On November 1st, NASA’s Lucy spacecraft achieved a significant milestone by conducting a flyby of not one, but two asteroids. The initial imagery from Lucy’s encounter revealed that the small main belt asteroid, Dinkinesh, is, in fact, a binary pair.
Hal Levison, principal investigator for Lucy, expressed his excitement, noting that the name “Dinkinesh” in the Amharic language, meaning “marvelous,” truly reflected the discovery. Originally slated for encounters with seven asteroids, the addition of Dinkinesh, two Trojan moons, and now this satellite, has expanded the mission’s scope to a total of eleven celestial encounters.
Leading up to the encounter, the Lucy team speculated about the possibility of Dinkinesh being a binary system due to observed changes in its brightness. The initial images provided conclusive evidence – Dinkinesh is indeed a close binary. Preliminary analysis suggests the larger component measures approximately 0.5 miles (790 m) at its widest, while the smaller is around 0.15 miles (220 m) in size.
This encounter primarily served as an in-flight test for the spacecraft, with a specific focus on evaluating the system’s ability to autonomously track an asteroid traveling at 10,000 mph, known as the terminal tracking system.
Tom Kennedy, guidance and navigation engineer at Lockheed Martin, hailed the success of the terminal tracking system, emphasizing that witnessing it in action surpassed simulations and tests.
While this encounter was primarily an engineering test, the scientists on the Lucy team are eagerly examining the data to gain valuable insights into the characteristics of small asteroids. Keith Noll, Lucy project scientist, highlighted the significance of this encounter with Dinkinesh, being the smallest main belt asteroid observed up close, and the added intrigue of it being a binary system.
The team expects to receive the remaining encounter data from the spacecraft over the next week, enabling a thorough evaluation of the spacecraft’s performance during the encounter. This data will also serve in preparations for Lucy’s next close-up observation of the main belt asteroid Donaldjohanson in 2025, positioning the spacecraft for its primary mission objective – encounters with the Jupiter Trojan asteroids, set to commence in 2027.