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Mars has many craters. Now it has two new ones, excavated by rocks that crashed into the planet late last year.
Mars will be fine. This is not a natural disaster. Not a sign that Earth is in recent danger from asteroids. The solar system is full of debris. Mars has a thin atmosphere, and when a meteoroid comes flying in from space, it’s unlikely to burn up before hitting the surface.
But what has surprised scientists, so much so that NASA scheduled a press conference Thursday to highlight the discovery, detailed in two papers published in the journal Science, is that the impacts of cratering were documented by two NASA spacecraft, an orbiter and a lander. . This was an ingenious demonstration of the combination of scientific resources, one providing an eye on impact events while the other provides an ear.
The result is an unusual set of data about the Martian interior, a topic of great interest to planetary scientists who want to understand why this rocky world that was probably warmer and wetter 4 billion years ago turned into a desert cold with no obvious signs of life.
And this was also an event for the record books: the largest cratering impact on one of the solar system’s rocky inner planets ever documented in real time, according to Philippe Lognonné, lead author of one of the newly published papers .
The largest of the new craters is about 150 meters wide and about 21 meters deep, and formed so violently that it threw rocks 40 kilometers (nearly 25 miles) from the impact, according to Liliya Posiolova, a scientist senior at Malin Space Science Systems. , which operates two cameras on NASA’s Mars Reconnaissance Orbiter.
The orbit often sees the results of small impacts, leaving a feature at most a few meters in diameter. But what scientists on Posiolova’s team saw in February was by far the largest crater detected by the orbiter. In fact, it was so big that he almost passed out.
“It’s a huge, huge feature. You’re trained to see small features. With your eyes, you’re looking for specks,” Posiolova said.
The crater was spotted on February 11, but scientists knew they had other images of the Martian surface taken daily and went back in time looking for when the crater first appeared.
Posiolova recalled that another spacecraft on Mars, NASA’s InSight lander, which has been stationed on the surface for four years to monitor seismic activity, had detected a large tremor on Christmas Eve. Suddenly, everything aligned. The first appearance of the crater in images taken from the orbiter coincided with the seismic signal recorded by the instrument on the surface.
The seismic data could then be analyzed in the context of distance to impact. This has helped refine existing models of Mars’ interior, Lognonné said.
The larger of the two craters was likely caused by an object between five and 12 meters in diameter, Posiolova said. Such an object would likely burn up in Earth’s atmosphere if it reached our planet, he said.
The origin of the meteoroids is unknown, but they likely came from the asteroid belt between Mars and Jupiter, he said.
“These impacts are very large, but we can continue to sleep well on Earth,” Lognonné said. “Our atmosphere protects us.”