Astrodynamics Astrodynamics The equation of the center, in astronomy and elliptical motion, is equal to the true anomaly minus the mean anomaly, i.e. the difference between the actual angular position in the elliptical orbit and the position the orbiting body would have if its angular motion was uniform. It arises from the ellipticity of the orbit, is zero at pericenter and apocenter, and reaches its greatest amount nearly midway between these points. ...more on Wikipedia about "Equation of the center"
Equatorial orbit is an orbit with inclination to the plane of reference (i.d. equator) equal to zero. ...more on Wikipedia about "Equatorial orbit"
An escape orbit (also known as C3 = 0 orbit) is the high-energy parabolic orbit around the central body. A body in this orbit has at each position the escape velocity with respect to this central body, for this position. If this energy were further increased the orbit would turn to a hyperbolic trajectory. ...more on Wikipedia about "Escape orbit"
In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinitely from the source of the field, as opposed to falling back or staying in an orbit within a bounded distance from the source. The object is assumed to be influenced by no forces except the gravitational field; in particular there is no propulsion, as by a rocket, there is no friction, as between the object and the Earth's atmosphere (these conditions correspond to freefall) and there is no gravitational radiation. This definition may need modification for the practical problem of two or more sources in some cases. In any case, the object is assumed to be a point with a mass that is negligible compared with that of the source of the field, usually an excellent approximation. It is commonly described as the speed needed to "break free" from a gravitational field. ...more on Wikipedia about "Escape velocity"
Evection (Latin for carrying away), in astronomy, is the largest inequality produced by the action of the Sun in the monthly revolution of the Moon around the Earth. The deviation expressed by it has a maximum amount of about 10 15 in either direction. It may be considered as arising from a semi-annual variation in the eccentrivity of the Moon's orbit and the position of its perigee. Evection was discovered by Claudius Ptolemy. ...more on Wikipedia about "Evection"
A geostationary orbit (abbreviated GEO) is a circular orbit directly above the Earth's equator (0ยบ latitude). Any point on the equator plane revolves about the Earth in the same direction and with the same period as the Earth's rotation. It is a special case of the geosynchronous orbit (abbreviated GSO), and the one which is of most interest to operators of artificial satellites (including communication and television satellites). Satellite locations may differ by longitude only (remember in geostationary orbit latitude is zero). ...more on Wikipedia about "Geostationary orbit"
The geostationary ring is a volume segment around the geostationary orbit defined by variations in altitude and declination that can occur for uncontrolled objects left in the geostationary orbit. ...more on Wikipedia about "Geostationary ring"
A geostationary transfer orbit (GTO) is a Hohmann transfer orbit around the Earth between a low Earth orbit (LEO) and a geostationary orbit (GEO). It is an ellipse where the perigee is a point on a LEO and the apogee has the same distance from the Earth as the GEO. ...more on Wikipedia about "Geostationary transfer orbit"
A geosynchronous orbit is a geocentric orbit that has the same orbital period as the sidereal rotation period of the Earth. It has a semi-major axis of 42,164 km ** . ...more on Wikipedia about "Geosynchronous orbit"
A graveyard orbit is an 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 additional space debris. It is used when the delta-v required to perform a de-orbit maneuver would be too high. De-orbiting a geostationary satellite would require a delta-v of about 1,500 m/s while re-orbiting it to a graveyard orbit would require about 11 m/s. ...more on Wikipedia about "Graveyard orbit"
In physics, gravitational potential is the potential energy per unit mass of an object due to its position in a gravitational field. The gravitational potential due to a point mass M is ...more on Wikipedia about "Gravitational potential"
In astrodynamics, gravity drag (or gravity losses) is inefficiency encountered by a spacecraft thrusting while moving against a gravitational field. ...more on Wikipedia about "Gravity drag"
An heliostationary orbit is an heliocentric orbit of approximately 24,360,000 km radius (0.162 84 AU, a little less than half of Mercury's orbital radius), with an eccentricity of zero and an inclination (to the Sun's equator) of zero. Its distinguishing characteristic is that a body in such an orbit has a period of revolution roughly equal to the Sun's equatorial period of rotation and appears to continuously hover above the same spot of the Sun's surface. A solar observation probe could be placed on such an orbit in the near future. ...more on Wikipedia about "Heliostationary orbit"
By analogy with the geosynchronous orbit, a heliosynchronous orbit is a heliocentric orbit of radius 24.360 G m (0.1628 AU) such that the object's period of revolution matches the Sun's period of rotation. The heliostationary orbit is the heliosynchronous orbit of inclination zero and eccentricity zero. ...more on Wikipedia about "Heliosynchronous orbit" This text is made on http://www.shortopedia.com
In astronautics and aerospace engineering, the Hohmann transfer orbit is an orbital maneuver that moves a spacecraft from one orbit to another using the lowest possible delta-v for the specific transfer. It was named after Walter Hohmann, the German scientist who published it in 1925. (See also interplanetary travel.) A Hohmann transfer orbit will take a spacecraft from low Earth orbit (LEO) to geosynchronous orbit (GEO) in just over five hours ( geostationary transfer orbit), from LEO to the Moon in about 5 days and from the Earth to Mars in about 260 days. However, Hohmann transfers are very slow for trips to more distant points, so when visiting the outer planets it is common to use a gravitational slingshot to increase speed in-flight. ...more on Wikipedia about "Hohmann transfer orbit"
In astrodynamics or celestial mechanics a hyperbolic trajectory is an 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 are also escape trajectories. Specific energy of hyperbolic trajectory orbit is positive. ...more on Wikipedia about "Hyperbolic trajectory"
Inclination in general is the angle between a reference plane and another plane or axis of direction. ...more on Wikipedia about "Inclination"
An inertial frame is a coordinate system defined by the non-accelerated motion of objects with a common direction and speed (as opposed to a non-inertial reference frame). ...more on Wikipedia about "Inertial frame of reference"
Intermediate circular orbit (ICO), also called medium earth orbit (MEO), is used by satellites between the altitudes of low earth orbit (up to 1400 km) and geosynchronous orbit (35,790 km). ...more on Wikipedia about "Intermediate circular orbit"
To compute the position of a satellite at a given time using Kepler's laws of planetary motion (the Keplerian problem) is a difficult problem. The opposite problem—to compute the time-of-flight given the starting and ending positions—is simpler. We present a derivation for the time-of-flight equation, also called Kepler's equation here. ...more on Wikipedia about "Keplerian problem"
A Klemperer rosette is a gravitational system of a number of heavier and lighter bodies, set out in a regular repeating pattern around a common barycenter, around which they all orbit. The simplest rosette would be series of alternating heavier and lighter bodies in a rhombic configuartion [H,L,H,L], where the two heavier masses weigh the same, and likewise the two lighter masses weigh the same. The number of "mass types" can be increased, so long as the arrangement pattern is cylic: e.g. [ 1,2,3 ... 1,2,3 ], [ 1,2,3,4,5 ... 1,2,3,4,5 ], [ 1,2,3,3,2,1 ... 1,2,3,3,2,1 ] etc. ...more on Wikipedia about "Klemperer rosette"
The Longitude of the ascending node (☊, also noted Ω) is one of the orbital elements used to specify the orbit of an object in space. For a Sun-orbiting body, it is the angle formed at the Sun from the First Point of Aries to the body's ascending node, measured in the reference plane (the ecliptic) and in the direct sense. ...more on Wikipedia about "Longitude of the ascending node"
In astrodynamics, the longitude of the periapsis (symbolized ) of an orbiting body is the longitude (measured from the point of the vernal equinox) at which the periapsis (closest approach to the central body) would occur if the body's inclination were zero. The longitude of periapsis is a compound angle, with part of it being measured in the plane of reference and the rest being measured in the plane of the orbit. Likewise, any angle derived from the longitude of periapsis (e.g. mean longitude and true longitude) will also be compound. ...more on Wikipedia about "Longitude of the periapsis"
A low Earth orbit (LEO) is an orbit around Earth between the atmosphere and the Van Allen radiation belt, with a low angle of inclination. These boundaries are not firmly defined but are typically around 200 - 1200 km (124 - 726 miles) above the Earth's surface. This is generally below intermediate circular orbit (ICO) and far below geostationary orbit. Orbits lower than this are not stable and will decay rapidly because of atmospheric drag. Orbits higher than this are subject to early electronic failure because of intense radiation and charge accumulation. Orbits with a higher inclination angle are usually called polar orbits. ...more on Wikipedia about "Low Earth orbit"
In aerospace engineering, the mass fraction is an important measure of a rocket's efficiency. For a given target orbit, a rocket's mass fraction is the portion of the rocket's pre-launch mass (fully fueled) that does not reach orbit. In the cases of a single stage to orbit vehicle the mass fraction is simply the fuel mass divided by the mass of the full spaceship, but with a rocket employing staging, which is the vast majority of them, the mass fraction is higher because parts of the rocket itself are dropped off en route. Mass fractions are typically around 0.8 to 0.9, with lower numbers being better. ...more on Wikipedia about "Mass fraction"
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