Lucy is the first reconnaissance of the Jupiter Trojan asteroids - objects that hold vital clues to deciphering the history of the Solar System. Due to an unusual and fortuitous orbital configuration, Lucy will perform an exhaustive landmark investigation that visits four of these primitive asteroids,

covering both the L and L swarms, all the known taxonomic types, and a nearly equal mass binary. It will use a suite of high-heritage remote 4 5

sensing instruments to map the geology, surface color and composition, thermal and other physical properties of our targets at close range - all this within constraints of the Discovery Program. Thus, Lucy, like the human fossil for which it is named, will revolutionize the understanding of our origins.

Mission Overview

Science Objectives

Importance to NASA Objectives - Decadal Survey Recommendation

Through its unique tour, Lucy will provide crucial input to four of the ten Priority Questions for Planetary Science as expressed by DS13:Through its unique tour, Lucy will provide crucial input to four of the ten Priority Questions for Planetary Science as expressed by DS13:

• What were the initial stages, conditions and processes of Solar System formation ...?• How did the giant planets ... accrete, and is there evidence that they migrated to new orbital positions?

• What governed the accretion ..., and what roles did bombardment by large projectiles play?

• What were the sources of primordial organic matter?

High Impact Science

Baseline Mission Trajectory Lucy’s Comprehensive Tour

Surface GeologySurface Composition Interior and Bulk Properties Satellite and Ring Search

Lucy will map albedo, shape, crater spatial and size-frequency distributions, determine the nature of crustal structure and layering, and determine the relative ages of surface units.

“Study of these objects [Trojans] is important because they may contain key information about the parent materials that accreted in the inner Solar System. An important science goal for this decade is to begin the scientific exploration of the trojan asteroids.” - Planetary Decadal Survey 2013 (DS13)

Lucy will map the color, composition and regolith properties of the surface and determine the distribution of minerals, ices and organics species.

Lucy will determine the masses and densities, and study sub-surface composition via crater windows, fractures, ejecta blankets, and exposed bedding.

Lucy will determine the number, size-frequency distribution and location of km-scale satellites and dense rings.

Ta009332-LUCY

p

L Trojans

5

L T

roja

ns4

Jupiter

Launch: October 2021Flyby 1 - 1981 EQ C-Type Main-Belt: April 20255

Flyby 2 - Eurybates C-Type Trojan: August 2027

Flyby 3 - 1999 VQ D-Type Trojan: October 2028 10Flyby 4 - Patroclus & Menoetius P - Type Trojan Binary: March 2032

Patroclus &Menoetius

Launch

1981 EQ5

1999 VQ10

Eurybates

Frame rotating with Jupiter

Earth

Lucy

Sun

p

p

p

p

pp

p

p

p

CapturedTrojans

TA009400-LUCY

Jupiter Saturn Uranus NeptuneDistance from Sun

Ejected Planetesimals

Trojans likely harbor objects that formed throughout the outer Solar System. It is only by sampling their complete diversity that their true scientific potential can be realized.

Lucy will study:• All Trojan Classes: • Both the L and L swarms.4 5

C-, D-, and P-types.

Use or disclosure of the data contained on this sheet is subject to Section A.4 restrictions.

SurveyingtheDiversityofTrojansFO1Lucy'sTour

TA009 -319 LUCY-E

January2031

Earth Gravity Assist 2Altitude = 300 km

DSM1372 m/s

J

B

Frame rotating with Jupiter

L Trojans

5

L T

roja

ns4

Jupiter

Earth

Sun

p

p

p

p

pp

p

p

p

April 20251981 EQ Encounter5

Approach Angle = 167 degrees, Velocity = 13.4 km/sMember of Young (~130Myr) Erigone Family

D

p

October2021

Launch2 2C3 = 51.5 km /S

A

DSM371 m/s

G

DSM2148 m/s

E

December2024

Earth Gravity Assist 1Altitude = 4501 km

C

DSM4623 m/s

I

LUCY

August 2027Eurybates Encounter

Approach Angle = 111 degrees, Velocity = 5.7 km/sLargest Member of Only Confirmed Trojan Family

F

October 2028

1999 VQ Encounter10

Approach Angle = 69 Degrees, Velocity = 7.0 km/sMember of Eurybates Family

H

March 2032Patroclus/Menoetius EncounterApproach Angle = 203 Degrees,

Velocity = 18.2 km/sLike-sized Binary; Possible Lone Survivor of

Initial Planetesimal Population

K

April 20281997 TS Encounter25

Anomalously LongRotational Period

SEO

Inclination (deg)

Eccentricity

Visible Albedo

Spin (hrs)

Diameter (km)

Type

Class

22

0.12

0.047

103

113/104

P

L Trojan5

Binary

4.4

0.19

0.1

Unknown

3.9

C

Main Belt

8.1

0.09

0.05

8.7

64

C

L Trojan4

12

0.07

0.08

515

34

D?

L Trojan4

8.5

0.04

0.08

13.5

51

D

L Trojan4

1981 EQ5 Eurybates1997 TS25

(SEO)1999 VQ10

Patroclus/Menoetius

18º14º 78º 126ºInitial Phase Angle

Lucy's innovative trajectory obtains flybys of all known Trojan spectral types and leverages the fortuitous alignment of Patroclus and Menoetius in the plane through the L swarm.5

SEO: Not in Current Tour

Color KeyC-type P-type D-type

Use or disclosure of the data contained on this sheet is subject to Section A.4 restrictions.