Green Propellant Infusion Mission

The Green Propellant Infusion Mission (GPIM) was a NASA technology demonstrator project that tested a less toxic and higher performance/efficiency chemical propellant for next-generation launch vehicles and CubeSat spacecraft. When compared to the present high-thrust and high-performance industry standard for orbital maneuvering systems, which for decades, have exclusively been reliant upon toxic hydrazine based propellant formulations, the "greener" hydroxylammonium nitrate (HAN) monopropellant offers many advantages for future satellites, including longer mission durations, additional maneuverability, increased payload space and simplified launch processing.

Source: Wikipedia — Green Propellant Infusion Mission (CC BY-SA 4.0)