NASA’s Green Propellant Mission Passes Key Milestone

An artist’s rendering of NASA’s Green Propellant Infusion Mission payload in flight aboard the Ball Aerospace BCP-100 spacecraft.
Credits: Ball Aerospace

NASA’s Green Propellant Green Propulsion Infusion Mission (GPIM) has passed a critical flight readiness milestone in anticipation of launch in early 2017, completing functional and equipment testing of its systems and software.

The mission which will provide on-orbit demonstration of a new, less toxic “green” propellant will be tested aboard a Ball Aerospace Configurable Platform 100 satellite, using a propulsion subsystem developed by Aerojet Rocketdyne.

During the course of its mission, the spacecraft will fire its five thrusters to perform a variety of tests to validate predicted performance and demonstrate reliability.

The propellant itself is a hydroxyl ammonium nitrate based fuel/oxidizer blend which was developed by the U.S. Air Force Research Lab and goes by the formal name AF-M315E.

According to NASA, it is 45% denser than the standard hydrazine mixture which most spacecraft use, and combined with higher ISP offers a 50% increase in efficiency in terms of propellant volume for a given tank size. It also has a lower freezing point, resulting in less demand for power to keep it at operating temperature. The real attraction however, is that it is simply not as nasty as hydrazine, reducing the burden of special handling procedures that increase launch preparation times and drive up costs.

NASA is not the only entity pursuing “green” propellants. In 2014, Sierra Nevada Corporation wholly acquired Orbital Technologies Inc (Orbitech), in part to integrate that company’s own green propellant into the reaction control system for SNC’s Dream Chaser space plane. The use of non-toxic propellant aided Dream Chaser’s winning entry in NASA’s Commercial Resupply Services 2 competition due to the fact that it allows for rapid removal of returned experiments without requiring de-contamination procedures. It also allows Dream Chaser to tentatively land at any commercial airfield with a long enough runway for similar reasons.