The quest for propulsion through gravity control was vaguely implied in various publications. Works by Cook and Cleaver summarized statements in the RIAS brochures. Cook had equated the broad range of RIAS's mission statements with those of Skunk Works. In 1958, Mallan reported "the control of the force of gravity itself for propulsion" was one of the unorthodox goals initiated by Trimble for RIAS.