Après le lancement réussi de la mission Hera et les premières images de la Terre et de la Lune fournies par les caméras de la sonde, qui fonctionne magnifiquement et se trouve déjà dans l'espace lointain, avec plusieurs charges utiles déjà opérationnelles, le directeur général de l'ESA s'est lui-même félicité du développement de Hera en un temps record, alors qu'il se trouvait à l'IAC 2024 à Milan. En effet, ce projet de 4 ans, pour un budget inférieur à celui demandé, était une « première ». Le Principal Investigateur de Hera, Patrick Michel, espère que la structure que nous avons utilisée pour le projet Hera, une équipe intégrée mélangeant l'équipe scientifique avec le P.I., l'équipe de projet de l'ESA, et les industries, inspirera le programme scientifique car le lancement de Hera vient en effet d’en démontrer son efficacité ! Alors que le voyage cosmique de Hera commence, nous nous engageons à impliquer tous les passionnés de ces aventures spatiales, d’apporter des surprises, des découvertes, en particulier aux plus jeunes, pour les former et en faire les prochains acteurs et responsables de l'exploration spatiale.

Plus d'informations ici : https://www.esa.int/Space_Safety/Hera/Planetary_defence_mission_Hera_heading_for_deflected_asteroid

After the successful launch of the Hera mission and the first images of the Earth and the Moon provided by the cameras of the probe, which is working magnificently and already in deep space, with several payloads already work-proof, the Director General of ESA himself welcomed the development of Hera in record time, while at the IAC 2024 in Milan. Indeed, this 4 years project, for a budget lower than requested, was a “first”. The Hera Principal investigator, Patrick Michel, hopes that the structure we used for the Hera project, an integrated team mixing scientific team with PI, ESA project team, and industries, will inspire the scientific program as the launch of Hera has indeed just demonstrated its effectiveness! While Hera’s cosmic trip begins, we are committed to involve all people passionate about these space adventures, their surprises, their discoveries, and particularly the youngest, to train them and make them the next actors and leaders of space exploration.

More here: https://www.esa.int/Space_Safety/Hera/Planetary_defence_mission_Hera_heading_for_deflected_asteroid

La mission de défense planétaire Hera, de l'ESA, achève ses essais de pré-lancement et vise l'astéroïde Didymos et sa lune Dimorphos, de véritables mondes à l'échelle miniature (cf. la photographie, avec crédits NASA / Johns Hopkins University APL).

Dans un numéro spécial de Nature Communications daté du 31 juillet 2024 ont été publié 5 articles présentant des études de cet astéroïde binaire. Ces travaux, auxquels ont participé les membres de l'équipe scientifique de la mission Hera, sont fondés sur les quelque cinq minutes et demie d'images rapprochées renvoyées par le vaisseau spatial DART de la NASA avant qu'il ne percute volontairement Dimorphos, ainsi que sur les images post-impact du microsatellite LiciaCube de l'agence spatiale italienne.

Pour en savoir plus, suivez ce lien (en anglais) vers le site webb de l'ESA:

https://www.esa.int/Space_Safety/Hera/Glimpses_of_Hera_s_target_asteroids_inspire_new_science

The Double Asteroid Redirection Test (DART, NASA) spacecraft revealed that the primary of the (65803) Didymos near-Earth asteroid (NEA) binary system is not exactly the expected spinning top shape observed for other km-size asteroids. Ground based radar observations predicted that such shape was compatible with the uncertainty along the direction of the asteroid spin axis. Indeed, Didymos shows crater and landslide features, and evidence for boulder motion at low equatorial latitudes. Altogether, the primary seems to have undergone sudden structural failure in its recent history, which may even result in the formation of the secondary. The high eccentricity of Didymos sets its aphelion distance inside the inner main belt, where it spends more than 1/3 of its orbital period and it may undergo many more collisions than in the NEA region. In this work, we investigate the collisional environment of this asteroid and estimate the probability of collision with multi-size potential impactors. We analyze the possibility that such impacts produced the surface features observed on Didymos by comparing collisional intervals with estimated times for surface destabilization by the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect. We find that collisional effects dominate over potential local or global deformation due to YORP spin up.

https://www.nature.com/articles/s41467-024-48094-7

On 26 September 2022, NASA’s Double Asteroid Redirection Test (DART) mission successfully impacted Dimorphos, the natural satellite of the binary near-Earth asteroid (65803) Didymos. Numerical simulations of the impact provide a means to find the surface material properties and structures of the target that are consistent with the observed momentum deflection efficiency, ejecta cone geometry and ejected mass. Our simulation that best matches the observations indicates that Dimorphos is weak, with a cohesive strength of less than a few pascals, like asteroids (162173) Ryugu and (101955) Bennu. We find that the bulk density of Dimorphos is lower than ~2,400 kg m−3 and that it has a low volume fraction of boulders (≲40 vol%) on the surface and in the shallow subsurface, which are consistent with data measured by the DART experiment. These findings suggest that Dimorphos is a rubble pile that might have formed through rotational mass shedding and reaccumulation from Didymos. Our simulations indicate that the DART impact caused global deformation and resurfacing of Dimorphos. ESA’s upcoming Hera mission may find a reshaped asteroid rather than a well-defined crater.

https://www.nature.com/articles/s41550-024-02200-3