NASA’s Lucy spacecraft detects the second asteroid during Dinkenish’s flyby

On November 1, NASA’s Lucy spacecraft flew by not only the first asteroid, but the first of two asteroids as well. The first images returned by Lucy reveal that the small main belt of the Dinkenish asteroid is actually a binary pair.

“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.”

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.

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.

“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 near-Earth binary asteroid Didymus and Demorphus that he saw went aroundBut 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.

Written by Katherine Kritke
Southwest Research Institute, San Antonio

Media Contact: Nancy N. Jones
NASA Goddard Space Flight Center, Greenbelt, Maryland.