Eccentricity measures how elongated an orbit is. A perfect circle has eccentricity of 0. A long, stretched ellipse approaches 1. Most operational satellites use near-circular orbits, but some of the most interesting missions use highly eccentric ones.
Eccentricity measures how elongated an orbit is. A perfect circle has eccentricity of 0. A long, stretched ellipse approaches 1. Most operational satellites use near-circular orbits, but some of the most interesting missions use highly eccentric ones.
Eccentricity (e) is a number from 0 to just below 1. It describes the shape of the ellipse — specifically, how much the two foci are separated.
Most active satellites in LEO and GEO use near-circular orbits for simplicity and consistent altitude. Highly eccentric orbits are specialised — used for high-latitude communications or deep-space transfers.
In an elliptical orbit, the satellite doesn't travel at constant speed. It speeds up near perigee (closest point) and slows down near apogee (furthest point) — Kepler's second law.
Russia can't easily use GEO for high-latitude comms — a GEO satellite sits over the equator, low on the horizon for Arctic regions. The solution: a Molniya orbit with high eccentricity and 63.4° inclination.
Near-circular orbits give consistent, predictable coverage. Highly eccentric orbits trade simplicity for specialised geometry — lingering where you need coverage most.