NASA’s Lucy spacecraft is preparing for a close encounter with a small asteroid this weekend as it continues its long journey toward the distant Trojan asteroids near Jupiter. Launched in 2021, Lucy is on an ambitious mission to explore 11 different asteroids, aiming to offer new insights into the early solar system and the remnants left behind from the time when planets were taking shape.
This weekend’s flyby marks the second time Lucy will closely pass an asteroid. The spacecraft will engage its trio of scientific instruments to study a space rock named Donaldjohanson, located within the main asteroid belt between Mars and Jupiter. At a distance of 139 million miles (223 million kilometers) from Earth, the data collected will take about 12 minutes to reach NASA’s mission controllers at Lockheed Martin in Colorado. The asteroid is named after the paleontologist who discovered the famous Lucy fossil in Ethiopia 50 years ago, and he will be present at Mission Control during the event, adding a symbolic touch to the occasion.
Lucy is expected to approach within 596 miles (960 kilometers) of Donaldjohanson, a celestial body estimated to be roughly 2.5 miles (4 kilometers) long, though its width is significantly smaller. Scientists hope this brief but high-speed flyby – with Lucy traveling at over 30,000 miles per hour (48,000 kilometers per hour) – will give them a more accurate understanding of the asteroid’s shape and dimensions. The object is believed to be a fragment from a massive collision that took place around 150 million years ago.
Lead scientist Hal Levison from the Southwest Research Institute noted that Donaldjohanson is not expected to be an ordinary rock, saying it could resemble a bowling pin or even a snowman, similar to Arrokoth – the oddly shaped Kuiper Belt object previously studied by NASA’s New Horizons mission. There’s also a chance it could be two distinct, elongated bodies positioned apart from one another.
During the flyby, Lucy will turn its antenna away from Earth to stay focused on the asteroid, which means real-time communication will pause temporarily. However, Levison expects most of the scientific data to be transmitted back within a day.
The real centerpiece of Lucy’s mission lies ahead: its visit to the Trojan asteroids, which share Jupiter’s orbit around the sun. These ancient rocks, both trailing and leading Jupiter, will be explored between 2027 and 2033, with Lucy expected to encounter eight of them, including several binary systems. Lucy’s first flyby happened in 2023, when it passed by the small asteroid Dinkinesh and discovered it had a tiny moon orbiting it.
