Repulsorlifts only worked within a gravity well, as the technology required mass to push against. For a typical habitable planet such as Alderaan, "antigrav range" was approximately six planetary diameters, or around seventy-five thousand kilometers. Repulsorlifts used minimal power and were reliable enough to be utilized continuously. Larger vessels were only able to make planetfall with the aid of massive ventral repulsorlift suspension units. In fact, the landing legs of a Lucrehulk-class Core Ship could not support the ship's immense weight without the aid of repulsorlifts.