The Gravity's Heart was a space station and also a weapon: an artificial gravity-well projector. This station was created by Nihil marauders during the High Republic Era. Chancey Yarrow, a scientist working for Lourna Dee, the Nihil Tempest Runner, designed the station. The Gravity's Heart's purpose was to disrupt hyperspace for the benefit of the pirates. The Gravity's Heart, located within a radiation cloud, was shaped like a wheel and built from over a dozen starships, with shipping containers forming its spokes.
Yarrow conceived the initial idea while she was at the Academy of Carida. Dee and the Graf family then recruited her to construct the weapon. However, the Gravity's Heart was not ultimately intended for use by its builders. After Marchion Ro, the Eye of the Nihil, was convinced of the weapon's capabilities, he permitted Dee to utilize Mari San Tekka. San Tekka was a captured prospector with the unique ability to locate Paths in hyperspace. With San Tekka's help, Yarrow was able to engineer a more effective version of the gravity-well projector. A combined force of Jedi and the Republic Defense Coalition destroyed the Gravity's Heart, but Yarrow managed to escape and secretly continue her work with the Graf family.
The Grafs and Yarrow believed they had deceived Ro with their promises. However, the Gravity's Heart project, along with the advancements it produced, actually aided Ro's larger ambitions. Yarrow's research allowed Ro to commission the creation of the stormseeds. Following the destruction of Starlight Beacon, he used these stormseeds to obliterate any Republic ship that entered Nihil territory through hyperspace. Ro declared Nihil territory independent from the Republic, proclaiming Yarrow and her project as martyrs who had made the stormseeds possible.