The Field Robotics Center (FRC) at Carnegie Mellon University developed a mobile robot to inspect interiors of fuel storage tanks, both above-ground (AST) and under-ground (UGST). Neptune inspects tanks for visible deterioration, using a video camera and inspects for wall and floor corrosion, using add-on sensors, as part of its standard capabilities. The system included a self-contained portable unit, which attaches to storage tanks. This unit deploys a small, reconfigurable robot, driven by dual magnetic tracks, carrying a camera and lights, navigation system, ultrasonic testing (UT) sensors, or other sensing probes. The robot’s reconfigurable design allowed it to fit through large tank openings (20″ O.D.) using a parallel-crawler configuration.