Final Slides Attitude Control System (ACS) – Lunar Transfer Brian Erson Final Slides Attitude Control System (ACS) – Lunar Transfer

Environmental Pertubations contribute to trajectory offsets Sun sensor Tells reaction wheels to make adjustments Thrusters fire to desaturate reaction wheels Star Sensors maintain inertial reference ACS aides OPS in maintaining trajectory

Importance of Attitude Control During Lunar Transfer Thrust Misalignment and Environmental perturbations contribute to trajectory offsets Reaction Wheels and Thrusters provide control to OTV during Lunar Transfer

Final ACS Numbers 100g payload 10kg payload Large payload Device Mass (kg) Cost ($) Power Required(W) Volume (m3) VF STC 1 (star sensor) 6.4 133,333 20.4 0.0163 VF SNS (sun sensor) 0.7 5 VF MR 4.0 10.4 76 0.009375 thruster 0.36 1,500 -- 0.000009 propellant 0.02 100 Inert Mass 1.9 1,000 0.0000696 Totals 19.8 403,000 101.4 0.0420536 Device Mass (kg) Cost ($) Power Required(W) Volume (m3) VF STC 1 (star sensor) 6.4 133,333 20.4 0.0163 VF SNS (sun sensor) 0.7 5 VF MR 10.0 20 120 0.009375 thruster 0.36 1,500 -- 0.000009 Propellant 1.26 100 Inert Mass 3.02 1,000 0.00126 Totals 31.74 403,000 145.4 0.043244 Large payload Note: Star and Sun sensors remain on Lander after separation Device Mass (kg) Cost ($) Power Required(W) Volume (m3) VF STC 1 (star sensor) 6.4 133,333 20.4 0.0163 VF SNS (sun sensor) 0.7 5 VF MR 19.6 42 280 0.0258 H202 thruster 0.36 2,500 -- 0.00003 H202 Propellant 10.6 100 Inert Mass 13.84 1,000 0.00957 Totals 73.9 404,000 305.4 0.068 Backup