The runabout is a true multi-role starship with engine efficiencies and cargo capacities proportional to larger vessels. The Danube-class project began as a vehicle study in 2363 at the ASDB for a ship that could perform a variety of scientific, re-supply, and personnel transfer missions. The prototype U.S.S Danube, NX-72003, was ordered constructed at the Utopia Planitia Fleet Yards in 2365, and began flight trials off the surface of Mars in early 2368. The finished vehicle measured 23.1 meters in length, 13.7 meters abeam, and 5.4 meters tall. As the Danube was making its preliminary warp tests within the solar system, the first production series was well along its final assembly cycle. The first 5 runabouts to be delivered to the fleet inventory were the USS Rio Grande, USS Mekong, USS Orinoco, USS Yangtzee Kiang, and USS Rubicon, all named after Earth Rivers, all were delivered to Deep Space 9 as transport craft and limited exploration vessels designed for operation in the Gamma Quadrant.