The Mars Insight probe detected seismic and sonic waves that originated when four space rocks smashed into the surface of the Red Planet.
insightThe seismometer felt vibrations from the impacts in 2020 and 2021, marking the first discoveries of meteorites to strike the planet since the probe began collecting data after its landing in 2018. 290 km) from the InSight site in the Elysium Planitia region of Marsa broad plain that extends across the Martian equator.
One space rock, the first discovered by scientists, made a dramatic and violent ingress on September 5, 2021, and exploded into pieces. At least three separate fragments smashed into the surface of Mars, each leaving a crater.
Related: NASA’s Mars Insight lander spotted from orbit covered in dust
NASA’s Mars Reconnaissance Orbiter (MRO) confirmed the location of these collisions from orbit. The spacecraft, which was launched in 2005, initially took black-and-white images of the regions using its context camera, revealing dark patches on Mars’ surface. After identifying these impact sites, follow up on the MRO by collecting color images and close-up shots using the High Resolution Imaging Science Experiment Camera (HIRISE). The meteorites may have left additional craters around these impact sites that are too small for HiRISE to identify them.
Research through past data collected by InSight revealed that the lander’s seismometer had already picked up three previous impacts on May 27, 2020, February 18, and August 31, 2021. The four impacts produced small earthquakes with a magnitude of no more than 2.0.
Ingrid Dubar, a planetary scientist at Brown University in Rhode Island and part of the team that made the discovery, said in statement.
Why so few influences?
Planetary scientists are baffled as to why InSight hasn’t detected more impacts of space rocks on the Red Planet. Not only does Mars sit next to the solar system’s main asteroid belt, which is a hotspot for space rock, but its thin atmosphere should allow meteorites to pass through it without destroying it. These factors mean that a higher proportion of space rocks must reach the surface of Mars than, say, Earth.
The researchers were fairly confident that the lack of observations was not a sign of a faulty InSight seismometer. During its nearly four years on the Red Planet, the instrument detected more than 1,300 earthquakes and was sensitive enough to detect seismic waves from thousands of miles away.
InSight scientists thought the effects might be hidden by wind noise on the Red Planet or by seasonal changes in the atmosphere. The researchers will now re-review the InSight data to look for seismic signatures of impacts from other space rocks.
Any such impacts could help scientists better understand the age of the surface of Mars. Calculating craters is one way scientists date a planet’s surface age, which means the new discovery and any additional impacts may be vital in building a timeline for Mars.
“The effects are the clocks of the solar system,” said Rafael Garcia, a planetary scientist at the Higher Institute of Space in France and lead author of the new research. “We need to know the impact rate today to estimate the age of the different surfaces.”
By combining InSight data regarding shock waves generated when space rocks hit the atmosphere with data collected from orbit, scientists may also be able to reconstruct the incoming trajectory of a specific meteorite.
“We are learning more about the impact process itself,” Garcia said. “We can now match different sizes of craters to specific seismic and acoustic waves now.”
And the researchers have a little longer to collect data with InSight than they thought. Dust buildup on the landing craft’s solar panels will reduce its power supply and will eventually force it to shut down; Previous estimates suggested this would happen in late summer, but mission personnel now believe it won’t happen even between October 2022 and January 2023.
A detailed paper on InSight’s findings was published Monday (September 19) in the journal natural earth sciences (Opens in a new tab).
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