NASA's Lucy spacecraft prepares for a close flyby of asteroid Donaldjohanson this weekend. The encounter offers a glimpse into the early solar system and prepares for its journey to the Trojans.
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| NASA’s Lucy spacecraft is set for a flyby of asteroid Donaldjohanson, marking its second asteroid encounter. The mission provides valuable data ahead of the spacecraft’s future journey to the Trojans. Image: NASA |
Houston, USA — April 19, 2025:
NASA’s Lucy spacecraft is poised for another significant milestone this weekend as it makes its second close encounter with an asteroid. This flyby, which will bring the spacecraft within 596 miles (960 kilometers) of asteroid Donaldjohanson, offers scientists an exciting opportunity to study the early solar system while preparing for an even more ambitious mission ahead.
Launched in 2021, Lucy is on a groundbreaking 12-year journey to study 11 asteroids, including a unique group of space rocks known as the Trojans. These Trojans orbit near Jupiter and are believed to be remnants of the solar system's formation over 4 billion years ago. Sunday’s flyby marks a crucial test run for the spacecraft as it prepares for its first encounter with a Trojan asteroid in 2027.
The asteroid in question, Donaldjohanson, is located in the main asteroid belt between Mars and Jupiter. It is about 2.5 miles (4 kilometers) long, although its exact size and shape are still unknown. This flyby will offer Lucy a chance to uncover more about the asteroid’s true nature, which remains a mystery. Scientists believe that Donaldjohanson could have an unusual shape, possibly resembling a bowling pin or even a snowman, similar to the distant Kuiper Belt object Arrokoth, which NASA explored in 2019. There’s also speculation that the asteroid might be composed of two separate elongated rocks that could be orbiting each other.
“We don’t know what to expect. That’s what makes this so exciting,” said Hal Levison, the mission’s lead scientist at the Southwest Research Institute. “It’s not going to be a basic potato shape. We already know that.”
During the flyby, Lucy will activate all three of its science instruments to capture images and gather data. However, because the spacecraft must rotate its antenna away from Earth to track the asteroid, real-time communication with Earth will not be possible during the encounter. Scientists at Lockheed Martin’s Mission Control in Colorado expect to receive the data approximately 12 minutes after it has been transmitted over the vast distance of 139 million miles (223 million kilometers) that separates Earth from the asteroid.
One of the unique aspects of this flyby is the presence of paleontologist Donald Johanson at Mission Control. Johanson, after whom the asteroid is named, is famous for discovering the fossilized remains of the human ancestor "Lucy" in Ethiopia 50 years ago—the same inspiration behind the spacecraft’s name. Johanson, along with scientists from NASA and Lockheed Martin, will closely monitor the flyby, marking a personal connection to the mission’s goal of exploring the early days of the solar system.
While this flyby of Donaldjohanson is important for Lucy’s mission, it also serves as valuable practice for its ultimate target—the Trojans. These ancient asteroids are thought to contain clues about the solar system’s formation, and studying them will help scientists gain insights into the conditions that led to the development of planets, moons, and other celestial bodies. By gathering data on Donaldjohanson, Lucy is preparing for its larger task of studying these relics from the birth of the solar system.
In the coming years, NASA’s Lucy mission will continue its journey, gathering data that will shed light on the mysteries of the solar system’s earliest days. The spacecraft’s upcoming rendezvous with the Trojans promises to be a milestone event in the exploration of our cosmic history, but for now, the close flyby of Donaldjohanson provides a crucial stepping stone on this ambitious mission. If all goes as planned, the data collected this weekend will provide new insights into the asteroid belt and set the stage for future discoveries in deep space.