In 2024 the Hera mission will revisit the asteroid punched by NASA

The European Space Agency (ESA) is sending a mission to investigate what happened to an asteroid that NASA punched in 2022. The Hera mission, launching in October, will head to asteroid Dimorphos, which NASA hit with its Double Asteroid Redirection Test (DART) mission.

The goal of DART was to check whether smashing a spacecraft into an asteroid would be a good way to defend Earth should an asteroid ever be heading in our direction. We know that the impact shifted Dimorphos’ trajectory around its parent asteroid, Didymos, shortening each orbit by about 33 minutes, but we don’t have details on how exactly that collision affected the asteroid or what happened afterwards.

“We need another spacecraft to go back to the crime scene in order to tell whether the impact left a crater or entirely reshaped the asteroid, because with the current data both scenarios are possible,” says Hera mission head Patrick Michel at the Côte d’Azur Observatory in France. “Hera is a detective that is going to do a complete investigation of the impact.”

The mission consists of one main spacecraft, which will fly as close as 1 kilometre to Dimorphos, and two tiny cube-shaped satellites intended to land on its surface and check it out up close. That investigation will be crucial to simulations of potentially dangerous asteroids and how to deflect them in the future, but it will also provide key scientific insights.

“Collisions play a key role in all the solar system history – we started growing planets by collisions, all the solid surfaces are populated with craters from collisions,” says Michel. “If we are going to build a complete model of the collision history of the solar system, we need to understand how these collisions work.” Hera will help reveal how collisions work in space – and how to make those collisions work for us.