spaceSpace and Physics

Humanity Is Getting Ready For The First Planetary Defense Test


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockSep 19 2019, 13:01 UTC

Artistic rendering of the double asteroid Didymos. ESA – Science Office

In just a few years, humanity will try to safely change the orbit of an asteroid. The space rock is not dangerous; the test will simply assess if we have sound technology and models to actually deflect an asteroid if the need were to arise.

The mission is part of the international Asteroid Impact and Deflection Assessment (AIDA) collaboration and members of the group recently presented some new ideas regarding AIDA at the European Planetary Science Congress & Division for Planetary Sciences of the American Astronomical Society Joint Meeting in Geneva.


The new insights come from the recent observation of asteroids from the OSIRIS-REx and Hayabusa-2 missions. Hayabusa-2, in particular, shot an impactor at asteroid Ryugu to collect a subsurface sample. The effects of the impact are being studied and this will inform the first mission of AIDA, known as the Double Asteroid Redirection Test (DART).

NASA’s DART will reach double asteroid Didymos in September 2022 and will impact the smaller of the two objects, Didymos B or Didymoon, and see if it can change its trajectory. Modeling what happened on Ryugu might be key to precisely working out what will happen to Didymoon.

“The impact with Hayabusa2 showed that there was no cohesion on the surface and the regolith behaved like pure sand. Gravity was dominating the process, rather than the intrinsic strength of the material from which the asteroid is made,” Dr Patrick Michel who presented the findings said in a statement.

“If gravity is also dominant at Didymos B, even though it is much smaller, we could end up with a much bigger crater than our models and lab-based experiments to date have shown. Ultimately, very little is known about the behaviour of these small bodies during impacts and this could have big consequences for planetary defence.”

Schematic of the DART mission shows the impact on Didymoon. NASA/Johns Hopkins Applied Physics Lab

The DART mission will launch in July 2021 and will be accompanied by LICIACube (Light Italian Cubesat for Imaging Asteroids), a small satellite developed by the Italian Space Agency (ASI), which will be deployed just before impact so it can take images of the event.

The second part of the AIDA mission involves the European Space Agency's Hera spacecraft, which, if approved, will arrive around the Didymos system in 2027 and will produce the most detailed assessment of the DART test.

“DART and Hera will provide valuable knowledge individually," said ESA's Michael Kuppers. "However, when combined together through the AIDA collaboration, the scientific and technical benefits are enhanced considerably. In an even wider context, comparing the physical properties of Didymos to those of Ryugu from JAXA’s Hayabusa2 mission and the Bennu asteroid studies by NASA’s OSIRIS-REx mission will significantly contribute to our understanding of how single and multiple asteroid systems form and evolve.” 

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