Perigee (aka Periapsis Or Perifocus)
Perigee is the point in the orbit of a celestial body (such as a planet, moon, or satellite) that is closest to the center of the body it orbits. It is also known as periapsis or perifocus. In the context of space and astronautical engineering, perigee is an important parameter to consider when planning and executing space missions. For example, a spacecraft in a low Earth orbit will have a perigee of approximately 160 kilometers above the Earth's surface, while a spacecraft in a geostationary orbit will have a perigee of approximately 35,786 kilometers above the Earth's surface. The perigee of a spacecraft can be raised or lowered by firing its engines at the appropriate time, which can be used to adjust the spacecraft's orbit or to perform a maneuver such as a rendezvous with another spacecraft or a landing on a celestial body.
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