The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
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Hera is an ESA mission that will be humankind’s first probe to rendezvous with a binary asteroid system, Didymos.
Didymos is a binary asteroid; the primary body has a diameter of around 780 m, whereas the Dimorphos secondary body has a diameter of around 160 m and rotates around the main asteroid at a distance of around 1.2 km.
Dimorphos was impacted by the NASA DART spacecraft on 26 September 2022, shifting its orbit around its parent. Returning to Dimorphos, Hera will perform a close-up survey of the asteroid moon to measure its mass, makeup and structure.
Hera will map Dimorphos’s entire surface down to a resolution of a few metres, and the surface surrounding the DART crater down to >10 cm resolution, through a series of daring flybys. It will also map much of the surface of the primary Didymos asteroid, providing crucial scientific data from two asteroids in a single mission.
A full picture of DART's kinetic impact and resulting momentum transfer will only become possible once Hera maps the mass of Dimorphos to a high level of certainty, turning DART's grand-scale experiment into a well understood and potentially repeatable planetary defence technique.