NASA’s Solar Electric Propulsion (SEP) project is developing critical technologies to enable cost-effective new trips to Mars and to asteroids across the inner solar system, and also to support a variety of commercial spaceflight activities. Pictured here, advanced solar array systems developed by DSS (left) and ATK (right) of Goleta, Calif. will use less propellant and weigh less than a comparable, conventional propulsion system. The solar arrays, coupled with electrostatic Hall thrusters, will deliver robust power capable of propelling robotic and crewed missions well beyond low-Earth orbit, sending exploration spacecraft to distant destinations or ferrying cargo to and from points of interest, laying the groundwork for new missions or resupplying those already under way.