Also known as a Hohmann transfer orbit, an elliptical trajectory, named after Walter Hohmann, along which a spacecraft may move from one orbit to another with the minimum expenditure of energy. Such an orbit just touches the original and destination orbits, and may be used for changing the orbit of an Earth satellite or for sending a probe to another planet. It involves two firings of the spacecraft's engine: one to break out of the original orbit and another to enter the destination orbit. Its chief disadvantage is that it requires relatively long flight times. This can be overcome by judicious use of gravity-assists.
Related category• CELESTIAL MECHANICS
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