An experimental 32nd-century Federation propulsion system, first fitted to the USS Voyager-J, which Starfleet eventually chose as its next-generation drive in preference to building more spore drives.
The pathway drive is a new form of faster-than-light propulsion developed by the rebuilt Federation after the Burn showed how dangerous a total dependence on dilithium and warp drive could be.
It is first mentioned in the Discovery episode Kobayashi Maru, where President Laira Rillak reveals that the USS Voyager-J is to carry the prototype and that she has been considering Michael Burnham for its command, before deciding that Burnham is not yet ready.
In Red Directive, at the start of the fifth season, Paul Stamets learns that Starfleet has settled on the pathway drive and is shelving the spore drive programme, leaving Discovery as the only ship of its kind.