Three years ago, a space mission marked history by modifying the trajectory of an asteroid. This experience opened the way to new methods to protect the earth from dangerous celestial bodies.
The images captured by the Licicube satellite revealed ejected debris with surprising energy. These observations Question the physical models used to predict the behavior of asteroids after an impact.
Credit: NASA DART Team and LICIACube
The DART mission has not only shortened the orbit of Dimorphos around Didymos, but also changed its shape. These results were considered to be proof of concept for the impact method kinetic. However, the study of debris shows that the big fragments move with more speed than expected. The ejected fragments could even represent a risk for March in several millennia. Their disposition in distinct groups shows even poorly understood physical phenomena.
Scientists attribute this to an additional pulse ‘received during their ejection. This additional energy could come from the release of gas trapped in the asteroid. Another hypothesis evokes resonance effects during fragmentation.
Debris arrangement remains a mystery. It could be linked to variations in the composition or internal structure of Dimorphos.
The latest Dart images before the impact with Dimorphos.
Crédit: John Hopkins University Applied Physics Laboratory
What is the kinetic impact method?
The kinetic impact method is to send a spacecraft hitting an asteroid to modify its trajectory. This technique is based on the transfer of movement quantity during the collision.
The effectiveness of this method depends on several factors, including the mass and speed of the impactor. The latest observations show that other parameters, such as the structure of the asteroid, play a crucial role.
Future missions will have to take these variables into account to optimize the impacts. Current simulations do not yet capture all the complexity of the phenomena in play.