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Major Tasks Completed

Major Tasks Completed. Effect of Earth’s oblatness on orbit parameters and relative distance to shuttle Propulsion method and selection of propulsion system and components Demonstration of relative orbit Total hours worked: 80 hrs.

robert-harrell
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Major Tasks Completed

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  1. Major Tasks Completed • Effect of Earth’s oblatness on orbit parameters and relative distance to shuttle • Propulsion method and selection of propulsion system and components • Demonstration of relative orbit • Total hours worked: 80 hrs

  2. Causes secular drift in right ascension, argument of perigee and mean anomaly Effect Of Earth’s Oblatness

  3. Earth’s Oblatness Continued • Magnitude of changes in orbital elements highly dependent in inclination angle

  4. Adjustment of inclination angle at ½ mission lifetime causes changes to go to zero • Only concerned with relative separation for 12 hr period • Maximum relative distance change of 17.4 m • Net relative distance from shuttle increasing, no need for orbit correction

  5. Propulsion System Selection Requirements • Thrust rating capable of providing short burn times • Small and light weight MOOG 58-118 Cold Gas Thruster • Specific impulse = 60 sec • Thrust = 3.6 N • Weight .023 kg

  6. Thruster Selection • Burn times dependent on thrust, mass of satellite and delta-V requirement Satellite specifications M = 50 kg delta-V max = .2119 m/s • Delta-T = 2.94 sec • MOOG model 58-118 fulfills all requirements

  7. Gas Tank Sizing Requirements • Fairly small size to fit nanosat requirements • High pressure capability • Thermal environment from -82.15 to 77.2 degrees Celsius Sizing • Pressure increases with temperature, T = 77.2 deg • Mass of gas, tank operating pressure and temperature determine size • N2 gas gives reasonable specific impulse and is inert

  8. Tanks sizing continued • For orbit transfer and drag • Delta-m = .1865 kg • Assume S.F. = 2 • Total mass = .373 kg • At 20.68 MPa, V = 1875 cm^3 • Volume requirement met to fulfill requirements Specifications m = 50 kg Specific impulse = 60 sec Total delta-V = 2.198 m/s

  9. Orbit Modeling Formation Flying Simulation • Supplied code allowed for 3D relative orbit modeling • Varied orbital elements, relative ellipse parameters, mass, area, thrust, etc. • Visualization of relative motion, orbit track over time, estimation of burn times for orbit transfer and orbit keeping.

  10. Conclusions and Recommendations Conclusions • No need to make orbit keeping maneuvers due to J2 • Cold gas thruster selected fulfills requirements, allows for short burn times • Relative elliptical orbit verified, estimated maneuver times to compensate for drag Recommendations • Select tank material suitable for thermal environment • Continue simulation and determination of burn times necessary to compensate for differential drag.

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