PI: Hal Levison DPI: Cathy Olkin SwRI Project Manager: John Andrews S/C Provider: LM Management: GSFC

2 Lucy is a Trojan asteroid tour  called for in Decadal Survey  It will perform flybys of 5 Trojans (includes SEO). Its strengths are:  High science return from never before encountered objects.  Low risk mission – high heritage.  Low cost mission – costs fit comfortably within AO constraints.  Timely – unique opportunity in launch window gets multiple high- value Trojans launch, encounters from

3 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. To boldly go where no one has gone before. Compare all Trojans types.  Contain C-, D-, and P-type spectral types. Trojans present us with a UNIQUE opportunity  To study Cs, Ds, and Ps in the same environment  Constrain planet migration models  Ds and Ps are more primitive then Cs  They likely formed at different locations  Were mixed together by planet formation and migration Science Motivation and Complications (DeMeo et al.)

4 We have found a trajectory that visits 5 Trojans and 1 MBA

-All known spectral types - Both the L 4 and L 5 swarms

7 (3548) Eurybates is the largest member of the only major disruptive collisional family. We have never visited such an object before. Will give unique insight into collisional processes Eurybates is a C-type?!? Rare in the Trojans. No D-type families in asteroid belt. Perhaps D’s disintegrate when hit. Perhaps D’s become C’s when hit. Lucy will help understand this. The Mystery of Asteroid Families (Broz et al.)

-All known spectral types - Both the L 4 and L 5 swarms -Disruptive collision remnant

9 (3548) Eurybates(21900) 1999 VQ 10 H D64 km51 km P rot8.7 hr13.5 hr e i8.1 deg8.5 deg typeCLikely D pvpv Colorgrayred The Perfect Couple

-All known spectral types - Both the L 4 and L 5 swarms -Disruptive collision remnant

11 (617) Patroclus and Menoetius H8.2 D141 km & 112 km P rot4.3 days e0.14 i22 deg typeP(!) We have been amazingly lucky and found multiple other targets that make this a much richer mission! Piece de Resistance

12 >>75% of Cold Classical KBOs are equal mass binaries o Most undisturbed population in the Solar System. Most objects formed this way? o Their formation is a mystery. Classical ideas don’t work. Most successful idea relies on pebble accretion. o (617) Patroclus is very similar. It will give insight into how these things came to be. The Mystery of Equal Mass Binaries

13 We will also be able to go to these objects. (11351) 1997 TS 25 (52246) 1981 EQ 5 TrojanPrimitive Main Belt Asteroid (used as test of s/c and instruments) H D34 km3.9 km a5.2 AU2.4 AU e i11.6 deg4.4 deg type?Likely C pvpv (TS 25 is an SEO to give us excellent mass margins)

EQ 5 is a member of the ~100Myr Erigone family We will get to see a young surface. Fresh craters will help us understand collisional evolution of AB. It will constrain space weathering. Will help us understand the Yarkovsky forces. EQ 5 is not Just Another Pretty Face

15 L’LORRI L’Ralph Radio Science L’TES Color visible imager and infrared imaging spectrometer Heritage: NH, O’REX High spatial resolution visible imager Heritage: NH Point FTIR spectrometer Heritage: O’REX, MGS No payload hardware Radio science experiment to derive mass from Doppler measurements Team Experience: Rosetta & New Horizons Payload

16 Pan: to 6m/px resolution 4 band color: to 33 m/px NIR spectra: 1 – 3.6 microns to 77 m/px TIR spectra: 6 – 100 microns to 8 km/px

-All known spectral types - Both the L 4 and L 5 swarms -Near-equal mass binary - Disruptive collision remnant -Very young MBA.