Low Earth Orbit (LEO) is a satellite system in which satellites operate at much lower altitudes than geostationary orbits. These satellites are positioned relatively close to Earth, making them particularly suitable for certain applications. Here’s a breakdown of LEO:
Orbital Characteristics:
- Altitude: Typically ranges from about 160 kilometers (100 miles) to 2,000 kilometers (1,200 miles) above the Earth’s surface.
- Orbital Period: Satellites in LEO complete an orbit in approximately 90 to 120 minutes, depending on their specific altitude.
Applications:
- Satellite Internet: Due to the lower latency compared to GEO satellites, companies like SpaceX’s Starlink and OneWeb are deploying satellite constellations in LEO to provide global internet coverage.
- Earth Observation: LEO is preferred for Earth observation and remote sensing satellites because of the detailed imagery that can be captured from a closer range.
- Space Stations: The International Space Station (ISS) orbits in LEO.
- Scientific Research: LEO allows for studies related to Earth’s atmosphere, space environment, and other phenomena.
- Satellite Communication: For short-term, fast communication.
Advantages:
- Low Latency: Communication delay is much lower than with satellites in higher orbits, making LEO suitable for real-time applications.
- High Resolution: Earth observation satellites in LEO can capture high-resolution imagery due to their proximity to Earth.
- Lower Launch Costs: It’s less expensive to launch satellites to LEO than to higher orbits.
- Natural Deorbiting: Satellites in LEO are more likely to deorbit naturally due to atmospheric drag, reducing space debris concerns in the long term.
Challenges:
- Shorter Lifespan: LEO satellites often have a shorter operational lifespan than those in higher orbits due to exposure to atmospheric drag.
- Frequent Handovers: For communication systems, the fast movement of LEO satellites across the sky means that ground stations have to frequently switch their connection from one satellite to the next.
- Orbit Congestion: With the increasing interest in mega-constellations for broadband, there’s concern about the potential for increased space debris in LEO.
- Complex Ground Infrastructure: To maintain continuous communication, a more sophisticated ground infrastructure is needed, which can be expensive.
Difference from Other Orbits:
- Geostationary Orbit (GEO): Much higher orbit at around 35,786 kilometers, where satellites appear stationary relative to a point on Earth. Suited for TV broadcasting and certain communication applications.
- Medium Earth Orbit (MEO): In between LEO and GEO, used primarily for navigation systems like GPS.
LEO is seeing a resurgence of interest, especially with private companies aiming to provide global broadband internet coverage. The potential of LEO to revolutionize global communications is vast, but it also brings challenges related to space traffic management and debris mitigation.