July 12, 2013
Another non-toxic replacement for hydrazine monopropellant has passed ground testing, paving the way for a satellite flight test as early as 2015.
Ball Aerospace and Aerospace Rocketdyne say their system, which uses a hydroxyl ammonium nitrate (HAN) mixture designated AF-M315E, with a special catalyst, has greater density than hydrazine for better storage efficiency, and produces better performance.
“When we look at this compared to a hydrazine monopropellant type of system, where we have a single fluid driving the system on the spacecraft, we have a 50% increase in performance over the standard hydrazine,” says Christopher McLean, principal investigator on NASA’s upcoming Green Propellant Infusion Mission (GPIM).
GPIM is scheduled to fly as a secondary payload on a SpaceX Falcon 9 Heavy, using a Ball Configurable Platform (BCP) 100 spacecraft bus and an Aerojet Rocketdyne thruster system that combines a 22N (5-lb.-thrust) thruster with four 1N units, all burning the “green” fuel to put the satellite testbed through the maneuvers an operational small satellite would see.
“These were selected because they have the largest market share, [so] we are developing the technologies that really meet the needs of the marketplace for this type of attitude control on a spacecraft,” McLean says.
Ecological Advanced Propulsion Systems (Ecaps), a unit of the Swedish Space Corporation, has tested a different green propellant — based on ammonium dinitramide — in space. The fuel was used in tandem with a hydrazine system on the Prisma mission’s Mango satellite to maneuver in formation with a smaller spacecraft.
Despite the completion of space qualification, sales of the Ecaps system have been slow to take off. Roger Myers of Aerojet Rocketdyne’s Redmond, Wash., facility said the performance of the U.S. system in the ground test is better than the Swedish approach, and suggested there may be safety issues with the by-products of its evaporation.
Ultimately Aerojet Rocketdyne hopes to “infuse” its new green technology into applications other than small satellites, including tactical missiles and large geostationary satellites, Myers said. The advantages of green propulsion over hydrazine, which requires special handling and equipment, should make it attractive wherever the toxic fuel is used.