NASA's Lucy spacecraft made a groundbreaking discovery during its flyby of the asteroid Dinkinesh in November 2023, revealing a pair of fused moons named Selam.

This unique contact binary system challenges existing asteroid formation models and suggests that small asteroids in the main belt may be more complex than previously thought.

Selam consists of two lobes of similar size, indicating a tidal lock with Dinkinesh, and the system's complex history likely involves the YORP effect and the recombination of surface material.

Despite not being the initial target of Lucy's mission, Selam's unique features, such as its spinning top-like shape and prominent equatorial ridge, were observed.

Selam orbits Dinkinesh at a distance of 3.1 kilometers, completing a rotation every fifty-two hours, while Dinkinesh rotates much faster, possibly due to the YORP effect.

Comparative studies with other systems like the Didymos binary system are planned to further investigate these processes.

Lucy’s mission aims to explore a total of 11 asteroids to better understand the formation of celestial bodies and how planets are made.