The space agency's Evolutionary Xenon Thruster (NEXT) project completed a continuous test the ion engine for more than 48,000 hours — over five and a half years — longer than any other space propulsion system ever tested. With low fuel weight and long-running efficiency, ion engines have become strong contenders for deep space missions.

Spacecraft traveling through miles of space require energy to keep moving. Ion propulsion engines can help to minimize the bulkiness of fuel, allowing for increased scientific exploration in smaller packages.