Like all rocket engines, the small thrusters that a spacecraft or satellite fires to maintain or change positions need fuel. Currently, many use hydrazine -- a toxic and corrosive fuel that requires special handling and equipment. NASA's Green Propellant Infusion Mission (GPIM) recently took another major step toward demonstrating the capabilities of a new propellant that is safer to handle on the ground and more efficient for thrusters in space. The GPIM spacecraft has passed a major flight readiness milestone marking the successful completion of functional and environmental testing of its systems and software, and is on track for launch in early 2017. "We are increasingly reliant on satellites for communications, for monitoring weather and conditions on Earth and for exploration of the universe," said Steve Jurczyk, associate administrator of NASA's Space Technology Mission Directorate. "It's important that we develop technology that increases protections for launch personnel and the environment, and that has the potential to reduce costs."