Thirteenth mission of the Discovery program; multiple-flyby reconnaissance of six Jupiter trojans
Lucy
Artist's conception of Lucy spacecraft flying past the Trojan asteroid 617 Patroclus and its binary companion Menoetius. Lucy will be the first mission to explore Jupiter's Trojan asteroids – ancient remnants of the outer solar system.
Animation of Lucy's trajectory around Sun Lucy· Sun· Earth· 52246 Donaldjohanson· 3548 Eurybates· 21900 Orus· 617 Patroclus
Lucy is a NASAspace probe on a 12-year journey to eight different asteroids, visiting a main beltasteroid as well as seven Jupiter trojans,[2][3] asteroids which share Jupiter's orbit around the Sun, orbiting either ahead of or behind the planet. All target encounters will be fly-by encounters.[4] The Lucy spacecraft is the centerpiece of a US$981 million mission.[5]
The mission is named after the Lucy hominin skeleton, because the study of Trojans could reveal the "fossils of planet formation": materials that clumped together in the early history of the Solar System to form planets and other bodies.[7] The Australopithecus itself was named after the 1967 Beatles song "Lucy in the Sky with Diamonds",[8] Lucy itself is also carrying a disc made of lab-grown diamonds for her L'TES instrument.[9]
Lucy was launched from Cape Canaveral LC-31 on 16 October 2021 on the 401 variant of a United Launch AllianceAtlas V launch vehicle, after which it will gain two gravity assists from Earth; one in 2022, and one in 2024.[10] In 2025, it will fly by the inner main-belt asteroid 52246 Donaldjohanson, which was named after the discoverer of the Lucy hominin fossil.[11] In 2027, it will arrive at the L4 Trojan cloud (the Greek camp of asteroids that orbits about 60° ahead of Jupiter), where it will fly by four Trojans, 3548 Eurybates (with its satellite), 15094 Polymele, 11351 Leucus, and 21900 Orus.[4] After these flybys, Lucy will return to Earth in 2031 for another gravity assist toward the L5 Trojan cloud (the Trojan camp which trails about 60° behind Jupiter), where it will visit the binary Trojan 617 Patroclus with its satelliteMenoetius in 2033. The mission may end with the Patroclus–Menoetius flyby, but at that point Lucy will be in a stable, 6-year orbit between the L4 and L5 clouds, and a mission extension will be possible.
Exploration of Jupiter Trojans is one of the high-priority goals outlined in the Planetary Science Decadal Survey. Jupiter Trojans have been observed by ground-based telescopes and the Wide-field Infrared Survey Explorer to be "dark with... surfaces that reflect little sunlight".[13] Jupiter is 5.2 AU (780×10^6 km; 480×10^6 mi) from the Sun, or about five times the Earth-Sun distance.[14] The Jupiter Trojans are at a similar distance but can be somewhat farther or closer to the Sun depending on where they are in their orbits. There may be as many Trojans as there are asteroids in the asteroid belt.[15]
NASA selected Lucy through the Discovery Program AO released on 5 November 2014.[16] Lucy was submitted as part of a call for proposals for the next mission(s) for Discovery Program that closed in February 2015. Proposals had to be ready to launch by the end of 2021. Twenty-eight proposals were received in all.
On 30 September 2015, Lucy was selected as one of five finalist missions, each of which received US$3 million to produce more in-depth concept design studies and analyses.[17][18][19][20] Its fellow finalists were DAVINCI, NEOCam, Psyche and VERITAS. On 4 January 2017, Lucy and Psyche were selected for development and launch.
On 31 January 2019, NASA announced that Lucy would launch in October 2021 on an Atlas V 401 launch vehicle from Cape Canaveral, Florida. The total cost for the launch is estimated to be US$148.3 million.[21] On 11 February 2019, SpaceX protested the contract award, claiming that it could launch Lucy into the same orbit at a "significantly cheaper cost". On 4 April 2019, SpaceX withdrew the protest.[22]
On 28 August 2020, NASA announced that Lucy had passed its Key Decision Point-D (KDP-D) with a "green light" to assemble and test the spacecraft and its instruments.[23] The spacecraft instruments arrived beginning with L'LORRI on 26 October 2020.[24] On 30 July 2021, the spacecraft was transported on a C-17 transport aircraft to Florida for launch preparations, and Lucy was encapsulated into the rocket fairing on 30 September 2021.
Lucy was launched on 16 October 2021 at 09:34 UTC[25][26] at the opening of its 23-day launch window.[26]
Payload
A plaque on the Lucy mission featuring 20 messages from people on EarthThe launch, 16 October 2021 at 5:34AM EDT
L'Ralph - panchromatic and color visible imager (0.4-0.85 μm) and infrared spectroscopic mapper (1-3.6 μm). L'Ralph is based on the Ralph instrument on New Horizons and was built at Goddard Space Flight Center. It will be used to measure silicates, ices, and organics at the surface.
L'TES - thermal infrared spectrometer (6-75 μm). L'TES is similar to OTES on the OSIRIS-REx mission and was built at Arizona State University. It will reveal the thermal characteristics of the observed Trojans, which will also inform the composition and structure of the material on the surface of the asteroids.
The radio science investigation will determine the mass of the Trojans by using the spacecraft radio telecommunications hardware and high-gain antenna to measure Doppler shifts.
The spacecraft is also adorned with a golden plaque containing its launch date, the positions of the planets at the launch date, the continents of Earth at the time of launch, its nominal trajectory, and twenty speeches, poems, and song lyrics from people such as Martin Luther King Jr., Carl Sagan, The Beatles, and more. Because the spacecraft will not leave the Solar System or be ditched into a planetary body, there is a chance that future generations of humanity will be able to recover it and with this mission "what was the foot of the walker becomes the path" of the human lineage.[27]
P-type asteroid that may be a collisional fragment of a larger P-type asteroid. Its red color suggests surface is rich in organic compounds called tholins.
Lucy will alternate visiting Jupiter's Greek (L4) and Trojan camps (L5) every six years.Animation of Lucy's trajectory around Sun - frame rotating with Jupiter Lucy· Sun· Earth· 52246 Donaldjohanson· 3548 Eurybates· Jupiter· 617 Patroclus
See also
DESTINY+, a planned JAXA mission to flyby multiple asteroids.
^ abFox, Karen; Johnson, Alana; Jones, Nancy (16 October 2021). "NASA, ULA Launch Lucy Mission to "Fossils" of Planet Formation". NASA. Retrieved 16 October 2021. This article incorporates text from this source, which is in the public domain. Cite error: The named reference "launch" was defined multiple times with different content (see the help page).
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