NASA launched the Lucy spacecraft which will study eight Trojan asteroids. Credit: NASA

NASA Spacecraft Sent Towards 8 Asteroids To Solve Early Solar System Mysteries


NASA launched its new interplanetary station Lucy that will explore Jupiter’s Trojan asteroids. In 12 years of operation, the device will study eight asteroids located at specific Lagrange points in the Sun-Jupiter system. The collected data should help astronomers learn a lot about the formation and evolution of the solar system.

What are the Lagrange points?

Lagrange points L 1, L 2, and L 3 are points of unstable equilibrium – the bodies that are in them will eventually be forced to leave them. At the other two Lagrange points, L 4 and L 5, the balance is stable – all the bodies that are in them should not change their position without external help.


However, in the late 1950s, NASA employee Robert Farquhar began researching Lagrange points for applicability in spacecraft design.

In his 1968 Ph.D. thesis, he first described halo orbits around Lagrange points and pointed out that they could be convenient to place space telescopes or vehicles that could correct their position using engines.

Lagrange points L4 and L5. Credit: Southwest Research Institute
Lagrange points L4 and L5. Credit: Southwest Research Institute

Farquhar proposed to place a relay satellite near point L 2 Earth-Moon systems so that astronauts can land on the far side of the Moon. It is curious that before Farquhar, the idea to place something man-made at the Lagrange points appeared back in 1961 in the novel by Arthur Clarke “A Fall of Moondust”.

Today, a huge number of spacecraft and telescopes operate in orbits around the points L 1 and L 2 of the Sun-Earth and Earth-Moon systems: SOHO, Herschel, Gaia, Spektr-RG and many others, and James Webb will also be placed there.

What makes the Trojan Asteroids important for astronomers?

Although the first asteroids were discovered over a century ago, scientists still have more questions about the nature and properties of Trojans than answers. They were observed only from a great distance, so astronomers even judge their shape on the basis of models.

It is known that Trojan asteroids differ from the usual asteroids of the Main Belt and in a number of characteristics are more similar to trans-Neptunian objects – low albedo, reddish color, strongly inclined orbits. It is believed that these objects may contain more water ice and complex organic molecules than many of the main belt asteroids.

There are also disputes over the mechanism of formation of Trojan asteroids in the orbit of Jupiter – so far, none of the theories can explain the observed parameters of their orbits.

Comparative sizes of the Trojan Asteroids targeted by Lucy. Credit: NASA
Comparative sizes of the Trojan Asteroids targeted by Lucy. Credit: NASA

There is a version that these are generally bodies from the Kuiper belt, which is located behind Neptune – if Jupiter and Saturn once influenced the orbit of Uranus and Neptune, and they sent a heap of Kuiper bodies in the direction of the offenders.

It is assumed that the Trojans formed in the inner part of the solar system, long before entering the orbits of giant planets like Jupiter which has the highest number of asteroid satellites.

Thus, the study of Trojans will provide planetary scientists with a large amount of information about what happened in the early solar system and the differences in the composition of the material of the protoplanetary disk at different distances from the Sun.

Hence the name of the new NASA mission – as at one time the skeleton of Australopithecus Lucy made a great contribution to anthropology, so the robotic “Lucy” will help to learn a lot about the past of the solar system.

NASA launched Lucy: Everything you need to know about the mission

Development and instruments

The development of Lucy began in 2017 and was carried out by NASA as part of the Discovery program. The device, with a total weight of 1,550 kilograms, is equipped with two huge 7.3-meter round solar batteries, a two-meter antenna, and a set of four scientific instruments – two cameras (multispectral and high resolution) and two spectrometers (infrared and thermionic).


NASA added a curious addition to the spacecraft – a commemorative plaque with messages from various cultural and scientific figures and a diagram showing the position of the planets at the time of the station’s launch.

Lucy's plaque with messages from important historical figures. Credit: NASA
Lucy’s plaque with messages from important historical figures. Credit: NASA

Mission objectives

The mission of the apparatus will be to study from the flyby trajectory of the Trojan asteroids of Jupiter, which are located in the vicinity of the Lagrange points L 4 and L 5 in the Sun – Jupiter system and orbital resonance 1: 1 with the planet.

Jupiter’s asteroids

These objects are found in many planets of the solar system, but Jupiter has the largest number of them – more than seven thousand. Their study will help planetary scientists better understand the processes that took place in the early solar system.

General view of "Lucy". Credit: Swri
General view of “Lucy”. Credit: Swri

Gravitational maneuvers and first flyby

In the next three years, the station will make two gravitational maneuvers near the Earth, and only after that it will go to its first target – the asteroid of the Main Belt (52246) Donaldjohanson. The first flyby has been scheduled for April 20, 2025.


Next targets

Then, Lucy will begin to study objects near point L 4 in the Sun-Jupiter system: on August 12, 2027, a flyby past the double Trojan (3548) Eurybates & Queta, on September 15, 2027 – past (15094) Polymele, on April 18, 2028 – past (11351 ) Leucus, and on November 11, 2028 – past the asteroid (21900) Orus.

Final objectives

After that, the station will perform another gravitational maneuver near the Earth and head to the L 5 point in the Sun-Jupiter system, where on March 2, 2033, it will examine Patroclus and Menoetius.

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Greshko, M. (2021, October 16). NASA’s Lucy Mission Blasts Off to unlock mysteries of the solar system. Science.
Pirani, S., Johansen, A., Bitsch, B., Mustill, A. J., & Turrini, D. (2019, February 20). The consequences of planetary migration on the minor bodies of the early solar system.
Potter, S. (2021, October 16). NASA, ULA launch Lucy Mission to ‘fossils’ of planet formation. NASA.
Roulette, J. (2021, October 16). NASA’s Lucy launches on 12-year mission to Jupiter’s trojan asteroids. The New York Times.
Thompson, A. (2021, October 16). NASA launches robotic archaeologist Lucy on ambitious mission to trojan asteroids.
Urrutia, D. E. (2021, October 15). Meet the 8 asteroids NASA’s Lucy spacecraft will visit.

Written by Vladislav Tchakarov

Hello, my name is Vladislav and I am glad to have you here on Curiosmos. As a history student, I have a strong passion for history and science, and the opportunity to research and write in this field on a daily basis is a dream come true.

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