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Fueling the future with green propellant

Green Propellant Infusion Mission propels industry toward safer, more efficient fuel

By Ricki Watkins

Consider this scenario: You’re headed across town when you realize your car’s gas tank is nearly empty. You pull into a gas station, but because gasoline is so toxic you need to climb inside the hazmat suit you keep in your trunk before you can pump gas. Sound awkward? That is the current challenge aerospace engineers face when they fuel an orbit-bound satellite with hydrazine prior to a launch. Hydrazine – an efficient but highly toxic monopropellant – emits noxious fumes, requiring propellant handlers to don 70-pound Self-Contained Atmospheric Protective Ensemble (SCAPE) suits for safety.

Ball engineers integrate the Aerojet Rocketdyne propulsion subsystem onto the Ball-built spacecraft bus.Enter AF-M315E – a safer, cleaner green fuel alternative that may soon allow engineers to exchange their SCAPE suits for lab coats and goggles.

AF-M315E is the result of 15 years of alternative fuel research by the U.S. Air Force Research Laboratory (AFRL) at Edwards Air Force Base. A blend of hydroxyl ammonium nitrate fuel and oxidizer, AF-M315E only emits non-toxic gases, such as water vapor and carbon dioxide, when it burns.

The fuel’s high safety rating translates to simpler ground procedures before launch, reduced hazard operations classification, simpler spacecraft systems and – most importantly - safer propellant handling and loading for workers. The new fuel will reduce ground processing time from weeks to days and has the potential to save about a half a million dollars per launch.

AF-M315E has great safety and cost benefits, not to mention its exceptional performance, but will it work on orbit? In 2012, NASA decided it was time to find out. So, the agency’s Space Technology Mission Directorate sponsored the Green Propellant Infusion Mission (GPIM), selecting Ball Aerospace to lead the GPIM team. Tasked with demonstrating a cradle-to-grave use of green propellant technology, the GPIM program will help to validate the fuel’s use in future missions.

“GPIM will be one of the first technologies demonstrated on-orbit by the Space Technology Mission Directorate under the Technology Demonstration Mission program.” said Trudy Kortes, program executive for NASA’s Technology Demonstration Missions. “After more than four years, we are thrilled to see this team's hard work, dedication, and innovation pay off."

Principal Investigator: Leading a team to success
The GPIM program team is unique in that it includes many different players across industry, NASA and the Air Force:
  • Ball Aerospace: Principal Investigator
  • Aerojet Rocketdyne: Co-Investigator
  • NASA Glenn Research Center: Co-Investigator
  • NASA Goddard Space Flight Center: Co-Investigator
  • NASA Kennedy Space Center: Co-Investigator
  • Air Force Research Laboratory: Co-Investigator
  • Air Force Space Missile Command
A Ball Aerospace engineer prepares the GPIM spacecraft for testing.As GPIM’s principal investigator (PI), it is Ball’s responsibility to facilitate interactions among these team members and to provide technical direction.

“Most of my job is figuring out where the technology holes are and trying to get the right people involved, creating a successful program,” said Chris McLean, Ball’s PI.

Usually, that’s easier said than done. But, McLean and Ball are setting an industry standard for managing and coordinating such a diverse team.

“This cooperative effort is an outstanding example of government organizations working with industry to solve technology challenges,” said Jim Oschmann, vice president and general manager of Civil Space at Ball.

What’s the secret to McLean’s success?

“This project has been about communication and building good working relationships,” he said “There are some exceptional people on this program.”

Mars and beyond: Expanding mission possibilities
So, what does the future of green propellant look like? McLean hopes to find the answer as he continues to work with industry partners and green propellant suppliers to develop a roadmap for the future of the technology.

“We want to get this green propellant on high asset missions – spaceflight not technology demos,” said McLean. “We want it to be a technology for future programs.”

One thing is for sure, AF-M315E’s enhanced performance and capabilities opens up a universe of mission possibilities.

AF-M315E offers nearly 50 percent better performance when compared to hydrazine – that’s like getting 50 percent more miles per gallon on your car! This will help to extend mission life, increase payload capacity and enhance spacecraft maneuverability.

Additionally, AF-M315E doesn’t freeze, allowing for missions in cold environments, such as the south pole of Mars (the poles can see temperatures as low as -225 degrees Fahrenheit). Think about what happens when your water pipes freeze – the ice expands and breaks the pipes. This is exactly what hydrazine will do if it freezes, which means a spacecraft has to divert precious power to keeping the fuel warm when it gets too cold. Alternatively, AF-M315E goes into a glass transition phase when it is exposed to extremely cold environments, which means it turns into a solid but does not expand, so the spacecraft only has to warm up the fuel when it needs it.

In addition to the promise of higher performance for future satellites, AF-M315E is also being examined for military uses, such as missile applications and auxiliary power units that currently use hydrazine.

Program overview: Bringing it all together
As GPIM’s prime contractor, Ball is charged with all system engineering, flight thruster performance verification, ground and flight data review, the spacecraft bus, assembly, integration and test, and launch and flight support.

In March 2016, Ball and NASA hosted a joint media and congressional event after the GPIM program completed functional and environmental testing.GPIM utilizes Ball’s standard spacecraft bus, the Ball Configurable Platform (BCP) 100. Ball built the GPIM bus in just 46 days. The BCP-100’s standard payload interface design allowed Ball to accommodate three new Air Force experimental payloads in the middle of the bus build.

During GPIM’s 13-month mission, the team will test the green fuel’s performance using Ball-developed flight software. Planned on-orbit maneuvers include attitude control demonstrations, spacecraft pointing and hold, thruster performance characterization and mapping, inclination change and orbit lowering.

GPIM recently passed a major flight readiness milestone with the successful completion of functional and environmental testing of its systems and software. The spacecraft is scheduled for launch in early 2017.
 
“Everyone in the industry, from NASA to our industry partners to green propellant suppliers, is eager to see 15 years of American-led research and development realized with this spaceflight mission,” Oschmann said.