SERT-1 (Space Electric Rocket Test) was a NASA probe used to test electrostatic ion thruster design and was built by NASA's Lewis Research Center (now NASA Glenn). SERT-1 was the first spacecraft to utilize ion engine design. It was launched on July 20, 1964 on a Scout rocket. It carried two electric propulsion engines; of the two, the first, an electron-bombardment ion engine ("Kaufman ion thruster") was run for a total of 31 minutes and 16 seconds. This was the first time that an ion engine of any type had been operated in space, and demonstrated that the neutralizer worked as predicted. (A second thruster, of a different type, failed to operate.)