Initial images of Trojan asteroid targets captured by NASA’s Lucy mission

Some of the asteroids that NASA’s Lucy mission will visit are still more than 330 million miles (530 million kilometers) from the spacecraft, which is more than three times the average distance between Earth and the sun. But despite the relatively large and small distance of these asteroids, Lucy captured views of four of them recently.

From March 25-27, 2023, Lucy used her highest resolution imager, L’LORRI, to capture her first views of Jupiter’s four Trojan asteroids. From left to right in the above image: Eurybates, Polymele, Leucus, and Orus.

Although all four images are at the same scale, the orientation of each is different, reflecting the different directions of L’LORRI’s camera as it turns to capture each subject.

Targets are also observed for different lengths of time based on their rotations:

• Eurybates images were taken over a period of 6.5 hours.
• Polymele, about 2.5 hours.
• Leucus, 2 hours.
• Urus, 10 hours.

These images are the first in a series of planned observations designed to measure how Trojan asteroids reflect light at higher angles than what can be observed from Earth. Although the asteroids are still just single points of light in these images, seen against a background of distant stars, the data will help the team choose exposure times for Lucy’s close-up observations of their targets.

Lucy will fly by these asteroids in 2027 and 2028 as the spacecraft travels through the swarm of small asteroids that lead Jupiter in its orbit around the sun. It’s been more than a year since Lucy’s 12-year voyage required close observation of nine Jupiter Trojans–the first space mission ever to visit it–and two major asteroids in the belt.