NASA’s Lucy spacecraft, launched in 2021, is gearing up for a major milestone this year: its second close approach to an asteroid. After successfully flying by its first target, the tiny asteroid Dinkinesh, in November 2023, Lucy is now on course to encounter another small space rock called 52246 Donaldjohanson on April 20, 2025. This encounter marks another important step in Lucy’s ambitious 12-year journey to unlock the mysteries of our solar system’s ancient past.
What is NASA’s Lucy Mission?
Lucy is on a unique mission: it’s the first spacecraft designed to study the Trojan asteroids—ancient remnants of the early solar system that travel in swarms along Jupiter’s orbit. By studying these asteroids, scientists hope to learn more about how our planets formed over four billion years ago.
Lucy’s long route includes close flybys of a total of 11 asteroids, making it one of the most wide-ranging missions ever attempted. Along the way, Lucy will pass through both the “Greek” and “Trojan” camps of asteroids, which orbit the Sun ahead of and behind Jupiter.
Why Is the Encounter with Donaldjohanson Important?
The upcoming flyby of Donaldjohanson is a crucial rehearsal for Lucy’s later encounters with the much larger and more distant Trojan asteroids. Donaldjohanson, named after the paleoanthropologist who discovered the famous “Lucy” fossil, is about 4 kilometers (2.5 miles) wide and sits in the main asteroid belt between Mars and Jupiter. Although it isn’t a Trojan asteroid, it presents Lucy’s team with a perfect practice target to test their instruments and maneuvering skills.
During this flyby, Lucy will pass within 425 miles (about 685 kilometers) of Donaldjohanson at a speed of over 10,000 miles per hour. The spacecraft’s cameras and scientific instruments will collect detailed images and data, helping engineers fine-tune their techniques for future, more complicated Trojan flybys.
What Did Lucy Learn from Its First Flyby?
Lucy’s first encounter, with the tiny asteroid Dinkinesh, was a huge success. The spacecraft’s instruments provided stunning pictures and valuable scientific data, including the surprise discovery that Dinkinesh had its own small moon! This success gave the team confidence and valuable experience in navigating close flybys and making real-time adjustments.
Preparing for the Next Challenge
The period leading up to the Donaldjohanson flyby is filled with careful planning. NASA’s team is sending commands to Lucy, testing all systems, and scheduling when to turn on different instruments. They are also refining Lucy’s flight path to ensure it passes at the right distance, angle, and speed.
On the day of the flyby, Lucy will take dozens of pictures and measure things like the asteroid’s shape, surface, and composition. These observations won’t just be used for science—they’ll help engineers make sure Lucy’s instruments are working perfectly before the spacecraft travels further out to the Trojan asteroids.
What Comes After Donaldjohanson?
After the 2025 encounter, Lucy will head toward its main targets—the Trojans. Between 2027 and 2033, Lucy is scheduled to visit at least seven different Trojan asteroids. These objects are considered “fossils” from the early solar system, offering clues to how planets like Earth, Jupiter, and Mars were built.
Why Is This Mission Important?
Lucy’s journey gives us a rare opportunity to study the leftovers from the solar system’s formation. Trojan asteroids are believed to be made of the same materials that formed the planets, but they have remained mostly unchanged for billions of years. By visiting these frozen relics up close, Lucy can help scientists answer some of the biggest questions about our origins—like where Earth’s water came from, and how the building blocks of life arrived on our planet.
The data Lucy collects could also help scientists plan future space missions, and maybe even help protect Earth from dangerous asteroids.
NASA’s Lucy mission is delivering on its promise to explore the farthest reaches of our solar system’s history. As Lucy prepares for its encounter with Donaldjohanson, the whole world is watching—and waiting to learn more about the mysteries hidden within ancient asteroids. The results from this flyby will not only help NASA make the mission even more successful but will also bring us one step closer to understanding the story of our solar system.
