Double Surprise: NASA’s Lucy spacecraft makes ‘remarkable’ discovery during flyby of asteroid Dinkenish

“Dinkenish has truly lived up to its name; this is fantastic,” said Hal Levison, referring to Dinkenish’s meaning in the Amharic language. Levison is the principal investigator for the Lucy of Boulder, Colorado, branch of the Southwest Research Institute in San Antonio. Originally selecting Lucy for the flyby, we planned to fly by seven asteroids. “With the addition of Dinkenish, two Trojan satellites, and now this satellite, we’ve brought the number to 11.”

Discovery of the binary system

In the weeks leading up to the spacecraft’s encounter with Dinkenish, the Lucy team wondered whether Dinkenish was a binary system, given how Lucy’s instruments could see the asteroid’s brightness change over time. The first photos from the meeting removed all doubts. Dinkinesh is a close duo. From preliminary analysis of the first images available, the team estimates that the larger object is about 0.5 miles (790 meters) across, while the smaller object is about 0.15 miles (220 meters) across.

Terminal tracking system testing

This encounter served as an in-flight test of the spacecraft, with a particular focus on testing the system that allows Lucy to autonomously track an asteroid as it passes by at 10,000 miles per hour, which is referred to as the Terminal Tracking System.

A series of images of the binary asteroid pair, Dinkinesh, as seen by the Terminal Tracking Camera (T2CAM) on NASA’s Lucy spacecraft during its closest approach on November 1, 2023. The images were taken 13 seconds apart. The apparent motion of the two asteroids is due to the motion of the spacecraft as it flies at 10,000 mph (4.5 km/s). These images have been enhanced and processed to improve contrast. Image source: NASA/Goddard/SwRI/Arizona State University

Scientific excitement and future missions

“This is a remarkable series of images,” said Tom Kennedy, a guidance and navigation engineer at Lockheed Martin in Littleton, Colorado. “It indicates that the ultimate tracking system is working as intended, even when the universe presented us with a more difficult target than we expected.” Simulation, testing and practice are one thing. It’s quite another to see it actually happen.

While this encounter was conducted as an engineering test, the team’s scientists are feverishly poring over the data to glean insight into the nature of small asteroids.

“We knew this would be the smallest main belt asteroid ever seen up close,” said Lucy project scientist Keith Noll of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The fact that there are two of them makes it even more exciting. In some ways, these asteroids look similar to the binary Didymos and Demorphos near-Earth asteroids observed by DART, but there are some interesting differences that we will investigate.”

It will take up to a week for the team to download the rest of the encounter data from the spacecraft. The team will use this data to evaluate the spacecraft’s behavior during the encounter and prepare for its next close look at the asteroid, the main belt of the Donald Johansson asteroid, in 2025. Lucy will then be well prepared to encounter the mission’s main targets. , Jupiter-Trojan asteroids, starting in 2027.