An orbit is the path followed by a satellite or spacecraft as it revolves around a celestial body, such as the Earth or another planet, under the influence of gravitational forces. Satellites are carefully placed in specific orbits to achieve desired objectives and perform various functions.
There are different types of orbits commonly used in space missions:
- Geostationary Orbit (GEO): This is a special type of orbit located approximately 35,786 kilometres (22,236 miles) above the Earth’s equator. Satellites in geostationary orbit appear stationary from the ground because they orbit at the same rate as the Earth rotates. These satellites are ideal for applications that require continuous coverage of a specific area, such as telecommunications, weather monitoring, and broadcasting.
- Low Earth Orbit (LEO): LEO is a relatively close orbit to the Earth, typically ranging from a few hundred kilometres to around 2,000 kilometres (about 124 to 1,243 miles) in altitude. Satellites in LEO orbit at high speeds, completing multiple orbits in a single day. This type of orbit is commonly used for Earth observation, remote sensing, scientific research, and satellite constellations like Starlink.
- Medium Earth Orbit (MEO): MEO is an intermediate orbit between LEO and geostationary orbit, typically ranging from a few thousand kilometres to around 20,000 kilometres (about 1,243 to 12,427 miles) in altitude. Navigation satellite systems like GPS (Global Positioning System) use MEO to provide accurate positioning and timing information to users on Earth.
- Polar Orbit: A polar orbit is an orbit that passes over or near the Earth’s poles, covering the entire surface of the Earth over time. Satellites in polar orbits typically travel from the North Pole to the South Pole and vice versa during each orbit. This type of orbit is often used for Earth observation, mapping, and scientific missions, as it allows comprehensive coverage of the planet.
- Polar-Sun Synchronous Orbit: The polar-sun synchronous orbit is a fascinating orbital path that combines the advantages of both polar and sun-synchronous orbits. Satellites in this orbit travel from the North Pole to the South Pole, maintaining a constant angle with respect to the sun. This unique characteristic ensures that the satellite passes over any given location on Earth at the same local solar time during each orbit. As the satellite’s position relative to the sun remains consistent, it can capture images and collect data under nearly identical lighting conditions during every pass. This consistency enhances the accuracy of data analysis and facilitates comparisons over time, making it ideal for climate research, vegetation monitoring, and land-use planning.
- ISS 51.6 Degree Orbit: The International Space Station (ISS) orbits the Earth at an inclination of approximately 51.6 degrees. This specific inclination is crucial as it allows the ISS to cover most of the inhabited regions on Earth during its orbits. The 51.6-degree orbit strikes a balance between providing broad coverage of diverse geographical regions and minimizing the fuel required for orbital adjustments. Being in a low Earth orbit, the ISS travels at high speeds, completing roughly 16 orbits around the Earth every day. This allows astronauts aboard the ISS to experience 16 sunrises and sunsets daily. The ISS serves as a remarkable laboratory for scientific research and international collaboration, fostering advancements in various fields, including biology, physics, astronomy, and materials science.
- 83-85 Degrees Orbit: Satellites in an orbit with an inclination of approximately 83 to 85 degrees cover polar regions and regions near the poles. These orbits are commonly used for remote sensing and polar observation missions. By covering areas closer to the poles, these satellites can capture valuable data for polar research, climate studies, and ice monitoring. Polar orbits at this inclination are well-suited for monitoring changes in sea ice extent, tracking polar wildlife, and studying high-latitude weather patterns. As these orbits provide excellent coverage of the poles, they are instrumental in understanding the dynamics of polar environments and their impact on global climate.
- Equatorial Orbit: Equatorial orbits are circular orbits that lie in the plane of the Earth’s equator. Satellites in equatorial orbits offer a fixed view of the Earth’s equatorial region and provide continuous coverage of the same area during their orbits. This stability is advantageous for communication and weather satellites. Communication satellites in equatorial orbits remain stationary relative to a specific location on Earth. This geostationary behavior allows them to provide consistent and reliable satellite communication services, including television broadcasting, internet connectivity, and telecommunication networks.
- 37 Degrees Orbit: An orbit with an inclination of approximately 37 degrees provides satellites with a middle ground between polar and equatorial orbits. Satellites in this orbit offer broader coverage than equatorial orbits, allowing them to pass over different latitudinal regions during each orbit. The 37-degree inclination orbit is commonly used for various Earth observation missions, such as monitoring weather patterns, natural disasters, and agricultural activities. The coverage of a range of latitudes makes it well-suited for studying mid-latitude regions and tracking weather systems that impact populated areas around the world.
- NASA – What Is an Orbit?
- European Space Agency – Types of orbits
- European Space Agency – Polar and Sun-synchronous orbit
- NASA – Space Station Orbit Tutorial.
- NASA Astrophysics Data System – Space Station Freedom assembly and operation at a 51.6 degree inclination orbit
- Wikipedia – List of orbits
- Spacesim – Equatorial orbit