NASA’s Lucy Spacecraft Braces For Second Asteroid Encounter in Deep Space — But It's Only a ‘Dress Rehearsal'

As humanity ventures deeper into the mysteries of space, spacecraft like NASA’s Lucy are at the forefront, revamping distant rocks into storytellers of our solar system’s origin. Launched in 2021, Lucy is on a 12-year journey across the solar system, focused on discovering secrets buried deep within ancient asteroids. After a successful first flyby in 2023, the mission is now entering a critical phase that will test the spacecraft’s full potential and set the stage for even more ambitious cosmic discoveries. On April 20, 2025, Lucy will perform its second asteroid encounter, stated NASA.

This second asteroid encounter will be with Donaldjohanson, a small main belt asteroid. It may seem like a casual flyby, but this event is important as it serves as a full-scale dress rehearsal for Lucy’s main objective (exploring the Trojan asteroids that share Jupiter’s orbit). These trojans are speculated to be time capsules, preserving material from the solar system's origin.

Encounter phase lead Michael Vincent of Southwest Research Institute (SwRI) noted, "If you were sitting on the asteroid watching the Lucy spacecraft approaching, you would have to shield your eyes staring at the Sun while waiting for Lucy to emerge from the glare," stated NASA.

At exactly 1:51 p.m. EDT, Lucy will sweep past Donaldjohanson at a distance of 596 miles (960 km), stated Daily Galaxy. Around 30 minutes before the flyby, Lucy will reorient itself to track the asteroid, depending on its terminal tracking system to lock on to its target. During this time, the spacecraft’s high-gain antenna will turn away from Earth, not permanently, but for the time being, it will suspend the communication, risky but required for the final output. This encounter will see all three of Lucy’s science instruments in action:

1. L’LORRI (a high-resolution greyscale imager)

2. L’Ralph (a color imager and infrared spectrometer)

3. L’TES (a far-infrared spectrometer)

Together, they will collect detailed visual and compositional data, giving scientists an unprecedented look at this 150-million-year-old asteroid fragment, one of the youngest ever visited by a spacecraft. However, it is not as easy as it seems. Lucy will cease tracking 40 seconds before closest approach to avoid pointing its instruments toward the scorching rays of the Sun.

Vincent remarked, "One of the weird things to wrap your brain around with these deep space missions is how slow the speed of light is…Lucy is 12.5 light minutes away from Earth, meaning it takes that long for any signal we send to reach the spacecraft. Then it takes another 12.5 minutes before we get Lucy’s response telling us we were heard," stated NASA.

Tom Statler, Lucy mission program scientist at NASA Headquarters in Washington, asserted, "Every asteroid has a different story to tell, and these stories weave together to paint the history of our solar system… Telescopic observations are hinting that Donaldjohanson is going to have an interesting story…" This rehearsal is a crucial preparation for the Trojan asteroid encounters, which represent the heart of Lucy’s mission. While Donaldjohanson may not be a Trojan, its role in Lucy’s journey is pivotal.