Hera approaches Dimorphos

ESA's Hera mission for planetary defence seen approaching the boulder-strewn Dimorphos asteroid. On 26 September 2022 NASA’s approximately half-tonne DART spacecraft impacted the boulder covered Dimorphos asteroid at a speed of 6.1 km/s. This first experiment in the kinetic impact method of asteroid deflection was successful: observations from Earth show the 11 hour 55 minute orbit of Dimorphos around its parent asteroid Didymos was shortened by around 33 minutes (measured to an uncertainty level of plus or minus a minute). Hera, due to arrive in the Didymos binary asteroid system at the end of 2026, will gather close-up data including ascertaining the mass and makeup of Dimorphos to help turn this grand-scale experiment into a well-understood and potentially repeatable planetary defence technique.