Nov. 3, 2023 — New images taken by NASA’s Lucy spacecraft confirm that the main belt minor asteroid Dinkinesh is a binary, two asteroids that orbit a common center of gravity. The SwRI-led mission will now fly past 11 asteroids in its 12-year mission to Jupiter’s Trojan asteroids. Dinkinesh was supposed to be the first asteroid that Lucy flew by, but it ended up being the first two.
“Dinkinesh has truly lived up to its name; that’s amazing,” said lead researcher Dr. Lucy. Hal Levison of SwRI’s Solar System Science and Exploration Division in Boulder, Colorado, referring to the meaning of Dinkinesh (“you are wonderful”) in Amharic. “When Lucy was originally selected for flight, we planned to fly past seven asteroids. With the addition of Dinkinesh, the two Trojan moons and now this satellite, we’ve brought that to 11.”
As Lucy approached Dinkinesh, the team noticed that the brightness of the asteroid was changing in an interesting way, and the team wondered if Dinkinesh was a binary system. When the spacecraft sent back its first images, it was confirmed: Dinkinesh is a nearby binary star. Based on a preliminary analysis of the first available images, the team estimates that the larger body is about 0.5 miles (790 m) across at its widest point, while the smaller one is about 220 m in size.
This Dinkinesh flyby was primarily a flight test of the spacecraft, specifically focused on testing the systems that allow Lucy to autonomously track the asteroid as it flies by at 10,000 miles per hour, referred to as the Terminal Tracking System.
“We’ve seen many asteroids up close, and one might think there’s little left to discover and surprise us.” Well, that’s obviously wrong. Dinkinesh and its mysterious crescent differ in some interesting ways from similar-sized near-Earth asteroids seen by spacecraft such as OSIRIS-REx and DART,” said Deputy Principal Investigator Dr. Simone Marchi of SwRI.
While this encounter was conducted as a technical test, the team’s scientists are excitedly examining the data to gain insights into the nature of the small asteroids.
“Sharing the anticipation of seeing the first images with the team was incredibly exciting, as was the lively discussion about the geology of these two remarkably small but fascinating targets. I look forward to discovering the color variations in this binary system,” said Dr. Silvia Protop from SwRI.
The Lucy team will continue to downlink the remaining rendezvous data from the spacecraft over the next week. They will use the data to evaluate Lucy’s behavior during the encounter and prepare for another close-up look at the asteroid, the main belt asteroid Donaldjohanson, in 2025. Lucy will then be well-prepared to observe the mission’s main targets, the Jupiter Trojan asteroids, starting in 2027.
For more information, visit Planetary Science or contact Joanna Quintanilla, +1 210 522 2073, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.
