&lt;p&gt;A key technical difference (aside from the differences in toxicity) between Hydrazine and the green propellant alternatives is the combustion temperature.&amp;nbsp; Both types of propellants are dispensed from their feed tanks through a catalyst material.&amp;nbsp; The catalyst decomposes (reacts) with each propellant and creates the high temperature exhaust gases that are used to either provide thrust (in the application of a rocket engine) or to spin the turbine which provides power to an APU or EPU.&amp;nbsp; Hydrazine decomposes at 900 deg C while the green propellants decompose at 1600 deg C.&amp;nbsp; However, the existing H-70 catalyst (Shell 405) works best with dual-bonded nitrogen mixtures.&amp;nbsp; Both ADN and HAN offer this dual-bonded feature.&amp;nbsp; Although the green propellants may burn hotter with their own proprietary catalyst material, they will burn cooler with the Shell 405 product.&lt;/p&gt;&lt;p&gt;Additionally, both propellants are mixed with water and the water content can be increased to further reduce combustion temperatures.&amp;nbsp; For this proposal, KSC will ship their green sensors (either for ADN or HAN) to MSFC and we in turn would instrument the EPU dedicated to that propellant.&amp;nbsp; Following completion of one month of testing the EPU instrumented with leak detection sensors, the hardware would be shipped to DFRC for a ground test inside an F-16 aircraft.&amp;nbsp; For the chosen aircraft, the existing H-70 system would be temporarily replaced with the MSFC provided green propellant EPU and the aircraft would be suspended off the ground (jacked) to simulate an engine failure and resultant use of the EPU.&amp;nbsp; The objective would be to show that the landing gear could be deployed and aero control surfaces would properly move to pilot commands.&lt;/p&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Alternative approaches to providing power to an APU include an external gas blowdown system, a Lithium Ion battery driven motor or a thermal battery driven motor.&amp;nbsp; All of these approaches have some drawbacks.&amp;nbsp; An external gas blowdown system may employ the use of a stored gas, most likely Helium, to drive the APU turbine.&amp;nbsp; The primary disadvantage to this system is the mass and volume required to store the compressed gas.&amp;nbsp; A similar approach that would minimize the mass and volume is to use gaseous Hydrogen tapped off a liquid propellant rocket engine.&amp;nbsp; However, APU checkouts would be problematic without the engine in operation.&amp;nbsp; An additional system would be required to provide the gas for checkout purposes.&amp;nbsp; In addition, future launch system elements may not have direct access to the liquid rocket engine and would require a disconnect for staging adding to its complexity.&amp;nbsp; Lithium Ion batteries require many cells that must be matched which drive the weight and costs.&amp;nbsp; The disadvantage of thermal batteries lies in its operation or turnaround.&amp;nbsp; For APU checkouts, an external power source is required and in the event of a launch abort or scrub, these batteries must be replaced.&amp;nbsp; These green propellants provide a high power density packaged power source that can be started multiple times with minimal effects on turnaround from issues presented.&amp;nbsp; In addition, this propellant could not only provide a propellant source for APU&amp;rsquo;s but also launch vehicle roll control.&lt;/p&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;