Lucy is off to Visit Jupiter’s Trojan Asteroids

NASA's Lucy spacecraft has been launched. On Saturday, October 16, the spacecraft was launched from Earth on an Atlas 5 rocket. Its primary goal is Jupiter's Trojan asteroids.
Before, spacecraft have visited asteroids and brought back samples. Lucy will visit eight asteroids. This includes seven Jupiter Trojans, and one main-belt. It will take Lucy twelve years to complete all these visits.

Trojan asteroids are asteroids which orbit Jupiter. They can be found in two groups, one that is ahead of Jupiter and the other behind it. Both are separated by 60 degrees. Nearly 10,000 Jupiter Trojans are known to exist. They look like fossils dating back to the early days when the Solar System was still in its embryonic stages.

The main asteroid belt is composed of the white ring and the Trojan camp. Image Credit: By Mdf at English Wikipedia Transferred from en.wikipedia to Commons., Public Domain,

Lucy is a true mission of discovery. It offers the chance to discover more about the mysterious Trojan asteroids, and better understand the formation, evolution, and history of the early solar systems, stated NASA's Thomas Zurbuchen.

What is Lucy trying to find? What is the difference between asteroids and fossils?

The nebular hypothesis is the most widely accepted theory about how the Solar System was formed. The nebular hypothesis states that the Solar System was formed from a cloud of dust and swirling gas. In the middle of this cloud, the Sun was formed and the planets ate up most of the rest. But not quite.

The formation of the planets was largely avoided by asteroids. Asteroids are made up of rock that is old and mostly unchanged. Scientists believe that the Trojan asteroids are remnants of the material which made the giant planets Jupiter, Saturn, Uranus and Neptune. They are a record of the conditions within the protoplanetary disk from which the planets were formed.

The Jupiter Trojans' surfaces are very different from each other, which is quite surprising. Scientists believe that they likely formed in different locations and were moved into their current orbits when the Solar Systems planets formed.

Lucy's primary mission is to decipher the meaning of all this diversity and learn more about the history of our planet. NASA has set four science objectives to help with this mission.

Surface geology is the study of the surface's shape, reflectivity, crater characteristics and crust structure. It also examines the relative ages of the surfaces.

Surface colour and composition: The characteristics of the regolith as well as the distribution and presence of minerals, ices and organics.

Interiors and Bulk Property: Lucy will examine any fractures, impact-craters and exposed bedding to determine the asteroids' interior composition.

Satellites and Rings - Lucy will locate any rings or satellites that the Trojan asteroids might have.

This diagram shows Lucy's orbital path. The spacecraft's path (green), is shown in a reference frame where Jupiter remains stationary. This gives the trajectory its pretzel-like appearance. Credit: Southwest Research Institute

Although Lucy's primary targets are the Trojan asteroids, the visit of the main belt asteroid by Lucy is scientifically fascinating. Donald Johanson, the man who discovered the Lucy fossil, is the name of this asteroid. Asteroid 52246 Donaldjohanson was likely formed from a recent collision in an asteroid belt. It is one of the youngest asteroids in the main Belt between Mars and Jupiter. Donaldjohanson is the first asteroid Lucy will visit on its journey to the Trojans. It will take place on April 20th 2025.

As a nod towards the fossil-like nature as asteroids, the Lucy mission's name is Australopithecus Afarensis, a fossilized skeleton from an early human species. Scientists hope that the Lucy mission will revolutionize our understanding about our evolution and the Solar System.