NASA launched a first-of-its kind mission — Lucy — to study Jupiter’s Trojan asteroids.

The space probe lifted off on schedule from Cape Canaveral Air Force Station in Florida on October 16. It was carried aloft by an Atlas V rocket from United Launch Alliance (UAL), a joint venture of Boeing Co and Lockheed Martin Corp.

Lucy’s mission is a 12-year expedition to study a record number of asteroids. No other single science mission has been designed to visit as many different objects independently orbiting the Sun in the history of space exploration.

What is the significance of Trojan asteroids?

• Lucy will be the first space mission to study the Trojans. 

• Scientific evidence indicates that Trojan asteroids are remnants of the material that formed giant planets. Studying them can reveal previously unknown information about their formation and our solar system’s evolution in the same way the fossilized skeleton of Lucy revolutionized our understanding of human evolution.

• The Trojans orbit the Sun in two loose groups, with one group leading ahead of Jupiter in its path, the other trailing behind. 

• The asteroids in Jupiter’s Trojan swarms are as far away from Jupiter as they are from the Sun.

• Clustered around the two Lagrange points equidistant from the Sun and Jupiter, the Trojans are stabilised by the Sun and its largest planet in a gravitational balancing act. 

• Scientists hope Lucy’s close-up fly-by of seven Trojans will yield new clues to how the solar system’s planets came to be formed some 4.5 billion years ago and what shaped their present configuration.

Why is the mission named Lucy?

• The Lucy mission is named after the fossilised skeleton of an early hominid found in Ethiopia in 1974 by Donald Johanson and Tom Gray. 

• That Lucy in turn was named by expedition member Pamela Alderman after a celebratory evening dancing and singing to the Beatles’ song “Lucy in the Sky With Diamonds”.

• Just as that Lucy fossil provided unique insights into humanity’s evolution, the Lucy mission promises to revolutionize our knowledge of planetary origins and the formation of the solar system.

The journey of Lucy

• Lucy will complete a 12-year journey to eight different asteroids — a main belt asteroid and seven Trojans.

• Lucy’s complex path will take it to both clusters of Trojans and give us our first close-up view of all three major types of bodies in the swarms (so-called C, P and D-types).

• The dark-red P and D-type Trojans resemble those found in the Kuiper Belt of icy bodies that extends beyond the orbit of Neptune. The C-types are found mostly in the outer parts of the Main Belt of asteroids, between Mars and Jupiter. 

• All of the Trojans are thought to be abundant in dark carbon compounds. Below an insulating blanket of dust, they are probably rich in water and other volatile substances.

• The spacecraft’s first Earth gravity assist in 2022 will accelerate and direct Lucy’s trajectory beyond the orbit of Mars. The spacecraft will then swing back toward Earth for another gravity assist in 2024, which will propel Lucy toward the Donaldjohanson asteroid – located within the solar system’s main asteroid belt – in 2025.

• Lucy will then journey toward its first Trojan asteroid encounter in the swarm ahead of Jupiter for a 2027 arrival. After completing its first four targeted fly-bys, the spacecraft will travel back to Earth for a third gravity boost in 2031, which will catapult it to the trailing swarm of Trojans for a 2033 encounter.

• The probe will use rocket thrusters to maneuver in space and two rounded solar arrays, each the width of a school bus, to recharge batteries that will power the instruments contained in the much smaller central body of the spacecraft.

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