SatellitenOrbits

SatellitenOrbits are the paths followed by artificial satellites as they travel around a planet or moon under the influence of gravity. In the simplest model, motion is described by Newton's law of gravitation and follows a conic section, with a circular orbit as a special case of minimum energy. The two-body approximation treats the satellite and central body while neglecting other gravitational influences, though real orbits are perturbed by the Moon and Sun, atmospheric drag, and the planet’s oblateness.

Orbits are commonly categorized by altitude and energy: low Earth orbit (LEO) up to about 2,000 kilometers above the surface with periods of roughly 90 to 120 minutes; medium Earth orbit (MEO) from about 2,000 to 35,786 kilometers; and geostationary orbit (GEO) at about 35,786 kilometers where a satellite appears fixed over a single longitude due to a 24-hour orbital period. Highly elliptical orbits (HEO) have large eccentricities, bringing satellites close to the planet at perigee and far away at apogee, useful for imaging and communications. Some orbits are polar or sun-synchronous to optimize coverage and lighting.

Each orbit is described by six classical orbital elements: semi-major axis (a), eccentricity (e), inclination (i), longitude of ascending node (Ω), argument of perigee (ω), and true anomaly (ν) at a reference epoch. These define size, shape, and orientation, and determine the ground track and timing of satellite passes.

Over time, perturbations alter the orbit. Atmospheric drag shrinks altitude in LEO; Earth's equatorial bulge causes regression of the ascending node and changes in inclination; and gravitational forces from the Moon and Sun, along with solar radiation pressure, modify orientation and shape. Spacecraft perform occasional maneuvers to maintain mission parameters, avoid debris, and satisfy repeat-pass or contact requirements.

Applications span communications, weather and Earth observation, navigation, and science missions. GEO satellites provide fixed-area coverage; MEO hosts navigation systems; LEO and sun-synchronous orbits enable high-resolution imaging and timely data.