ESA's Hera Will View Asteroid Scars from DART's Strike

The European Space Agency’s Hera spacecraft is scheduled to rendezvous next month with the Didymos-Dimorphos binary asteroid system, moving at 12 kilometers per second relative to Earth. Hera will inspect Dimorphos after NASA’s Double Asteroid Redirection Test struck the 151-meter moonlet at 6.6 km/s in 2022. DART shortened Dimorphos’s original 11-hour, 55-minute orbit around the 780-meter-wide Didymos by about 32 minutes and produced a debris stream observed in the following weeks. Hera’s arrival observations are expected to provide the first close-up images of Dimorphos since the impact. Hera launched aboard a SpaceX Falcon 9 from Cape Canaveral on 7 October 2024 and took just over two years to reach the asteroid pair, which lies 1.5 astronomical units from the Sun. Didymos, discovered in 1996, rotates once every 2.2 hours and completes an orbit around the Sun every 2.1 years. Hera will deploy the CubeSats Milani and Juventas after rendezvous: Milani will analyze dust and spectral composition, while Juventas will compare the asteroids’ internal structures and may approach or rest on Dimorphos. After its nominal mission ends in 2027, Hera could be extended to test autonomous spacecraft-control techniques.