Green propellants

    Introduction             

                    Green propellants are Eco-friendly  fuels which replaces the  Hydrazine monopropellants compared to commercial monopropellant these green propellants are less toxic, gives high performance and also high specific Impulse.This technology is already used by NASA's Green propulsion Infusion mission in which green propulsions are used as monopropellants for that mission. Which gives 50% higher perforance while compared to commercial monopropellant. The monopropellant that are used for this mission is "Hydroxylammonium Nitrate" which provides many advantages for future space missions by increasing the payload, simplified launch processing and long mission duration. 

Green propulsion Infusion Mission

                  Green propulsion Infusion mission  is a NASA's Technology demonstrator project which tests less toxic and Eco-friendly propulsion are used i.e. Green propellants names "Hydroxylammonium Nitrate" which gives 50 percent higher performance. This entire program was managed by NASA's Marshall Space flight centre which is in Alabama. The complete details of Green Propulsion Infusion Mission are as follows;

• Mission Type         :     Technology Demonstrator
• Manufacturer         :     Bail Aerospace
• Launch date           :     25th June 2019
• Launch site            :     Kennedy space centre
• Rocket                    :     Falcon Heavy
• propellant              :     Hydroxylammonium Nitrate(NH₃OHNO₃) fuel/oxidizer blend 
• Mission Duration  :     13 months
• cost of program   :     US $ 45 million 
• Website link          :      https://www.nasa.gov/mission_pages/tdm/green/index.html

                  Hydroxylammonium Nitrate fuel/oxidizer blend also known as AF-M315E and it offers nearly 50 percent higher performance.fig (a). shows the entire GPIM mission system and as follows;

fig.(a).Green Propellant Infusion Mission (GPIM)  mission system 

Fig. Green Design

 

                                                   Orbital maneuvering system of GPIM

 Impact of Green propulsions

                        Basically the main target of the green propellants are to reduce the cost and complexity besides Environmental pollution and also increase the performance much more than commercial monopropellants which are using now-a-days.

The main targets of Green propellants are;

1. Low Toxicity
2. Low Cost
3. High performance
4. Low pollution Impact

                        Whenever we are dealing with commercial monopropellants we have to protect ourself by wearing a suit and also there will be a risk of inhalation which causes several diseases like cancer whereas for green propulsions there will be low risk of inhalation, easy to handle and also parallel operations will also be done. Due to less toxicity the cost required will be less and it also be easily transportable from one place to another.  

                    HAN based liquid propellant suits best for the green propulsions and figure (b) shows the  impact of HAN based monopropellant on green propellants are given as follows;

fig.(b).HAN Based liquid monopropellant 

              
HAN Based Thruster

                            Generally for HAN Based monopropellant thruster catalyst plays a key role in while decomposition. Some of the catalysts are platinum, Rhodium, palladium. At the time of decomposition the catalyst will be fixed either initial temperature or increased temperature. The process flow of the HAN Based monopropellant in the nozzle as shown in figure (c) and is as follows;

                 Fig(c). process flow of HAN monopropellant 

 

 Conclusion

                            Green propulsions palys a vital role in coming future Especially HAN Based monopropellants will accelerate the commercial monopropellants and also latest trends will discussed for future developments and the effects of green propellants are listed below;

• Low  cost of operation
• Increase in performance 
• Higher specific Impulse
• Low Toxicity or Eco-friendly