Lucy mission: NASA's journey to the Trojan asteroids

The Lucy mission will study the Trojan asteroids in a bid to shed light on the formation of the solar system.
The Lucy mission will study the Trojan asteroids in a bid to shed light on the formation of the solar system. (Image credit: Naeblys via Getty Images)

The Lucy mission is a NASA probe that will explore a set of asteroids near Jupiter known as the Trojans. These ancient space rocks hold important clues to the creation of our solar system and, potentially, the origin of life on Earth. The Lucy mission was launched at 5:34 a.m. EDT (09:34 GMT) on Oct. 16, 2021 from the Kennedy Space Center atop a United Launch Alliance (ULA) Atlas V rocket

Lucy mission quick facts

– Launched: Oct.16, 2021 at 5:34 a.m. EDT (09:34 GMT) 

– Launch site: Kennedy Space Center

–Rocket:  United Launch Alliance (ULA) Atlas V rocket

– Target: The Trojan asteroids

– Estimated Cost: $981 million

– Arrival at first target: 2025

– Status: In progress

Along with a mission called Psyche, Lucy was approved in January 2017 as part of NASA's Discovery program, which supports focused and relatively cheap planetary missions. A year after approval, the mission was officially given a schedule and a set of eight asteroid targets. 

Lucy is named for a famous female Australopithecus afarensis fossil found in Ethiopia that, as a relative of modern humans, helped illuminate the evolution of our species. It is hoped that the spacecraft Lucy will similarly elucidate our solar system's earliest days. 

Related: The greatest asteroid missions of all time!

Lucy mission targets: The Trojan asteroids

An artist's concept of NASA's Lucy mission, which will study Jupiter's Trojan asteroids. (Image credit: NASA/Southwest Research Institute)
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The probe's main objects of study are the Trojan asteroids. These objects are thought to be remnants from the primordial disk that formed the sun and planets, which were captured by Jupiter's gravity sometime near the beginning of the solar system. 

Lucy will be the first mission to visit the Trojans, which are each named for famous figures from the Trojan war in Greek mythology. 

According to NASA (opens in new tab), the Trojans share Jupiter's orbit around the sun in two loose groups, with one set slightly ahead of the gas giant and another behind it. "The Trojans are stabilized by the sun and its largest planet in a gravitational balancing act," the agency wrote.

After being launched from Earth, the spacecraft will first make a quick flyby of a main belt asteroid in 2025. The small space rock is named 52246 Donaldjohanson after the paleontologist who discovered the fossil Lucy. Situated between Mars and Jupiter, the fly-by will serve primarily as a test for the spacecraft's instruments, according to the Southwest Research Institute (SwRI) (opens in new tab), which helps oversee the craft. 

If all goes according to plan, between 2027 and 2033, Lucy will then fly past six Trojan asteroids, including three different asteroid subclasses and two objects that rotate around each other. NASA has said that "no other space mission in history has been launched to as many different destinations in independent orbits around our sun."

The mission's targets include C-type, D-type, and P-type asteroids, each of which will help scientists better understand the solar system's genesis, according to SwRI (opens in new tab).

Lucy mission orbital path among the Trojan asteroids that trail and lead Jupiter. (Image credit: Southwest Research Institute)
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Lucy's instruments

Lucy spans more than 46 feet (14 meters) from tip to tip, larger than a 4-story building, though much of that width will be the enormous solar panels (opens in new tab) used to power the spacecraft, according to NASA. The spacecraft will carry an instrument that can measure the surface temperatures of its target asteroids, providing information about their composition, two high-resolution cameras, and a device that uses infrared light to inspect and identify ice, organic material, and different minerals in each asteroid.


The 'Two in one' instrument contains Lucy's color camera (the Multispectral Visible Imaging Camera, MVIC) and infrared imaging spectrometer which will be used to find out what the asteroids are made from using the Linear Etalon Imaging Spectral Array (LEISA).


The Long Range Reconnaissance Imager will capture high resolution black and white images of the target asteroids. According to NASA, It is affectionately referred to (opens in new tab) as Lucy's "eagle eyes" as it has the highest spatial resolution of all Lucy's cameras. 


The infrared Thermal Emission Spectrometer will remotely measure the surface temperature of the target asteroids. 

High Gain Antenna 

This large 2-meter-wide antenna will beam back close up images of the Trojan asteroids and the signal will also help scientists determine the mass of the asteroids by measuring changes in frequency caused by the Dopler effect. 

Terminal Tracking Cameras (T2CAM)

These tracking cameras will not only keep track of the asteroids during Lucy’s encounters but also provide wide-field images of the targets to help scientists get a better idea of their shape.

Lucy solar array trouble

NASA’s Lucy mission launched at 5:34 a.m. EDT (09:34 GMT) on Oct. 16, 2021 from the Kennedy Space Center atop a United Launch Alliance (ULA) Atlas V rocket. (Image credit: NASA/Kevin O'Connell and Bob Lau)
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Approximately one hour after launch, Lucy began to deploy the two large solar arrays as scheduled. However, early analysis suggested that only one of the two arrays, each more than 24 feet (7 meters) across, deployed and latched successfully. Mission specialists continue to troubleshoot the glitch that kept the other solar array from properly deploying. 

According to a NASA statement (opens in new tab) published Nov. 5, the issue could have been caused by a lanyard that helps the array deploy. "Initial tests indicate that the lanyard that pulls out the solar array may not have completed the process successfully; however, it is still uncertain what caused this condition," NASA officials wrote in the statement. "The team is conducting more tests to determine if this is indeed the case, and what the root cause might be."

Except for the solar array, everything else on the Lucy spacecraft is in good working order. Engineers are still assessing whether the solar array glitch will force mission personnel to adapt any of its future plans. 

What are C-type asteroids?

Lucy will fly by two C-type asteroids: the previously mentioned main asteroid belt object Donaldjohanson and a Trojan named Eurybates. 

C-type asteroids are rich in carbon and are where most meteorites on Earth originated. The OSIRIS-REx and Hayabusa 2 missions have previously collected samples from C-type asteroids to bring back to our planet for study.

What are D-type and P-type asteroids?

It will also inspect two D-type asteroids, which are named Leucus and Orus, and three P-type asteroids, one named Polymele and a binary asteroid pair orbiting one another called Patroclus and Menoetius. 

D-type and P-type asteroids are much redder than C-type asteroids and are hypothesized to be rich in organic and volatile elements. No mission has ever flown past a D- or P-type asteroid before. 

The asteroids are expected to provide a wealth of information, especially about the organic material that would have rained down on our planet in its earliest days and potentially helped trigger the creation of living organisms. Each target is also thought to contain water ice underneath its rocky surface. 

The final encounter with Patroclus and Menoetius is considered particularly special because the pair spend most of their time orbiting high above the main ecliptic plane of the solar system and are therefore hard to reach. The elusive asteroid pair will be passing through a region that is accessible to Lucy in March of 2033, when the spacecraft is scheduled to reach them.

Additional Lucy mission resources

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Adam Mann Contributor

Adam Mann is a journalist specializing in astronomy and physics stories. His work has appeared in the New York Times, New Yorker, Wall Street Journal, Wired, Nature, Science, and many other places. He lives in Oakland, California, where he enjoys riding his bike. Follow him on Twitter @adamspacemann or visit his website at (opens in new tab).