What is low Earth orbit (LEO)?

How it works

NASA defines low Earth orbit as any Earth-centered orbit at an altitude of 2,000 km (1,200 miles) or less. The European Space Agency (ESA) says satellites generally do not fly below about 180 km because of the effect of Earth's atmosphere. It attributes the 2,000 km ceiling to the Van Allen radiation belts that lie above.

A satellite in LEO travels at roughly 7.8 km per second and completes a lap in about 90 minutes, according to ESA. So the International Space Station circles the planet about 16 times a day. ESA adds that communications satellites in LEO often fly as a constellation of many similar spacecraft. Together they provide continuous coverage, it says.

Why it matters

Being close to the ground has practical uses. ESA notes that the short distance gives imaging satellites higher-resolution pictures and makes the space station easier for astronauts to reach. NASA says the region is close enough to make transport, communication, observation and resupply convenient.

Most catalogued objects in orbit are in LEO. ESA's annual Space Environment Report, issued on May 1, 2026, counted 16,946 payloads (satellites and other spacecraft, active or inactive) orbiting Earth at the end of 2025. It counted 14,906 of them in LEO. Counting debris, rocket bodies and unidentified objects as well, the report put the LEO total at 25,060 of 44,964 objects.

Where things stand in 2026

ESA's summary of the report was published on September 14, 2026. It says more than 300 launches in 2025 placed over 4,000 new payloads in orbit. SpaceX's Starlink network alone had more than 11,000 operational satellites in late August 2026, Space.com reported.

Disposal deadlines have tightened. Guidelines from the Inter-Agency Space Debris Coordination Committee set a maximum of 25 years for a retired satellite to leave LEO, the ESA report notes. On September 29, 2022, the US Federal Communications Commission adopted a rule requiring satellites in LEO to deorbit no later than five years after their missions end. ESA introduced a five-year limit for its own projects in 2023, according to the report.

The ESA report nonetheless concludes that current compliance with debris guidelines is insufficient for a sustainable orbital environment in the long term. It expects collisions among debris already in orbit to keep increasing the debris population in LEO even with no further launches.