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During its first asteroid flyby, NASA’s Lucy mission experienced an unexpected surprise captured by its cameras.
Lucy, the spacecraft, soared past Dinkinesh, a small asteroid situated within our solar system’s primary asteroid belt between the orbits of Mars and Jupiter. However, it turned out that what astronomers initially believed to be a single asteroid was actually a binary pair of space rocks.
Dubbed Dinkinesh, which means “marvelous” in the Amharic language of Ethiopia, amazed Hal Levison, the principal investigator for Lucy at the Southwest Research Institute.
“This is truly marvelous,” stated Levison. “When Lucy was originally selected for the mission, we planned to visit seven asteroids. But with the addition of Dinkinesh, two Trojan moons, and now this satellite, we’ve ramped it up to 11.”
Astronomers first suspected Dinkinesh’s dual nature when Lucy’s instrument suite detected variations in brightness in the weeks leading up to the spacecraft’s close encounter on Wednesday.
Unlocking the Secrets of the Dinkinesh Duo
The Lucy team estimates that the larger asteroid is half a mile (805 meters) wide, while the smaller one measures 0.15 miles (220 meters) across.
During the closest approach on Wednesday afternoon, Lucy came within 265 miles (425 kilometers) of the asteroid’s surface.
The close encounter aimed to test Lucy’s equipment suite, including its terminal tracking system, enabling the spacecraft to autonomously locate and monitor the space rock while traveling at 10,000 miles per hour (4.5 kilometers per second).
“These images are absolutely awesome. They demonstrate the successful operation of the terminal tracking system, even when faced with a more challenging target than anticipated,” commented Tom Kennedy, a guidance and navigation engineer at Lockheed Martin, a NASA partner in the Lucy mission.
“Simulating, testing, and practicing is one thing, but witnessing it actually unfold is an entirely different experience,” Kennedy added.
The data collected during the flyby will provide valuable insights into small asteroids, allowing for comparisons with previous observations made by other NASA missions.
“We knew this was going to be the smallest main belt asteroid ever seen up close,” said Keith Noll, Lucy project scientist from NASA’s Goddard Space Flight Center. “The fact that it is a binary pair makes it even more exciting. While these asteroids may resemble near-Earth asteroid binary Didymos and Dimorphos observed by DART in some ways, there are intriguing differences that we’ll be investigating.”
In September 2022, NASA’s DART mission deliberately collided with Dimorphos, a small moon orbiting the near-Earth asteroid Didymos, to showcase the technology required for altering the trajectory of a space rock.
Preparing for Future Flybys
The data acquired during the Lucy mission flyby will continue to be transmitted to Earth over the next week. This information will aid the mission team in preparing for future asteroid flybys, including a close encounter with another main belt asteroid known as Donaldjohanson in 2025.
Lucy’s primary objective is to explore Jupiter’s Trojan asteroid swarms, previously uncharted territory. Named after characters from Greek mythology, Trojan asteroids form two swarms — one leading Jupiter, the largest planet in our solar system, and another trailing behind it.
So far, scientists’ understanding of the Trojans has been limited to artistic renderings or animations due to their distant nature. Lucy will provide the first high-resolution images, offering detailed glimpses of these asteroids’ appearance.
Lucy is scheduled to reach the Trojan asteroids in 2027, with each flyby involving asteroids of different sizes and colors.
The mission takes its name from the Lucy fossil, the remains of an ancient human ancestor discovered in Ethiopia in 1974. The fossil has enabled researchers to reconstruct aspects of human evolution. Likewise, the NASA Lucy mission aims to shed light on the history of our solar system.
The Trojan asteroids, numbering about 7,000, are remnants of material from the formation of giant planets like Jupiter, Saturn, Uranus, and Neptune. The largest among them measures 160 miles (257 kilometers) across.
By studying these asteroids, the mission will enable researchers to journey back in time and gain insights into the formation of the solar system 4.5 billion years ago, as well as unravel the factors that determined the current planetary configurations.
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