Originally used in mass numbers on the airports of Old Terra, what has since become known as a ground tug has settled into use on DropPorts throughout the Human Sphere. They often have two uses, the first being to help move Aerodyne DropShips from the runway to their final resting place. The second use for a ground tug is the one many consider to be far more valuable. They and their trailer carry cargo from DropShips to the warehouses that surround them. Most DropPorts have at least one ground tug, while the more busy ones often have enough to empty a DropShip in mere minutes. The ground tugs are an integral part of the fragile interstellar economy that links the planets of the Human Sphere.