New Horizons and Planetary Exploration

Abstract

NASA’s New Horizons Pluto–Kuiper Belt mission was selected for development on November 29, 2001, following a competitive selection resulting from a NASA mission announcement of opportunity. New Horizons undertook the first exploration of the Pluto system and the Kuiper Belt. It also represents a watershed development in the scientific exploration of a new class of bodies in the solar system—dwarf planets, worlds with exotic volatiles on their surfaces, rapidly (possibly hydrodynamically) escaping atmospheres, and giant impact-derived satellite systems. It also provided other valuable contributions to planetary science, including the first dust density measurements beyond 18 au (astronomical units), cratering records that shed light on both the ancient and present-day Kuiper Belt object (KBO) impactor population down to tens of meters, and a key comparator to the puzzlingly active former dwarf planet and Neptunian satellite, Triton, which is in the same size class as the small planets like Pluto and Eris. The ~475-kg spacecraft carries seven scientific instruments, including imagers, spectrometers, a radio science instrument, a plasma and particles suite, and a dust counter built by university students. New Horizons demonstrated the ability of principal investigator–led missions to use nuclear power sources and to be launched to the outer solar system. As well, the mission has demonstrated the ability of nontraditional entities, like the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institute (SwRI), to explore the outer solar system, giving NASA new programmatic flexibility and enhancing its competitive options when selecting outer planet missions. This article, which heavily adapts and borrows from a 2008 Space Science Reviews article (vol. 140, pp. 3–21), is a historical overview of the origins of the New Horizons mission.