Apoapsis Records is an independent boutique record label currently based in London UK, founded by brothers Vasileios Angelis and Apostolos Angelis in 2009, in order to release their own music. The label started initially in Greece and later on moved to London UK. Apoapsis Records focuses mainly on Electronic music in the genres of Orchestral, Classical, Ethnic and Electronica and has released over 100 original recordings. Apoapsis Records was the first label worldwide that actively joined and supported the DR movement (Pleasurize Music non-profit Organization for more Dynamic Range in produced music) for an end of the Loudness war.
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The idea for the name and logo comes from the astronomical term Apoapsis: An apsis (Greek apsis) is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. The point of farthest excursion is called the Apoapsis (Greek apó, “from”). It’s actually the point in an orbit farthest from the body being orbited.
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Initially, Surveyor entered a highly elliptical orbit that took 45 hours to complete. The orbit had a periapsis of above the northern hemisphere, and an apoapsis of above the southern hemisphere.
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A circular orbit is a special case, wherein the foci of the ellipse coincide. The point where the orbiting body is closest to Earth is called the perigee, and is called the periapsis (less properly, "perifocus" or "pericentron") when the orbit is about a body other than Earth. The point where the satellite is farthest from Earth is called the apogee, apoapsis, or sometimes apifocus or apocentron. A line drawn from periapsis to apoapsis is the line-of-apsides.
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As a result, as a planet approaches periapsis, the planet will increase in speed as its potential energy decreases; as a planet approaches apoapsis, its velocity will decrease as its potential energy increases.
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The estimated semi-major axis of the planet's orbit is 1.2 astronomical units (AU), which would give it a periapsis distance of 0.9 AU and an apoapsis distance of 1.5 AU. By comparison, the star has a radius of 0.07 AU.
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Pallava Bagla, Science Magazine. 17 February 2017. The orbiter, depending on its final configuration, would have a science payload capability of approximately with 500 W available power. The initial elliptical orbit around Venus is expected to have at periapsis and at apoapsis.
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First evaluation of the orbital insertion showed that the orbiter had reached its first milestone at Mars. The orbit was later adjusted by four more main engine firings to the desired 259 km × 11,560 km near-polar (86 degree inclination) orbit with a period of 7.5 hours. Near periapsis (nearest to Mars) the top deck is pointed down towards the Martian surface and near apoapsis (farthest from Mars in its orbit) the high gain antenna will be pointed towards Earth for uplink and downlink. After 100 days the apoapsis was lowered to 10,107 km and periapsis raised to 298 km to give an orbital period of 6.7 hours.
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A typical Titan encounter changed the spacecraft's velocity by 0.75 km/s, and the spacecraft made 127 Titan encounters. These encounters enabled an orbital tour with a wide range of periapsis and apoapsis distances, various alignments of the orbit with respect to the Sun, and orbital inclinations from 0° to 74°.
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The most appreciable changes in their orbits occur approximately every 6.2 years, when the periapsis of Pandora lines up with the apoapsis of Prometheus, when they approach to within approximately 1400 km. Prometheus is itself a significant perturber of Atlas, with which it is in a 53:54 mean-longitude resonance.
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After the ε ring, the α and β rings are the brightest of Uranus's rings. Like the ε ring, they exhibit regular variations in brightness and width. They are brightest and widest 30° from the apoapsis and dimmest and narrowest 30° from the periapsis. The α and β rings have sizable orbital eccentricity and non- negligible inclination.
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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 equal to the rotational period of the body which contains the barycenter of the orbit.
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The orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the solar system. Using JPL Horizons, the barycentric orbital elements for epoch 2030-Jan-01 generate a semi-major axis of 7,500 AU, an apoapsis distance of 15,000 AU, and a period of approximately 650,000 years. Before entering the planetary region (epoch 1950), C/2007 Q3 had a calculated barycentric orbital period of ~6.4 million years with an apoapsis (aphelion) distance of about 69,000 AU (1.09 light-years). The comet was probably in the outer Oort cloud for millions or billions of years with a loosely bound chaotic orbit until it was perturbed inward.
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The Voyager 2 spacecraft observed a strange signal from the ε ring during the radio occultation experiment. The signal looked like a strong enhancement of the forward- scattering at the wavelength 3.6 cm near ring's apoapsis. Such strong scattering requires the existence of a coherent structure. That the ε ring does have such a fine structure has been confirmed by many occultation observations.
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A small radial impulse given to a body in orbit changes the eccentricity, but not the orbital period (to first order). A prograde or retrograde impulse (i.e. an impulse applied along the orbital motion) changes both the eccentricity and the orbital period. Notably, a prograde impulse at periapsis raises the altitude at apoapsis, and vice versa, and a retrograde impulse does the opposite.
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The inner of the two Martian moons, Phobos, is in a subsynchronous orbit of Mars with an orbital period of only 0.32 days. The outer moon Deimos is in supersynchronous orbit around Mars. The Mars Orbiter Mission—currently orbiting Mars—is placed into highly elliptical supersynchronous orbit around Mars, with a period of 76.7 hours and a planned periapsis of and apoapsis of .
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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. In this case, not only the distance, but also the speed, angular speed, potential and kinetic energy are constant. There is no periapsis or apoapsis. This orbit has no radial version.
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A despun dish antenna provided S and X band communication with Earth. A Star-24 solid rocket motor was integrated into the spacecraft to provide the thrust to enter orbit around Venus. From Venus orbit insertion to July 1980, periapsis was held between (at 17 degrees north latitude) to facilitate radar and ionospheric measurements. The spacecraft was in a 24-hour orbit with an apoapsis of .
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The telescope had an initial orbit of with a periapsis of , an apoapsis of , with inclination 98.0° and eccentricity 0.064048, giving it a period of 99.2 minutes. The orbit was sun-synchronous, and the attitude of the spacecraft could be controlled through reaction wheels. The momentum stored in the reaction wheels throughout the orbit was regularly dumped via magnetic coils that interacted with the Earth's magnetic field.
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Thus, the angular rate is faster nearer periapsis and slower near apoapsis. The same is so for the Moon's orbit around the Earth. Because of these variations in angular rate, the actual time between lunations may vary from about 29.18 to about 29.93 days. The long-term average duration is daysCRC Handbook of Chemistry and Physics, page F-258 (29 d 12 h 44 m 2.8016 s).
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The initial transfer orbit was at an inclination of 26.2 degrees. It had a periapsis of 171 km and an apoapsis of 3,524 km and an orbital period of 619 minutes.NASA Space Science Data Coordinated Archive The orbit was circularized at the operational geosynchronous altitude by a solid propellant apogee kick motor (AKM). The satellite's main body was 1.7 meters high by 2.7 meters in diameter and a hexagonal shape.
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The resolved η ring demonstrates the optically thin broad component. The geometric thickness of the ε ring is not precisely known, although the ring is certainly very thin—by some estimates as thin as 150 m. Despite such infinitesimal thickness, it consists of several layers of particles. The ε ring is a rather crowded place with a filling factor near the apoapsis estimated by different sources at from 0.008 to 0.06.
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On September 17, 2002, a team of astronomers led by Geoffrey Marcy announced the discovery of a giant planet around Tau1 Gruis. The radial velocity measurements suggest that the star has a companion with at least 1.23 times the mass of Jupiter. The planet's orbit stays inside the system's habitable zone for most of its revolution around the star, though at apoapsis, the planet falls outside of this zone.
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The apsides are the orbital points closest (periapsis) and farthest (apoapsis) from its primary body. The apsidal precession is the first time derivative of the argument of periapsis, one of the six main orbital elements of an orbit. Apsidal precession is considered positive when the orbit's axis rotates in the same direction as the orbital motion. An apsidal period is the time interval required for an orbit to precess through 360°.
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As of 6 August, AMC-14 orbit is vastly different. Figures for perigee (periapsis), apogee (apoapsis) and Inclination are given in the info box at the beginning of this article, Inclination has dropped to 17.7 and Eccentricity has decreased to 0.199. As of January 29, 2009, after more than 6 months of low-thrust maneuvering, AMC-14 had finally reached an inclined (13.1°) geosynchronous orbit at 34.8°East under US DoD ownership.
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These variations are connected with the variations of the ring width, which is 19.7 km at the periapsis and 96.4 km at the apoapsis. As the ring becomes wider, the amount of shadowing between particles decreases and more of them come into view, leading to higher integrated brightness. The width variations were measured directly from Voyager 2 images, as the ε ring was one of only two rings resolved by Voyager's cameras.
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These orbital variations cause the axial tilt (the angle between rotational and orbital axes) to vary between 0 and 0.33°. Ganymede participates in orbital resonances with Europa and Io: for every orbit of Ganymede, Europa orbits twice and Io orbits four times. Conjunctions (alignment on the same side of Jupiter) between Io and Europa occur when Io is at periapsis and Europa at apoapsis. Conjunctions between Europa and Ganymede occur when Europa is at periapsis.
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Ridges and grooves are also present on moon's surface. The orbit of Pandora appears to be chaotic, as a consequence of a series of four 118:121 mean-motion resonances with Prometheus. The most appreciable changes in their orbits occur approximately every 6.2 years, when the periapsis of Pandora lines up with the apoapsis of Prometheus and the moons approach to within about . Pandora also has a 3:2 mean-motion resonance with Mimas.
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Orbital studies of the new comet soon revealed that it was orbiting Jupiter rather than the Sun, unlike all other comets known at the time. Its orbit around Jupiter was very loosely bound, with a period of about 2 years and an apoapsis (the point in the orbit farthest from the planet) of . Its orbit around the planet was highly eccentric (e = 0.9986). Tracing back the comet's orbital motion revealed that it had been orbiting Jupiter for some time.
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A Broadband Imaging X-ray All-sky Survey, or ABRIXAS was a space-based German X-ray telescope. It was launched on 28 April 1999 in a Kosmos-3M launch vehicle from Kapustin Yar, Russia, into Earth orbit. The orbit had a periapsis of , an apoapsis of , an inclination of 48.0° and an eccentricity of 0.00352, giving it a period of 96 minutes. The telescope's battery was accidentally overcharged and destroyed three days after the mission started.
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An artist's conception of aerobraking with the Mars Reconnaissance Orbiter An example of Aerobraking Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is used when a spacecraft requires a low orbit after arriving at a body with an atmosphere, and it requires less fuel than does the direct use of a rocket engine.
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Aerocapture is a related but more extreme method in which no initial orbit-injection burn is performed. Instead, the spacecraft plunges deeply into the atmosphere without an initial insertion burn, and emerges from this single pass in the atmosphere with an apoapsis near that of the desired orbit. Several small correction burns are then used to raise the periapsis and perform final adjustments. This method was originally planned for the Mars Odyssey orbiter, but the significant design impacts proved too costly.
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The Small Astronomy Satellite 2, also known also as SAS-2, SAS B or Explorer 48, was a NASA gamma ray telescope. It was launched on 15 November 1972 into the low Earth orbit with a periapsis of 443 km and an apoapsis of 632 km. It completed its observations on 8 June 1973. SAS 2 was the second in the series of small spacecraft designed to extend the astronomical studies in the X-ray, gamma-ray, ultraviolet, visible, and infrared regions.
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Mars Orbiter Mission 2 (MOM 2), also called Mangalyaan-2 ("Mars-craft", from mangal, "Mars" and यान yān, "craft, vehicle"), is India's second interplanetary mission planned for launch to Mars in 2024 by the Indian Space Research Organisation (ISRO). Alt URL However, in a recorded interview in October 2019, VSSC director has indicated possibility of inclusion of a lander and rover. The orbiter will use aerobraking to lower its initial apoapsis and enter into an orbit more suitable for observations.
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During every atmospheric pass, the spacecraft slowed down by a slight amount because of atmospheric resistance. The density of the Martian atmosphere at such altitudes is comparatively low, allowing this procedure to be performed without damage to the spacecraft. This slowing caused the spacecraft to lose altitude on its next pass through the orbit's apoapsis. Surveyor had planned to use this aerobraking technique over a period of four months to lower the high point of its orbit from to altitudes near .
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In celestial mechanics, the eccentricity vector of a Kepler orbit is the dimensionless vector with direction pointing from apoapsis to periapsis and with magnitude equal to the orbit's scalar eccentricity. For Kepler orbits the eccentricity vector is a constant of motion. Its main use is in the analysis of almost circular orbits, as perturbing (non-Keplerian) forces on an actual orbit will cause the osculating eccentricity vector to change continuously. For the eccentricity and argument of periapsis parameters, eccentricity zero (circular orbit) corresponds to a singularity.
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The burn was monitored from ESA's Control Centre, ESOC, in Darmstadt, Germany. Seven further orbit control maneuvers, two with the main engine and five with the thrusters, were required for Venus Express to reach its final operational 24-hour orbit around Venus. Venus Express entered its target orbit at apoapsis on 7 May 2006 at 13:31 UTC, when the spacecraft was from Earth. At this point the spacecraft was running on an ellipse substantially closer to the planet than during the initial orbit.
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Mars Orbiter Mission 2 (MOM 2), also called Mangalyaan-2, is India's second interplanetary mission planned for launch to Mars by the Indian Space Research Organisation (ISRO). As per some reports emerged, the mission was to be an orbiter to Mars proposed for 2024. Alt URL However, in a recorded interview in October 2019, VSSC director has indicated the inclusion of a lander and rover. The orbiter will use aerobraking to lower its initial apoapsis and enter into an orbit more suitable for observations.
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There is no standard name for the class. The name Apohele was proposed by the discoverers of , and is the Hawaiian word for orbit, from apo 'circle' and hele 'to go';(Ulukau Hawaiian Electronic Library) it was chosen partially because of its similarity to the words aphelion (apoapsis) and helios. Other authors adopted the designation Inner Earth Objects (IEOs). Still others, following the general practice to name a new class of asteroids for the first recognized member of that class, use the designation Atira asteroids.
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Maximum (instantaneous) orbital speed occurs at periapsis (perigee, perihelion, etc.), while minimum speed for objects in closed orbits occurs at apoapsis (apogee, aphelion, etc.). In ideal two-body systems, objects in open orbits continue to slow down forever as their distance to the barycenter increases. When a system approximates a two-body system, instantaneous orbital speed at a given point of the orbit can be computed from its distance to the central body and the object's specific orbital energy, sometimes called "total energy". Specific orbital energy is constant and independent of position.
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By further using data compression, the effective data rate could be raised to 1,000 bits per second. The data collected on Jupiter and its moons was stored in the spacecraft's onboard tape recorder, and transmitted back to Earth during the long apoapsis portion of the probe's orbit using the low-gain antenna. At the same time, measurements were made of Jupiter's magnetosphere and transmitted back to Earth. The reduction in available bandwidth reduced the total amount of data transmitted throughout the mission, although 70% of Galileo science goals could still be met.
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A close-up view of the ε ring of Uranus The ε ring is the brightest and densest part of the Uranian ring system, and is responsible for about two-thirds of the light reflected by the rings. While it is the most eccentric of the Uranian rings, it has negligible orbital inclination. The ring's eccentricity causes its brightness to vary over the course of its orbit. The radially integrated brightness of the ε ring is highest near apoapsis and lowest near periapsis. The maximum/minimum brightness ratio is about 2.5–3.0.
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Venera 16 was launched on June 7, 1983, at 02:32:00 UTC and reached Venus' orbit on October 11, 1983. The spacecraft was inserted into Venus orbit a day apart from Venera 15, with its orbital plane shifted by an angle of approximately 4° relative to one another probe. This made it possible to reimage an area if necessary. The spacecraft was in a nearly polar orbit with a periapsis ~1000 km, at 62°N latitude, and apoapsis ~65000 km, with an inclination ~90°, the orbital period being ~24 hours.
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Braille has an unusually inclined orbit, and belongs to the somewhat rare class of asteroids known as Mars-crossing asteroids. Simulations of its orbit by scientists of the Deep Space 1 project predict that it will evolve into an Earth-crossing orbit in about 4000 years. Although its closest approach to the Sun is closer than Mars orbit, its highly elliptical orbit takes it almost half-way to Jupiter at its apoapsis, and as such its semi-major axis is too large for it to be classified as an Amor asteroid.
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The probe reached Mars on 12 February. At 14:44:25 the spacecraft's engines ignited to begin its orbit insertion burn, which successfully placed it into an Areocentric orbit with a periapsis of , an apoapsis of , and 35.3 degrees inclination. The spacecraft's pressurised instrument compartment began to leak as soon as the spacecraft entered orbit around Mars, which controllers believed to be the result of a micrometeoroid impact during orbital insertion. It ceased operations on 28 February, having returned 180 photographic frames, 43 of which were of usable quality.
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C/1999 F1 made its closest approach to Neptune in August 2017. Using JPL Horizons, the barycentric orbital elements for epoch 2035-Jan-01 generate a semi-major axis of 33,300 AU, an apoapsis distance of 66,600 AU, and a period of approximately 6 million years. Comet West has a similar period. The generic JPL Small-Body Database browser uses a near-perihelion epoch of 2001-May-19 which is before the comet left the planetary region and makes the highly eccentric aphelion point inaccurate since it does not account for any planetary perturbations.
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Four to five (preferably five) days before arrival, the spacecraft was to release both Surface Stations to land at two separate sites in the northern hemisphere. After release, the spacecraft would perform a deflection maneuver to change the orbiter's trajectory to a fly-by path in preparation for orbit insertion. At the appropriate moment, with the main engine of the propulsion unit facing the direction of flight, the spacecraft would make a burn to slow down and enter Mars orbit. Initial Mars orbit would have a periapsis of 500 km, an apoapsis of about 52,000 km, with an orbital period of 43.09 hours.
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The pair share a close, elliptical orbit with a period of 4.55970 days. The orbital eccentricity is 0.277, which means that at the separation at closest approach, or periapsis, is only 57% of the distance at their greatest separation, or apoapsis. There is a third, more distant companion at an angular separation of around 1 arcsecond that may be orbiting the pair with a period of about 64 years. The pair that share the close orbit, Epsilon Lupi Aa and Epsilon Lupi Ab, have estimated masses of 13.24 and 11.46 times the mass of the Sun, respectively.
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Completion of the orbital insertion placed the orbiter in a highly elliptical polar orbit with a period of approximately 35.5 hours. Shortly after insertion, the periapsis – the point in the orbit closest to Mars – was from the surface ( from the planet's center). The apoapsis – the point in the orbit farthest from Mars – was from the surface ( from the planet's center). When MRO entered orbit, it joined five other active spacecraft that were either in orbit or on the planet's surface: Mars Global Surveyor, Mars Express, 2001 Mars Odyssey, and the two Mars Exploration Rovers (Spirit and Opportunity).
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Using JPL Horizons with an observed orbital arc of 271 days, the barycentric orbital elements for epoch 2500 generate a hyperbolic orbit with an eccentricity of 1.0004. (Solution using the Solar System Barycenter and barycentric coordinates. Select Ephemeris Type:Elements and Center:@0) (saved Horizons output file 2011-Aug-08) Before entering the planetary region (epoch 1600), Elenin had a calculated barycentric orbital period of tens of millions of years with an apoapsis (aphelion) distance of about . Elenin was probably in the outer Oort cloud with a loosely bound chaotic orbit that was easily perturbed by passing stars.
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Flight profile of Venera 15 Venera 15 was launched on June 2, 1983, at 02:38:39 UTC and reached Venus' orbit on October 10, 1983. The spacecraft was inserted into Venus orbit a day apart from Venera 16, with its orbital plane shifted by an angle of approximately 4° relative to the other probe. This made it possible to reimage an area if necessary. The spacecraft was in a nearly polar orbit with a periapsis ~1000 km, at 62°N latitude, and apoapsis ~65000 km, with an inclination ~90°, the orbital period being ~24 hours.
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Instead, the new plan was to place the probe in a highly elliptical orbit with an apoapsis of a hundred thousand kilometers and a periapsis of a few thousand kilometers from Venus. Engineers planned for the alternate orbit to be prograde (in the direction of the atmospheric super- rotation) and lie in the orbital plane of Venus. The method and orbit were announced by JAXA in February 2015, with an orbit insertion date of 7 December 2015. The probe reached its most distant point from Venus on 3 October 2013 and had been approaching the planet since then.
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The transverse orbital speed is inversely proportional to the distance to the central body because of the law of conservation of angular momentum, or equivalently, Kepler's second law. This states that as a body moves around its orbit during a fixed amount of time, the line from the barycenter to the body sweeps a constant area of the orbital plane, regardless of which part of its orbit the body traces during that period of time. This law implies that the body moves slower near its apoapsis than near its periapsis, because at the smaller distance along the arc it needs to move faster to cover the same area.
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C/2000 U5 (LINEAR) is a single-apparition comet discovered on October 29, 2000, by Lincoln Near-Earth Asteroid Research. The comet has an observation arc of 362 days allowing a good estimate of the orbit. C/2000 U5 is, as of 2015, the 13th most hyperbolic comet ever discovered and will leave the Solar System. Before entering the inner Solar System for a 2000 perihelion passage, C/2000 U5 had a barycentric (epoch 1960-Jan-01) orbit with an apoapsis distance of 5,473 AU (0.09 light years), and a period of approximately 143,000 years. The comet came to perihelion on March 13, 2000.
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First, during its first five orbits of the planet (one Earth week), MRO used its thrusters to drop the periapsis of its orbit into aerobraking altitude. This altitude depends on the thickness of the atmosphere because Martian atmospheric density changes with its seasons. Second, while using its thrusters to make minor corrections to its periapsis altitude, MRO maintained aerobraking altitude for 445 planetary orbits (about five Earth months) to reduce the apoapsis of the orbit to . This was done in such a way so as to not heat the spacecraft too much, but also dip enough into the atmosphere to slow the spacecraft down.
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Extra fuel is required to compensate for the fact that the bursts take time; this is minimized by using high-thrust engines to minimize the duration of the bursts. For transfers in Earth orbit, the two burns are labelled the perigee burn and the apogee burn (or apogee kickJonathan McDowell, "Kick In the Apogee: 40 years of upper stage applications for solid rocket motors, 1957-1997", 33rd AIAA Joint Propulsion Conference, July 4, 1997. abstract. Retrieved 18 July 2017.); more generally, they are labelled periapsis and apoapsis burns. Alternately, the second burn to circularize the orbit may be referred to as a circularization burn.
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HD 80606, a sun-like star in a binary system, orbits a common center of gravity with its partner, HD 80607; the two are separated by 1,200 AU on average. Research conducted in 2003 indicates that its sole planet, HD 80606 b is a future hot Jupiter, modeled to have evolved in a perpendicular orbit around 5 AU from its sun. The 4-Jupiter mass planet is projected to eventually move into a circular, more aligned orbit via the Kozai mechanism. However, it is currently on an incredibly eccentric orbit that ranges from approximately one astronomical unit at its apoapsis and six stellar radii at periapsis.
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The S/C was launched from an American Lockheed L-1011-385-1-15 TriStar registered N140SC with a Pegasus-XL rocket from Gando Air Base in the Canary Islands the 21st of April 1997. It was successfully put on a near-circular close orbit of 585 km of apoapsis and 566 km of periapsis with and inclination of 151º (29º retrograde) and an orbital period of 96 minutes. After 5 years of successful operation, the satellite reentered the atmosphere on 14 February 2002. During its whole service life it was operated by INTA, who monitored the satellite from the Maspalomas Station (15º 37' 45” W, 27º 45' 49” N).
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Hohmann transfer orbit, 2, from an orbit (1) to a higher orbit (3) A Hohmann transfer orbit is the simplest maneuver which can be used to move a spacecraft from one altitude to another. Two burns are required: the first to send the craft into the elliptical transfer orbit, and a second to circularize the target orbit. To raise a circular orbit at v_1, the first posigrade burn raises velocity to the transfer orbit's periapsis velocity: :\Delta v_1\ = v_p - v_1 The second posigrade burn, made at apoapsis, raises velocity to the target orbit's velocity: :\Delta v_2\ = v_2 - v_a A maneuver to lower the orbit is the mirror image of the raise maneuver; both burns are made retrograde.
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In astronautics and aerospace engineering, the bi-elliptic transfer is an orbital maneuver that moves a spacecraft from one orbit to another and may, in certain situations, require less delta-v than a Hohmann transfer maneuver. The bi-elliptic transfer consists of two half-elliptic orbits. From the initial orbit, a first burn expends delta-v to boost the spacecraft into the first transfer orbit with an apoapsis at some point r_b away from the central body. At this point a second burn sends the spacecraft into the second elliptical orbit with periapsis at the radius of the final desired orbit, where a third burn is performed, injecting the spacecraft into the desired orbit.
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In general, inclination changes can require a great deal of delta-v to perform, and most mission planners try to avoid them whenever possible to conserve fuel. This is typically achieved by launching a spacecraft directly into the desired inclination, or as close to it as possible so as to minimize any inclination change required over the duration of the spacecraft life. Maximum efficiency of inclination change is achieved at apoapsis, (or apogee), where orbital velocity v\, is the lowest. In some cases, it may require less total delta v to raise the satellite into a higher orbit, change the orbit plane at the higher apogee, and then lower the satellite to its original altitude.
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Since the radial distance r cannot be a negative number, neither can its inverse u; therefore, u2 must be a positive number. If u1 is also positive, it is the smallest possible value of u, which corresponds to the largest possible value of r, the distance of furthest approach (apoapsis). If u1 is zero or negative, then the smallest possible value of u is zero (the orbit goes to infinity); in this case, the only relevant values of φ are those that make u positive. For an attractive force (α < 0), the orbit is an ellipse, a hyperbola or parabola, depending on whether u1 is positive, negative, or zero, respectively; this corresponds to an eccentricity e less than one, greater than one, or equal to one.
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However, the predictions of Newtonian gravity do not match the observations, as discovered in 1859 from observations of Mercury. If the potential energy between the two bodies is not exactly the 1/r potential of Newton's gravitational law but differs only slightly, then the ellipse of the orbit gradually rotates (among other possible effects). This apsidal precession is observed for all the planets orbiting the Sun, primarily due to the oblateness of the Sun (it is not perfectly spherical) and the attractions of the other planets to one another. The apsides are the two points of closest and furthest distance of the orbit (the periapsis and apoapsis, respectively); apsidal precession corresponds to the rotation of the line joining the apsides.
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More generally, firing a rocket engine to place a vehicle into the desired final orbit from a transfer orbit is labelled an "orbital insertion burn" or, if the desired orbit is circular, a circularization burn. For orbits around bodies other than Earth, it may be referred to as an apoapsis burn. The amount of fuel carried on board a satellite directly affects its lifetime, therefore it is desirable to make the apogee kick maneuver as efficient as possible. The mass of most geostationary satellites at the beginning of their operational life in geostationary orbit is typically about half that when they separated from their vehicle in geostationary transfer orbit, with the other half having been fuel expended in the apogee kick maneuver.
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Bi- elliptic transfer from blue to red circular orbit In astronautics and aerospace engineering, the bi-elliptic transfer is an orbital maneuver that moves a spacecraft from one orbit to another and may, in certain situations, require less delta-v than a Hohmann transfer maneuver. The bi-elliptic transfer consists of two half elliptic orbits. From the initial orbit, a delta-v is applied boosting the spacecraft into the first transfer orbit with an apoapsis at some point r_b away from the central body. At this point, a second delta-v is applied sending the spacecraft into the second elliptical orbit with periapsis at the radius of the final desired orbit, where a third delta-v is performed, injecting the spacecraft into the desired orbit.
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The satellite was part of the Soviet Union's RORSAT programme, a series of reconnaissance satellites which observed ocean traffic, including surface vessels and nuclear submarines, using active radar. It was assigned the Kosmos number 954 and was launched on 18 September 1977 at 13:55 UTC from the Baikonur Cosmodrome, on a Tsyklon-2 carrier rocket. With an orbital inclination of 65°, a periapsis of and apoapsis of , it orbited the Earth every 89.5 minutes. Powered by a liquid sodium–potassium thermionic converter driven by a nuclear reactor containing around of uranium-235, the satellite was intended for long-term on-orbit observation, but by December 1977 the satellite had deviated from its designed orbit and its flightpath was becoming increasingly erratic.
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More recent closeup images from the Cassini probe show that the F Ring consists of one core ring and a spiral strand around it. They also show that when Prometheus encounters the ring at its apoapsis, its gravitational attraction creates kinks and knots in the F Ring as the moon 'steals' material from it, leaving a dark channel in the inner part of the ring (see video link and additional F Ring images in gallery). Since Prometheus orbits Saturn more rapidly than the material in the F ring, each new channel is carved about 3.2 degrees in front of the previous one. In 2008, further dynamism was detected, suggesting that small unseen moons orbiting within the F Ring are continually passing through its narrow core because of perturbations from Prometheus.
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Its Laplace orbital resonance with Europa and Ganymede maintains Io's eccentricity and prevents tidal dissipation within Io from circularizing its orbit. The eccentricity leads to vertical differences in Io's tidal bulge of as much as as Jupiter's gravitational pull varies between the periapsis and apoapsis points in Io's orbit. This varying tidal pull also produces friction in Io's interior, enough to cause significant tidal heating and melting. Unlike Earth, where most of its internal heat is released by conduction through the crust, on Io internal heat is released via volcanic activity and generates the satellite's high heat flow (global total: 0.6–1.6 W). Models of its orbit suggest that the amount of tidal heating within Io changes with time, and that the current heat flow is not representative of the long-term average.
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The bi-elliptic transfer consists of two half-elliptic orbits. From the initial orbit, a first burn expends delta-v to boost the spacecraft into the first transfer orbit with an apoapsis at some point r_b away from the central body. At this point a second burn sends the spacecraft into the second elliptical orbit with periapsis at the radius of the final desired orbit, where a third burn is performed, injecting the spacecraft into the desired orbit. While they require one more engine burn than a Hohmann transfer and generally require a greater travel time, some bi-elliptic transfers require a lower amount of total delta-v than a Hohmann transfer when the ratio of final to initial semi-major axis is 11.94 or greater, depending on the intermediate semi-major axis chosen.
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Magellan to Venus On August 10, 1990, Magellan encountered Venus and began the orbital insertion maneuver which placed the spacecraft into a three- hour, nine minute, elliptical orbit that brought the spacecraft 295-kilometers from the surface at about 10 degrees North during the periapsis and out to 7762-kilometers during apoapsis. During each orbit, the space probe captured radar data while the spacecraft was closest to the surface, and then transmit it back to Earth as it moved away from Venus. This maneuver required extensive use of the reaction wheels to rotate the spacecraft as it imaged the surface for 37-minutes and as it pointed toward Earth for two hours. The primary mission intended for the spacecraft to return images of at least 70 percent of the surface during one Venusian day, which lasts 243 Earth days as the planet slowly spins.
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In other cases, boosting up to a relatively high altitude apoapsis gives low speed before performing the plane change and this can give lower total delta-v. The slingshot effect can be used to give a boost of speed/energy; if a vehicle goes past a planetary or lunar body, it is possible to pick up (or lose) some of that body's orbital speed relative to the sun or another planet. Another effect is the Oberth effect—this can be used to greatly decrease the delta-v needed, because using propellant at low potential energy/high speed multiplies the effect of a burn. Thus for example the delta-v for a Hohmann transfer from Earth's orbital radius to Mars's orbital radius (to overcome the sun's gravity) is many kilometres per second, but the incremental burn from low Earth orbit (LEO) over and above the burn to overcome Earth's gravity is far less if the burn is done close to Earth than if the burn to reach a Mars transfer orbit is performed at Earth's orbit, but far away from Earth.
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The tidal forces experienced by Io are about 20,000 times stronger than the tidal forces Earth experience due to the moon, and the vertical differences in its tidal bulge, between the times Io is at periapsis and apoapsis in its orbit, could be as much as .Interplanetary Low Tide - NASA Science Mission Directorate The friction or tidal dissipation produced in Io's interior due to this varying tidal pull, which, without the resonant orbit, would have gone into circularizing Io's orbit instead, creates significant tidal heating within Io's interior, melting a significant amount of Io's mantle and core. The amount of energy produced is up to 200 times greater than that produced solely from radioactive decay. This heat is released in the form of volcanic activity, generating its observed high heat flow (global total: 0.6 to 1.6×1014 W). Models of its orbit suggest that the amount of tidal heating within Io changes with time; however, the current amount of tidal dissipation is consistent with the observed heat flow.
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Animation of Akatsuki trajectory around Venus from 1 December 2015 After performing the last of a series of four trajectory correction maneuvers between 17 July and 11 September 2015, the probe was established on a trajectory to fly past Venus on 7 December 2015, when Akatsuki would make a maneuver to enter Venus orbit after a 20-minute burn with four thrusters that were not rated for such a hefty propulsive maneuver. Instead of taking about 30 hours to complete an orbit around Venus—as was originally planned—the new orbit targeted would place Akatsuki in a nine-day orbit after an adjustment in March 2016. After JAXA engineers measured and calculated its orbit following the 7 December orbital insertion, JAXA announced on 9 December that Akatsuki had successfully entered the intended elliptical orbit, as far as from Venus, and as close as from Venus's surface with an orbital period of 13 days and 14 hours. A follow-up thruster burn on 26 March 2016 lowered Akatsuki's apoapsis to about and shortened its orbital period from 13 to 9 days.
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Astronomical timing as the basis for designating the temperate seasons dates back at least to the Julian calendar used by the ancient Romans. It continues to be used on many modern Gregorian calendars worldwide, although some countries like Australia, New Zealand, Pakistan and Russia prefer to use meteorological reckoning. The precise timing of the seasons is determined by the exact times of transit of the sun over the tropics of Cancer and Capricorn for the solstices and the times of the sun's transit over the equator for the equinoxes, or a traditional date close to these times. The following diagram shows the relation between the line of solstice and the line of apsides of Earth's elliptical orbit. The orbital ellipse (with eccentricity exaggerated for effect) goes through each of the six Earth images, which are sequentially the perihelion (periapsis—nearest point to the sun) on anywhere from 2 January to 5 January, the point of March equinox on 19, 20 or 21 March, the point of June solstice on 20 or 21 June, the aphelion (apoapsis—farthest point from the sun) on anywhere from 4 July to 7 July, the September equinox on 22 or 23 September, and the December solstice on 21 or 22 December.
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