A subsynchronous orbit is an
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such a ...
of a
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...
that is nearer the planet than it would be if it were in
synchronous orbit A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body.
Simplified meanin ...
, i.e. the orbital period is less than the
sidereal day
Sidereal time (as a unit also sidereal day or sidereal rotation period) (sidereal ) is a timekeeping system that astronomers use to locate celestial objects. Using sidereal time, it is possible to easily point a telescope to the proper coor ...
of the planet.
[
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Technical considerations
An Earth satellite that is in (a prograde) subsynchronous orbit will appear to drift eastward as seen from the Earth's surface.[
]
Economic importance in commercial spaceflight
The '' Geosynchronous-belt subsynchronous orbital regime'' is regularly used in spaceflight
Spaceflight (or space flight) is an application of astronautics to fly spacecraft into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in o ...
. This orbit is typically used to house working communication satellites
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...
that have not yet been deactivated, and may be still be used again in geostationary service if the need arises.[
]
See also
*Supersynchronous orbit
A supersynchronous orbit is either an orbit with a period greater than that of a synchronous orbit, or just an orbit whose apoapsis (apogee in the case of the Earth) is higher than that of a synchronous orbit. A synchronous orbit has a period equa ...
*List of orbits
Summary
A simple list of just the common orbit abbreviations.
List of abbreviations of common Earth orbits
List of abbreviations of other orbits
Classifications
The following is a list of types of orbits:
Centric classifications
* Gal ...
References
Orbits
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