At the beginning of their journey in 2371, Captain Janeway was hoping to find these along the way to shorten their journey home from the Delta Quadrant. (VOY: "Caretaker") In 2372, after the USS Voyager was duplicated by an encounter with a subspace divergence field, the crew discovered a spatial rift on deck 15, linking the two Voyagers, which existed at the same physical location, but slightly out of phase with each other. When Kes accidentally traveled through the rift, she lost consciousness due to the shock of spatial transition. The crew was eventually able to rig a portable phase discriminator to protect those traveling through from the transition, allowing both crews to interact with each other. (VOY: "Deadlock")