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Hera is a European Space Agency (ESA) mission to visit the asteroid Didymos and its moon Dimorphos as part of the NASA/ESA Asteroid Impact and Deflection Assessment (AIDA) collaboration. The initial misson of the collaboration, the NASA Double Asteroid Redirection Test (DART) will have visited the asteroids earlier and impacted Dimorphos with sufficient momentum to effect a measurable change in its orbit. Hera will revisit the system roughly 5 years later for a follow-up assessment, primarily pertaining to planetary defense and evaluation of the kinetic impact deflection. The planetary defense objectives of the Hera mission are to: measure the mass of Dimorphos to determine precisely the momentum transfer efficiency; investigate the crater in detail to improve our understanding of the cratering process in the low-gravity regime and the mechanisms by which the crater formation is related to the momentum transfer efficiency; observe subtle dynamic effects (e.g. libration imposed by the impact, orbital and spin excitation of Dimorphos) that are impossible to detect by groundbased observations; and characterize the surface and interior of Dimorphos to allow scaling of the momentum transfer efficiency to different asteroids. The science objectives include characterizing the binary system, surface structures, regolith mobility and surface geophysics.

Hera is scheduled to launch in October 2024 and arrive at the Didymos system in December 2026 on an Ariane 6. The payload is still under discussion, but will include imaging systems and possibly a laser altimeter. There are also plans to carry two 6U cubesats, Juventas and APEX, for further asteroid studies.

For more information on the initial AIDA mission to Didymos, DART, see:

Alternate Names

  • Asteroid Impact and Deflection Assessment (AIDA)

Facts in Brief

Launch Date: 
Launch Vehicle: 
Launch Site: ,

Funding Agency

  • European Space Agency (International)


  • Planetary Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. Patrick MichelMission Principal
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