Editing Communications satellite (section)

=== Low Earth orbit (LEO) ===
{{Main|Low Earth orbit}}
{{legend|cyan|[[Low Earth orbit]]}}
A [[low Earth orbit]] (LEO) typically is a circular orbit about {{convert|160|to|2,000|km|mi}} above the Earth's surface and, correspondingly, a period (time to revolve around the Earth) of about 90 minutes.<ref>{{Cite web|url=http://www.unoosa.org/documents/pdf/spacelaw/sd/IADC-2002-01-IADC-Space_Debris-Guidelines-Revision1.pdf|title=IADC Space Debris Mitigation Guidelines|date=September 2007|publisher=INTER-AGENCY SPACE DEBRIS COORDINATION COMMITTEE: Issued by Steering Group and Working Group 4|quote=Region A, Low Earth Orbit (or LEO) Region – spherical region that extends from the Earth's surface up to an altitude (Z) of 2,000 km}}</ref>

Because of their low altitude, these satellites are only visible from within a radius of roughly {{convert|1,000|km|mi}} from the sub-satellite point. In addition, satellites in low Earth orbit change their position relative to the ground position quickly. So even for local applications, many satellites are needed if the mission requires uninterrupted connectivity.

Low-Earth-orbiting satellites are less expensive to launch into orbit than geostationary satellites and, due to proximity to the ground, do not require as high [[signal strength]] (signal strength falls off as the square of the distance from the source, so the effect is considerable). Thus there is a trade off between the number of satellites and their cost.

In addition, there are important differences in the onboard and ground equipment needed to support the two types of missions.