1. Attitude Control – Arbitrary Payload Christine Troy Assistant Project Manager Webmaster Lunar Descent Attitude Control Analysis Design Alternative Evaluation Arbitrary Payload Integration Manager Christine Troy Attitude

2. Problem Size of attitude control system increases with increased mass in low lunar orbit (LLO) Previous analysis simply assumed linear scale up of mass from 10 kg case More detailed analysis required Number of thrusters to counteract thrust offset Mass and cost of thrusters Mass and cost of required propellant Analysis showed 14N H2O2 thrusters used in 10 kg case unsuitable for arbitrary payload (44-1500 thrusters required) Christine Troy Attitude

3. Recommendation: Use 355 N H2O2 thrusters for attitude control on arbitrary payload regardless of launch vehicle (4-60 thrusters required) Allocate 2% of wet lander mass for attitude control for arbitrary payload Christine Troy Attitude

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6. - First number in each cell is when 14N H2O2 thrusters are used. - Second number in each cell is when 400N hydrazine thrusters are used. - Third number in each cell is when 355N H2O2 thrusters are used. Christine Troy Attitude 6

7. References Rauschenbakh, Boris, Michael Ovchinnikov, and Susan McKenna-Lawlor. Essential Spaceflight Dynamics and Magnetospherics. Dordrecht, The Netherlands: Kluwer Academic Publishers, 2003. Monopropellant Hydrazine Thrusters. Astrium Space Propulsion. 21 Jan 2009. http://cs.astrium.eads.net/sp/SpacecraftPropulsion/MonopropellantThrusters.html Hydrazine. Astronautix. 4 March 2009. http://www.astronautix.com/props/hydazine.htm Propellant Grade Hydrogen Peroxide. Peroxide Propulsion. 4 March 2009. http://www.peroxidepropulsion.com/hydrogen-peroxide.php H202 Monoprop Thruster. General Kinetics, Inc. 4 March 2009. http://www.gkllc.com/products/Rocket_Engine_Catalog_mono-prop-2004.pdf Christine Troy Attitude