One option for a Mars Ascent Vehicle (MAV) for a potential Mars Sample Retrieval (MSR) mission is a two stage vehicle, each stage with a solid rocket motor. Early design iterations assumed a center perforated bore for both 1stand 2ndstage grains. However trajectory analysis showed that the progressive thrust trace exhibited from center perforated bores resulted in the maximum dynamic pressure (max q) occurring about the same time as 1st stage burnout which would cause severe controllability issues. To maximize controllability the 1ststage grain was redesigned to have regressive thrust trace similar to what is used in (Northrup Grumman Innovation Systems' (formerly Orbital ATK's) STAR 20 motor. Using a regressive thrust trace resulted in the max q occurring well within the 1st stage burn time as well as a significantly reduced dynamic pressure at 1ststage burnout. Even with the improved 1st stage grain design the RCS system still required immense thrust to maintain control during the coast period. An aft ramp was employed to stabilize the vehicle and to minimize the requirements levied upon the RCS system. Cold gas systems as well as monopropellant hydrazine systems were considered. The cold gas system proved to be the heavier of the two options due to higher propellant mass and a heavy high pressure tank. While the hydrazine system was the lighter weight option, fitting the thrusters within the vehicle outer mold line (OML) will be problematic. Additionally, hydrazine's freezing point of 2 °C is well above the Martian ambient surface temperature which will increase the power demand due to the need for more heaters. This paper discusses the design approach for the solid rocket motors and RCS system for a two stage sample return MAV. Technology gaps and required development efforts are outlined as well as topics for future trade study.
Mars Ascent Vehicle (MAV) Propulsion Subsystems Design
2019-03-01
3604043 byte
Conference paper
Electronic Resource
English
Mars Ascent Vehicle Solid Propulsion Configuration
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