EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

The ESA Hera mission to the binary asteroid (65803) Didymos:Planetary Defense and Science

Michael Küppers1, Patrick Michel2, Stephan Ulamec3, Alan Fitzsimmons4, Simon Green5, Monica Lazzarin6, Ian Carnelli7, Paolo Martino7, and the The Hera Science Team*
Michael Küppers et al.
  • 1European Space Astronomy Centre, Science Operations Department, Villanueva de la Cañada, Spain (
  • 2Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Nice, France
  • 3DLR RB-MUSC, Linder Höhe 1, 51147 Cologne, Germany
  • 4Astrophysics Research Centre, Queen's University Belfast, Belfast BT7 1NN, Northern Ireland
  • 5School of Physical Sciences, The Open University, Robert Hooke Building, Walton Hall, Milton Keynes MK7 6AA, UK
  • 6Department of Physics and Astronomy, Padova University, Vicolo dell'Osservatorio 3, 35122 Padova, Italy
  • 7ESA-ESTEC, Keplerlaan 1, Noordwijk 2200 AG, The Netherlands
  • *A full list of authors appears at the end of the abstract

The impact of the NASA DART spacecraft on the 160 m-diameter natural satellite called Dimorphos
of the binary asteroid 65803 Didymos on 26 September 2022 will change its orbital period around
Didymos. The change can be detected by Earth-based observers. Before impact, DART will deploy the Italian LICIACube that will
provide images of the first instants after impact. ESA’s Hera spacecraft will rendezvous Didymos four
years after the impact.

Hera will characterize in detail the properties of a Near-Earth Asteroid that are most relevant to
planetary defense:
•Measuring the mass of Dimorphos to determine the momentum transfer efficiency from DART
•Investigating in detail the crater produced by DART to improve our understanding of the cratering
process and the mechanisms by which the crater formation drives the momentum transfer
•Observing subtle dynamical effects (e.g. libration imposed by the impact, orbital and spin
excitation of Dimorphos) that are difficult to detect for remote observers.
•Characterising the surface and interior of Dimorphos to allow scaling of the momentum transfer
efficiency to different asteroids.

Hera will also provide unique asteroid science. It will rendezvous for the first
time with a binary asteroid. The secondary has a diameter of only 160 m, the smallest asteroid visited so far. Moreover, for the first time, internal and subsurface properties will be directly measured. From small asteroid internal and surface structures, through
rubble-pile evolution, impact cratering physics, to the long-term effects of space weathering in the
inner Solar System, Hera will have a major impact on many fields. How do binaries form? What is the surface composition of the asteroid pair? What are its internal properties?  What are the surface structure and regolith mobility on both Didymos and Dimorphos?
And what will be the size and the morphology of the crater left by DART? These questions and many others will be addressed by Hera as a natural outcome of its investigations focused on planetary defense.

The Hera Science Team:

Patrick Michel, Adriano Campo Bagatin, Benoît Carry, Sébastien Charnoz, Julia de Leon, Alan Fitzsimmons, Simon F. Green, Alain Hérique, Martin Juzi, Özgür Karatekin, Tomas Kohout, Monica Lazzarin, Naomi Murdoch, Tatsuki Okada, Ernesto Palomba, Petr Pravec, Colin Snodgrass, Paolo Tortora, Kleomenis Tisganis, Stephan Ulamec, Jean-Baptiste Vincent, Kai Wünnemann, Elisabetta Dotto, Nancy Chabot, Andy F. Cheng, Andy Rivkin, Olivier Barnouin, Carolyn Ernst, Angela Stickle, Derek C. Richardson, Cristina Thomas, Masahiko Arakawa, Hirdy Miyamoto, Akiko Nakamura, Seiji Sugita, Makoto Yoshikawa, Paul Abell, Erik Asphaug, Ronald-Louis Ballouz, William F. Bottke Jr., Dante S. Lauretta, Kevin J. Walsh

How to cite: Küppers, M., Michel, P., Ulamec, S., Fitzsimmons, A., Green, S., Lazzarin, M., Carnelli, I., and Martino, P. and the The Hera Science Team: The ESA Hera mission to the binary asteroid (65803) Didymos:Planetary Defense and Science, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6375,, 2022.