On Mars, craters abound, testifying to a tumultuous past and a unique geological environment. Compared to Earth, their presence is much more pronounced due to the lack of erosion forces and less active plate tectonics. However, not all of these craters are the direct result of asteroid impacts. A recent study, presented at the 55th Annual Lunar and Planetary Science Conference in Texas, revealed fascinating details about one crater in particular, named Corinto, located in the Elysium Planitia region, north of the equator of March.
An extended “ray system”
Corinto is a relatively young crater with an estimated age of 2.34 million years. Its imposing size, with a diameter of approximately fourteen kilometers and a depth of one kilometer, makes it one of the youngest craters of this size on Mars. However, what makes Corinto particularly intriguing is its extensive “ray system” that results from ejecta thrown up during the initial impact.
Concretely, when an impact occurs on a planet like Mars, the energy released by the asteroid or meteoroid creates a crater by digging into the surface and projects materials in all directions. These materials, called ejecta, are often launched at extremely high speeds. When they fall back onto the surface, they form what are called rays, which are trails of debris scattered around the central point of impact.
In Corinto’s case, its extensive ray system indicates that the initial impact generated a significant amount of ejecta that spread across large areas of the Martian surface. Furthermore, it was found that most of the ejecta moved south, particularly towards the southwest of the crater. This suggests that the celestial object’s impact angle was oblique enough to push most of the debris in that specific direction.
This observation is important because it allows scientists to reconstruct the initial impact. By studying the spatial distribution of ejecta and determining their predominant direction, researchers can also better understand the characteristics of the impactor and the resulting geological effects on the surface of Mars.
Two billion secondary craters
In recent work, researchers have looked into the impact of Corinto and its consequences on the Martian environment. Data collected by the Mars Reconnaissance Orbiter (MRO), notably thanks to the High Resolution Imaging Science Experiment (HiRISE) and the Context Camera (CTX), were used to analyze the characteristics of the numerous surrounding craters.
Using this data, the researchers analyzed the characteristics of small craters located near the main Corinto crater and sought to differentiate those caused by ejecta from those caused by other factors, such as individual asteroid impacts. . These observations ultimately made it possible to estimate that approximately two billion secondary craters more than ten meters in diameter are from Corinto ejecta. They also extend up to 1850 kilometers away.
Analysis of different types of ejecta craters also revealed five distinct “facies”each with specific characteristics that set them apart from others in shape, size and appearance.
Credits: Golombek et al.
This discovery raises important questions about Mars’ geological processes and their broader understanding. If a single impact can generate such a quantity of secondary craters over such a large distance, this indeed calls into question our existing models of crater formation and Martian geological dynamics. However, further research is needed to fully understand the implications of this finding.
