Cinetheodolites, a type of tracking telescope apparently developed under the supervision of Clyde Tombaugh at the White Sands Missile range. Their scientific use- to track orbital trajectories between here and the moon. In order to pave the way for the moon visit, it was first necessary to determine that there weren't fast spinning tracks of asteroids lying in belts between here and there. The negative result was the third great achievement of his career. First of course being the discovery of Pluto, which was supposed to be Planet X, but wasn't. The second being the result of continuous skysearch for the 12 years following the Pluto discovery, through which he proved to wide acceptance that there were no other planets beyond Pluto (i.e., that Planet X did not exist).