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80-541: Superbird-C2 , known as Superbird-7 before launch, is a geostationary communications satellite operated by JSAT Corporation and designed and manufactured by Mitsubishi Electric (MELCO) on the DS2000 satellite bus . It had a launch weight of 4,820 kg (10,630 lb), a 15-year design life and was the first commercial communications satellite built in Japan. Its payload is composed of 28 Ku-band transponders with

160-483: A delta-v of approximately 50 m/s per year. A second effect to be taken into account is the longitudinal drift, caused by the asymmetry of the Earth – the equator is slightly elliptical ( equatorial eccentricity ). There are two stable equilibrium points sometimes called "gravitational wells" (at 75.3°E and 108°W) and two corresponding unstable points (at 165.3°E and 14.7°W). Any geostationary object placed between

240-407: A disk galaxy 's general rotation are more likely to be found in the galactic halo than in the galactic disk . The Milky Way 's outer halo has many globular clusters with a retrograde orbit and with a retrograde or zero rotation. The structure of the halo is the topic of an ongoing debate. Several studies have claimed to find a halo consisting of two distinct components. These studies find

320-427: A geostationary transfer orbit (GTO), an elliptical orbit with an apogee at GEO height and a low perigee . On-board satellite propulsion is then used to raise the perigee, circularise and reach GEO. Satellites in geostationary orbit must all occupy a single ring above the equator . The requirement to space these satellites apart, to avoid harmful radio-frequency interference during operations, means that there are

400-431: A geosynchronous equatorial orbit ( GEO ), is a circular geosynchronous orbit 35,786 km (22,236 mi) in altitude above Earth's equator , 42,164 km (26,199 mi) in radius from Earth's center, and following the direction of Earth's rotation . An object in such an orbit has an orbital period equal to Earth's rotational period, one sidereal day , and so to ground observers it appears motionless, in

480-515: A "dual" halo, with an inner, more metal-rich, prograde component (i.e. stars orbit the galaxy on average with the disk rotation), and a metal-poor, outer, retrograde (rotating against the disc) component. However, these findings have been challenged by other studies, arguing against such a duality. These studies demonstrate that the observational data can be explained without a duality, when employing an improved statistical analysis and accounting for measurement uncertainties. The nearby Kapteyn's Star

560-564: A fast prograde rotation with a period of several hours much like most of the planets in the Solar System. Venus is close enough to the Sun to experience significant gravitational tidal dissipation , and also has a thick enough atmosphere to create thermally driven atmospheric tides that create a retrograde torque . Venus's present slow retrograde rotation is in equilibrium balance between gravitational tides trying to tidally lock Venus to

640-455: A fixed position in the sky. The concept of a geostationary orbit was popularised by the science fiction writer Arthur C. Clarke in the 1940s as a way to revolutionise telecommunications, and the first satellite to be placed in this kind of orbit was launched in 1963. Communications satellites are often placed in a geostationary orbit so that Earth-based satellite antennas do not have to rotate to track them but can be pointed permanently at

720-567: A fully owned subsidiary of SKY Perfect JSAT Group . On the SKY Perfect JSAT board meeting of 6 August 2008, it was resolved to merge SKY Perfect Communications, JSAT Corporation and Space Communications Corporation. The merger would see SKY Perfect absorb JSAT and SCC and both legacy companies dissolved. Thus, by the time of launch, Superbird-7 was a JSAT spacecraft. Superbird-7 was successfully launched along AMC-21 by an Ariane 5 ECA on 14 August 2008, at 20:44 UTC . It separated from

800-415: A geostationary orbit in particular, it ensures that it holds the same longitude over time. This orbital period, T , is directly related to the semi-major axis of the orbit through the formula: where: The eccentricity is zero, which produces a circular orbit . This ensures that the satellite does not move closer or further away from the Earth, which would cause it to track backwards and forwards across

880-579: A geostationary satellite to globalise communications. Telecommunications between the US and Europe was then possible between just 136 people at a time, and reliant on high frequency radios and an undersea cable . Conventional wisdom at the time was that it would require too much rocket power to place a satellite in a geostationary orbit and it would not survive long enough to justify the expense, so early efforts were put towards constellations of satellites in low or medium Earth orbit. The first of these were

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960-552: A higher graveyard orbit to avoid collisions. In 1929, Herman Potočnik described both geosynchronous orbits in general and the special case of the geostationary Earth orbit in particular as useful orbits for space stations . The first appearance of a geostationary orbit in popular literature was in October 1942, in the first Venus Equilateral story by George O. Smith , but Smith did not go into details. British science fiction author Arthur C. Clarke popularised and expanded

1040-399: A known position) and providing an additional reference signal. This improves position accuracy from approximately 5m to 1m or less. Past and current navigation systems that use geostationary satellites include: Geostationary satellites are launched to the east into a prograde orbit that matches the rotation rate of the equator. The smallest inclination that a satellite can be launched into

1120-408: A large area of the earth's surface, extending 81° away in latitude and 77° in longitude. They appear stationary in the sky, which eliminates the need for ground stations to have movable antennas. This means that Earth-based observers can erect small, cheap and stationary antennas that are always directed at the desired satellite. However, latency becomes significant as it takes about 240 ms for

1200-516: A limited number of orbital slots available, and thus only a limited number of satellites can be operated in geostationary orbit. This has led to conflict between different countries wishing access to the same orbital slots (countries near the same longitude but differing latitudes ) and radio frequencies . These disputes are addressed through the International Telecommunication Union 's allocation mechanism under

1280-403: A perpendicular rotation that is neither prograde nor retrograde. An object with an axial tilt between 90 degrees and 180 degrees is rotating in the opposite direction to its orbital direction. Regardless of inclination or axial tilt, the north pole of any planet or moon in the Solar System is defined as the pole that is in the same celestial hemisphere as Earth's north pole. All eight planets in

1360-510: A planet's gravity, it can be captured into either a retrograde or prograde orbit depending on whether it first approaches the side of the planet that is rotating towards or away from it. This is an irregular moon . In the Solar System, many of the asteroid-sized moons have retrograde orbits, whereas all the large moons except Triton (the largest of Neptune's moons) have prograde orbits. The particles in Saturn's Phoebe ring are thought to have

1440-407: A prograde orbit, because in this situation less propellant is required to reach the orbit. When a galaxy or a planetary system forms , its material takes a shape similar to that of a disk. Most of the material orbits and rotates in one direction. This uniformity of motion is due to the collapse of a gas cloud. The nature of the collapse is explained by conservation of angular momentum . In 2010

1520-405: A retrograde orbit around the Sun. Most Kuiper belt objects have prograde orbits around the Sun. The first Kuiper belt object discovered to have a retrograde orbit was 2008 KV 42 . Other Kuiper belt objects with retrograde orbits are (471325) 2011 KT 19 , (342842) 2008 YB 3 , (468861) 2013 LU 28 and 2011 MM 4 . All of these orbits are highly tilted, with inclinations in

1600-453: A retrograde orbit because they originate from the irregular moon Phoebe . All retrograde satellites experience tidal deceleration to some degree. The only satellite in the Solar System for which this effect is non-negligible is Neptune's moon Triton. All the other retrograde satellites are on distant orbits and tidal forces between them and the planet are negligible. Within the Hill sphere ,

1680-406: A signal to pass from a ground based transmitter on the equator to the satellite and back again. This delay presents problems for latency-sensitive applications such as voice communication, so geostationary communication satellites are primarily used for unidirectional entertainment and applications where low latency alternatives are not available. Geostationary satellites are directly overhead at

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1760-468: A total bandwidth of 828 MHz . It was originally ordered by Space Communications Corporation (SCC), owned by the Mitsubishi Group keiretsu , also the parent company of MELCO, but it was later merged and absorbed by JSAT Corporation. By the time of the actual launch it was a fully used Superbird-C2 as a replacement for Superbird-C to provide communications services to Japan, East Asia and

1840-482: Is approximately 120 degrees. Pluto and its moon Charon are tidally locked to each other. It is suspected that the Plutonian satellite system was created by a massive collision . If formed in the gravity field of a planet as the planet is forming, a moon will orbit the planet in the same direction as the planet is rotating and is a regular moon . If an object is formed elsewhere and later captured into orbit by

1920-406: Is approximately parallel with the plane of the Solar System. The reason for Uranus's unusual axial tilt is not known with certainty, but the usual speculation is that it was caused by a collision with an Earth-sized protoplanet during the formation of the Solar System. It is unlikely that Venus was formed with its present slow retrograde rotation, which takes 243 days. Venus probably began with

2000-399: Is difficult to telescopically analyse the rotation of most asteroids. As of 2012, data is available for less than 200 asteroids and the different methods of determining the orientation of poles often result in large discrepancies. The asteroid spin vector catalog at Poznan Observatory avoids use of the phrases "retrograde rotation" or "prograde rotation" as it depends which reference plane

2080-427: Is in a retrograde orbit. A celestial object's axial tilt indicates whether the object's rotation is prograde or retrograde. Axial tilt is the angle between an object's rotation axis and a line perpendicular to its orbital plane passing through the object's centre. An object with an axial tilt up to 90 degrees is rotating in the same direction as its primary. An object with an axial tilt of exactly 90 degrees, has

2160-490: Is meant and asteroid coordinates are usually given with respect to the ecliptic plane rather than the asteroid's orbital plane. Asteroids with satellites, also known as binary asteroids, make up about 15% of all asteroids less than 10 km in diameter in the main belt and near-Earth population and most are thought to be formed by the YORP effect causing an asteroid to spin so fast that it breaks up. As of 2012, and where

2240-591: Is possible. The last few giant impacts during planetary formation tend to be the main determiner of a terrestrial planet 's rotation rate. During the giant impact stage, the thickness of a protoplanetary disk is far larger than the size of planetary embryos so collisions are equally likely to come from any direction in three dimensions. This results in the axial tilt of accreted planets ranging from 0 to 180 degrees with any direction as likely as any other with both prograde and retrograde spins equally probable. Therefore, prograde spin with small axial tilt, common for

2320-452: Is that of the launch site's latitude, so launching the satellite from close to the equator limits the amount of inclination change needed later. Additionally, launching from close to the equator allows the speed of the Earth's rotation to give the satellite a boost. A launch site should have water or deserts to the east, so any failed rockets do not fall on a populated area. Most launch vehicles place geostationary satellites directly into

2400-403: Is the gravitational constant , (6.674 28 ± 0.000 67 ) × 10  m kg s . The magnitude of the acceleration, a , of a body moving in a circle is given by: where v is the magnitude of the velocity (i.e. the speed) of the satellite. From Newton's second law of motion , the centripetal force F c is given by: As F c = F g , so that Replacing v with the equation for

2480-463: Is thought to have ended up with its high-velocity retrograde orbit around the galaxy as a result of being ripped from a dwarf galaxy that merged with the Milky Way. Close-flybys and mergers of galaxies within galaxy clusters can pull material out of galaxies and create small satellite galaxies in either prograde or retrograde orbits around larger galaxies. A galaxy called Complex H, which

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2560-781: Is typically 70°, and in some cases less. Geostationary satellite imagery has been used for tracking volcanic ash , measuring cloud top temperatures and water vapour, oceanography , measuring land temperature and vegetation coverage, facilitating cyclone path prediction, and providing real time cloud coverage and other tracking data. Some information has been incorporated into meteorological prediction models , but due to their wide field of view, full-time monitoring and lower resolution, geostationary weather satellite images are primarily used for short-term and real-time forecasting. Geostationary satellites can be used to augment GNSS systems by relaying clock , ephemeris and ionospheric error corrections (calculated from ground stations of

2640-408: Is used to provide visible and infrared images of Earth's surface and atmosphere for weather observation, oceanography , and atmospheric tracking. As of 2019 there are 19 satellites in either operation or stand-by. These satellite systems include: These satellites typically capture images in the visual and infrared spectrum with a spatial resolution between 0.5 and 4 square kilometres. The coverage

2720-487: The Pacific Ocean . In April 2005, Space Communications Corporation (SCC) issued an Request for proposal (RFP) for Superbird-7, a spacecraft destined to replace the aging Superbird-C . On 28 June 2005, Mitsubishi Electric (MELCO) got first contract negotiations right, and on31 October 2005, SCC and MELCO successfully concluded the contract negotiation. On 1 November 2005, SCC makes the orders to MELCO official for

2800-481: The Radio Regulations . In the 1976 Bogota Declaration , eight countries located on the Earth's equator claimed sovereignty over the geostationary orbits above their territory, but the claims gained no international recognition. A statite is a hypothetical satellite that uses radiation pressure from the sun against a solar sail to modify its orbit. It would hold its location over the dark side of

2880-533: The Solar System orbit the Sun in the direction of the Sun's rotation, which is counterclockwise when viewed from above the Sun's north pole . Six of the planets also rotate about their axis in this same direction. The exceptions – the planets with retrograde rotation – are Venus and Uranus . Venus's axial tilt is 177°, which means it is rotating almost exactly in the opposite direction to its orbit. Uranus has an axial tilt of 97.77°, so its axis of rotation

2960-528: The Solar System , the orbits around the Sun of all planets and most other objects, except many comets , are prograde. They orbit around the Sun in the same direction as the sun rotates about its axis, which is counterclockwise when observed from above the Sun's north pole. Except for Venus and Uranus , planetary rotations around their axis are also prograde. Most natural satellites have prograde orbits around their planets. Prograde satellites of Uranus orbit in

3040-407: The Sun . The inclination of moons is measured from the equator of the planet they orbit. An object with an inclination between 0 and 90 degrees is orbiting or revolving in the same direction as the primary is rotating. An object with an inclination of exactly 90 degrees has a perpendicular orbit that is neither prograde nor retrograde. An object with an inclination between 90 degrees and 180 degrees

3120-732: The USNS Kingsport docked in Lagos on August 23, 1963. The first satellite placed in a geostationary orbit was Syncom 3 , which was launched by a Delta D rocket in 1964. With its increased bandwidth, this satellite was able to transmit live coverage of the Summer Olympics from Japan to America. Geostationary orbits have been in common use ever since, in particular for satellite television. Today there are hundreds of geostationary satellites providing remote sensing and communications. Although most populated land locations on

3200-430: The centripetal force required to maintain the orbit ( F c ) is equal to the gravitational force acting on the satellite ( F g ): From Isaac Newton 's universal law of gravitation , where F g is the gravitational force acting between two objects, M E is the mass of the Earth, 5.9736 × 10  kg , m s is the mass of the satellite, r is the distance between the centers of their masses , and G

3280-429: The speed of an object moving around a circle produces: where T is the orbital period (i.e. one sidereal day), and is equal to 86 164 .090 54  s . This gives an equation for r : The product GM E is known with much greater precision than either factor alone; it is known as the geocentric gravitational constant μ = 398 600 .4418 ± 0.0008 km s . Hence Retrograde and prograde motion In

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3360-441: The westerlies or from west to east through the trade wind easterlies. Prograde motion with respect to planetary rotation is seen in the atmospheric super-rotation of the thermosphere of Earth and in the upper troposphere of Venus . Simulations indicate that the atmosphere of Pluto should be dominated by winds retrograde to its rotation. Artificial satellites destined for low inclination orbits are usually launched in

3440-461: The 100°–125° range. Meteoroids in a retrograde orbit around the Sun hit the Earth with a faster relative speed than prograde meteoroids and tend to burn up in the atmosphere and are more likely to hit the side of the Earth facing away from the Sun (i.e. at night) whereas the prograde meteoroids have slower closing speeds and more often land as meteorites and tend to hit the Sun-facing side of

3520-424: The Earth at a latitude of approximately 30 degrees. A statite is stationary relative to the Earth and Sun system rather than compared to surface of the Earth, and could ease congestion in the geostationary ring. Geostationary satellites require some station keeping to keep their position, and once they run out of thruster fuel they are generally retired. The transponders and other onboard systems often outlive

3600-431: The Earth. Most meteoroids are prograde. The Sun's motion about the centre of mass of the Solar System is complicated by perturbations from the planets. Every few hundred years this motion switches between prograde and retrograde. Retrograde motion, or retrogression, within the Earth's atmosphere is seen in weather systems whose motion is opposite the general regional direction of airflow, i.e. from east to west against

3680-476: The Solar System are tidally locked to their host planet, so they have zero rotation relative to their host planet, but have the same type of rotation as their host planet relative to the Sun because they have prograde orbits around their host planet. That is, they all have prograde rotation relative to the Sun except those of Uranus. If there is a collision, material could be ejected in any direction and coalesce into either prograde or retrograde moons, which may be

3760-535: The Sun and atmospheric tides trying to spin Venus in a retrograde direction. In addition to maintaining this present day equilibrium, tides are also sufficient to account for evolution of Venus's rotation from a primordial fast prograde direction to its present-day slow retrograde rotation. In the past, various alternative hypotheses have been proposed to explain Venus's retrograde rotation, such as collisions or it having originally formed that way. Despite being closer to

3840-504: The Sun than Venus, Mercury is not tidally locked because it has entered a 3:2 spin–orbit resonance due to the eccentricity of its orbit. Mercury's prograde rotation is slow enough that due to its eccentricity, its angular orbital velocity exceeds its angular rotational velocity near perihelion , causing the motion of the sun in Mercury's sky to temporarily reverse. The rotations of Earth and Mars are also affected by tidal forces with

3920-455: The Sun, but they have not reached an equilibrium state like Mercury and Venus because they are further out from the Sun where tidal forces are weaker. The gas giants of the Solar System are too massive and too far from the Sun for tidal forces to slow down their rotations. All known dwarf planets and dwarf planet candidates have prograde orbits around the Sun, but some have retrograde rotation. Pluto has retrograde rotation; its axial tilt

4000-400: The absence of servicing missions from the Earth or a renewable propulsion method, the consumption of thruster propellant for station-keeping places a limitation on the lifetime of the satellite. Hall-effect thrusters , which are currently in use, have the potential to prolong the service life of a satellite by providing high-efficiency electric propulsion . For circular orbits around a body,

4080-447: The case for the moons of dwarf planet Haumea , although Haumea's rotation direction is not known. Asteroids usually have a prograde orbit around the Sun. Only a few dozen asteroids in retrograde orbits are known. Some asteroids with retrograde orbits may be burnt-out comets, but some may acquire their retrograde orbit due to gravitational interactions with Jupiter . Due to their small size and their large distance from Earth it

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4160-413: The cluster and this can lead to disks and their resulting planets having inclined or retrograde orbits around their stars. Retrograde motion may also result from gravitational interactions with other celestial bodies in the same system (See Kozai mechanism ) or a near-collision with another planet, or it may be that the star itself flipped over early in their system's formation due to interactions between

4240-464: The collection of artificial satellites in this orbit is known as the Clarke Belt. In technical terminology the orbit is referred to as either a geostationary or geosynchronous equatorial orbit, with the terms used somewhat interchangeably. The first geostationary satellite was designed by Harold Rosen while he was working at Hughes Aircraft in 1959. Inspired by Sputnik 1 , he wanted to use

4320-520: The concept in a 1945 paper entitled Extra-Terrestrial Relays – Can Rocket Stations Give Worldwide Radio Coverage? , published in Wireless World magazine. Clarke acknowledged the connection in his introduction to The Complete Venus Equilateral . The orbit, which Clarke first described as useful for broadcast and relay communications satellites, is sometimes called the Clarke orbit. Similarly,

4400-470: The direction Uranus rotates, which is retrograde to the Sun. Nearly all regular satellites are tidally locked and thus have prograde rotation. Retrograde satellites are generally small and distant from their planets, except Neptune 's satellite Triton , which is large and close. All retrograde satellites are thought to have formed separately before being captured by their planets. Most low-inclination artificial satellites of Earth have been placed in

4480-453: The direction the star is rotating. A second such planet was announced just a day later: HAT-P-7b . In one study more than half of all the known hot Jupiters had orbits that were misaligned with the rotation axis of their parent stars, with six having backwards orbits. One proposed explanation is that hot Jupiters tend to form in dense clusters, where perturbations are more common and gravitational capture of planets by neighboring stars

4560-405: The discovery of several hot Jupiters with backward orbits called into question the theories about the formation of planetary systems. This can be explained by noting that stars and their planets do not form in isolation but in star clusters that contain molecular clouds . When a protoplanetary disk collides with or steals material from a cloud this can result in retrograde motion of a disk and

4640-659: The equator and appear lower in the sky to an observer nearer the poles. As the observer's latitude increases, communication becomes more difficult due to factors such as atmospheric refraction , Earth's thermal emission , line-of-sight obstructions, and signal reflections from the ground or nearby structures. At latitudes above about 81°, geostationary satellites are below the horizon and cannot be seen at all. Because of this, some Russian communication satellites have used elliptical Molniya and Tundra orbits, which have excellent visibility at high latitudes. A worldwide network of operational geostationary meteorological satellites

4720-474: The equilibrium points would (without any action) be slowly accelerated towards the stable equilibrium position, causing a periodic longitude variation. The correction of this effect requires station-keeping maneuvers with a maximal delta-v of about 2 m/s per year, depending on the desired longitude. Solar wind and radiation pressure also exert small forces on satellites: over time, these cause them to slowly drift away from their prescribed orbits. In

4800-490: The first commercial communications satellite to be built in Japan, the Superbird-7. The contract called for on orbit delivery, with MELCO handling every detail from construction to launch procurement and on orbit testing for final hand over to the customer. It was not only the first SCC order for a commercial communications satellite built in Japan, but the first such order ever. This event meant that MELCO officially entered

4880-553: The following properties: An inclination of zero ensures that the orbit remains over the equator at all times, making it stationary with respect to latitude from the point of view of a ground observer (and in the Earth-centered Earth-fixed reference frame). The orbital period is equal to exactly one sidereal day. This means that the satellite will return to the same point above the Earth's surface every (sidereal) day, regardless of other orbital properties. For

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4960-523: The ground. All geostationary satellites have to be located on this ring. A combination of lunar gravity, solar gravity, and the flattening of the Earth at its poles causes a precession motion of the orbital plane of any geostationary object, with an orbital period of about 53 years and an initial inclination gradient of about 0.85° per year, achieving a maximal inclination of 15° after 26.5 years. To correct for this perturbation , regular orbital stationkeeping maneuvers are necessary, amounting to

5040-508: The market. Superbird-7 was expected to weight around 5,000 kg (11,000 lb), have 28 Ku-band transponders , a design life of 15 years and be launched on the first quarter of 2008. It was going to be renamed as Superbird-C2 once in orbit and be stationed on the 144° East where it would replace the aging Superbird-C . It was expected to offer its services in Japan, Eastern Asia and the Pacific Ocean. In March 2008, SCC becomes

5120-576: The on-orbit tests and performed the necessary acceptance tests. This concluded the commission phase and the spacecraft was put into service. On 1 August 2012, JSAT and Panasonic Avionics Corporation announced an agreement for under which Panasonic would commit to use the Superbird-C2 beams for its eXConnect in-flight Internet connectivity service in South East Asia. Geostationary orbit A geostationary orbit , also referred to as

5200-538: The passive Echo balloon satellites in 1960, followed by Telstar 1 in 1962. Although these projects had difficulties with signal strength and tracking, issues that could be solved using geostationary orbits, the concept was seen as impractical, so Hughes often withheld funds and support. By 1961, Rosen and his team had produced a cylindrical prototype with a diameter of 76 centimetres (30 in), height of 38 centimetres (15 in), weighing 11.3 kilograms (25 lb), light and small enough to be placed into orbit. It

5280-476: The planet now have terrestrial communications facilities ( microwave , fiber-optic ), with telephone access covering 96% of the population and internet access 90%, some rural and remote areas in developed countries are still reliant on satellite communications. Most commercial communications satellites , broadcast satellites and SBAS satellites operate in geostationary orbits. Geostationary communication satellites are useful because they are visible from

5360-485: The position in the sky where the satellites are located. Weather satellites are also placed in this orbit for real-time monitoring and data collection, and navigation satellites to provide a known calibration point and enhance GPS accuracy. Geostationary satellites are launched via a temporary orbit , and placed in a slot above a particular point on the Earth's surface. The orbit requires some stationkeeping to keep its position, and modern retired satellites are placed in

5440-621: The prograde direction, since this minimizes the amount of propellant required to reach orbit by taking advantage of the Earth's rotation (an equatorial launch site is optimal for this effect). However, Israeli Ofeq satellites are launched in a westward, retrograde direction over the Mediterranean to ensure that launch debris does not fall onto populated land areas. Stars and planetary systems tend to be born in star clusters rather than forming in isolation. Protoplanetary disks can collide with or steal material from molecular clouds within

5520-439: The region of stability for retrograde orbits at a large distance from the primary is larger than that for prograde orbits. This has been suggested as an explanation for the preponderance of retrograde moons around Jupiter. Because Saturn has a more even mix of retrograde/prograde moons, however, the underlying causes appear to be more complex. With the exception of Hyperion , all the known regular planetary natural satellites in

5600-428: The resulting planets. A celestial object's inclination indicates whether the object's orbit is prograde or retrograde. The inclination of a celestial object is the angle between its orbital plane and another reference frame such as the equatorial plane of the object's primary. In the Solar System , inclination of the planets is measured from the ecliptic plane , which is the plane of Earth 's orbit around

5680-507: The rotation is known, all satellites of asteroids orbit the asteroid in the same direction as the asteroid is rotating. Most known objects that are in orbital resonance are orbiting in the same direction as the objects they are in resonance with, however a few retrograde asteroids have been found in resonance with Jupiter and Saturn . Comets from the Oort cloud are much more likely than asteroids to be retrograde. Halley's Comet has

5760-524: The same plane, altitude and speed; however, the presence of satellites in eccentric orbits allows for collisions at up to 4 km/s. Although a collision is comparatively unlikely, GEO satellites have a limited ability to avoid any debris. At geosynchronous altitude, objects less than 10 cm in diameter cannot be seen from the Earth, making it difficult to assess their prevalence. Despite efforts to reduce risk, spacecraft collisions have occurred. The European Space Agency telecom satellite Olympus-1

5840-405: The sky. A geostationary orbit can be achieved only at an altitude very close to 35,786 kilometres (22,236 miles) and directly above the equator. This equates to an orbital speed of 3.07 kilometres per second (1.91 miles per second) and an orbital period of 1,436 minutes, one sidereal day . This ensures that the satellite will match the Earth's rotational period and has a stationary footprint on

5920-402: The solar system's terrestrial planets except for Venus, is not common for terrestrial planets in general. The pattern of stars appears fixed in the sky, insofar as human vision is concerned; this is because their massive distances relative to the Earth result in motion imperceptible to the naked eye. In reality, stars orbit the center of their galaxy. Stars with an orbit retrograde relative to

6000-400: The spacecraft at 21:09 UTC and less than an hour later, at 22:03 UTC, it had already spread its solar panels . After the successful launch, Superbird-7 was renamed as Superbird-C2. On 17 October 2008, MELCO announced that they had performed the final handover of the spacecraft to JSAT. They had performed all orbital maneuvers to its correct orbital slot on the 144° East position, had completed

6080-436: The star's magnetic field and the planet-forming disk. The accretion disk of the protostar IRAS 16293-2422 has parts rotating in opposite directions. This is the first known example of a counterrotating accretion disk. If this system forms planets, the inner planets will likely orbit in the opposite direction to the outer planets. WASP-17b was the first exoplanet that was discovered to be orbiting its star opposite to

6160-485: The thruster fuel and by allowing the satellite to move naturally into an inclined geosynchronous orbit some satellites can remain in use, or else be elevated to a graveyard orbit . This process is becoming increasingly regulated and satellites must have a 90% chance of moving over 200 km above the geostationary belt at end of life. Space debris at geostationary orbits typically has a lower collision speed than at low Earth orbit (LEO) since all GEO satellites orbit in

6240-566: Was spin stabilised with a dipole antenna producing a pancake shaped beam. In August 1961, they were contracted to begin building the real satellite. They lost Syncom 1 to electronics failure, but Syncom 2 was successfully placed into a geosynchronous orbit in 1963. Although its inclined orbit still required moving antennas, it was able to relay TV transmissions, and allowed for US President John F. Kennedy in Washington D.C., to phone Nigerian prime minister Abubakar Tafawa Balewa aboard

6320-417: Was orbiting the Milky Way in a retrograde direction relative to the Milky Way's rotation, is colliding with the Milky Way. NGC 7331 is an example of a galaxy that has a bulge that is rotating in the opposite direction to the rest of the disk, probably as a result of infalling material. The center of a spiral galaxy contains at least one supermassive black hole . A retrograde black hole – one whose spin

6400-499: Was struck by a meteoroid on August 11, 1993, and eventually moved to a graveyard orbit , and in 2006 the Russian Express-AM11 communications satellite was struck by an unknown object and rendered inoperable, although its engineers had enough contact time with the satellite to send it into a graveyard orbit. In 2017, both AMC-9 and Telkom-1 broke apart from an unknown cause. A typical geostationary orbit has

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