USS Cassini class Deep Space Galaxy Exploration Vessel

The first "non-combat" tri-nacelle starship was the Phase-III refit of the Pioneer/Crossfield/Discovery family of deep space science vessels. The Cassini class uses an improved Trans-Dimensional drive system that is further towards the "Transwarp" method of jump through hyperspace than is the Mark-I of the Discovery class which is closer to a "Slipstream" style of drive.
Three LN-69 warp nacelles were used. One LN-69P (Port emission), LN-69S (Starboard emission), and one LN-69C (Central emission) to generate a stable wormhole the ship can jump through. Unlike the previous drive system, the Mark-II Transdimensional drive required the Cassini class of starship to scan the electromagnetic field of the galaxy for "transport lines" it used to travel on akin to a cable-car through hyperspace. The Mark-II had to be used in specific locations in the galaxy for it to work, otherwise the ship would simply jump to anywhere in the galaxy that the electromagnetic field took it to.