7 Things to Know About NASA’s Lucy Mission to the Jupiter Trojan Asteroids

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Artist’s depiction of Lucy zipping past a Trojan asteroid.

Artist’s depiction of Lucy zipping past a Trojan asteroid.
Image: Southwest Research Institute

NASA’s launch window for the Lucy spacecraft opens during the early hours of Saturday, October 16. Here’s what you need to know about this thrilling mission and how you can watch the launch live online.

Lucy is packed and ready to go. The uncrewed spacecraft now sits atop a United Launch Alliance Atlas V 401 rocket, as the science community eagerly awaits the commencement of this unprecedented mission to the Jupiter Trojan asteroids. Fingers crossed, Lucy will spend the next 12 years inspecting a record-breaking number of asteroids, none of which have ever been explored before.

Watch the launch live online

NASA hopes to launch Lucy on Saturday, October 16, at 5:34 a.m. EDT (2:34 a.m. PDT). The launch window will remain open until November 5, giving plenty of wiggle room in case of bad weather or other delays. Coverage will begin at 5:00 a.m. EDT (2:00 a.m. PDT), which you can watch on NASA Television, the NASA app, or at the embedded video provided below.

The Atlas V rocket will lift off from Space Launch Complex 41 at Cape Canaveral Space Force Station in Florida. Lucy won’t head directly for the Trojans, as it needs to make two passes of Earth, the first in 2022 and the second in 2024, for the extra gravitational boost.

Lucy is not actually going to Jupiter

For this $981 million mission, Lucy won’t be going anywhere near Jupiter. The Jupiter Trojan asteroids orbit the Sun in two loose but discernible clumps, one in front of Jupiter’s orbital path and the other behind. These asteroids are packed together at two Lagrange points, in which the distance to Jupiter and the Sun are approximately equal. The Trojan asteroids are trapped in stable orbits and have been that way for billions of years—a very good thing, from a scientific perspective.

Time-lapse animation showing the movements of the two Trojan clumps (in green) and the inner planets (not to scale).
Image: Astronomical Institute of CAS/Petr Scheirich

During an interview with NASA, principal investigator Hal Levison from the Southwest Research Institute described the Trojans as the “fossils of planetary formation.” The Trojans are the leftovers from the earliest days in the solar system, so by studying these primordial objects, scientists will better understand the processes that delivered organic materials and water to Earth—the basic building blocks of life.

Named for a fossil

Fittingly, the Lucy spacecraft is named after the famous Australopithecine fossil found in 1974. As NASA explains, the ancient skeleton “provided unique insight into humanity’s evolution,” and likewise, “the Lucy mission will revolutionize our knowledge of planetary origins and the formation of the solar system.” Paleontologists had named the Lucy fossil after the Beatles’ song, “Lucy in the Sky With Diamonds,” making the spacecraft’s name even more fitting.

Diagram showing Lucy’s path (in green) as it visits asteroids within the two Trojan clumps.

Diagram showing Lucy’s path (in green) as it visits asteroids within the two Trojan clumps.
Image: Southwest Research Institute

More destinations than any other space mission

Lucy has a big job ahead, as it will visit one asteroid in the Main Belt between Jupiter and Mars and seven Trojan asteroids. No other space mission in history has visited so many celestial objects in independent orbits around the Sun.

Traveling at an average speed of 39,000 miles per hour (63,000 km/hr), the 52-foot-long probe will visit asteroid Donaldjohansen in the Main Belt before reaching the Trojans. Starting in 2027, Lucy will visit Eurybates and its binary partner Queta, followed by Polymele, Leucus, Orus, and the binary pair Patroclus and Menoetius. Lucy will travel to both Trojan clusters, which are located 500 million miles (800 million kilometers) from the Sun.

Depiction of the seven Trojan asteroids on Lucy’s itinerary.

Depiction of the seven Trojan asteroids on Lucy’s itinerary.
Image: NASA/Goddard Space Flight Center Conceptual Image Lab

Lucy will study three different types of asteroids: C, P, and D. C-type asteroids are common in the outer realms of the Main Belt, while P-type and D-type asteroids are reminiscent of icy Kuiper Belt objects from beyond the orbit of Neptune. All Trojans are believed to contain high levels of dark carbon compounds and even volumes of water and other volatile compounds.

Expect hi-resolution photos

Lucy’s LOng Range Reconnaissance Imager, or L’LORRI, will allow the probe to capture high-resolution images of the asteroids. Even at the expected distances of 620 miles (1,000 km), Lucy should still be able to capture small details and features, including elephant-sized craters.

Using its onboard instruments, Lucy will map the surface geology of each asteroid, study surface composition and color, determine the mass and densities of each object, and look for previously unseen companions and rings.

Lucy carries messages from humanity

A special plaque is coming along for the ride. In addition to a diagram of our solar system’s planets, the plaque contains messages from key 20th century thinkers, including Albert Einstein, Martin Luther King Jr., and Carl Sagan.

Lucy’s plaque.

Lucy’s plaque.
Image: SWRI

Quotes from contemporary writers and poets have also been included, including contributions from Rita Dove, Joy Harjo, and Amanda Gorman, who read an original poem during President Joe Biden’s inauguration ceremony. Gorman’s poem reads as follows:

Remember the earth whose skin you are: red earth, black earth, yellow earth, white earth, brown earth, we are earth.

Remember the plants, trees, animal life who all have their tribes, their families, their histories, too.

Remember you are all people and all people are you. Remember you are this universe and this universe is you.

Remember.

A probe for the ages

When the primary mission concludes in 2033, Lucy will remain in a stable orbit around the Sun. The spacecraft will likely remain operational after that, and it may even visit some more asteroids. But there it will stay, “passing through the alternating Trojan swarms for hundreds of thousands, if not millions, of years,” according to NASA.

It all starts on Saturday, assuming everything goes well with the launch.

More: A Last-Minute Nuke to Shatter an Incoming Asteroid Could Actually Work, Study Suggests.

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