Hera distinguishes its two asteroid targets for the first time

ESA’s Hera spacecraft has resolved Didymos and its smaller companion, Dimorphos, as separate objects for the first time after braking maneuvers slowed its approach. Dimorphos occupies only about one pixel in this image; ESA says the first detailed images will arrive on November 25. [7] Why it matters: Dimorphos is the first Solar System object whose orbit was measurably shifted by human action, but scientists still need its mass, structure and impact damage to explain the deflection and make kinetic impact a better-understood planetary-defense technique. [7] Key insights: Two thruster firings reduced Hera’s speed relative to the asteroids to 20 meters per second, enabling a controlled approach rather than a rapid flyby. [7] | The targets differ substantially in size: Dimorphos measures 151 meters across, compared with 780 meters for Didymos. [7] | The impact produced a greater deflection than simulations predicted; determining whether it excavated a crater or reshaped Dimorphos is part of explaining that difference. [7] Cheatsheet facts: What happened: Hera separated the previously unresolved asteroid pair in an image taken from 1,280 kilometers away. [7] | Why: The mission will investigate the properties and impact damage that explain Dimorphos’s altered orbit. [7] | The catch: Dimorphos is only about one pixel across in this first image, so its surface remains unresolved. [7] | What's next: ESA identifies November 25 as the date for the first detailed images of Dimorphos. [7]