The kinetic energy of the dart impact changed Dimorphos rotation speed by less than 1%.
What do we see in today’s NASA image?
On September 26, 2022, in the first test mission to defend the planet, the Dart spacecraft (DART) captured this close-up view three seconds before impact with the surface of Dimorphos, the small moon of asteroid Didymus 65803. The general shape of the spaceship with its two long solar panels is drawn at the intended collision point between two boulders. The larger boulder is about 6.5 meters wide.
The approximate mass of Dimorphos (the smaller member of the near-Earth binary asteroid system) was about 5 billion kilograms, while the Dart spacecraft (Double Asteroid Redirection Test) had a mass of about 570 kilograms. The kinetic energy of the spacecraft’s impact reduced Dimorphos’ rotation speed by less than 1% and its 12-hour period around its companion asteroid to 33 minutes.
In addition to successfully changing the asteroid’s orbit, this planetary-scale collision gave the 150-meter Dimorphos a comet-like tail.
