NASA’s Lucy spacecraft is on epic mission to study Trojan Asteroids
Launched in October 2021, NASA's Lucy mission is on a mission to explore Jupiter's Trojan asteroid swarms over a period of 12 years. These captured asteroids trail and lead the gas giant in its orbit around the Sun. Scientists hope the mission will shed light on the chaotic infancy of the Solar System.
NASA’s Lucy spacecraft blasted into space on top of an Atlas V rocket in a predawn launch from Cape Canaveral, Florida, USA on 16 October, 2021. The spacecraft is on a 12-year mission to explore the Trojan asteroids of Jupiter. These are mysterious relics from the construction of the Solar System, that were captured by the gas giant and exist in two swarms. One swarm leads Jupiter, while another trails in its orbit around the Sun. These swarms orbit the Sun in the L4 and L5 Lagrange points of the Jupiter-Sun system, which are islands of stable gravity.
These captured asteroids swarms are believed to contain pristine material from the birth of the Sun, 4.6 billion years ago. The Lucy spacecraft is packed with sophisticated payloads to investigate the chemical secrets of these cosmic fossils. The mission is named after Lucy, the 3.2 million-year-old hominid skeleton that reshaped our understanding of human evolution. Scientists hope that the spacecraft will reshape our understanding of the evolution of the Solar System.
Precise operations
Lucy’s journey spans six billion kilometres, and uses gravitational slingshots to build up speed and conserve fuel. In each of these gravitational assists, Lucy steals some of the rotational energy of the Earth to accelerate it towards Jupiter. The mission engineers have slotted in encounters with main belt asteroids after each of these flybys. The ground teams used this encounter to test the instruments on board, and calibrate them. After visiting the leading L4 swarm, Lucy will return to the Earth for another flyby before heading out to the trailing L5 swarm.
Lucy's complex journey to the leading and trailing swarms of Jupiter Trojans. (Image Credit: NASA).
Lucy is carrying a camera, an emission spectrometer, a colour imager and infrared spectrometer. These tools mapped the cratered surface of Donaldjohanson, investigated the thermal properties, and the composition. The asteroid is made up of carbon-rich silicates. The mission teams are adding more opportunistic targets during the course of the mission. During the course of the mission, the spacecraft will visit eight Trojan asteroids and three main belt asteroids. The eight targets are distributed across both the swarms.
Lucy’s targets
After the first Earth flyby, Lucy observed the asteroid Dinkinesh in 2023 and discovered the moonlet named Selam, before swinging past the Earth in another gravity-assist in 2004. On 20 April, 2025, it encountered the Donaldjohanson, named after the American paleoanthropologist who discovered the Lucy skeleton. In 2027, the spacecraft will encounter Eurybates and its moon Queta, Polymele, Leucus, Orus before returning to the Earth and heading out to the L5 swarm to study the binary pair of Patroclus and Menoetius. At that point, Lucy will enter into a stable orbit between the L4 and L5 swarms, allowing the mission to be extended.
In total, Lucy is observing at least eight Trojan asteroids and three asteroids in the main belt. These asteroids range in size from 20 metres to over 100 kilometres across, and consist of a variety of asteroids. Lucy has a pair of 7.3 metre wide circular solar panels, that need to extract every bit of energy from the Sun. Only four per cent of the energy received by the Earth reaches the orbit of Jupiter. During the flybys, Lucy is designed to execute precise manoeuvres without real time commands, using onboard sensors to track targets and adjust its orientation.
Cultural aspects
The spacecraft itself is named after the Australopithecus skeleton that transformed our understanding of human evolution. The mission is infused with philosophical and artistic depth. The connection between cosmic and earthly evolution is etched into a plaque carried by the spacecraft, containing quotes from popular science communicator Carl Sagan regarding humanity’s place in the cosmos, and a message from Yoko Ono calling for peace across time. There are also quotes from all the Beatles, who sang ‘Lucy in the Sky with Diamonds’. The plaque also has quotes from Orhan Pamuk and Albert Einstein. The orbital trajectory of the Lucy mission is also etched into the plaque, with a time capsule for 4021 imagining future generations reflecting on the legacy and journey of the mission. Most of the Trojan asteroids are named after characters from The Iliad. Despite having left the Earth forever, Lucy is a cultural artifact that celebrates the curiosity and creativity of humans.