Lucy in the Sky With Trojans: NASA's Next Big Asteroid Mission

NASA has a spacecraft sitting on the pad right now that’s about to embark on one of the longer road trips in the history of planetary exploration. It’s called Lucy, and if everything goes to plan it launches next month on a United Launch Alliance Atlas V rocket, kicking off a 12-year mission to Jupiter’s Trojan asteroids.

If you haven’t heard of the Trojans, you’re not alone — they don’t get nearly the attention that Mars or the outer ice giants do. These are two swarms of asteroids that share Jupiter’s orbit around the Sun, parked at gravitationally stable points roughly 60 degrees ahead of and behind the planet. Thousands of them have been cataloged, and the working theory is that they’re leftover material from the early solar system, effectively frozen in place since the planets finished forming about 4.5 billion years ago.

That’s the whole reason for the mission’s name. Lucy is named after the famous hominin fossil discovered in Ethiopia in the 1970s, which reshaped our understanding of human evolution. The idea is that just as that skeleton gave scientists a window into where we came from, this spacecraft’s targets could be “fossils” of planetary formation — chunks of primordial material that never got folded into a planet and have just been drifting out there, largely unchanged, for billions of years.

An ambitious itinerary

What makes this mission stand out isn’t just the destination, it’s the sheer number of stops. Lucy is slated to visit eight different asteroids over its lifetime: two objects in the main asteroid belt between Mars and Jupiter, plus six Trojans split between the leading and trailing swarms. No previous spacecraft has attempted to survey that many small bodies in a single mission. Most asteroid and comet missions we’ve seen — think Rosetta, OSIRIS-REx, Hayabusa2 — have been one-target affairs, with years of cruise time dedicated to a single rendezvous. Lucy is essentially doing a grand tour.

Getting to that many targets across two different swarms on opposite sides of Jupiter’s orbit requires some seriously clever trajectory design, including multiple gravity-assist flybys of Earth along the way. It’s a reminder that a lot of the “action” in space missions isn’t the launch itself, it’s the years of quiet orbital mechanics that follow.

Scientifically, the payoff could be significant. We still don’t have a great handle on the composition of these bodies — whether the leading and trailing swarms differ from each other, what that says about how material got distributed during the solar system’s chaotic youth, and whether any of it overlaps with the story told by more famous objects like Bennu or Ryugu. A mission that samples eight different bodies, even without bringing material back to Earth, gives researchers a much broader dataset than any single flyby could.

Assuming an on-time October launch, this is going to be a mission worth checking in on periodically for over a decade. Not a bad way to spend the 2020s and early 2030s.