Low Earth orbit
Also called: LEO · Topic: Atmosphere: Composition, Structure and Elements of Weather · NCERT: Beyond NCERT
Meaning
Low Earth orbit (LEO) is the band of space closest to the Earth where satellites can circle the planet. It starts at about 160 km and goes up to about 2,000 km above the surface. This puts it in the thermosphere and the exosphere, the two highest layers of the atmosphere. A satellite here moves very fast and goes round the Earth in about 90 minutes to two hours. Being this close helps cameras take sharp pictures and keeps signal delays short, so most satellites use LEO. Because it is so crowded, LEO collects the most space debris, which means human-made junk such as dead satellites and rocket parts. The very thin air at these heights slowly drags objects down until they burn up. At greater heights this can take many years. LEO is shared by every country, so it is treated as a global commons.
Example
The International Space Station is in LEO at about 400 km, inside the thermosphere. Pieces from India's PSLV-C3 rocket stage, which broke up in 2001, are also in LEO. Some were still in orbit at the end of 2025.
Don't confuse with
- Geostationary orbit: This orbit is about 36,000 km above the equator, far higher than LEO. A satellite there takes exactly one day to go round the Earth, so it stays over the same spot. India's weather satellite INSAT-3DS works this way.