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NASA\u2019s Lucy spacecraft made a successful flyby of the second asteroid on its must-see list over the weekend, and sent back imagery documenting the elongated object\u2019s bizarre double-lobed shape.<\/p>\n
It turns out that asteroid Donaldjohanson \u2014 which was named after the anthropologist who discovered the fossils of a human ancestor called Lucy \u2014 is what\u2019s known as a contact binary, with a couple of ridges in its narrow neck. In today\u2019s image advisory, NASA compares the ridged structure to a pair of nested ice cream cones.<\/p>\n
\u201cAsteroid Donaldjohanson has strikingly complicated geology,\u201d said Hal Levison, a planetary scientist at the Southwest Research Institute who serves as the Lucy mission\u2019s principal investigator. \u201cAs 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.\u201d<\/p>\n
Lucy came as close as 600 miles (960 kilometers) to Donaldjohanson on April 20, snapping images every two seconds or so as it zoomed past. The pictures confirmed the asteroid\u2019s status as a contact binary \u2014 that is, a compound object formed by the sticky collision of two smaller celestial bodies. Donaldjohanson is somewhat larger than it was previously thought to be, with a length of about 5 miles (8 kilometers) and a width of 2 miles (3.5 kilometers) at the widest point.<\/p>\n<\/p><\/div>\n
The Easter encounter took place three and a half years after Lucy was launched, and 17 months after the 52-foot-wide probe flew past its first target asteroid, Dinkinesh, and a mini-moon called Selam. Like Donaldjohanson, Selam was found to be a contact binary.<\/p>\n
Researchers consider both of Lucy\u2019s encounters in the main asteroid belt, which lies between the orbits of Mars and Jupiter, to be mere warmups for the mission\u2019s main event: a detailed study of so-called Jupiter Trojan asteroids. Such asteroids are trapped harmlessly at resonance points in Jupiter\u2019s orbit due to the giant planet\u2019s gravitational influence. No spacecraft has ever gotten close to a Jupiter Trojan.<\/p>\n
Tom Statler, NASA program scientist for the $989 million Lucy mission, said the quality of the early imagery demonstrates the \u201ctremendous capabilities\u201d of Lucy\u2019s instruments. \u201cThe potential to really open a new window into the history of our solar system when Lucy gets to the Trojan asteroids is immense,\u201d he said.<\/p>\n
Over the next few weeks, researchers will retrieve, process and analyze data from Lucy\u2019s black-and-white imager as well as its color imager, infrared spectrometer and thermal infrared spectrometer. The spacecraft is scheduled to spend most of this year traveling through the main asteroid belt.<\/p>\n
Lucy\u2019s first encounter with a Jupiter Trojan asteroid, known as Eurybates, is due to take place in August 2027. Four additional Trojan encounters will follow between 2027 and 2033.<\/p>\n<\/p><\/div>\n