The Asteroid Impact & Deflection Assessment (AIDA) mission, a joint ESA-NASA cooperative project, will be the first space experiment to investigate a binary near-Earth asteroid and to demonstrate asteroid impact hazard mitigation by using a kinetic impactor.

A pair of spacecraft – ESA’s Asteroid Impact Mission (AIM) and NASA’s Double Asteroid Redirection Test (DART) – will rendezvous with the binary near-Earth asteroid (65803) Didymos.

AIM is due for launch in October 2020 and rendezvous with the Didymos asteroid and its small natural satellite, dubbed Didymoon, in May 2022.

This binary system is a so-called Apollo asteroid. It was discovered on April 11, 1996 by Joe Montani at Spacewatch at the Kitt Peak National Observatory in Arizona.

Egg-shaped Didymoon (160 m in diameter) orbits the diamond-shaped Didymos asteroid (750 m in diameter) every 12 hours at an altitude of 1,100 m.

Ground-based observations show that Didymos is probably a common chondrite, or stony asteroid formed of dust from the primitive Solar System.

“To protect Earth from potentially hazardous impacts, we need to understand asteroids much better – what they are made of, their structure, origins and how they respond to collisions,” said Dr Patrick Michel, a scientist at the University of Nice in France and the lead of the AIM Investigation Team.

“AIDA will be the first mission to study an asteroid binary system, as well as the first to test whether we can deflect an asteroid through an impact with a spacecraft.”

“The European part of the mission, AIM, will study the structure of Didymoon and the orbit and rotation of the binary system, providing clues to its origin and evolution.”

AIM will measure Didymoon’s mass shape, density and dynamic properties and map the asteroid’s surface at visible and infrared wavelengths, as well as using radar to probe beneath the surface.

It will deploy a small lander, MASCOT-2, in order to transmit and receive radio signals through Didymoon to investigate the internal structure.

In October 2022, AIM will move to a safe distance to observe DART’s impact with Didymoon and analyze the plume of material ejected.

It will then resume its mapping and monitoring mission to study internal material revealed in the crater and any changes to Didymoon’s orbit.

The combination of AIM and DART will give new insights into the relationship between an asteroid’s surface and its interior, and new understanding of how asteroids and binary systems form.

AIM will also deploy three cubesat to assist with observations and to test new science and technology capabilities, including intersatellite communications links in deep space.

The AIDA mission was discussed last week at the European Planetary Science Congress 2015 in Nantes, France.

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P. Michel et al. 2015. Asteroid Impact and Deflection Assessment (AIDA) mission: science investigation of a binary system and mitigation test. EPSC Abstracts, vol. 10, EPSC2015-123

P. Michel et al. 2015. AIDA: Asteroid Deflection and Assessment Study Mission under study at ESA and NASA. EPSC 2015