Satellite Orbits

An orbit is classified by its altitude, which sets the period, delay, path loss and number of satellites needed for continuous global coverage.

Orbit	Altitude	Period	Main uses
LEO	$0.5$–$2000\,km$	$90$–$120\,min$	Mobile, imaging, broadband constellations
MEO	$2$–$20000\,km$	Several hours	Navigation (GPS/GNSS)
GEO	$\approx35786\,km$	h	TV broadcast, FSS, VSAT
HEO	Highly elliptical	Varies	High-latitude coverage

Orbit classification by altitude.

Concentric orbit altitudes: LEO, MEO and GEO around the Earth.

• LEO: Low delay and low path loss; ideal for broadband constellations and mobile services, but the satellite moves fast, so many satellites and frequent inter-satellite handovers are needed.

• MEO: Fewer satellites than LEO for global coverage with moderate delay and loss; the natural home of navigation systems, but still needs tracking or constellation planning.

• GEO: A circular equatorial orbit whose period equals one sidereal day, so the satellite appears fixed. Fixed antennas need no tracking and three satellites cover almost the whole Earth except the poles, at the cost of high delay, high loss and poor polar coverage.

Note

Key Point — Conditions for a geostationary orbit

Circular orbit, in the equatorial plane, moving west-to-east (same sense as Earth’s rotation), with an orbital period of one sidereal day ($23\,h\,56\,\text{min}\approx86164\,s$).

Feature	LEO	MEO	GEO
Altitude	Low	Medium	km
Delay / path loss	Lowest	Medium	Highest
Coverage / satellite	Small	Medium	Very large
Satellites for global	Many	Moderate	$\approx3$
Tracking (fixed term.)	Needed	Needed	Not needed
Use	Broadband, imaging	GPS/GNSS	TV, VSAT, FSS

LEO versus MEO versus GEO.