sun synchronous Satellite

A Sun-synchronous satellite is a type of satellite that has an orbit designed to pass over the same part of the Earth at roughly the same local solar time on each pass. This is accomplished by having the satellite orbit the Earth in such a way that its plane of orbit precesses (rotates) approximately one degree per day, matching the Earth's annual orbit around the Sun.

Key characteristics of Sun-synchronous satellites include:

1. Consistent Lighting Conditions: Because the satellite passes over the same area at the same local solar time, the lighting conditions are very consistent from day to day. This is particularly useful for imaging and remote sensing satellites, as it allows for more straightforward comparison of images taken on different days.

2. Polar Orbits: These satellites typically follow near-polar orbits, meaning they pass close to the North and South Poles on each orbit. This allows them to cover most of the Earth's surface over a series of orbits.

3. Altitude: The altitude of a Sun-synchronous satellite is usually between 600 and 800 kilometers above the Earth's surface. This allows for a balance between detailed imaging and coverage area.

Sun-synchronous orbits are commonly used for Earth observation satellites, weather satellites, and reconnaissance satellites. Examples of such satellites include the Landsat series, Sentinel-2, and many of the satellites in the Copernicus program.