NASA’s Lucy spacecraft is headed to Jupiter’s orbit to study asteroids called Trojans. Recently, during its journey, it made a quick flyby of another small asteroid called Dinkinesh. The spacecraft confirmed its flyby of the asteroid this week, but when it returned the photos it took, it had a surprise: A second, even smaller asteroid was hiding next to Dinkinesh.
Lucy took pictures using its Lucy Long-Range Reconnaissance Imager (L’LORRI) camera, which confirmed that the larger asteroid is about 0.5 miles wide and the smaller asteroid is just 0.15 miles wide. As the spacecraft approached Dinkinesh, the Lucy team wondered whether it might be part of a pair, called a binary system, because its brightness changed over time. This speculation was confirmed when the spacecraft flew by and took photographs.
According to the team, the pair is similar to the asteroid binary into which NASA intentionally crashed a spacecraft for the DART mission last year.
“We knew this would be the smallest main-belt asteroid ever seen up close,” Lucy project scientist Keith Noll of NASA’s Goddard Space Flight Center said in a statement. “The fact that it’s two makes it even more exciting. In some ways, these asteroids look very similar to the near-Earth asteroid binaries Didymos and Dimorphos that DART observed, but there are actually some interesting differences that we’ll examine.
As well as being the first opportunity to study these asteroids, the flyby was also used as a test of Lucy’s ability to lock onto the asteroid and point its instruments at the target.
“It’s a wonderful 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,” said Tom Kennedy, guidance and navigation engineer at Lockheed Martin. “It’s one thing to simulate, test and practice. It’s quite another to see it actually happen.”
Dinkinesh means “wonderful” in Amharic, an Ethiopian language, and was chosen because it is the Ethiopian name of Lucy, the human ancestor fossil after whom the mission is named.
“Dinkinesh really lived up to its name; It’s amazing,” said Hal Levison of the Southwest Research Institute, Lucy’s principal investigator. “When Lucy was originally selected for flight, we planned to fly by seven asteroids. “With the addition of Dinkinesh, the two Trojan moons, and now this satellite, we’ve increased that to 11.”