiter’s team used the High-Resolution Imaging Science Experiment (HiRISE) camera to get a close-up of the craters in color.
“After waiting three years for InSight to spot an impact, these craters looked beautiful,” said Brown University’s Ingrid Daubar, co-author of a new research paper on the discovery and a Mars impact specialist.
After sifting through previous data, scientists confirmed that three additional impacts had occurred on May 27, 2020, February 18, 2021, and August 31, 2021.
Researchers have pondered why they haven’t spotted more meteor impacts on Mars.
The Red Planet sits adjacent to the Solar System’s main asteroid belt, which provides copious amounts of space rock to scar the planet’s surface.
Because Martian atmosphere is only 1 percent as thick as Earth’s, more meteoroids pass through it without dissipating.
The InSight seismometer has already registered more than 1,300 marsquakes.
The instrument, provided by the French space agency Center National d’Études Spatiales, is so sensitive that it can detect seismic waves thousands of kilometers away.
But the September 5, 2021 event marks the first time an impact has been confirmed as the cause of such waves.
The InSight team suspects other impacts may have been masked by wind noise or seasonal changes in the atmosphere.
But now that the distinctive seismic signature of an impact on Mars has been spotted, scientists expect to be hiding even more in InSight’s nearly four-year data.
The US space agency has released a recording of one of the Mars meteorite impacts, in which a distinctive “bloop” sound is heard three times as the space rock enters the atmosphere, explodes into pieces, and hits the surface
The impacts ranged from 53 to 180 miles (85 to 290 kilometers) from the stationary lander’s position in a region of Mars called Elysium Planitia, a smooth plain north of the planet’s equator
Seismic data offer several clues that will help researchers better understand the Red Planet.
Most marsquakes are caused by subsurface rocks fractured by heat and pressure. Studying how the resulting seismic waves change as they travel through different materials offers scientists a way to study the crust, mantle and core of Mars.
The four meteorite impacts confirmed so far produced small tremors with a magnitude of no more than 2.0.
These smaller tremors offer scientists only a glimpse of Mars’ crust, while seismic signals from larger tremors, such as the magnitude 5 event in May 2022, can also reveal details about the planet’s mantle and core.
But the implications will be crucial in refining the Mars timeline.
Seismic data offer several clues that will help researchers better understand the Red Planet
“Impacts are the clocks of the solar system,” said the study’s lead author, Raphael Garcia of the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France.
“We need to know the impact rate today to estimate the age of different surfaces.”
Scientists can estimate the age of a planet’s surface by counting its impact craters — the more they see, the older the surface.
InSight data can be used in combination with orbital imagery to reconstruct a meteorite’s trajectory and the magnitude of its shock wave.
Each meteoroid creates a shockwave when it hits the atmosphere and an explosion when it hits the ground. These events send sound waves through the atmosphere.
The larger the explosion, the more this sound wave tilts the ground when it reaches InSight.
The lander’s seismometer is sensitive enough to measure how much the ground tilts during such an event and in which direction.
“We’re learning more about the impact process itself,” Garcia said. “We can now associate different crater sizes with specific seismic and acoustic waves.”
The new paper was published in the journal Nature Geoscience.
