NASA’s Lucy spacecraft recently flew by its first two asteroids on Nov. 1. Its instruments revealed that the small main belt asteroid Dinkinesh is a binary pair.
Based on the changes in the asteroid’s brightness with time, as seen by Lucy’s instruments, scientists previously assumed that Dinkinesh might be a binary system. The images from this flyby removed all doubt. The larger body is estimated to be around 0.5 miles (790 m) at its widest, while the smaller is about 0.15 miles (220 m) in size.
While referring to the meaning of Dinkinesh in the Amharic language, ‘marvelous’ Hal Levison- principal investigator for Lucy from Boulder, Colorado- said, “Dinkinesh really did live up to its name; this is marvelous. When Lucy was originally selected for flight, we planned to fly by seven asteroids. With the addition of Dinkinesh, two Trojan moons, and now this satellite, we’ve turned it up to 11.”
This encounter primarily served as an in-flight test of the spacecraft, explicitly focusing on testing the system that allows Lucy to autonomously track an asteroid as it flies past at 10,000 mph, referred to as the terminal tracking system.
Tom Kennedy, guidance and navigation engineer at Lockheed Martin in Littleton, Colorado, said, “This is an awesome series of images. They indicate that the terminal tracking system worked as intended, even when the universe presented us with a more difficult target than we expected. It’s one thing to simulate, test, and practice. It’s another thing entirely to see it happen.”
Keith Noll, Lucy project scientist from NASA‘s Goddard Space Flight Center in Greenbelt, Maryland, said, “We knew this was going to be the smallest main belt asteroid ever seen up close. The fact that it is two makes it even more exciting. In some ways, these asteroids look similar to the near-Earth asteroid binary Didymos and Dimorphos that DART saw. Still, there are some fascinating differences that we will be investigating.”