NEAT: A Multi-Comet Flyby Mission that Performs Discovery-Level Science on a SIMPLEx Budget

The Nucleus Evolution & Activity Tour (NEAT) is a proposed solar-electric-propelled small-satellite mission (ESPA class) that will perform low-altitude low-velocity flybys of comet nuclei with a suite of four cameras. NEAT’s primary target will be Comet 73P/Schwassmann-Wachmann 3. Comet 73P first fragmented in 1995, exposing its interior to space, and has demonstrated additional activity and possible additional fragmentation during subsequent perihelion passages. Attempts to explore comet interiors (e.g., Deep Impact, Rosetta), have provided only limited information about their respective targets. Major questions remain regarding the size-distribution of material comprising comets, and the distribution of volatiles and porosity with depth, limiting what we can learn from comets about the era of planet formation. NEAT aims to explore 73P’s exposed interior, thereby rapidly advancing our understanding of how comets are constructed and evolve with time. Further, though some comets are known to spontaneously fragment, the mechanism by which they do remains poorly known. Disruption does not appear to be correlated with orbital parameters, and does not always lead to the catastrophic disruption of the entire nucleus. NEAT’s proposed exploration of the recently fragmented comet 73P will provide the necessary data to constrain this common, though poorly known method through which small bodies disassemble. Comet nuclei have also proven to be diverse, hosting differing morphologies that are the result of differences in dynamical age, orbital conditions, rotation state, shape, and varying seasonal effects. NEAT’s exploration of comet 73P will provide the first close-up observations of a fragmenting comet, helping to decipher both how comets form and are destroyed. Future comet exploration will require a mix of both flybys and more complex rendezvous efforts like Rosetta, including sample return. NEAT represents an inexpensive option for continuing cometary exploration.