Hera, the European Space Agency’s first mission for planetary defence, arrives at its target body during November, with the goal of gathering precious data on the kinetic impact method of asteroid deflection – while also solving various scientific enigmas.
The small-car-sized spacecraft is headed to the 151-m-diameter Dimorphos asteroid, which orbits in turn around its 780-m Didymos parent. Dimorphos is already historic as the first object in the Solar System to have had its orbit changed by human action – when NASA’s DART spacecraft impacted it on 26 September 2022.
DART’s impact caused a brightening visible from distant Earth telescopes, but nobody knows what it did to Dimorphos itself. Hera is going there to perform a close-up crash site survey, to help turn DART’s kinetic impact experiment into a well understood planetary defence deflection technique.
Scientists are hoping for bonus science as well. Past spacecraft close encounters have revealed asteroids to be dynamic environments with complex histories – and many outstanding questions still to be answered. Here are 10 asteroid mysteries that Hera will explore.