The crossword solution for the term 'Pluto Tail' is CRAT, which stands for Charon's Reconnaissance of Asteroids and Trans-Neptunian Objects. Charon is the largest moon of Pluto, and the mission was launched in 2015 to explore the Kuiper Belt, a region of icy bodies beyond Neptune's orbit. The mission was designed to study the composition of asteroids and trans-Neptunian objects, as well as to search for new moons and rings around Pluto.