NASA’s Lucy spacecraft is set for a close encounter with a small asteroid this weekend as it continues its ambitious journey toward a distant cluster of asteroids near Jupiter. This will mark Lucy’s second visit to an asteroid on its 12-year mission to study 11 space rocks in total.
Launched in 2021, Lucy’s mission aims to shed light on the formation of our solar system by examining ancient asteroid remnants. The upcoming flyby serves as a key test run for the spacecraft’s more significant destination in 2027 — its first Trojan asteroid, which orbits near Jupiter.
On Sunday, Lucy will activate its trio of scientific instruments to study a harmless asteroid named Donaldjohanson, located roughly 139 million miles (223 million kilometers) from Earth in the main asteroid belt between Mars and Jupiter. Due to the vast distance, each transmission from the spacecraft will take about 12 minutes to reach mission control in Colorado.
The asteroid’s namesake, famed paleontologist Donald Johanson, will be present at Lockheed Martin’s Mission Control during the flyby. Johanson discovered the fossil of the early human ancestor “Lucy” in Ethiopia nearly 50 years ago — the spacecraft is named in honor of that historic find.
During the flyby, Lucy will pass within 596 miles (960 kilometers) of the asteroid, which is about 2.5 miles (4 kilometers) long but appears narrower in width. Scientists expect this encounter to provide more accurate measurements of its shape and size. The spacecraft will be moving at a speed exceeding 30,000 miles per hour (48,000 kilometers per hour) during the flyby.
This asteroid is believed to be one of many fragments left behind from a massive collision that took place approximately 150 million years ago. According to Hal Levison, the mission’s lead scientist from the Southwest Research Institute, this asteroid likely has a unique form.
“It’s not going to be a basic potato. We already know that,” Levison said, suggesting the rock could resemble a bowling pin or even have a shape similar to Arrokoth — the snowman-like object in the Kuiper Belt that NASA’s New Horizons visited in 2019. There’s also a possibility that it could turn out to be two separate, elongated asteroids.
“We don’t know what to expect. That’s what makes this so cool,” Levison added.
During the close pass, Lucy will temporarily lose contact with Earth as it adjusts its antenna to stay focused on the asteroid. Mission teams expect to receive most of the science data within about 24 hours after the event.
After this flyby, Lucy’s major mission will take it to the Trojan asteroids — clusters of ancient bodies that travel along Jupiter’s orbit, both ahead of and behind the giant planet. Between 2027 and 2033, Lucy will visit eight of these Trojans, including a few pairs that orbit together.
Lucy’s first asteroid visit happened in 2023 when it zipped past Dinkinesh, a tiny asteroid in the main belt. That flyby led to an unexpected discovery — Dinkinesh has a small moon orbiting it.