The employees of the Lucy mission have published the results of a scientific study on the asteroid Donaldjohanson. They were able to determine its approximate age and origin.
The Lucy mission was launched in 2021. Its main task is to study Jupiter’s Trojan asteroids. The spacecraft will also visit several points of interest on the way to its target. The first was the small asteroid Dinkinesh, whose flyby took place on November 1, 2023. It was revealed to have a tiny companion, which was named Selam.
The next flyby of the companion object will take place on April 20, 2025. Lucy will pass at a distance of 960 km from asteroid Donaldjohanson. While the upcoming encounter is primarily a dress rehearsal before the mission’s main science program begins, a new study suggests that this small asteroid may hold a few surprises.
Based on ground-based observations, Donaldjohanson appears to be an unusual object. Its diameter is approximately 4 kilometers. The asteroid is composed of silicate rocks and probably contains clay and organic matter. The data indicates that it is a rather elongated slowly rotating object. This may be due to thermal torques that have slowed its rotation over time.
The study found that Donaldjohanson is likely a member of the Erigone family, a group of asteroids in similar orbits formed when a larger parent asteroid split apart in the inner part of the Main Belt. Astronomers estimate that this occurred about 150 million years ago at the junction of the Jurassic and Cretaceous periods.
The site of the Erigone family formation is near the regions of origin of the near-Earth asteroids Bennu and Ryugu, which were recently visited by the OSIRIS-REx and Hayabusa-2 missions. Therefore, astronomers are looking forward to Lucy’s upcoming visit. Although Donaldjohanson’s currently known characteristics are very different from those of Bennu and Ryugu, unexpected connections can be found between them.
According to NASA
