A Recent Impact on Mars Shook the Planet to Its Mantle
New research suggests a large impact recently shook Mars deeper than thought.
Research involving two NASA missions—the Mars Reconnaissance Orbiter and the late InSight lander—has shed light on meteorite impacts and the seismic signals they produce. In a crucial finding, these signals may penetrate deeper inside Mars than previously thought. This could change how we view the interior of Mars itself.
The study comes from two papers published this week in the journal of Geophysical Research Letters. The primary data comes from NASA’s InSight mission, which was the first dedicated geodesy mission to Mars. Insight landed in the Elysium Planitia region of Mars on November 26th, 2018, and carried the first dedicated seismometer to the Red Planet. During its four years of operation, Insight detected over 1,300 ‘marsquakes’ until the mission’s end in 2022. Most were due to geologic activity, while a few were due to distant meteorite impacts. Occasionally, InSight would even observe ‘land tides’ caused by the passage of the moon Phobos overhead.
A Distant Mars Impact
As on Earth, the detection of seismic waves gives scientists the opportunity to probe the interior of Mars, providing clues about the density, depth, and thickness of the crust, mantle, and core. Impacts have been previously correlated to seismic waves captured by InSight: a fresh crater seen by NASA's Mars Reconnaissance Orbiter (MRO) in 2022 was correlated to an impact in the Amazonis Planitia region. But this was the first time an impact in the quake-prone Cerberus Fossae area was linked to InSight detections. This find is especially intriguing, as the area is a quarter of the world away from the InSight landing site, at 1,640 kilometers (1,019 miles) distant.
The discovery of the 21.5-meter (71 foot) crater, comparable in size to a semi-truck, immediately presented scientists with a mystery. The impact crater was more distant than anticipated. The Martian crust was thought to have a dampening effect on distant impacts, but this demonstrates that the impact produced seismic waves that took a more direct route through the planet’s deeper mantle.
A New View of the Interior of Mars?
This discovery has significant implications for our understanding of the planetary interior, suggesting that our models of Mars may need revision.
“Composition of the crust and how seismic waves travel through them play a key role,” says Andrew Good (NASA-JPL). “While there are no current plans for follow-on seismometers on Mars, there is a seismometer planned for the Moon in the near future,” he explained, referring to the Farside Seismic Suite planned for 2026.
The methods used to image the tiny crater are notable too. NASA’s venerable MRO produces tens of thousands of Martian surface images through its onboard Context Camera. For years, researchers have relied on a machine learning algorithm to sift through the images, identifying fresh impact sites that do not appear in previous frames. These newly identified areas are then flagged for detailed examination by the mission’s high-resolution HiRISE camera.
To date, the team has identified 123 new craters within 3,000 kilometers (1,864 miles) of the InSight landing site, 49 of which (including the Cerberus Fossae impact) match with InSight seismology data.
“Manually finding these would take years,” notes InSight team member Valentin Bickel (University of Bern, Switzerland) in a recent press release. “Using this tool, we reduced the workload from tens of thousands of images to just a handful in a matter of days.”
InSight's Legacy
The InSight mission provided an abundance of data regarding Mars’ seismology and geology. Its Seismic Experiment for Interior Structure (SEIS) instrument performed as designed. However, the Heat Flow and Physical Properties Package failed to reach its target depth necessary for meaningful science about the planet's interior. Currently, there are no dedicated follow-up geology missions planned for Mars. Exciting discoveries such as this may have to wait until potential crewed missions are executed in the 2030s.
The InSight mission was a collaborative effort between NASA, the German Space Agency (DLR), and the French Space Agency (CNES), with additional contributions from other international partners.
It's exciting to see that missions such as InSight continue to yield scientific revelations long after their operational phase has ended.
For More Information
- NASA's InSight Lander Finds Marsquakes from Meteoroids Go Deeper Than Expected
- Geophysical Research Letters Paper on Recent Mars Impacts
References
David Dickinson, Universe Today, "A Recent Impact on Mars Shook the Planet to Its Mantle." Retrieved from: Universe Today site
Latest report from NASA on the InSight mission impacts and data analysis.
