“A genuine space success story,” is how Experiments Manager William Kerslake described NASA’s second Space Electric Rocket Test (SERT II), the first long-duration operation of ion thrusters in space. SERT II provided researchers with data for years beyond its expected lifetime and was a rare example of an entire mission – including the launch, propulsion system, spacecraft, and control center – being handled by one organization: NASA’s Lewis Research Center in Cleveland (today, NASA Glenn). The concept of electric propulsion thrusters dates back to the early 20th century, but because they must…