Trojans' Origin 0.4 0.20 Trojans' Colors Lucy Is a Trojan Tour: Ejected Planetesimals → It Will Perform ﬂybys of 6 Jupiter Trojans 0.3 0.15

Home , Menoetius

Trojan Colors Trojan Albedos Trojans' origin 0.4 0.20 Trojans' colors Lucy is a Trojan Tour: Ejected Planetesimals → It will perform ﬂybys of 6 Jupiter Trojans 0.3 0.15

→ 2021 launch, encounters from 2025-2033 Albedo

Captured

0.2 m 0.10

→ High science return from never before μ Trojans encountered population J-K Lucy Targets Hot Population 3.4 0.1 0.05 Science Motivation: Emery et al. 2011 Cold Population → Trojans are thought to be remnants 0.0 0.00 Grav et al. 2012 of giant planet formation -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.00 0.05 0.10 0.15 0.20 Invariant Visible Albedo 0.85-J Jupiter Saturn Uranus Neptune Kuiper Belt Plane

→ Trojans are not a homogeneous population: TA009386-LUCY Distance from Sun 1. Contain C, D, and P spectral types (i.e. gray, red, and very red) Trojans present us with a unique opportunity to constrain 2. Have albedos from 4% to 15% planet formation: 3. Wide range of colors 1. They likely formed at different locations (Ds/Ps more primitive than Cs) 2. Were mixed together by planet formation and migration

– Lucy's Payload – T2Cam L'LORRI T2Cam L'Ralph L'LORRI L'Ralph (MVIC+LEISA) L'TES Heritage: OSIRIS-Rex Heritage: New Horizons (NH) Heritage NH, OSIRIS-REx Heritage: OSIRIS-REx, Provider: MSS Provider: APL Provider: GSFC Mars Global Surveyor iFOV = 75 µrad IFOV: 5 μrad – MVIC: Provider: ASU FOV = 10.8 x 8.1 deg FOV: 0.29 x 0.29 deg IFOV: 29 μrad Spectral range: 6-100 μm Spectral Range: 0.4 – 0.8 µm Panchromatic 0.35 – 0.85 μm FOV: 8.3 deg LEISA Spectral range: 0.4-0.85 μm Radio Science: L'TES – LEISA: L'LORRI 2-way Doppler T2 Cam IFOV: 80 μrad measurement MVIC Pan L'TES FOV: 4.6 x 3.2 deg Uses RF system MVIC Color 102 103 104 105 Spectral range: 1.0-3.8 μm Wavelength – Lucy's Science Objectives – 1. Surface composition 2. Surface geology 3. Interior and bulk properties

Lucy will map the color, Lucy will map albedo, shape, Lucy will determine the masses composition and regolith crater spatial and size- and densities, and study sub- properties of the surface and frequency distributions, surface composition via crater determine the distribution of determine the nature of windows, fractures, ejecta minerals, ices and organic crustal structure and blankets, and exposed bedding. species. layering, and determine the relative ages of surface units.

Lucy's twisting trajectory allows it to ﬂy by 6 different Trojans so we can better understand where and how they formed and why they differ

M Orus Encounter Jupiter November 11 2028 L Velocity = 7.1 km/s DSM 5 Frame rotating with Jupiter Jul 23 2028 Solar Phase=126º ΔV = 346.7 m/s Close Approach = 1000 km

C K EGA 1 Leucus Encounter Oct 16 2022 April 18 2028 Altitude = 300 km L Velocity = 5.9 km/s 5 Solar Phase=104º T Close Approach = 1000 km A E rojans An anomalously slow rotator. Launch* EGA 2 Oct 16 2021 Dec 13 2024 C3 = 28.6 km2/s2 Altitude = 350 km O J Patroclus + Menoetius Encounter DSM 4 rojans March 2 2033 Sep 29 2027 T Velocity = 8.8 km/s ΔV = 122.0 m/s 4 L Solar Phase= 56º G Earth Close Approach = 1223 km DSM 3 Apr 3 2027 Like-sized binary; possible lone survivor ΔV=311.4 m/s Lucy of initial planetesimal population. ° I Sun Polymele Encounter

September 15 2027 Velocity = 6.0 km/s Solar Phase= 82º Close Approach = 399 km Lucy’s innovative trajectory obtains ﬂybys of all known Trojan spectral types and leverages the F fortuitous alignment of Patroclus and Menoetius in the plane through the L swarm. DonaldJohanson Encounter 5 Color Key Patroclus/ April 20 2025 C-type P-type D-type DonaldJohanson Eurybates Polymele Leucus Orus Velocity = 13.4 km/s Menoetius H Solar Phase = 15º L Trojan Eurybates Encounter L Trojan L Trojan L Trojan L Trojan 5 Close Approach = 800 km Class Main Belt 4 4 4 4 Binary August 12 2027 Member of young (~130Myr) N Type Velocity = 5.8 km/s Erigone family. EGA 3 C C P D D P Dec 26 2030 Solar Phase= 81º Diameter (km) 3.9 64 21 34 51 113/104 Close Approach = 1000 km Altitude = 660 km Largest member of the Spin (hrs) Unknown 8.7 6.1 440 13.5 103 only conﬁrmed Trojan family. D B Albedo 0.1 0.05 0.09 0.08 0.08 0.047 DSM 2 DSM 1 Feb 2 2024 Apr 19 2022 Eccentricity 0.19 0.09 0.01 0.07 0.04 0.12 ΔV = 898.5 m/s ΔV = 13.5 m/s Inclination 4.4° 8.1° 13° 12° 8.5° 22°

Pole Position (143°, -45°) (28°, -58°) Unknown or Unknown Unknown or (236°, -61°) (long, lat) (325°, -61°) (236°, -68°)

*this ﬁgure is for the opening of the launch window

TA009801-LUCY3 – Lucy's Exciting Targets – The perfect couple The mystery of collisional families The mystery of equal mass binaries More diversity! 0.6 Eurybates and Orus have very Broz et al. 2011 Leucus Polymele p similar orbits and sizes, but Eurybates is the largest 0.5 Patroclus-Menoetius is an equal-mass binary, similar to many cold classical Kuiper Belt Objects. different physical properties! member of the only major 0.4 disruptive collisional family 0.3 50 km among Trojans. Their formation challenges current ideas! Artist conception based on lightcurves Eurybates collisional family Eurybates Orus 0.2 50 km Eurybates is a C-type, rare 0.1 in the Trojans. Perhaps D's pseudo-proper inclination sin/ Patroclus 50 km Menoetius 0.0 become C's when hit. 5.2 5.24 5.28 5.32 5.36 pseudo-proper semimajor axis ap (AU)

Artist conception based on lightcurves Artist conception based on lightcurves

Po1031-LUCY Po1048-LUCY