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Suppose we want to move a satellite in a circular orbit to a position ∆ϑ apart in the same orbit, in a time ∆t (assumed to be several orbital times at least). The general approach is to transfer to a lower (for positive ∆ϑ ) or higher (for ∆ϑ < 0 ) nearby
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The only practical way to accelerate something in free space is by reaction. The idea is the same as in air breathing propulsion (to push something backwards) but in rockets the “something” must be inside and is lost. Here is a revealing derivation of the thrust equation for vacuum:
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The result appears to be trivial, but it is not. Notice that the “velocity increment” ∆V is actually equal to the decrease in orbital velocity. The rocket is pushing forward, but the velocity is decreasing. This is because in a r-2 force field, the kinetic energy is equal in magnitude but of the opposite sign
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1. Constant Power and Thrust: Prescribed Mission Time Starting with a mass M0 , and operating for a time t an electric thruster of jet speed c, such as to accomplish an equivalent (force-free) velocity change of ∆V , the final
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Lecture 1a: Mission Requirements for Space Propulsion Missions Requiring High Thrust (chemical thrusters) Planetary takeoff (launch rockets) Planetary landing (Viking, Lunar Lander…) Apogee kick (GTO-GEO transfer motors) Perigee kick (GTO to escape) Rapid maneuvering (proximity ops., spacecraft attitude control)
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accelerations account for non-central forces(drag, thrust, etc. X-axis in zenith, y-axis in frames velocity, and z-axis in transverse directions 8 Free orbit solution where 'A and 'B' are lengths and'a andB are phase angles
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Definitions What is Systems Engineering? the ensemble of coordinated analyses, simulations, and processes which lead to a technical product which best meets the needs of an identified customer What does it mean to manage systems engineering?
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人教版高中物理必修2第六章 万有引力与航天2. 太阳与行星间的引力课件(1)
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人教版高中物理必修2第六章 万有引力与航天2. 太阳与行星间的引力教案(4)
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人教版高中物理必修2第六章 万有引力与航天2. 太阳与行星间的引力教案(2)
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