In 2259 the Enterprise tried to divert a comet away from the inhabited world of Persephone III, only to find the comet protected by a powerful alien ship.
The comet was on course to strike Persephone III, home to a pre-warp civilization, and the Enterprise moved to push it aside. A landing party that included Nyota Uhura found the comet was more than ice, and Uhura discovered that music could open a way inside.
An ancient vessel whose crew called themselves Shepherds attacked the Enterprise for tampering with the comet, which they considered sacred. Pike's crew found a way to change its course without destroying it, and the crisis ended peacefully.