Somewhere beyond the orbit of Mars, past the great belt of rock that lies between the planets, a small robotic traveler has entered a place no machine from Earth had ever been built to visit. Lucy, launched in October 2021, has reached the Trojan asteroid swarm that rides in step with Jupiter around the Sun, five years and more than two billion miles into its journey. Its purpose is to read the fossils of the early Solar System, since these ancient, lightly altered bodies may help scientists understand how the planets came to be and why they settled where they are today.
NASA's Lucy Becomes First Spacecraft to Reach Jupiter's Trojan Asteroid Region After 2.2 Billion-Mile Journey
No spacecraft had ever gone to study the Trojans.
Mark
Lucy has entered the Trojan region. What exactly changed this week?
Mimi
Nothing you could see. It's the first time any spacecraft has arrived at L4, where the swarm ahead of Jupiter travels, five years and 2.2 billion miles after launch.
Mark
But there's no boundary. How do they know it's there?
Mimi
Engineers used radio signals from the spacecraft plus images of the surrounding stars to fix its position.
Luke
So the entry is a position calculation, not an observed event. Worth saying plainly.
Mark
Fair. And the asteroids are close together, then?
Mimi
Quite the opposite. NASA estimates they're about 6 million miles apart on average, so they'll look like points of light, not a crowded field.
Mark
Why does the science matter?
Mimi
The Trojans are primitive, and scientists hope they'll sharpen theories about how the planets formed about 4.5 billion years ago and moved to where they are.
Luke
That's a hope, not a result. The actual data starts with Eurybates on August 11, 2027.
Mark
And the earlier flybys?
Mimi
Dinkinesh gave a surprise, a small satellite called Selam that is itself a contact binary. Donaldjohanson was about five miles long.
Luke
Those are main-belt targets, so they don't tell us anything about the Trojans yet.
O Pulso
- Lucy has become the first spacecraft to enter the Trojan region at Jupiter's L4 point, a place with no visible boundary, confirmed only through radio signals and star images.
- Thousands of asteroids share Jupiter's orbit here, and from the spacecraft they will appear as faint points of light drifting across the stars.
- Engineers are readying the craft and its instruments for a flyby of Eurybates on August 11, 2027, a brief window of only a few hours.
- The mission will pass four leading-group targets through 2028, then return in 2030 for a gravity assist that sends it to the trailing Trojans, with Patroclus and Menoetius due in March 2033.
Somewhere beyond the orbit of Mars, past the great belt of rock that lies between the planets, a small robotic traveler has entered a place no machine from Earth had ever been built to visit. Lucy, launched in October 2021, has reached the Trojan asteroid swarm that rides in step with Jupiter around the Sun, five years and more than two billion miles into its journey. Its purpose is to read the fossils of the early Solar System, since these ancient, lightly altered bodies may help scientists understand how the planets came to be and why they settled where they are today.
NASA's Lucy spacecraft has done something no craft has done before. After five years of flight and more than 2.2 billion miles, it has entered the region where Jupiter's Trojan asteroids travel, a stable zone at the planet's L4 point that lies ahead of Jupiter in its orbit around the Sun. Earlier missions visited Jupiter only to borrow its gravity for journeys elsewhere. None were built to study these swarms.
There was no line to cross, since the region has no physical edge. Engineers confirmed Lucy's arrival by tracking its radio signals and comparing star images. From the spacecraft, the asteroids will look like tiny moving points of light, spaced millions of miles apart.
The Trojans are considered primitive remnants of the early Solar System, and scientists hope they can sharpen their understanding of how the planets formed some 4.5 billion years ago. Lucy has already rehearsed its work. In 2023 it found a small companion around the asteroid Dinkinesh, a contact binary unlike any seen before, and in 2025 it imaged Donaldjohanson.
The real work begins on August 11, 2027, when Lucy flies past Eurybates. Polymele, Leucus and Orus follow through 2028. After a return toward Earth in 2030, the spacecraft will head to the trailing swarm, where its final target, the binary pair Patroclus and Menoetius, is expected in March 2033.
NASA's Lucy spacecraft has crossed into the region of space where one of Jupiter's two great asteroid swarms travels, and no spacecraft has ever done that before. The agency reported that Lucy reached the zone five years after it left Earth, having covered more than 2.2 billion miles since its launch on October 16, 2021.
The place Lucy has entered is Jupiter's Lagrange point 4, or L4. Jupiter shares its path around the Sun with two large groups of asteroids, the Trojans. One group, at L4, moves ahead of the planet. The other, at L5, trails behind it. NASA describes these regions as islands of stability, where thousands of asteroids stay in orbit because of the combined gravitational pull of the Sun and Jupiter. Earlier spacecraft have visited Jupiter, but they used its gravity to swing toward other destinations. None went to study the Trojans.
Because the region has no physical boundary, there was no line to cross on a map. Mission engineers confirmed Lucy's position using radio signals from the spacecraft together with images of the stars around it. Each swarm sits roughly 484 million miles from Jupiter, about the same distance as Jupiter is from the Sun. Within a swarm, NASA estimates the asteroids are on average about 6 million miles apart, so from Lucy's vantage they will appear as tiny points of light moving against the stars. A trajectory animation from NASA's Scientific Visualization Studio, released on October 27, 2026, traces the route from launch to L4, showing Trojans as light orange dots and main-belt objects as white dots.
The scientific payoff is about origins. The Trojans are primitive bodies, and scientists hope they can help refine theories of how the planets formed about 4.5 billion years ago and how they reached their present positions.
The close-up work begins on August 11, 2027, when Lucy flies past Eurybates, the first of four targets in the leading group. The team is preparing the spacecraft, its instruments and the encounter procedures for the few hours available to study the asteroid at close range. Polymele follows in September 2027, then Leucus in April 2028 and Orus in November 2028.
Lucy has already practiced on the main belt. On November 1, 2023, it passed the asteroid Dinkinesh and found that it had a small satellite, named Selam. Selam turned out to be a contact binary, two joined bodies, a configuration not previously seen in a satellite orbiting another asteroid. On April 20, 2025, Lucy passed Donaldjohanson at a distance of about 600 miles (960 kilometers). Images showed an asteroid about five miles (eight kilometers) long and 2 miles (3.5 kilometers) wide at its broadest.
After the four encounters in the leading group, Lucy will return toward Earth in 2030 for a third and final gravity assist, which will redirect it to L5 and the trailing Trojans. Its last scheduled targets there are Patroclus and Menoetius, a binary pair that the spacecraft is expected to examine in March 2033.
Citações Notáveis
NASA describes the Trojan regions as islands of stability where thousands of asteroids remain in orbit.— NASA, as reported by The Times of India
Quer a matéria completa?
Leia o original em The Times of India ↗
Technology