Imaging Lunar Craters with the Lucy Long Range Reconnaissance Imager (L'LORRI): A Resolution Test for NASA's Lucy Mission

NASA's Lucy mission is designed to better understand the unique population of Trojan asteroids. Trojans were probably captured in Jupiter's L4 and L5 points early in the solar system's evolution and little altered since then. A critical investigation of Lucy is to use its highest-resolution camera, the Lucy Long Range Reconnaissance Imager (L'LORRI), to image Trojans' surfaces to understand their geology and impact crater populations. Through crater statistics, the population of smaller bodies that produced those impacts, relative age differences across the bodies, and other comparative investigations between bodies can be studied. Mapping the crater population to the minimum diameters needed to achieve Lucy's objectives might require image subsampling and deconvolution ("processing") to improve the spatial resolution, a process whereby multiple, slightly offset images are merged to create a single, better-sampled image and deconvolved with L'LORRI's point-spread function. Lucy's first Earth Gravity Assist (EGA1) provided an opportunity to test this process's accuracy using L'LORRI images of the Moon, whose crater population is well characterized and therefore provides ground-truth testing. Specifically, the lunar crater imaging by L'LORRI during EGA1 allowed us to compare crater statistics derived from raw and processed L'LORRI images with ground-truth statistics derived from higher-resolution lunar imaging from other missions. The results indicate the processing can improve impact crater statistics such that features can be identified and measured to ~70% the diameter that they can otherwise be reliably mapped on native L'LORRI images. This test's results will be used in the observation designs for the Lucy flyby targets

A brief history of spacecraft missions to asteroids and protoplanets

There are hundreds of thousands of known asteroids, yet only 14 have been visited by spacecraft thus far, and 9 of those were targets of opportunity. The remaining five asteroids (Braille, Eros, Itokawa, Vesta, and Ceres) were visited by four missions dedicated to asteroid research (Deep Space 1, NEAR-Shoemaker, Hayabusa, and Dawn, respectively). In fact, of these five asteroids, Vesta and Ceres are perhaps better defined as protoplanets because of their sizes and the emerging evidence for their physical and chemical evolution. Two more near-Earth asteroids will be visited in 2018, followed by even more visits in 2023 and 2030. This asteroid mission chronology is listed in Table 1.1. This chapter will tell the story of these asteroid missions and visit each of them in turn to briefly review some of the exciting science results. The story begins with asteroid 951 Gaspra and continues down the list in Table 1.1, according to the target asteroid name presented in chronological order

In Situ Science and Instrumentation for Primitive Bodies

Our study began with the goal of developing new methods to test the radically new understanding of solar system formation that has recently emerged, and to identify innovative instrumentation targeted to this purpose. In particular, we were seeking to test predictions of dynamical models such as the Nice model, and to do so through interdisciplinary collaboration between the planetary dynamics communities that have formulated (and largely dominated discussion of) these new ideas, and the meteoritics and cosmochemistry communities who will be most involved in any in-situ mission to an outer solar system body. Our study was principally focused on coming up with explicit tests of the predictions of these new dynamical models of solar system evolution