Hera begins the close audit of humanity's first asteroid deflection

ESA's Hera has reached the Didymos-Dimorphos binary asteroids about 196.8 million kilometres from Earth and begun close inspection. In 2022 the 580-kilogram DART spacecraft hit the roughly 151-metre Dimorphos at about 6.1 kilometres per second, shortening its orbit around the roughly 780-metre Didymos by about 33 minutes, more than forecast. The collision is estimated to have ejected about 16 million kilograms of material, adding momentum through the debris. Hera will measure Dimorphos's mass, internal structure, shape and crater and deploy two CubeSats. First detailed images are planned for November 25; only then can one successful experiment become a predictable, repeatable defence method.