Asteroid Impact & Deflection Assessment mission
AIM is proposed as ESA's contribution to a larger international endeavour, the Asteroid Impact & Deflection Assessment (AIDA) mission.
A close-Earth encounter of the binary asteroid 65803 Didymos (1996 GT) in October 2022 provides the optimal target for such a mission, allowing an impact on Didymos' secondary body to change its orbital period around the primary by a measureable amount – as seen both from ground observatories and from a rendezvous spacecraft.
As part of AIDA, two independent spacecraft would be sent to Didymos:
- An asteroid impactor - the NASA Double Asteroid Redirection Test (DART) Mission led by the John Hopkins’ Applied Physics Laboratory in the United States
- An asteroid rendezvous spacecraft - the ESA Asteroid Impact Mission (AIM).
The two missions' schedules would be synchronised. Despite the joint coordination, both spacecraft would still be able to pursue their missions fully independently. Therefore if for some reason one of the spacecraft cannot contribute to the joint campaign, the other would still be able to achieve its individual mission goals.
AIM itself is foreseen for launch in October 2020. In late 2022, the NASA-led part of AIDA would arrive: the Double Asteroid Redirection Test, or DART, probe will approach the binary system – then crash straight into the asteroid moon at about 6 km/s.
AIM will observe closely as DART hits Didymoon. In the aftermath, it will perform detailed before-and-after comparisons on the structure of the body itself, as well as its orbit, to characterise DART’s kinetic impact and the consequences.
The results will allow laboratory impact models to be calibrated on a large-scale basis, to fully understand how an asteroid would react to this kind of energy. This will shed light on the role the ejecta plume plays in deflecting the asteroid's trajectory; this is a fundamental part of the energy transfer dynamics and has been under scientific debate for over a decade.
In addition, DART’s shifting of Didymoon’s orbit would mark the first time humanity has altered the dynamics of a Solar System body in a measurable way.
The results should provide a baseline for planning any future planetary defence strategies, offering insight into the kind of force needed to shift the orbit of any incoming asteroid, and better understand how the technique could be applied if a real threat were to occur.
AIM and DART are self-standing; each mission on its own will provide valuable knowledge. However, when combined together this knowledge will be multiplied considerably.
AIDA would return fundamental new information on the mechanical response and impact cratering process at the scale of a real asteroid, and consequently on the collisional evolution of asteroids with implications for planetary defence, human spaceflight, and near-Earth object science and resource utilization.
The joint mission should also gather unique information on an asteroid's strength, surface physical properties and internal structure. In addition to the operations in space, Earth-based optical and radar observations, numerical simulation studies and laboratory experiments would be an integral part of the AIDA mission.
AIDA is a joint collaboration between ESA, the German Aerospace Center (DLR), Observatoire de la Côte d´Azur (OCA), NASA, and the John Hopkins University Applied Physics Laboratory (JHU/APL).