Ground-based characterization of Eurybates and Orus, two fly-by targets of the Lucy Discovery mission
Abstract
Lucy is a proposed NASA Discovery mission designed to perform close fly-bys with six Jupiter Trojan asteroids. The mission, which is currently in the Phase A development phase, is planned to launch in 2021 and arrive at the Trojan L4 cloud in 2027.We report on ground-based light curve observations of two of Lucy's fly-by target candidates: (3548) Eurybates and (21900) Orus. The goal is to characterize their shape, spin state and photometric properties both to aid in the planning of the mission, and to complement the space-borne data.Each object has been observed over 5 apparitions in a wide range of geocentric ecliptic longitudes. Shape and spin state modeling was performed by using the convex shape inversion method (Kaasalainen, Mottola & Fulchignoni, 2002). Eurybates is a retrograde rotator with a sidereal rotation Psid=8.702724±0.000009 h. It has a moderately elongated shape with equivalent axial ratios a/b=1.08, b/c=1.16. No obvious signs of global non-convexities and/or albedo variegation are detected in its light curves. Orus is also a retrograde rotator with a period Psid=13.48617±0.00007 h. Its approximate axial ratios are a/b=1.14, b/c=1.12. The presence of a large, planar facet in the proximity of the model's North Pole suggests the presence of a large polar crater.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #48
- Pub Date:
- October 2016
- Bibcode:
- 2016DPS....4820804M