Time capsules from the birth of our Solar System more than 4 billion years ago, the swarms of Trojan asteroids associated with Jupiter are thought to be remnants of the primordial material that formed the outer planets. The Trojans orbit the Sun in two loose groups, with one group leading ahead of Jupiter in its path, the other trailing behind. Clustered around the two Lagrange points equidistant from the Sun and Jupiter, the Trojans are stabilized by the Sun and its largest planet in a gravitational balancing act. These primitive bodies hold vital clues to deciphering the history of the solar system, and perhaps even the origins of organic material on Earth.
NASA's Lucy will
be the first space mission to study the Trojans. The mission takes its name
from the fossilized human ancestor (called “Lucy” by her discoverers) whose
skeleton provided unique insight into humanity's evolution. Likewise, the
Lucy mission will revolutionize our knowledge of planetary origins and the
formation of the solar system.
Lucy is slated to launch in October 2021 and,
with boosts from Earth's gravity, will complete a 12-year journey to eight
different asteroids — a Main Belt asteroid and seven Trojans, four of which are
members of “two-for-the-price-of-one” binary systems. 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).
This diagram illustrates Lucy's orbital path. The
spacecraft’s path (green) is shown in a frame of reference where Jupiter
remains stationary, giving the trajectory its pretzel-like shape. After launch
in October 2021, Lucy has two close Earth flybys before encountering its Trojan
targets. In the L4 cloud Lucy will fly by (3548) Eurybates (white) and its
satellite, (15094) Polymele (pink), (11351) Leucus (red), and (21900) Orus
(red) from 2027-2028. After diving past Earth again Lucy will visit the L5
cloud and encounter the (617) Patroclus-Menoetius binary (pink) in 2033. As a
bonus, in 2025 on the way to the L4, Lucy flies by a small Main Belt asteroid,
(52246) Donaldjohanson (white), named for the discoverer of the Lucy fossil.
After flying by the Patroclus-Menoetius binary in 2033, Lucy will continue
cycling between the two Trojan clouds every six years.
Image Credit: Southwest
Research Institute
Source: https://www.nasa.gov/image-feature/lucy-is-going-to-space
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