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We Love Lucy

by Perry Pezzolanella

There are many worlds to explore, planets, moons, asteroids, Kuiperoids, comets, but there are some that are usually forgotten. Among these are the Trojan clusters of asteroids that are in stable, locked orbits ahead (preceding) and behind (trailing) Jupiter. Scientists think they may be ancient relics from the creation of the Solar System. A mission approved in early 2017 may confirm this.

Lucy, named after the famous humanoid fossil, is a spacecraft that will explore these fossil beds of asteroids. It will study the Trojan asteroids known as the Greek camp which precedes Jupiter in its orbit, and the Trojan camp which trails Jupiter. Telescopic observations indicate these are primitive, and there are no known meteorite collections. The origin of these asteroids is a mystery, but the orbits of the giant planets most likely migrated closer to the Sun and then moved outward and captured asteroids in these stable traps. These could be a variety of asteroids that could hold clues to the conditions and development of the infant Solar System.

There are three key questions regarding the study of the Trojan asteroids:

•What were the initial stages, conditions, and processes of Solar System formation, and what was the nature of the interstellar matter that was incorporated?

•What governed the accretion, supply of water, chemistry, and internal differentiation of the inner planets; the evolution of their atmospheres; and what role did bombardment by large projectiles play?

•What were the primordial forces that led to organic matter and where does organic synthesis continue today?

The Lucy mission will use copies of the New Horizons Pluto spacecraft instruments to aid in the study, the LORRI high resolution camera and the RALPH color camera. It will also use a thermal emission spectrometer from the OSIRIS-Rex asteroid Bennu mission.

The Lucy mission will explore a main belt asteroid on its way to the Trojans where it will explore four Trojans in the Greek camp and one in the Trojan camp. It will launch October 2021 and fly past the tiny asteroid Donaldjohanson in the main belt in April 2025. It will then fly out to the Greek camp of Trojans and explore the asteroids Eurybates, Polymele, Lencus, and Orus between August 2027 and November 2028. It will then fly back past Earth’s orbit and cross the Solar System to encounter Patroclus/Menoetius, a binary system, in March 2033. An extended mission until at least 2040 is possible with more main belt and Trojan asteroids surveyed.

This will be an epic mission with so many asteroids being encountered close up in regions of the Solar System not yet explored. The flybys will be brief, but intense. Scientists are sure to love the discoveries made by the Lucy mission.