Transphasic torpedo

The transphasic torpedo was a Starfleet weapon developed sometime in the 2380s in a future alternate timeline. It was designed specifically to handle the Borg threat, with input by Captain Kathryn Janeway and the crew of the USS Voyager.

In 2378, the point to which Admiral Janeway from the alternate timeline had travelled back in time, the Admiral introduced Captain Janeway to this technology for use in reaching a Borg transwarp hub accessing the Borg transwarp network to return to Earth. When entering the nebula where the transwarp hub was located, one transphasic torpedo was enough to destroy a Borg cube. Despite the use of transphasic torpedoes to destroy three cubes, the Borg Collective had not yet adapted to the torpedoes when Voyager fired at the interspacial manifolds in the transwarp network. All remaining torpedoes are now in the hands of Starfleet. (VOY]: "Endgame")


 * Despite the power of the transphasic torpedo, they were not shown or mentioned in Star Trek: Nemesis, possibly due to research or them being stored away by Starfleet to prevent suspicion from other species and to prevent a major power shift. They may have also been mothballed or destroyed due to temporal considerations. Another possibility is that, since Voyager states that its photon torpedoes are irreplaceable, the transphasic torpedoes might be similarly so, despite having the resources of Starfleet. It might just be that Starfleet has not put the Torpedo into Mass Production yet.  Or, as it was specifically designed for use against the Borg, it may exploit some unique aspect of Borg technology and be of little use against other targets.

In Star Trek: Pioneer the torpedoes were stored in Starfleet's experimental weapons headquarters. In 2383 a team from the mirror universe lead by Captain Janeway beamed into the building from their universe and downloaded data on every weapon stored there including the transphasic torpedoes. In the mirror universe they were not immediatly put into mass production due to technological limitations however a few experimental variants were given to the more powerful ships in the Terran starfleet. (Star Trek: Pioneer: "Dark Reflection")