Aschelan V was the Cardassian planet whose munitions depot was the intended target of the Dreadnought missile after B'Elanna Torres reprogrammed it for the Maquis, before the weapon vanished into the Delta Quadrant.
Aschelan V is mentioned in the Voyager episode Dreadnought. The self-guided Cardassian missile had been launched against a Maquis base but failed to detonate, and Torres rewrote its computer to strike the fuel and munitions installation on Aschelan V instead.
The weapon never arrived. It was lost in the Badlands and, like Voyager, was carried across the galaxy by the Caretaker.
In 2372 the crew find it travelling through the Delta Quadrant. Its damaged logic has concluded that the inhabited world Rakosa V is Aschelan V, and it refuses to believe otherwise. Torres boards the missile and argues with her own programming before breaching its containment field and destroying it short of the planet.