The InSight lander of NASA has detected seismic waves from four space rocks that floated on Mars. Credit: NASA/JPL-Caltech/University of Arizona
In the last two years, SEIS, the Mars lander's seismometer, has detected vibrations from four different impacts.
The InSight lander of NASA has detected seismic waves from four space rocks that exploded on Mars in 2020 and 2021. These are the first impacts detected by the spacecraft's seismometer since InSight touched down on the Red Planet in 2018. In fact, it is the first time seismic and acoustic waves have been detected on Mars.
A new scientific paper explains the impacts, which ranged between 53 and 180 miles (85 and 290 kilometers) from InSight's location, in the Elysium Planitia area on Mars. It was published on September 19 in the journal Nature Geoscience.
For the First Time, InSight Detects an Impact: These craters were formed by a meteoroid impact on Mars on September 5, 2021, the first to be detected by NASA's Mars Reconnaissance Orbiter, capturing an enhanced-color photo of the impact in order to make details more visible to the human eye.
The first of the four confirmed meteoroids made the most dramatic entrance: It exploded into at least three shards that each left a crater after entering Mars' atmosphere on September 5, 2021.
The Mars Reconnaissance Orbiter of NASA then flew over the estimated impact site to confirm the location. The orbiter's team then used the High-Resolution Imaging Science Experiment camera, or HiRISE, to obtain a color close-up of the craters (the meteoroid might have left additional craters on the surface, but they would be too small to see in HiRISE's images).
In this video, learn more about the first meteoroid impact NASA's InSight lander detected on Mars. Credit: NASA/JPL-Caltech
“Those craters looked incredible after three years of InSight waiting to detect an impact,” said Ingrid Daubar of Brown University. She is a co-author of the paper and a specialist in Mars impacts.
Researchers concluded that three other impacts had occurred on May 27, 2020, February 18, 2021, and August 31, 2021.
Scientists are puzzled as to why they haven't discovered more meteoroid impacts on Mars. The Red Planet is next to the solar system's main asteroid belt, which should provide ample space rocks to scar the planet's surface. Additionally, far more meteoroids pass through Mars' atmosphere without disintegrating because it is only 1% as thick as Earth's.
Due to a peculiar atmospheric effect, the sound of a meteoroid striking Mars is like a "bloop." The sound can be heard three times: when the meteoroid enters the Martian atmosphere, bursts into pieces, and impacts the surface. Credit: NASA/JPL-Caltech/CNES/IPGP
The SEIS, InSight's seismometer, has detected over 1,300 marsquakes. Provided by France's space agency, the Centre National d'Études Spatiales, the instrument is so sensitive that it can detect seismic waves from thousands of miles away. However, the event on September 5, 2021 marks the first time an impact has been verified as the cause of such waves.
Researchers believe that wind or seasonal variations in the atmosphere may have obscured other impacts. However, now that the distinctive seismic signature of an impact on Mars has been discovered, they anticipate to uncover more hidden within InSight's nearly four-year archive.
Scientists will be able to use seismic data to understand Mars' crust, mantle, and core. The majority of marsquakes are caused by subsurface rocks cracking due to heat and pressure.
The four meteoroid impacts confirmed so far have produced small earthquakes with a magnitude of no more than 2.0. Investigators have only a brief glimpse into the Martian crust, while seismic signals from larger earthquakes, such as the magnitude 5 event in May 2022, can reveal further information about the planet's mantle and core.
Collage of three other meteoroid impacts detected by NASA's InSight lander and captured by the agency's Mars Reconnaissance Orbiter using its HiRISE camera
Nevertheless, the impacts will be critical to reworking Mars' timeline. "Impacts are the clocks of the solar system," said the paper's lead author, Raphael Garcia of the Institut Supérieur de l'Aéronautique and de l'Espace in Toulouse, France.
Scientists can estimate the age of a planet's surface by counting its impact craters: The more they see, the older the surface. Researchers may then estimate how many more impacts occurred earlier in the solar system's history.
The data from InSight, combined with orbital photographs, can be used to reconstruct a meteoroid's trajectory and the size of its shock wave. These phenomena send sound waves through the atmosphere, which impacts the ground when it hits InSight. The lander's seismometer is sufficiently sensitive to detect how much the ground tilts from such an event and in what direction.
Garcia said: "We're getting better acquainted with the impact process." "We can now match different sizes of craters to specific seismic and acoustic waves."
This image shows NASA's Mars InSight probe on the surface of the Martian planet. Credit: NASA
The lander has time to explore Mars. Dust buildup on the lander's solar panels is reducing its power, and will eventually result in the spacecraft being halted. It's difficult to predict when the lander will be shut down between October of this year and January 2023, according to scientists.
Raphael F. Garcia, Ingrid J. Daubar, Éric Beucler, Liliya V. Posiolova, Benjamin Fernando, Gunnar Speth, Léo Martire, Anna Horleston, Taichi Kawamura, Matthieu Plasman, Domenico Giardini, Mike Malin, and William Bruce Banerdt, 19 September 2022, Nature Geoscience. DOI: 10.1038/s41561-022-01014-0
More on the Mission
InSight is managed by NASA's Science Mission Directorate in Washington, D.C. The InSight spacecraft, including its cruise stage and lander, was built by Lockheed Martin Space in Denver, which oversees spacecraft operations for the mission.
The InSight mission is being supported by a number of European institutions, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR). CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris); Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the heat Flow and Physical Properties Package (HP