Quick Read
- NASA’s Lucy spacecraft flew within 600 miles of asteroid Donaldjohanson on April 20, 2025.
- The asteroid is a contact binary, resembling two nested ice cream cones.
- Images reveal the asteroid is larger than expected, measuring 5 miles long and 2 miles wide.
- This flyby serves as a dress rehearsal for Lucy’s upcoming encounters with Jupiter Trojan asteroids.
- Data from the spacecraft’s instruments will provide insights into the solar system’s formation.
NASA’s Lucy Spacecraft Completes Flyby of Asteroid Donaldjohanson
On April 20, 2025, NASA’s Lucy spacecraft achieved a significant milestone by completing a close flyby of asteroid Donaldjohanson, located in the main asteroid belt between Mars and Jupiter. The spacecraft passed within 600 miles (960 kilometers) of the asteroid, capturing detailed images and data that provide new insights into its structure and composition. This encounter marks Lucy’s second asteroid flyby and serves as a critical preparation for its primary mission to study Jupiter Trojan asteroids.
Key Observations from the Flyby
Initial images from Lucy’s Long-Range Reconnaissance Imager (L’LORRI) reveal that Donaldjohanson is a contact binary—a celestial object formed by the collision of two smaller bodies. The asteroid’s unique shape, described as resembling two nested ice cream cones, surprised scientists. Hal Levison, principal investigator for the Lucy mission at the Southwest Research Institute (SwRI) in Boulder, Colorado, noted, “Asteroid Donaldjohanson has strikingly complicated geology. As we study the complex structures in detail, they will reveal important information about the building blocks and collisional processes that formed the planets in our Solar System.”
Donaldjohanson is larger than previously estimated, measuring approximately 5 miles (8 kilometers) in length and 2 miles (3.5 kilometers) in width at its widest point. The asteroid’s elongated shape and narrow neck connecting its two lobes were confirmed through images taken during the closest approach, which occurred at 1:51 p.m. EDT (17:51 UTC). However, the full asteroid could not be captured in a single frame due to its size exceeding the imager’s field of view.
Scientific Instruments and Data Collection
The Lucy spacecraft is equipped with advanced scientific instruments designed to analyze asteroids in detail. In addition to L’LORRI, the mission utilizes the L’Ralph color imager and infrared spectrometer, as well as the L’TES thermal infrared spectrometer. These instruments are expected to provide comprehensive data on Donaldjohanson’s composition, surface features, and thermal properties.
Data from the flyby will be downlinked over the course of a week, enabling scientists to construct a more complete picture of the asteroid’s overall shape and characteristics. The encounter also allowed the mission team to conduct a series of dense observations, testing the spacecraft’s capabilities and refining operational procedures ahead of its primary mission targets.
Significance of the Flyby
Although Donaldjohanson is not a primary science target for the Lucy mission, this flyby serves as a “dress rehearsal” for future encounters with Jupiter Trojan asteroids. These asteroids, trapped in Jupiter’s orbit due to its gravitational influence, are considered time capsules from the early solar system. Lucy’s primary mission includes eight planned Trojan flybys between 2027 and 2033, starting with the asteroid Eurybates in August 2027.
Tom Statler, program scientist for the Lucy mission at NASA Headquarters in Washington, emphasized the importance of these early encounters. “These early images of Donaldjohanson are again showing the tremendous capabilities of the Lucy spacecraft as an engine of discovery. The potential to really open a new window into the history of our solar system when Lucy gets to the Trojan asteroids is immense,” he said.
Mission Overview and Future Plans
Launched in 2021, Lucy is the thirteenth mission in NASA’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. The spacecraft was built by Lockheed Martin Space in Littleton, Colorado, with contributions from various institutions, including the Southwest Research Institute, Johns Hopkins Applied Physics Laboratory, and Arizona State University.
Lucy will spend the remainder of 2025 traveling through the main asteroid belt, continuing to refine its trajectory and prepare for its primary mission. The spacecraft’s advanced navigation and imaging systems, combined with its suite of scientific instruments, are expected to yield groundbreaking discoveries about the origins and evolution of our solar system.
The successful flyby of Donaldjohanson demonstrates the spacecraft’s ability to conduct complex maneuvers and collect high-quality data, paving the way for its ambitious exploration of the Jupiter Trojan asteroids. As scientists analyze the data from this encounter, they look forward to uncovering more secrets about the building blocks of planets and the processes that shaped our cosmic neighborhood.