Space Academy · Contents · Chapter 2 · Nederlandse versie
Chapter 2: Orbits: LEO, MEO, GEO, HEO and beyond
How an orbit works, which orbits exist and what they are for, and the trade-off between coverage, revisit, latency and sharpness that every satellite or constellation designer has to make. With an interactive orbit widget.
2.1How an orbit works
A satellite is constantly falling towards the Earth — but moves sideways so fast that it keeps missing it.
Read §2.1 →2.2LEO — low Earth orbit
From ± 160 to 2,000 km: close, sharp and fast — but only briefly overhead.
Read §2.2 →2.3MEO — medium Earth orbit
Between 2,000 and 35,786 km: the domain of the navigation satellites.
Read §2.3 →2.4GEO — geostationary orbit
At 35,786 km above the equator a satellite turns as fast as the Earth: it seems to hang still.
Read §2.4 →2.5HEO — Molniya and Tundra
An elongated orbit that dwells over the northern hemisphere — where GEO falls short.
Read §2.5 →2.6Sun-synchronous and polar
Over the same point at the same time every day — ideal for comparing images.
Read §2.6 →2.7Other orbits
Transfer orbits, graveyard orbits and the space beyond GEO.
Read §2.7 →2.8Trade-offs and constellations
No orbit is good at everything: every choice trades coverage, revisit, latency and sharpness against each other.
Read §2.8 →