Can we deflect a city-killing asteroid? The Hera mission is finding out.

The European Space Agency’s Hera mission revisits the Dimorphos asteroid to investigate the aftermath of NASA’s DART collision. By analyzing the crater and structural integrity of this binary system, Hera aims to transform a one-off planetary defense experiment into a reliable, repeatable strategy for protecting Earth from future impacts.

On 26 September 2022, NASA’s DART spacecraft struck the Dimorphos asteroid at 6.1 km/s, successfully altering its orbit around the larger Didymos. While this proved that kinetic impact can deflect an asteroid, scientists still lack critical data regarding the target's mass, composition, and whether the impact caused it to fracture. Hera will conduct the first detailed survey of a binary asteroid system, which represents 15% of all known asteroids.

The mission serves as a testbed for advanced space technology, including the deployment of shoebox-sized CubeSats and a vision-based navigation system for autonomous flight. By turning Dimorphos into the most studied asteroid in history, Hera provides the essential knowledge required to defend against bodies capable of destroying entire cities, a capability that distinguishes modern humanity from the dinosaurs.

Source: Solving asteroid mysteries | Hera planetary defence mission