The DART experiment revealed an effective method for protecting Earth from asteroids.

The test bombardment of the asteroid Dimorphos provided crucial information about the potential consequences of striking a space object that poses a threat to Earth. Researchers discovered that the degree of curvature on its surface plays a significant role. This insight has enabled them to calculate the most effective methods for diverting a massive asteroid on a collision course with our planet.

2025-02-25 10:01:58https://naked-science.ru/article/astronomy/dart-podskazal-kak-sbit-a

The binary asteroid system Didymos-Dimorphos poses no threat to Earth: nearly three decades of observations since its discovery show that this pair has never approached Earth closer than just over seven million kilometers. This distance is more than 18 times farther than the Moon. However, formally, anything that comes within seven and a half million kilometers and has sizes ranging from 100 to 150 meters is considered potentially hazardous.

The diameters of Didymos and Dimorphos are approximately 800 and 170 meters, respectively. These asteroids orbit the Sun. At their closest point in their orbit (perihelion), they nearly reach the orbit of Venus, while at their farthest (aphelion), they are much farther than Mars.

NASA selected this system for a recent experiment due to its favorable ballistic parameters: the orbit's characteristics are such that the spacecraft launched towards them does not require much "effort" to achieve a trajectory that brings it close.

The DART (Double Asteroid Redirection Test) experiment successfully took place on September 26, 2022. The smaller object, Dimorphos, was chosen as the target: a collision with a 600-kilogram probe would have more significant consequences for it.

The test results were even "better" than the developers had anticipated: they primarily relied on the force of impact, but additionally gained substantial reactive thrust from the material ejected from the surface. Furthermore, the asteroid even deformed and changed its overall appearance: it turned out to be a "rubble pile" (similar to Ryugu and Bennu), meaning it is not a monolithic body but a collection of smaller rocks, and the bombardment shook this entire pile.

Recently, an international team of astronomers shared new observations of the debris cloud formed by the impact. In an article for the journal Nature Communications, they explained that the appearance and direction of the debris cloud's spread are largely influenced by the curvature of Dimorphos's surface, but most importantly, the asteroid's shape affects the impact effectiveness: the more curved the surface of the celestial body, the less it "suffers."

For comparison, the researchers modeled the result of the same impact against an imaginary "flat wall" instead of the rounded asteroid. It turned out that the curvature of Dimorphos's surface reduced the momentum transfer by 44 percent, effectively weakening it by almost half.

This led scientists to a conclusion that could be beneficial in the event of a dangerous asteroid threatening humanity in the future: it seems that launching a single impactor, even a very heavy one, would be "inefficient." According to calculations, it would be much more effective to attack the mass with several small spacecraft that could strike either simultaneously or one after another at different points on the surface. Together, they could deliver an impact of similar strength to that of one massive "impactor," but achieve far greater results.