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  • Feasibility of a Single Port Hybrid Propulsion System for a Mars Ascent Vehicle

    Paper number

    IAC-10.C4.6.6

    Author

    Ms. Ashley Chandler, Stanford University, United States

    Coauthor

    Prof. Brian Cantwell, Stanford University, United States

    Coauthor

    Prof. G. Scott Hubbard, Stanford University, United States

    Coauthor

    Dr. A. Karabeyoglu, Space Propulsion Group, Inc., United States

    Year

    2010

    Abstract
    The Mars Sample Return (MSR) mission is one of the highest priority items planned for future Mars exploration.  The Mars Ascent Vehicle (MAV), has been identified a critical area needing major technological development.  The MAV propulsion system is required to remain on the surface of Mars for more than a year, during which time it will be subjected to more intense thermal cycling than has been encountered in previous systems.  The diurnal surface temperature variations on Mars can be from -110 to +25°C.  In addition, stringent geometric constraints and a maximum total mass limit of 300 kg are imposed on the MAV.  Previous designs required substantial thermal protection, which often rendered them infeasible. 
    
    A hybrid system design for the MAV has been developed using a paraffin-based fuel and nitrous oxide oxidizer.  The regression rate of this fuel is three to four times higher than that of HTPB enabling a single port design for both stages of the MAV.  Compared to a bi-propellant liquid system the hybrid can be more compact. Compared to a conventional solid the hybrid is less compact but can give better performance. In the context of the MAV, polymeric fuels such as HTPB have a relatively high glass transition temperature that can lead to grain fracture during launch in the low temperature Mars environment. Paraffin-based fuels are primarily crystalline with a much lower glass transition temperature (-108°C) than typical solid propellants. Therefore, it is expected to survive the Martian environment including any temporary departures below the glass transition temperature because the transition is weak. Nitrous oxide has a freezing point of -90.8°C and should require minimal or no thermal control during the thermal cycling on Mars. 
      
    In order to increase the technological readiness level of this non-legacy design, environmental testing of the fuel is being conducted at NASA Ames and compared with theoretical heat transfer data from a commercial code (COMSOL).  Additionally, a system is being built to visualize the combustion mechanism responsible for the high mass flux of the paraffin-based fuel, one of its most crucial benefits.  Through these tests and design studies, we hope to determine if a hybrid system can enable a MSR mission.
    Abstract document

    IAC-10.C4.6.6.brief.pdf

    Manuscript document

    IAC-10.C4.6.6.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.