Satellite constellation

Satellites are typically placed in sets of complementary orbital planes and connect to globally distributed ground stations.

For some applications, in particular digital connectivity, the lower altitude of MEO and LEO satellite constellations provide advantages over a geostationary satellite, with lower path losses (reducing power requirements and costs) and latency.

In this way, the geometry can be preserved without excessive station-keeping thereby reducing the fuel usage and hence increasing the life of the satellites.

A class of circular orbit geometries that has become popular is the Walker Delta Pattern constellation.

Here, the satellites are in near-polar circular orbits across approximately 180 degrees, travelling north on one side of the Earth, and south on the other.

The active satellites in the full Iridium constellation form a Walker Star of 86.4°: 66/6/2, i.e. the phasing repeats every two planes.

[citation needed] Several existing satellite constellations typically use a single orbital shell.

The GPS constellation calls for 24 satellites to be distributed equally among six orbital planes . Notice how the number of satellites in view from a given point on the Earth's surface, in this example at 40°N, changes with time.
A bright artificial satellite flare is visible above the Very Large Telescope . Satellite constellations could have an impact on ground-based astronomy. [ 1 ]