abstract:A gravity turn or zero-lift turn is a maneuver used in launching a spacecraft into, or descending from, an orbit around a celestial body such as a planet or a moon. It is a trajectory optimization that uses gravity to steer the vehicle onto its desired trajectory.
Furthermore, an attainable set for initialconditionsof the gravity-turn descent is deduced according to the constraints of thrust, fuelandstates of the soft landingsystem.
And there is no indication that the reason why decaying dams are found at each point where the town brook falls ten feet is because there used to be a dozen factories on its banks using the gravity power of falling water to turn out a variety of industrial products.
And dark energy may turn out to be almost the mirror opposite of gravity - a repulsive rather than an attractive force, and one that strengthens with distance rather than weakening.
An anomaly in the orbit of Mercury provided one of the first clues that the laws of gravity as described by Newton were incomplete, which, in turn, led Einstein to general relativity.