Medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), is the region of space around the Earth above low Earth orbit A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km. Given the rapid orbital decay of objects below approximately 200 km, the commonly accepted definition for LEO is between 160 - 2,000 km (100 - 1,240 miles) above the Earth's surface (altitude of 2,000 kilometres (1,243 mi)) and below geostationary orbit A geostationary orbit is a geosynchronous orbit directly above the Earth's equator (0° latitude), with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. These characteristics are required so that, from locations on the surface of the Earth, geostationary objects appear motionless in the sky, making (altitude of 35,786 kilometres (22,236 mi)).[1]
The most common use for satellites In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavor. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon in this region is for navigation, such as the GPS The Global Positioning System is a space-based global navigation satellite system that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely (with an altitude of 20,200 kilometres (12,552 mi)), Glonass GLONASS is a radio-based satellite navigation system, developed by the former Soviet Union and now operated for the Russian government by the Russian Space Forces. It is an alternative and complementary to the United States' Global Positioning System (GPS), the Chinese Compass navigation system, and the planned Galileo positioning system of the (with an altitude of 19,100 kilometres (11,868 mi)) and Galileo Galileo is a global navigation satellite system currently being built by the European Union (EU) and European Space Agency (ESA). The €3.4 billion project is an alternative and complementary to the U.S. Global Positioning System (GPS) and the Russian GLONASS. On 30 November 2007 the 27 EU transportation ministers involved reached an agreement (with an altitude of 23,222 kilometres (14,429 mi)) constellations. Communications satellites that cover the North and South Pole are also put in MEO.[2]
The orbital periods Copernicus devised a mathematical formula to calculate a planet's sidereal period from its synodic period of MEO satellites range from about 2 to 24 hours.[3] Telstar The first two Telstar satellites were "Telstar 1", launched July 10, 1962 and operational until February 21, 1963, and "Telstar 2", launched May 7, 1963 and operational until May 16, 1965. They were experimental, and nearly identical. Telstar 1 relayed the first television pictures, telephone calls and fax images through space, one of the first and most famous experimental satellites, orbits in MEO.[4]
The orbit has a moderate number of satellites.
See also
Notes
- ^ MEO 【Intermediate Circular Orbit】 (Medium Earth Orbit) - e-Words - A Glossary of Computers and Internet
- ^ Satellite Basics: Solution Benefits
- ^ What is MEO satellite? - a definition from Whatis.com - see also: MEO, medium earth orbit satellite
- ^ Medium Earth Orbit
| Orbits In physics, an orbit is the gravitationally curved path of one object around a point or another body, for example the gravitational orbit of a planet around a star |
|
|
Types |
|
| General |
Box In stellar dynamics a box orbit refers to a particular type of orbit which can be seen in triaxial systems, that is, systems which do not possess a symmetry around any of its axes. They contrast with the loop orbits which are observed in spherically symmetric or axisymmetric systems · Capture In astrodynamics or celestial mechanics a parabolic trajectory is a Kepler orbit with the eccentricity equal to 1. When moving away from the source it is called an escape orbit, otherwise a capture orbit. It is also sometimes referred to as a C3=0 orbit · Circular Below we consider a circular orbit in astrodynamics or celestial mechanics under standard assumptions. Here the centripetal force is the gravitational force, and the axis mentioned above is the line through the center of the central mass perpendicular to the plane of motion · Elliptical In astrodynamics or celestial mechanics an elliptic orbit is a Kepler orbit with the eccentricity less than 1; this includes the special case of a circular orbit, with eccentricity equal to zero. In a stricter sense is a Kepler orbit with the eccentricity greater than 0 and less than 1, excluding the circular orbit. In a wider sense it is a Kepler / Highly elliptical Highly elliptical orbit is an elliptic orbit characterized by a relatively low-altitude perigee and an extremely high-altitude apogee. These extremely elongated orbits can have the advantage of long dwell times at a point in the sky during the approach to and descent from apogee. Visibility near apogee can exceed twelve hours of dwell at apogee · Escape In astrodynamics or celestial mechanics a parabolic trajectory is a Kepler orbit with the eccentricity equal to 1. When moving away from the source it is called an escape orbit, otherwise a capture orbit. It is also sometimes referred to as a C3=0 orbit · Graveyard A graveyard orbit, also called a supersynchronous orbit, junk orbit or disposal orbit, is an orbit significantly above synchronous orbit where spacecraft are intentionally placed at the end of their operational life. It is a measure performed in order to lower the probability of collisions with operational spacecraft and of the generation of · Hyperbolic trajectory In astrodynamics or celestial mechanics a hyperbolic trajectory is a Kepler orbit with the eccentricity greater than 1. Under standard assumptions a body traveling along this trajectory will coast to infinity, arriving there with hyperbolic excess velocity relative to the central body. Similarly to parabolic trajectory all hyperbolic trajectories · Inclined A satellite is said to occupy an inclined orbit around the Earth if the orbit exhibits an angle other than zero degrees with the equatorial plane. This angle is called the orbit's inclination. A planet is said to have an inclined orbit around the Sun if it has an angle other than zero to the plane of the ecliptic / Non-inclined A non-inclined orbit is an orbit which is contained in the plane of reference. It therefore has inclination equal to zero, if the orbit is retrograde. If the plane of reference is the equator, these orbits are called equatorial; if the plane of reference is the ecliptic, they are called ecliptic. As these orbits lack nodes, the ascending node is · Osculating In astronomy, and in particular in astrodynamics, the osculating orbit of an object in space is the gravitational Kepler orbit (i.e. ellipse or other conic) that it would have about its central body (corresponding to its actual position and velocity for that given moment of time) if perturbations were not present · Parabolic trajectory In astrodynamics or celestial mechanics a parabolic trajectory is a Kepler orbit with the eccentricity equal to 1. When moving away from the source it is called an escape orbit, otherwise a capture orbit. It is also sometimes referred to as a C3=0 orbit · Parking A parking orbit is a temporary orbit used during the launch of a satellite or other space probe. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory. The alternative to a parking orbit is direct injection, where the rocket fires continuously until its fuel is exhausted, · Synchronous A synchronous orbit is an orbit in which an orbiting body 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 (semi Categories: Celestial mechanics | Orbits | Astrodynamics | Earth orbits · sub A subsynchronous orbitis an orbit of a satellite that is nearer the planet than it would be if it were in synchronous orbit, i.e. the orbital period is less than the sidereal day of the planet. An Earth satellite that is in subsynchronous orbit will appear to drift eastward as seen from the Earth's surface)
|
|
| Geocentric A geocentric orbit involves any object orbiting the Earth, such as the Moon or artificial satellites. Currently there are approximately 2,465 artificial satellites orbiting the Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. Over 16,291 previously launched objects have decayed into the Earth's atmosphere |
Geosynchronous A geosynchronous orbit is an orbit around a planet or moon with an orbital period that matches the planet or moon's sidereal rotation period. The term most frequently refers to objects that orbit the Earth, and this article reflects that. The synchronization of rotation and orbital period means that for an observer at a fixed location on the · Geostationary A geostationary orbit is a geosynchronous orbit directly above the Earth's equator (0° latitude), with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. These characteristics are required so that, from locations on the surface of the Earth, geostationary objects appear motionless in the sky, making · Sun-synchronous A sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time. This consistent lighting is a useful characteristic · Low Earth A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km. Given the rapid orbital decay of objects below approximately 200 km, the commonly accepted definition for LEO is between 160 - 2,000 km (100 - 1,240 miles) above the Earth's surface · Medium Earth · High Earth · Molniya A Molniya orbit is a type of highly elliptical orbit with an inclination of 63.4 degrees and an orbital period of precisely one half of a sidereal day. Molniya orbits are named after a series of Soviet/Russian Molniya communications satellites which have been using this type of orbit since the mid 1960s · Near-equatorial A near equatorial orbit is an orbit that lies close to the equatorial plane of the object orbited. This orbit allows for rapid revisit times of near equatorial ground sites.[citation needed] · Orbit of the Moon The orbit of the Moon around the Earth is completed in approximately 27.3 days. The Earth and Moon orbit about their common center of mass, which lies about 4,700 kilometres from Earth's center . On average, the Moon is at a distance of about 385,000 km from the center of the Earth, which corresponds to about 60 Earth radii. With a mean orbital · Polar A polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of (or very close to) 90 degrees to the equator. Except in the special case of a polar geosynchronous orbit, a satellite in a polar orbit will pass over the equator at a different · Tundra Tundra orbit is a type of highly elliptical geosynchronous orbit with a high inclination and an orbital period of one sidereal day (almost 24 hours). A satellite placed in this orbit spends most of its time over a chosen area of the Earth, a phenomenon known as apogee dwell. The ground track of a satellite in a tundra orbit is a closed " · Two-line elements A Two-Line Element set is a set of orbital elements that describe the orbit of an earth satellite. A computer program called a model can use the TLE to compute the precise position of a satellite at a particular time. The TLE is in a format specified by NORAD and used by NORAD and NASA. The TLE can be used directly by the SGP4 model (or one of the
|
|
| About other points |
Areosynchronous Areosynchronous orbits are class of synchronous orbits for artificial satellites around the planet Mars. As with all synchronous orbits, an areosynchronous orbit has an orbital period equal in length to Mars' sidereal day. A satellite in areosynchronous orbit does not necessarily maintain a fixed position in the sky as seen by an observer on the · Areostationary An areostationary orbit is a circular areosynchronous orbit in the Martian equatorial plane about 17,000 km (10,600 miles) above the surface, any point on which revolves about Mars in the same direction and with the same period as the Martian surface. Although no artificial satellites have been placed so far in this orbit, it is of interest to · Halo A halo orbit is a periodic, three-dimensional orbit near the L1, L2, or L3 Lagrange points in the three-body problem of orbital mechanics. A spacecraft in a halo orbit does not technically orbit the Lagrange point itself , but travels in a closed, repeating path near the Lagrange point. Halo orbits are the result of a complicated interaction · Lissajous In orbital mechanics, a Lissajous orbit is a quasi-periodic orbital trajectory that an object can follow around a Lagrangian point of a three-body system without requiring any propulsion. Lyapunov orbits around a libration point are curved paths that lie entirely in the plane of the two primary bodies. In contrast, Lissajous orbits include · Lunar In astronomy, lunar orbit refers to the orbit of an object around the Moon · Heliocentric A heliocentric orbit is an orbit around the Sun. In our Solar System, all planets, comets, and asteroids are in such orbits, as are many artificial probes and pieces of debris. Ganymede, by contrast, is not in a heliocentric orbit as it orbits Jupiter. An interior heliocentric orbit is an orbit inside the orbit of the Earth, for example the orbit · Heliosynchronous By analogy with the geosynchronous orbit, a heliosynchronous orbit is a heliocentric orbit where the satellite's period of revolution matches the Sun's period of rotation. These orbits occur at a radius of 24.360 Gm around the Sun, a little less than half of the orbital radius of Mercury
|
|
|
|
|
|
|
|
|
|
|
|
| List of orbits |
|
Categories: Celestial mechanics | Orbits | Earth orbits
