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Brian Erson Attitude Control Systems. Trans Lunar Phase Alternative Design Comparison. 1. Orbit Transfer Vehicle Stabilization. 2. Mass Layout. Conclusion: Mass difference represents a savings of > 34.6 kg with 3-axis stabilized spacecraft.
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Brian ErsonAttitude Control Systems Trans Lunar Phase Alternative Design Comparison 1 [Brian Erson] [Attitude]
Orbit Transfer Vehicle Stabilization 2 [Brian Erson] [Attitude]
Mass Layout Conclusion: Mass difference represents a savings of >34.6 kg with 3-axis stabilized spacecraft * Conservative estimate minimally affected by stabilization method 3 [Brian Erson] [Attitude]
Backup Slide 1 Attitude Control Mass Calculations: 3-axis Sun Sensors 0.7 Star Sensors 6.4 Reaction Wheels 6 H2O2 Thrusters 1 Propellant(H2O2)* 26 Total: 40.1 kg Spin Conical Scanner 6 Doppler Device 1 H2O2 Thrusters 1 Propellant(H202)* * 19.1 Total: 27.1 *Prop Mass Includes Lunar Descent 4 [Brian Erson] [Attitude]
Backup Slide 2 • **H2O2 De-Saturation(DS) Mass Calculation: • DS of reaction wheels: • Estimate of DS maneuvers/day: 6 • Reaction wheel max torque: 0.03 N-m • H2O2 Thrust: 9.5 N/kg • Max Mission Length: 365 days • Total Mission DS H2O2 mass: • (365)(6)(1/9.5)(0.03) = 6.9 kg 5 [Brian Erson] [Attitude]
Backup Slide 3 • Other Mass Calculations: • Power: • Masses based on posted Power Group Data • Mass of battery without solar cells based on assumption of >1.2 kW needed to power OTV • Communication: • 3 kg mass based on posted Com Group Data • Thermal: • 3 axis mass based on posted data • Spin stabilized Thermal Protection: • Assume 15 rpm • Mass = [(1/15(17.1))+4*] =~ 5 kg • *Estimated mass of standard thermal protection 6 [Brian Erson] [Attitude]
References • http://sciencelinks.jp/j-east/article/200313/000020031303A0423712.php • http://cat.inist.fr/?aModele=afficheN&cpsidt=4572226 • http://cs.astrium.eads.net/sp/SpacecraftPropulsion/Propellant%20Tanks/Spin_Stabilised%20Tanks.html • http://www.peroxidepropulsion.com/article/5 • http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050243594_2005246327.pdf • http://www.sandia.gov/ess/Publications/Conferences/2002/ESKRA%20-%20NiMetalHydride.pdf 7 [Brian Erson] [Attitude]