NASA's probe, Lucy, reveals hidden surprise during flyby of asteroid. Asteroid Dinkinesh, located within the main asteroid belt between Mars and Jupiter, was discovered to have a small moon of its own. This diminutive asteroid moon is in an incredibly close orbit, making it indistinguishable from a significant distance.
This discovery implies that there may be a multitude of binary asteroids in the cosmos, far more than we currently recognize. The fact that there are so many binary systems could help us learn more about how celestial bodies in the Solar System form and interact with each other.
"Well, that is clearly wrong. Dinkinesh, and its enigmatic moonlet, differ in some interesting ways from the similarly sized near-Earth asteroids that have been seen by spacecraft like OSIRIS-REx and DART."
Within the Solar System, we are aware of a variety of binary, trinary, and even a solitary quaternary asteroid. However, the precise extent of these clustered celestial bodies remains uncertain. There have even been instances where objects appear to have formed from the fusion of space rocks.
Asteroids do exhibit a propensity to congregate, such as in the main asteroid belt and the swarms of Trojan asteroids sharing Jupiter's orbit. Nevertheless, the frequency at which they closely approach one another, resulting in gravitational binding, remains unclear.
Scientists began to suspect the presence of a moon around Dinkinesh as Lucy approached the asteroid. This idea came from the object's changing brightness, which is a common sign that a second object is entering and leaving the field of view because of the binary's orbital motions, changing the total amount of light reflected from the asteroid.
A representation of NASA's probe, Lucy, in space
Upon reaching proximity, Lucy confirmed these suspicions as it whizzed by at a speed of 16,100 kilometers (10,000 miles) per hour. The spacecraft clearly observed two objects engaged in a closely choreographed orbital dance. Preliminary measurements suggest that the larger rock is approximately 790 meters (2,600 feet) at its widest point, while the smaller one measures a relatively modest 220 meters (720 feet) in size.
"The fact that it is two makes it even more exciting. In some ways, these asteroids look similar to the near-Earth asteroid binary Didymos and Dimorphos that DART saw, but there are some really interesting differences that we will be investigating."
Asteroids, particularly those situated in the orbit of Jupiter, are believed to consist of materials that were present during the early stages of the Solar System, preserving them in a relatively pristine condition.
Lucy's primary mission objective is to investigate these asteroids, providing insights into the formation of the Solar System and the origins of the planets. Over the course of its 12-year mission, Lucy will closely examine two asteroids located in the main asteroid belt and nine Trojan asteroids.
Some planets, especially the rocky inner planets, are thought to have formed by smaller rocks coming together and fusing together. Finding more binary asteroid systems like Dinkinesh could help us learn a lot more about this basic process of how planets form.
The process of extracting the remaining data from Lucy regarding Dinkinesh will require additional time, providing valuable information not only about the asteroid itself but also about the spacecraft's operational performance.
In the meantime, Lucy is en route to its next encounter in the main asteroid belt, the asteroid Donaldjohanson, with a scheduled rendezvous set for 2025.