Drs. Xavier and Maria Fernandes were working on a prototype coaxial warp drive and achieved great results with the theoretical model. They utilized the USS Auckland (NCC-4100) as a testbed in the 2350s. Unfortunately, the test was a failure, severely damaging the ship. The survivors gathered on a nearby M-class planet, but the Auckland's explosion, coupled with the damage to space, severely affected the planet's inhabitants, slowly driving them mad. (Star Trek: The Cantabrian Expeditions: "Salvation")
Unfortunately, the ship utilizing the coaxial warp drive was unstable when it dropped out of warp. In theory, a coaxial warp drive explosion could collapse space within a radius of a billion kilometers. Tom Paris suggested, and implemented, a symmetric warp field to contain any instabilities in a space-folding core. The core stablised shortly after.
The drive's core was a device that drew in subatomic particles and reconfigured them, thus allowing the space-folding mechanism to work. The device, however, was not compensating for instabilities in the particles. Paris suggested using a carburetor-like device, diluting the subatomic energy flow slightly to counter it. With the modification, Steth's ship was able to use the coaxial warp drive successfully.
- Before the incident involving Steth, Voyager personnel believed the coaxial warp drive to be "merely hypothetical" technology. This indicates that the failed Fernandes experiment and invention were not widely known beyond top-secret circles in Starfleet. Indeed, in Star Trek: The Cantabrian Expeditions, it is implied that only Antonio Fernandes and Daniel Radke know about his parents' failed attempt on the Auckland.