The Lucy Long Range Reconnaissance Imager (L’LORRI)

Abstract

NASA’s Lucy mission spacecraft was launched on 16 October 2021 and will perform the initial in situ investigation of the Jovian Trojan asteroids (Levison et al. 2021, 2024). The Lucy LOng Range Reconnaissance Imager (L’LORRI) is a panchromatic visible light (420–795 nm, 50% QE points), narrow-angle (field of view = 0.29°), high spatial resolution (1.0 ^′′ pixel ⁻¹) imager used on the Lucy mission for both science observations and optical navigation. L’LORRI is designed to provide maps of the sunlit portions of the Trojan surfaces to a resolution of ∼10 m (after deconvolution), which will enable crater counting to constrain the surface ages. L’LORRI’s high sensitivity and large dynamic range permits imaging of the low albedo Trojans at moderately large phase angles (down to I/F values of ∼0.0014 with SNR ≈ 30 using an exposure time of 100 ms), as well as providing early acquisitions of the Trojans during the approach phase, searches for Trojan activity that are ∼10× better than can be obtained from Earth, and deep searches for potential Trojan satellites down to $V \approx 20.4$ at spatial resolutions far surpassing that available from Earth. This paper describes the L’LORRI instrument design and the requirements that drove the design. We present results from L’LORRI’s ground calibration campaign, summarize the L’LORRI in-flight calibration plan, and describe typical L’LORRI operations scenarios during the Trojan flybys. We also present an analysis of in-flight data taken during the first year of Lucy operations, which show that most aspects of L’LORRI’s performance are nominal (i.e., as predicted), but the telescope’s point spread function is slightly degraded relative to pre-flight predictions. Nevertheless, L’LORRI is still expected to fulfill all of its scientific objectives, which should revolutionize our view of the Jovian Trojans.