Low Earth orbit (LEO) is an orbit around the Earth that is between 160 km (100 miles) and 2,000 km (1,200 miles) above the surface. It is the lowest altitude orbit that can be stable for a satellite to orbit the Earth.
LEO is a popular orbit for many types of satellites, including communication, navigation, weather, and scientific research satellites. This is because LEO provides a good balance between the benefits of being close to the Earth and the challenges of operating in the harsh environment of space.
Some of the benefits of LEO include:
- Good visibility: From LEO, the Earth's surface is visible, allowing satellites to gather high-resolution imagery and communicate with ground stations.
- Low latency: The distance between the satellite and the Earth's surface is relatively short, resulting in lower latency (time delay) for signals transmitted between the satellite and the ground.
- Easy to reach: LEO is relatively easy to reach with a rocket, making it a popular choice for launching satellites.
However, LEO also presents some challenges, such as:
- Radiation: The Earth's radiation belts, which are regions of intense radiation that surround the planet, can pose a risk to satellites in LEO.
- Atmospheric drag: The Earth's atmosphere extends to about 1,000 km (620 miles) above the surface, and satellites in LEO must contend with atmospheric drag, which can slow them down and affect their orbits.
- Crowded orbits: LEO is a popular orbit, and there are many satellites and debris in this region, which can increase the risk of collisions.
Unlike higher orbits, like geostationary satellites that seem glued to a specific spot in the sky, LEO satellites are whizzing around Earth at about 17,500 miles per hour, completing a full loop in around 90 minutes.
This breakneck pace allows them to:
- Deliver data at lightning speed: Thanks to their proximity, LEO satellites transmit information with minimal delay, making them ideal for real-time applications like GPS, satellite internet, and even disaster response.
- Offer high-resolution imagery: Their close-up view of Earth allows them to capture detailed images and data, invaluable for weather forecasting, environmental monitoring, and even mapping projects.
- Support space exploration: The International Space Station and other research platforms like SpaceX's Starlink constellation reside in LEO, providing crucial infrastructure for scientific experiments and astronaut training.
However, this close proximity comes with its own challenges:
- Short lifespan: Due to the constant drag of Earth's atmosphere, LEO satellites have a shorter lifespan than those in higher orbits, necessitating more frequent replacements].
- Greater vulnerability: Their lower altitude makes them susceptible to space debris and cosmic radiation, requiring additional shielding and protective measures.
- Limited coverage: While they offer high-speed data for specific areas, providing global coverage requires a network of many LEO satellites, constantly on the move.
Despite these challenges, LEO's advantages continue to attract attention. From revolutionizing telecommunications and Earth observation to supporting space exploration, LEO is a bustling orbital neighborhood with incredible potential.