The results of the NASA mission to collide a probe with the asteroid Dimorphos turned out to be much larger in scale than originally assumed. It was revealed that the directed impact changed not only the orbit of the satellite but also the trajectory of the entire binary system around the Sun. This event became the first case in history where a human-made object was able to consciously correct the flight of a celestial body on a solar system scale. In conditions of real danger, those “tiny fractions” recorded by instruments could become the decisive factor between a global catastrophe and a successful outcome.
The DART Experiment: Billiards in deep space
In September 2022, as part of the DART mission, NASA sent a spacecraft on a direct collision course with Dimorphos. The goal of this daring experiment was to test the “kinetic impactor” strategy. Scientists wanted to understand: is it physically possible to deflect a massive asteroid if it were ever headed toward Earth? The impact was successful, moving Dimorphos into a new, shorter orbit around its larger neighbor—the asteroid Didymos.
However, a surprise awaited the researchers. The collision generated a giant plume of dust and rock fragments that stretched in space for thousands of kilometers. This ejection of matter acted like an improvised jet engine, creating additional recoil. It is reported in the scientific journal Science Advances that the impulse was so strong that it affected the movement of the entire pair of asteroids along their common path around the sun.
The magic of a fraction of a second: Why it matters
To confirm this effect, a research group led by Rahil Makadia from the University of Illinois analyzed 22 archival images capturing the passage of Didymos against the background of distant stars. Meticulous calculations showed that the orbital velocity of the binary system changed by 11.7 micrometers per second.
At first glance, the figures seem negligible: the system’s orbital period around the Sun, which lasts 770 days, was reduced by only 0.15 seconds. However, on a cosmic scale and over time, this is a colossal achievement. As Makadia notes, even such a microscopic course change, made years before a potential collision, could result in a dangerous object flying past our planet at a safe distance of tens of thousands of kilometers.
Tens of thousands of “invisible” threats
Asteroids are a harsh legacy from the time of our planetary system’s formation. These rocky lumps are often very difficult to spot due to their small size and dark surfaces. Nevertheless, even an object with a diameter of a few dozen meters is capable of wiping an entire metropolis off the face of the earth upon collision with Earth. According to the European Space Agency (ESA), about 36,000 asteroids whose orbits dangerously approach Earth’s are currently under observation. And this list is regularly updated with new names.A fresh example of such alarm was the asteroid 2024 YR4, discovered in December 2024. Its diameter was estimated at 40–90 meters, and at the beginning of last year, astronomers seriously discussed the risk of its collision with Earth in 2032—the probability was estimated at nearly three percent. Fortunately, additional measurements allowed the threat to be ruled out, but this case once again highlighted the relevance of planetary defense technologies. The success of the NASA mission proves: Earth is developing a real “shield” capable of correcting the movement of cosmic wanderers in deep space.
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