After five years and a journey of over 2.2 billion miles, a human-made object has entered a previously unexplored region of our solar system. NASA's Lucy mission has officially reached the domain of the Trojan asteroids, a major milestone.
A First for Space Exploration
NASA confirmed
in late October 2026 that the Lucy spacecraft, launched on October 16, 2021, has entered the first of two massive swarms of asteroids that share an orbit with Jupiter. These objects, known as the Trojan asteroids, have never been visited by a spacecraft before. Lucy is now cruising into a region known as the L4 Lagrange point, one of two gravitationally stable 'islands' where thousands of these ancient bodies travel about 484 million miles ahead of Jupiter. This achievement marks the beginning of the primary phase of Lucy's ambitious 12-year mission to study the 'fossils' of our solar system.
What Are the Trojan Asteroids?
The Trojan asteroids are considered time capsules from over 4.5 billion years ago. They are thought to be leftover remnants from the formation of the giant outer planets like Jupiter, Saturn, Uranus, and Neptune. Unlike asteroids in the main belt between Mars and Jupiter, the Trojans are trapped in two large groups by the combined gravitational pull of the Sun and Jupiter. One group, the 'Greek camp', travels ahead of Jupiter, while the second, the 'Trojan camp', trails behind it. Because they have remained in these stable orbits for billions of years, scientists believe studying them up close can reveal vital clues about how the planets formed and settled into their current orbits.
A Long and Eventful Journey
Lucy's five-year voyage has been anything but quiet. Shortly after launch, engineers on the ground had to troubleshoot one of its large, circular solar arrays which failed to fully deploy. From millions of miles away, they successfully devised a plan to get the array almost fully open and stable, ensuring the mission could proceed. The spacecraft has also completed two gravity-assist flybys of Earth, in October 2022 and December 2024, to build up speed for its journey to the outer solar system. Along the way, it conducted practice runs by visiting main-belt asteroids, making a surprising discovery in November 2023 when it found that its first target, Dinkinesh, had its own satellite, which was later revealed to be a 'contact binary'—two objects touching each other.
What's Next on Lucy's Itinerary?
Though Lucy has entered the Trojan region, its first closeup encounter is still on the horizon. The asteroids in the swarm are millions of miles apart, so they will appear only as pinpricks of light until Lucy gets much closer to its targets. The first Trojan flyby is scheduled for August 11, 2027, when Lucy will study Eurybates and its small moon, Queta. This will be followed by encounters with Polymele in September 2027, Leucus in April 2028, and Orus in November 2028. After touring this first swarm, Lucy's complex trajectory will bring it back toward Earth for a final gravity assist in 2030. This manoeuvre will slingshot the spacecraft toward Jupiter's trailing swarm of Trojans, setting up the mission's grand finale: a visit to the binary asteroid pair Patroclus and Menoetius in March 2033.
