The asteroid demorphs into a loose pile of rubble. This new discovery by researchers in Bern explains that the asteroid's orbit was altered more than expected by a deliberate collision with a probe from the US space agency NASA.

“An asteroid like this is the best possible scenario for diversionary efforts,” said astrophysicist Sabina Radukan of the University of Bern on Monday.

With the “DART” mission, NASA wanted to divert the asteroid demorphose from its orbit. To do this, in September 2022, he let a probe hit the asteroid at high speed. NASA's goal is to shorten Dimorphos' orbit to ten minutes. This target was clearly exceeded: the reduction was 33 minutes.

An international research team led by the University of Bern has now simulated the impact using computer models. This simulation matches the post-impact observations better, suggesting that the asteroid is a pile of debris loosely bound together by gravity. The results were published Monday in the journal Nature Astronomy.

“A harder block of rock is less likely to be deflected by impact,” Radukan explained. This is because if the rocky mass had been there, less material would have been ejected by the asteroid impact. This ejected matter plays a greater role in orbital deflection than impact.

The “DART” mission was the first maneuver in space to test defenses against an Earth-threatening asteroid. NASA hopes the $330 million asteroid defense mission will provide insights into how to protect Earth without approaching celestial bodies. However, Dimorphos is not a threat to humanity.