Why will Hera Explore an Asteroid that was Previously Impacted by DART?

Hera is an ESA mission that will build upon the work initiated by DART, a NASA mission that successfully impacted Dimorphos, the moonlet of the double asteroid Didymos, on Sept. 27th, 2022.

Learning Objective: 

Learn the reasons for the Hera mission which aims to explore an asteroid that has already been impacted and possibly modified by another probe, DART.


Overview:

The Hera Mission is the first ESA Space Safety mission and will build upon the efforts initiated by NASA’s DART mission, which impacted Dimorphos, the moonlet of the double asteroid (65803) Didymos, in 2022, as part of the first real scale planetary defense test.

Specifics:

Both DART and Hera are part of AIDA, an international space cooperation of scientists supporting the development and data interpretation of the NASA DART and ESA Hera missions. This initiative, named in full the Asteroid Impact and Deflection Assessment, aims to demonstrate the kinetic effects of a spacecraft impacting a small asteroid and assessing its efficiency.

The initial plan for this collaboration involved the Asteroid Impact Mission (AIM), developed by ESA, which was intended to arrive first, to observe and analyse the initial properties of the double asteroid and, thereafter, the effects of the impact of the NASA’s Double Asteroid Redirection Test (DART) impactor on the moon Dimorphos. However, AIM full funding was not approved by ESA delegations in 2016 and was eventually approved in 2019 under the new name Hera, which serves a similar purpose to the original design but as a result of the approval delay arriving after the impact.

In September 2022, the DART probe successfully impacted Dimorphos, the small moon of asteroid Didymos. Hera is scheduled to launch in October 2024, with an arrival at the asteroid system in fall 2026.

The Didymos-Dimorphos system shortly before the DART impact in September 2022 (NASA/Johns Hopkins APL)

Preliminary results – shortly before the impact, the images transmitted in 2022 by the DRACO camera onboard the DART probe and the accompanying Italian cubesat LiciaCube, as well as observations by ground-based and space-based telescopes, facilitated several discoveries and led to numerous studies in subsequent years.

These findings include significant data regarding the topography and geology of the asteroids, evidence suggesting that Dimorphos may originated from Didymos at some point, discrepancies in the ages of these two bodies, and the similarities in their characteristics to other asteroids such as (162173) Ryugu and (101955) Bennu.

This data has been incorporated into the post-impact results, which resulted in a reduction of Dimorphos’ orbital period around Didymos, which was initially 11h55mn, by 33 minutes. The ejecta generated by the impact produced a debris tail that was detectable by both the Hubble Space Telescope and ground-based telescopes.

Notably using all its instruments, among them and for the first time a radar that will perform the first internal structure measurements of the asteroid, the Hera spacecraft and its two cubesats (named Juventas and Milani) will provide during their close operations a great amount of data and therefore much more detailed documentation of Didymos, Dimorphos, and DART impact outcome, facilitating a more effective assessment of all the stages involved in the kinetic impact technique and its potential applications in various scenarios for the defence of planet Earth.

Hera mission timeline (European Space Agency)

Learn more about this subject by visiting these websites: 

Hera Mission

Space Safety – Hera Mission

Hera’s navigation around the asteroids – VIDEO (ESA)

LEARN – How could we deflect an asteroid?

LEARN – How can we characterize asteroids?

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