Lucy will perform the first reconnaissance of the Trojans, a population of primitive asteroids orbiting in tandem with Jupiter. Because the Trojans are remnants of the primordial material that formed the outer planets, they hold vital clues to deciphering the history of the solar system. Lucy, like the human fossil for which it is named, aims to revolutionize the understanding of our origins.


One of the most puzzling characteristics of the Trojans is that they are very different from one another. Understanding the causes of the differences between the Trojans will provide unique and critical knowledge on planetary origins, the source of volatiles and organics on the terrestrial planets, and the evolution of the planetary system as a whole.


Lucy will use a remote-sensing instrument suite to study the geology, surface composition, and bulk physical properties of these bodies at close range. The payload includes three complementary imaging and mapping instruments, including a color imaging and infrared mapping spectrometer, a high-resolution visible imager, and a thermal infrared spectrometer. In addition, Lucy will perform radio science investigations using its telecommunications system to determine the masses and densities of the Trojan targets.