NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab
This image shows the “moonrise” of a newly discovered second asteroid behind Dinginesh, captured by Lucy’s Long Range Reconnaissance Imager.
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When NASA’s Lucy mission flew by its first asteroid this week, its cameras captured a surprise.
The Lucy spacecraft was zoomed by the small asteroid Dinginesh, located in our Solar System’s main asteroid belt between the orbits of Mars and Jupiter. But what astronomers thought was an asteroid was actually a binary pair of space rocks.
Hal Levison, Lucy’s principal investigator at the Southwest Research Institute, said Dinginesh, which means “wonderful” in the Ethiopian Amharic language, “really lived up to its name.”
“It’s fantastic,” Levison said in a statement. “When Lucy was first selected for the flight, we planned to fly by seven asteroids. With Dinginesh, the two Trojan moons and now this satellite, we’ve turned it up to 11.
Astronomers had their first hints that Dinginesh might be a pair when Lucy’s instrument suite detected changes in brightness in the weeks leading up to the spacecraft’s close approach on Wednesday.
Lucy’s team believes the large asteroid is half a mile (805 meters) wide and the smaller space rock is 0.15 miles (220 meters) across.
Lucy came within 265 miles (425 kilometers) of the asteroid’s surface during its closest approach Wednesday afternoon.
The close approach is designed to help the Lucy spacecraft test its suite of equipment, including its Terminal Tracking System, which allows the spacecraft to automatically detect and keep in view of the space rock as it flies by at 10,000 miles per hour (4.5 kilometers per second). )
“It’s an amazing set of images. They indicate that the terminal tracking system performed as planned, even when the universe presented us with a more difficult target than we expected,” Tom Kennedy, a guidance and navigation engineer at Lockheed Martin, said in a statement. (Lockheed Martin is NASA’s partner in the Lucy mission.)
“It’s a matter of simulating, testing and practicing,” Kennedy added. “It’s another thing to see it actually happen.”
Data collected during the flyby will provide insight into the small asteroids, comparing them to others observed by previous NASA missions.
“We know this will be the smallest main belt asteroid ever seen,” said Lucy Project Scientist Keith Noll of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Two makes it even more exciting. In some ways these asteroids are similar The near-Earth asteroid binaries seen by DART are Didymos and DimorphosBut there are some interesting differences, which we will investigate.
In September 2022, NASA’s DART mission intentionally crashed into Dimorphos, a small moon orbiting the near-Earth asteroid Didymos, to demonstrate the technology needed to alter the trajectory of a space rock.
Data collected during the Lucy mission flyby will return to Earth next week. The information will help the mission team prepare for the spacecraft’s future asteroid flybys, including a close encounter with another major belt asteroid called Donald Johansson in 2025.
Lucy’s main goal is to explore Jupiter’s unexplored Trojan asteroid clusters. The Trojan asteroids, which get their name from Greek mythology, orbit the Sun in two clusters – one ahead of our Solar System’s largest planet, Jupiter, and the other behind.
Until now, scientists’ main views of the Trojans have mostly been artists’ renderings or animations, as the space rocks are too far away to see in detail through telescopes. Lucy will provide the first high-resolution images of what these asteroids look like.
Lucy is scheduled to reach the Trojan asteroids in 2027. Each of Lucy’s asteroids varies in size and color.
The work borrows its name Lucy FossilRemains of an ancient human ancestor discovered in Ethiopia in 1974. The skeleton has helped researchers piece together aspects of human evolution, and NASA Lucy team members hope their work will achieve a similar feat in the history of our solar system.
There are about 7,000 Trojan asteroids, and the largest is 160 miles (257 kilometers) across. Asteroids are fossil-like material left over from the formation of giant planets in our solar system, including Jupiter, Saturn, Uranus, and Neptune.
The mission will help researchers learn how the Solar System formed 4.5 billion years ago and unlock how the planets ended up in their current locations.