The photo on the left captures an operating electric Hall thruster identical to those that will propel NASA's Psyche spacecraft, which is set to launch in August 2022 and travel to the main asteroid belt between Mars and Jupiter. The xenon plasma emits a blue glow as the thruster operates. The photo on the right shows a similar non-operating Hall thruster. The photo on the left was taken at NASA's Jet Propulsion Laboratory in Southern California; the photo on the right was taken at NASA's Glenn Research Center.
Psyche's Hall thrusters will be the first to be used beyond lunar orbit, demonstrating that they could play a role in supporting future missions to deep space. The spacecraft is set to launch in August 2022 and will travel to its target, a metal-rich asteroid also named Psyche, under the power of solar electric propulsion. This super-efficient mode of propulsion uses solar arrays to capture sunlight that is converted into electricity to power the spacecraft's thrusters. The thrusters work by turning xenon gas, a neutral gas used in car headlights and plasma TVs, into xenon ions. As the xenon ions are accelerated out of the thruster, they create the thrust that will propel the spacecraft.
Arizona State University in Tempe leads the Psyche mission. JPL is responsible for the mission's overall management, system engineering, integration and test, and mission operations. Maxar Technologies in Palo Alto, California, supplied the thrusters and built the high-power solar electric propulsion spacecraft chassis.
For more information about NASA's Psyche mission, go to: http://www.nasa.gov/psyche or https://psyche.asu.edu/
More information on Psyche's solar electric propulsion is available here: https://psyche.asu.edu/2018/01/19/electric-thrusters-psyche-spacecraft-work/