<P> Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft . The motion of these objects is usually calculated from Newton's laws of motion and Newton's law of universal gravitation . It is a core discipline within space mission design and control . Celestial mechanics treats more broadly the orbital dynamics of systems under the influence of gravity, including spacecraft and natural astronomical bodies such as star systems, planets, moons, and comets . Orbital mechanics focuses on spacecraft trajectories, including orbital maneuvers, orbit plane changes, and interplanetary transfers, and is used by mission planners to predict the results of propulsive maneuvers . General relativity is a more exact theory than Newton's laws for calculating orbits, and is sometimes necessary for greater accuracy or in high - gravity situations (such as orbits close to the Sun). </P> <Ul> <Li> Low Earth orbit (LEO): Geocentric orbits with altitudes up to 2,000 km (0--1,240 miles). </Li> <Li> Medium Earth orbit (MEO): Geocentric orbits ranging in altitude from 2,000 km (1,240 miles) to just below geosynchronous orbit at 35,786 kilometers (22,236 mi). Also known as an intermediate circular orbit . These are "most commonly at 20,200 kilometers (12,600 mi), or 20,650 kilometers (12,830 mi), with an orbital period of 12 hours ." </Li> <Li> Both Geosynchronous orbit (GSO) and Geostationary orbit (GEO) are orbits around Earth matching Earth's sidereal rotation period . All geosynchronous and geostationary orbits have a semi-major axis of 42,164 km (26,199 mi). All geostationary orbits are also geosynchronous, but not all geosynchronous orbits are geostationary . A geostationary orbit stays exactly above the equator, whereas a geosynchronous orbit may swing north and south to cover more of the Earth's surface . Both complete one full orbit of Earth per sidereal day (relative to the stars, not the Sun). </Li> <Li> High Earth orbit: Geocentric orbits above the altitude of geosynchronous orbit 35,786 km (22,240 miles). </Li> </Ul> <Li> Low Earth orbit (LEO): Geocentric orbits with altitudes up to 2,000 km (0--1,240 miles). </Li> <Li> Medium Earth orbit (MEO): Geocentric orbits ranging in altitude from 2,000 km (1,240 miles) to just below geosynchronous orbit at 35,786 kilometers (22,236 mi). Also known as an intermediate circular orbit . These are "most commonly at 20,200 kilometers (12,600 mi), or 20,650 kilometers (12,830 mi), with an orbital period of 12 hours ." </Li>

Which of the following is occurring while a satellite is in orbit around earth