1.
NASA
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President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
2.
CNES
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The Centre national détudes spatiales is the French government space agency. Its headquarters are located in central Paris and it is under the supervision of the French Ministries of Defence and it operates from the Toulouse Space Center and Guiana Space Centre, but also has payloads launched from space centres operated by other countries. The president of CNES is Jean-Yves Le Gall, CNES is member of Institute of Space, its Applications and Technologies. CNES benefits from the second largest national budget allocated to space, CNES was established under President Charles de Gaulle in 1961. CNES was responsible for the training of French astronauts, until the last active CNES astronauts transferred to the European Space Agency in 2001. As of January 2015, CNES is working with Germany and a few governments to start a modest research effort with the hope to propose a LOX/methane reusable launch vehicle by mid-2015. If built, flight testing would not start before approximately 2026. Hammaguir missile range built in Algeria,1963 Cats launched into space via Véronique rockets. 1965 First French satellite put in orbit,1969 French Guiana Space Centre completed. Commercial competition in space is fierce, so launch services must be tailored to space operators’ needs, the new versions of Ariane 5 can launch large satellites or perform dual launches while the Vega and Soyuz-2 are small and medium-lift launchers. CNES is taking part in the Galileo navigation programme alongside the European Union, in addition to Spot and the future Pleiades satellites, CNES is working for the defence community as prime contractor for the Helios satellites. France’s contribution to the International Space Station is giving French scientists the opportunity to perform experiments in microgravity. The CNES is studying formation flying, a technique whereby several satellites fly components of a much heavier, CNES is collaborating with other space agencies in a number of projects. Joint missions with NASA result in PARASOL and CALIPSO satellites, CNES plays a major role in the construction and operation of the Soil Moisture and Ocean Salinity satellite. In December 2006, CNES announced that it would publish its UFO archive online by late January or mid-February, most of the 6,000 reports have been filed by the public and airline professionals. Jacques Arnould, an official for the French Space Agency, said that the data had accumulated over a 30-year period and that they were often reported to the Gendarmerie. In the last two decades of the 20th century, France was the country whose government paid UFO investigators, employed by CNESs UFO section GEPAN, later known as SEPRA. On March 22,2007, CNES released its UFO files to the public through its website, the CNES has several tracking stations
3.
Satellite bus
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A satellite bus or spacecraft bus is the general model on which multiple-production satellite spacecraft are often based. The bus is the infrastructure of a spacecraft, usually providing locations for the payload, a bus-derived satellite would be used as opposed to a one-off, or specially produced satellite, such as Prospero X-3. Bus-derived satellites are usually customized to customer requirements, for example with specialized sensors or transponders, comparison of satellite buses Service module Satellite Glossary JWST Observatory, The Spacecraft Bus Spitzers Spacecraft Bus Gunters Space Page, Spacecraft buses
4.
Thales Alenia Space
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The company is Europes largest satellite manufacturer. Alcatel Alenia Space was established on June 1,2005 by the merger of Alcatel Space and Alenia Spazio and was owned by Alcatel-Lucent, the creation of the company was concurrent with the creation of Telespazio Holding. This too was a merger of Finmeccanica and Alcatel businesses, on April 5,2006 Alcatel agreed to sell its share of Alcatel Alenia Space to Thales Group. The European Union agreed in this operation on April 10,2007. The company built the Multi-Purpose Logistics Modules, which was used to transport cargo inside the Space Shuttle orbiters and they also built several modules for the International Space Station, those modules are Cupola, Columbus, Harmony, Tranquility and Leonardo. They currently build the vessels for the Automated Transfer Vehicle. In the mid-1990s, the United States stopped issuing licenses to companies to allow them to launch on Chinese launch vehicles out of fear that this would help Chinas military. In the face of this, Thales Alenia Space built the Chinasat-6B satellite with no components from the United States whatsoever and this allowed it to be launched on a Chinese launch vehicle without violating U. S. ITAR restrictions. The launch, on a Long March 3B rocket, was conducted on July 5,2007. Cannes Mandelieu Space Center Official website
5.
Delta II
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Delta II is an American expendable launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and entered service in 1989, Delta II vehicles included the Delta 6000, and two Delta 7000 variants. In the early 1980s, all United States expendable launch vehicles were planned to be phased out in favor of the Space Shuttle, production of Delta, Atlas-Centaur, and Titan 34D had ended. McDonnell Douglas, at time the manufacturer of the Delta family. These were intended to launch a series of GPS Block II satellites, the Air Force exercised additional contract options in 1988, expanding this order to 20 vehicles, and NASA purchased its first Delta IIs in 1990 for the launch of three Earth-observing satellites. The first Delta II launch occurred in 1989, with a Delta 6925 boosting the first GPS Block II satellite into a 20,000 km high orbit, the first Delta II 7000-series flew in 1990, replacing the RS-27 engine of the 6000-series with the more powerful RS-27A. Additionally, the steel-cased Castor 4A solid boosters of the 6000 series were replaced with the composite-cased GEM40, all further Delta II launches except three were of this upgraded configuration, and the 6000-series was retired in 1992. McDonnell Douglas began Delta III development in the mid-90s as increasing satellite mass required more powerful launch vehicles, the upgraded boosters would still find use on the Delta II, leading to the Delta II Heavy. In total, the Delta II family has launched 153 times, no one was injured, and the launch pad itself was not seriously impacted, though several cars were destroyed and a few buildings were damaged. In 2007, Delta II completed its 75th consecutive successful launch, with the launch of SMAP in 2015, the Delta II has enjoyed 98 consecutive successful launches, with two more scheduled in 2017 and 2018. Should these launches be successful, the Delta II would achieve an unprecedented 100 consecutive launch successes, the first stage of the Delta II is propelled by a Rocketdyne RS-27 main engine burning RP-1 and liquid oxygen. This stage is referred to as the Extra-Extended Long Tank Thor. The RS-27 used on the 6000-series Delta II produced 915 kN, the stage is 26 meters long and 2.4 meters wide, weighs over 100 t when fueled, and burns for 260 seconds. In addition, two LR101-NA-11 vernier engines provide guidance for the first stage, for additional thrust during launch, the Delta II uses solid boosters. For the 6000-series, Delta II used Castor 4A boosters, while the 7000-series uses Graphite-Epoxy Motors manufactured by ATK, the vehicle can be flown with three, four, or, most commonly, nine boosters. The second stage of Delta II is the Delta-K, powered by a restartable Aerojet AJ10-118K engine burning hypergolic Aerozine-50 and these propellants are highly toxic and corrosive, and once loaded the launch must occur within approximately 37 days or the stage will have to be refurbished or replaced. This stage also contains a combined platform and guidance system that controls all flight events. The Delta-K stage is 6 meters long and 2.4 meters wide, contains up to 6 t of propellant, for low Earth orbit, Delta II is not equipped with a third stage
6.
Vandenberg Air Force Base
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Vandenberg Air Force Base is a United States Air Force Base 9.2 miles northwest of Lompoc, California. It is under the jurisdiction of the 30th Space Wing, Air Force Space Command, Vandenberg AFB is a Department of Defense space and missile testing base, with a mission of placing satellites into polar orbit from the West Coast using expendable boosters. Wing personnel also support the Services LGM-30G Minuteman III Intercontinental Ballistic Missile Force Development Evaluation program, in addition to its military mission, the base also leases launch pad facilities to SpaceX, as well as 100 acres leased to the California Spaceport in 1995. Established in 1941, the base is named in honor of former Air Force Chief of Staff General Hoyt Vandenberg, the host unit at Vandenberg AFB is the 30th Space Wing. The 30th SW is home to the Western Range, manages Department of Defense space and missile testing, Wing personnel also support the Air Forces Minuteman III Intercontinental Ballistic Missile Force Development Test and Evaluation program. The Western Range begins at the boundaries of Vandenberg and extends westward from the California coast to the Western Pacific. Operations involve dozens of federal and commercial interests, the wing is organized into operations, launch, mission support and medical groups, along with several directly assigned staff agencies. 30th Launch Group The 30th Launch Group is responsible for booster and satellite technical oversight and launch processing activities to launch, integration. The group consists of a military, civilian and contractor team with more than 250 personnel directly supporting operations from the Western Range. 1st Air and Space Test Squadron 4th Space Launch Squadron 30th Operations Group The 30th Operations Group provides the capability for West Coast spacelift. Operations professionals are responsible for operating and maintaining the Western Range for spacelift, missile test launch, aeronautical, 30th Mission Support Group The 30th Mission Support Group supports the third largest Air Force Base in the United States. It is also responsible for quality-of-life needs, housing, personnel, services, civil engineering, contracting, 30th Medical Group The 30th Medical Group provides medical, dental, bio-environmental and public health services for people assigned to Vandenberg Air Force Base, their families and retirees. It is Vandenbergs only National Historic Landmark that is open for scheduled tours through the 30th Space Wings Public Affairs office. The current display area is made up of two exhibits, the Chronology of the Cold War and the Evolution of Technology, there are plans to evolve the center in stages from the current exhibit areas as restorations of additional facilities are completed. In 1941 the United States Army sought more and better training centers for the development of its armored. In March 1941, the Army acquired approximately 86,000 acres of open ranch lands along the Central Coast of California between Lompoc and Santa Maria, most of the land was purchased. Smaller parcels were obtained either by lease, license, or as easements, with its flat plateau, surrounding hills, numerous canyons, and relative remoteness from populated areas, the Army was convinced it had found the ideal training location. Construction of the Army camp began in September 1941, although its completion was still months away, the Army activated the camp on 5 October, and named it Camp Cooke in honor of Major General Phillip St. George Cooke
7.
Vandenberg AFB Space Launch Complex 2
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Space Launch Complex 2 is an active rocket launch site at Vandenberg Air Force Base, in California, USA. It consists of two launch pads, the East pad, which has been demolished, was used for Delta, Thor-Agena and Thorad launches between 1966 and 1972. The West pad, SLC-2W, has used for Delta, Thor-Agena, and Delta II launches since 1966. Space Launch Complex 2 was originally part of Launch Complex 75, when this complex was split up in 1966, the first launch to be made from the newly redesignated Space Launch Complex 2 was that of a Delta E with ESSA-3 on 2 October 1966 from SLC-2E. The first launch from SLC-2W after redesignation was of a Thor-Agena with OPS1584 on 29 December 1966, SLC-2E and SLC-2W are located approximately 2,000 feet apart
8.
Geocentric orbit
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A geocentric orbit or Earth orbit involves any object orbiting the Earth, such as the Moon or artificial satellites. In 1997 NASA estimated there were approximately 2,465 artificial satellite orbiting the Earth and 6,216 pieces of space debris as tracked by the Goddard Space Flight Center. Over 16,291 previously launched objects have decayed into the Earths atmosphere, altitude as used here, the height of an object above the average surface of the Earths oceans. Analemma a term in astronomy used to describe the plot of the positions of the Sun on the celestial sphere throughout one year, apogee is the farthest point that a satellite or celestial body can go from Earth, at which the orbital velocity will be at its minimum. Eccentricity a measure of how much an orbit deviates from a perfect circle, eccentricity is strictly defined for all circular and elliptical orbits, and parabolic and hyperbolic trajectories. Equatorial plane as used here, an imaginary plane extending from the equator on the Earth to the celestial sphere, escape velocity as used here, the minimum velocity an object without propulsion needs to have to move away indefinitely from the Earth. An object at this velocity will enter a parabolic trajectory, above this velocity it will enter a hyperbolic trajectory, impulse the integral of a force over the time during which it acts. Inclination the angle between a plane and another plane or axis. In the sense discussed here the reference plane is the Earths equatorial plane, orbital characteristics the six parameters of the Keplerian elements needed to specify that orbit uniquely. Orbital period as defined here, time it takes a satellite to make one orbit around the Earth. Perigee is the nearest approach point of a satellite or celestial body from Earth, sidereal day the time it takes for a celestial object to rotate 360°. For the Earth this is,23 hours,56 minutes,4.091 seconds, solar time as used here, the local time as measured by a sundial. Velocity an objects speed in a particular direction, since velocity is defined as a vector, both speed and direction are required to define it. The following is a list of different geocentric orbit classifications, Low Earth orbit - Geocentric orbits ranging in altitude from 160 kilometers to 2,000 kilometres above mean sea level. At 160 km, one revolution takes approximately 90 minutes, medium Earth orbit - Geocentric orbits with altitudes at apogee ranging between 2,000 kilometres and that of the geosynchronous orbit at 35,786 kilometres. Geosynchronous orbit - Geocentric circular orbit with an altitude of 35,786 kilometres, the period of the orbit equals one sidereal day, coinciding with the rotation period of the Earth. The speed is approximately 3,000 metres per second, high Earth orbit - Geocentric orbits with altitudes at apogee higher than that of the geosynchronous orbit. A special case of high Earth orbit is the elliptical orbit
9.
Low Earth orbit
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A low Earth orbit is an orbit around Earth with an altitude between 160 kilometers, and 2,000 kilometers. Objects below approximately 160 kilometers will experience very rapid orbital decay, with the exception of the 24 human beings who flew lunar flights in the Apollo program during the four-year period spanning 1968 through 1972, all human spaceflights have taken place in LEO or below. The International Space Station conducts operations in LEO, the altitude record for a human spaceflight in LEO was Gemini 11 with an apogee of 1,374.1 kilometers. All crewed space stations to date, as well as the majority of satellites, have been in LEO, objects in LEO encounter atmospheric drag from gases in the thermosphere or exosphere, depending on orbit height. Due to atmospheric drag, satellites do not usually orbit below 300 km, objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt. The mean orbital velocity needed to maintain a stable low Earth orbit is about 7.8 km/s, calculated for circular orbit of 200 km it is 7.79 km/s and for 1500 km it is 7.12 km/s. The delta-v needed to achieve low Earth orbit starts around 9.4 km/s, atmospheric and gravity drag associated with launch typically adds 1. 3–1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s. Equatorial low Earth orbits are a subset of LEO and these orbits, with low inclination to the Equator, allow rapid revisit times and have the lowest delta-v requirement of any orbit. Orbits with an inclination angle to the equator are usually called polar orbits. Higher orbits include medium Earth orbit, sometimes called intermediate circular orbit, orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation. Although the Earths pull due to gravity in LEO is not much less than on the surface of the Earth, people, a low Earth orbit is simplest and cheapest for satellite placement. It provides high bandwidth and low communication time lag, but satellites in LEO will not be visible from any point on the Earth at all times. Earth observation satellites and spy satellites use LEO as they are able to see the surface of the Earth more clearly as they are not so far away and they are also able to traverse the surface of the Earth. A majority of satellites are placed in LEO, making one complete revolution around the Earth in about 90 minutes. The International Space Station is in a LEO about 400 km above the Earths surface, since it requires less energy to place a satellite into a LEO and the LEO satellite needs less powerful amplifiers for successful transmission, LEO is used for many communication applications. Because these LEO orbits are not geostationary, a network of satellites is required to provide continuous coverage, lower orbits also aid remote sensing satellites because of the added detail that can be gained. Remote sensing satellites can also take advantage of sun-synchronous LEO orbits at an altitude of about 800 km, envisat is one example of an Earth observation satellite that makes use of this particular type of LEO. The LEO environment is becoming congested with space debris due to the frequency of object launches and this has caused growing concern in recent years, since collisions at orbital velocities can easily be dangerous, and even deadly
10.
Semi-major and semi-minor axes
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In geometry, the major axis of an ellipse is its longest diameter, a line segment that runs through the center and both foci, with ends at the widest points of the perimeter. The semi-major axis is one half of the axis, and thus runs from the centre, through a focus. Essentially, it is the radius of an orbit at the two most distant points. For the special case of a circle, the axis is the radius. One can think of the axis as an ellipses long radius. The semi-major axis of a hyperbola is, depending on the convention, thus it is the distance from the center to either vertex of the hyperbola. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction. Thus a and b tend to infinity, a faster than b, the semi-minor axis is a line segment associated with most conic sections that is at right angles with the semi-major axis and has one end at the center of the conic section. It is one of the axes of symmetry for the curve, in an ellipse, the one, in a hyperbola. The semi-major axis is the value of the maximum and minimum distances r max and r min of the ellipse from a focus — that is. In astronomy these extreme points are called apsis, the semi-minor axis of an ellipse is the geometric mean of these distances, b = r max r min. The eccentricity of an ellipse is defined as e =1 − b 2 a 2 so r min = a, r max = a. Now consider the equation in polar coordinates, with one focus at the origin, the mean value of r = ℓ / and r = ℓ /, for θ = π and θ =0 is a = ℓ1 − e 2. In an ellipse, the axis is the geometric mean of the distance from the center to either focus. The semi-minor axis of an ellipse runs from the center of the ellipse to the edge of the ellipse, the semi-minor axis is half of the minor axis. The minor axis is the longest line segment perpendicular to the axis that connects two points on the ellipses edge. The semi-minor axis b is related to the axis a through the eccentricity e. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction
11.
Orbital eccentricity
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The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is an orbit, values between 0 and 1 form an elliptical orbit,1 is a parabolic escape orbit. The term derives its name from the parameters of conic sections and it is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the galaxy. In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit, the eccentricity of this Kepler orbit is a non-negative number that defines its shape. The limit case between an ellipse and a hyperbola, when e equals 1, is parabola, radial trajectories are classified as elliptic, parabolic, or hyperbolic based on the energy of the orbit, not the eccentricity. Radial orbits have zero angular momentum and hence eccentricity equal to one, keeping the energy constant and reducing the angular momentum, elliptic, parabolic, and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity. From Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros out of the center, from ἐκ- ek-, eccentric first appeared in English in 1551, with the definition a circle in which the earth, sun. Five years later, in 1556, a form of the word was added. The eccentricity of an orbit can be calculated from the state vectors as the magnitude of the eccentricity vector, e = | e | where. For elliptical orbits it can also be calculated from the periapsis and apoapsis since rp = a and ra = a, where a is the semimajor axis. E = r a − r p r a + r p =1 −2 r a r p +1 where, rp is the radius at periapsis. For Earths annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈1.034 relative to center point of path, the eccentricity of the Earths orbit is currently about 0.0167, the Earths orbit is nearly circular. Venus and Neptune have even lower eccentricity, over hundreds of thousands of years, the eccentricity of the Earths orbit varies from nearly 0.0034 to almost 0.058 as a result of gravitational attractions among the planets. The table lists the values for all planets and dwarf planets, Mercury has the greatest orbital eccentricity of any planet in the Solar System. Such eccentricity is sufficient for Mercury to receive twice as much solar irradiation at perihelion compared to aphelion, before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit
12.
Apsis
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An apsis is an extreme point in an objects orbit. The word comes via Latin from Greek and is cognate with apse, for elliptic orbits about a larger body, there are two apsides, named with the prefixes peri- and ap-, or apo- added to a reference to the thing being orbited. For a body orbiting the Sun, the point of least distance is the perihelion, the terms become periastron and apastron when discussing orbits around other stars. For any satellite of Earth including the Moon the point of least distance is the perigee, for objects in Lunar orbit, the point of least distance is the pericynthion and the greatest distance the apocynthion. For any orbits around a center of mass, there are the terms pericenter and apocenter, periapsis and apoapsis are equivalent alternatives. A straight line connecting the pericenter and apocenter is the line of apsides and this is the major axis of the ellipse, its greatest diameter. For a two-body system the center of mass of the lies on this line at one of the two foci of the ellipse. When one body is larger than the other it may be taken to be at this focus. Historically, in systems, apsides were measured from the center of the Earth. In orbital mechanics, the apsis technically refers to the distance measured between the centers of mass of the central and orbiting body. However, in the case of spacecraft, the family of terms are used to refer to the orbital altitude of the spacecraft from the surface of the central body. The arithmetic mean of the two limiting distances is the length of the axis a. The geometric mean of the two distances is the length of the semi-minor axis b, the geometric mean of the two limiting speeds is −2 ε = μ a which is the speed of a body in a circular orbit whose radius is a. The words pericenter and apocenter are often seen, although periapsis/apoapsis are preferred in technical usage, various related terms are used for other celestial objects. The -gee, -helion and -astron and -galacticon forms are used in the astronomical literature when referring to the Earth, Sun, stars. The suffix -jove is occasionally used for Jupiter, while -saturnium has very rarely used in the last 50 years for Saturn. The -gee form is used as a generic closest approach to planet term instead of specifically applying to the Earth. During the Apollo program, the terms pericynthion and apocynthion were used when referring to the Moon, regarding black holes, the term peri/apomelasma was used by physicist Geoffrey A. Landis in 1998 before peri/aponigricon appeared in the scientific literature in 2002
13.
Orbital inclination
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Orbital inclination measures the tilt of an objects orbit around a celestial body. It is expressed as the angle between a plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth directly above the equator, the plane of the orbit is the same as the Earths equatorial plane. The general case is that the orbit is tilted, it spends half an orbit over the northern hemisphere. If the orbit swung between 20° north latitude and 20° south latitude, then its orbital inclination would be 20°, the inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the plane and the plane of reference, normally stated in degrees. For a satellite orbiting a planet, the plane of reference is usually the plane containing the planets equator, for planets in the Solar System, the plane of reference is usually the ecliptic, the plane in which the Earth orbits the Sun. This reference plane is most practical for Earth-based observers, therefore, Earths inclination is, by definition, zero. Inclination could instead be measured with respect to another plane, such as the Suns equator or the invariable plane, the inclination of orbits of natural or artificial satellites is measured relative to the equatorial plane of the body they orbit, if they orbit sufficiently closely. The equatorial plane is the perpendicular to the axis of rotation of the central body. An inclination of 30° could also be described using an angle of 150°, the convention is that the normal orbit is prograde, an orbit in the same direction as the planet rotates. Inclinations greater than 90° describe retrograde orbits, thus, An inclination of 0° means the orbiting body has a prograde orbit in the planets equatorial plane. An inclination greater than 0° and less than 90° also describe prograde orbits, an inclination of 63. 4° is often called a critical inclination, when describing artificial satellites orbiting the Earth, because they have zero apogee drift. An inclination of exactly 90° is an orbit, in which the spacecraft passes over the north and south poles of the planet. An inclination greater than 90° and less than 180° is a retrograde orbit, an inclination of exactly 180° is a retrograde equatorial orbit. For gas giants, the orbits of moons tend to be aligned with the giant planets equator, the inclination of exoplanets or members of multiple stars is the angle of the plane of the orbit relative to the plane perpendicular to the line-of-sight from Earth to the object. An inclination of 0° is an orbit, meaning the plane of its orbit is parallel to the sky. An inclination of 90° is an orbit, meaning the plane of its orbit is perpendicular to the sky
14.
Longitude of the ascending node
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The longitude of the ascending node is one of the orbital elements used to specify the orbit of an object in space. It is the angle from a direction, called the origin of longitude, to the direction of the ascending node. The ascending node is the point where the orbit of the passes through the plane of reference. Commonly used reference planes and origins of longitude include, For a geocentric orbit, Earths equatorial plane as the plane. In this case, the longitude is called the right ascension of the ascending node. The angle is measured eastwards from the First Point of Aries to the node, for a heliocentric orbit, the ecliptic as the reference plane, and the First Point of Aries as the origin of longitude. The angle is measured counterclockwise from the First Point of Aries to the node, the angle is measured eastwards from north to the node. pp.40,72,137, chap. In the case of a star known only from visual observations, it is not possible to tell which node is ascending. In this case the orbital parameter which is recorded is the longitude of the node, Ω, here, n=<nx, ny, nz> is a vector pointing towards the ascending node. The reference plane is assumed to be the xy-plane, and the origin of longitude is taken to be the positive x-axis, K is the unit vector, which is the normal vector to the xy reference plane. For non-inclined orbits, Ω is undefined, for computation it is then, by convention, set equal to zero, that is, the ascending node is placed in the reference direction, which is equivalent to letting n point towards the positive x-axis. Kepler orbits Equinox Orbital node perturbation of the plane can cause revolution of the ascending node
15.
Argument of periapsis
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The argument of periapsis, symbolized as ω, is one of the orbital elements of an orbiting body. Parametrically, ω is the angle from the ascending node to its periapsis. For specific types of orbits, words such as perihelion, perigee, periastron, an argument of periapsis of 0° means that the orbiting body will be at its closest approach to the central body at the same moment that it crosses the plane of reference from South to North. An argument of periapsis of 90° means that the body will reach periapsis at its northmost distance from the plane of reference. Adding the argument of periapsis to the longitude of the ascending node gives the longitude of the periapsis, however, especially in discussions of binary stars and exoplanets, the terms longitude of periapsis or longitude of periastron are often used synonymously with argument of periapsis. In the case of equatorial orbits, the argument is strictly undefined, where, ex and ey are the x- and y-components of the eccentricity vector e. In the case of circular orbits it is assumed that the periapsis is placed at the ascending node. Kepler orbit Orbital mechanics Orbital node
16.
Mean anomaly
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In celestial mechanics, the mean anomaly is an angle used in calculating the position of a body in an elliptical orbit in the classical two-body problem. Define T as the time required for a body to complete one orbit. In time T, the radius vector sweeps out 2π radians or 360°. The average rate of sweep, n, is then n =2 π T or n =360 ∘ T, define τ as the time at which the body is at the pericenter. From the above definitions, a new quantity, M, the mean anomaly can be defined M = n, because the rate of increase, n, is a constant average, the mean anomaly increases uniformly from 0 to 2π radians or 0° to 360° during each orbit. It is equal to 0 when the body is at the pericenter, π radians at the apocenter, if the mean anomaly is known at any given instant, it can be calculated at any later instant by simply adding n δt where δt represents the time difference. Mean anomaly does not measure an angle between any physical objects and it is simply a convenient uniform measure of how far around its orbit a body has progressed since pericenter. The mean anomaly is one of three parameters that define a position along an orbit, the other two being the eccentric anomaly and the true anomaly. Define l as the longitude, the angular distance of the body from the same reference direction. Thus mean anomaly is also M = l − ϖ, mean angular motion can also be expressed, n = μ a 3, where μ is a gravitational parameter which varies with the masses of the objects, and a is the semi-major axis of the orbit. Mean anomaly can then be expanded, M = μ a 3, and here mean anomaly represents uniform angular motion on a circle of radius a
17.
Satellite
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In the context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are called artificial satellites to distinguish them from natural satellites such as Earths Moon. In 1957 the Soviet Union launched the worlds first artificial satellite, since then, about 6,600 satellites from more than 40 countries have been launched. According to a 2013 estimate,3,600 remained in orbit, of those, about 1,000 were operational, the rest have lived out their useful lives and become space debris. Approximately 500 operational satellites are in orbit,50 are in medium-Earth orbit. A few large satellites have been launched in parts and assembled in orbit. Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, Satellites are used for many purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, well-known classes include low Earth orbit, polar orbit, and geostationary orbit. A launch vehicle is a rocket that throws a satellite into orbit, usually it lifts off from a launch pad on land. Some are launched at sea from a submarine or a mobile maritime platform, Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control, the first fictional depiction of a satellite being launched into orbit was a short story by Edward Everett Hale, The Brick Moon. The idea surfaced again in Jules Vernes The Begums Fortune, in 1903, Konstantin Tsiolkovsky published Exploring Space Using Jet Propulsion Devices, which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the speed required for a minimal orbit. In 1928, Herman Potočnik published his book, The Problem of Space Travel — The Rocket Motor. He described the use of orbiting spacecraft for observation of the ground, in a 1945 Wireless World article, the English science fiction writer Arthur C. Clarke described in detail the possible use of communications satellites for mass communications. He suggested that three geostationary satellites would provide coverage over the entire planet, the first artificial satellite was Sputnik 1, launched by the Soviet Union on October 4,1957, and initiating the Soviet Sputnik program, with Sergei Korolev as chief designer. This in turn triggered the Space Race between the Soviet Union and the United States, Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere
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Ocean current
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Depth contours, shoreline configurations, and interactions with other currents influence a currents direction and strength. Therefore ocean currents are primarily horizontal water movements, Ocean currents flow for great distances, and together, create the global conveyor belt which plays a dominant role in determining the climate of many of the Earth’s regions. More specifically, ocean currents influence the temperature of the regions through which they travel, for example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any region at the same latitude. Another example is Lima, Peru where the climate is cooler than the tropical latitudes in which the area is located, in these wind driven currents, the Ekman spiral effect results in the currents flowing at an angle to the driving winds. In addition, the areas of ocean currents move somewhat with the seasons. Deep ocean basins generally have a surface current, in that the eastern equatorward-flowing branch is broad. These western boundary currents are a consequence of the rotation of the Earth, Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation is known as the oceans conveyor belt. These currents, called submarine rivers, flow under the surface of the ocean and are hidden from immediate detection, where significant vertical movement of ocean currents is observed, this is known as upwelling and downwelling. Deep ocean currents are currently being researched using a fleet of robots called Argo. The South Equatorial Currents of the Atlantic and Pacific straddle the equator, though the Coriolis effect is weak near the equator, water moving in the currents on either side of the equator is deflected slightly poleward and replaced by deeper water. Thus, equatorial upwelling occurs in these westward flowing equatorial surface currents, upwelling is an important process because this water from within and below the pycnocline is often rich in nutrients and greatly benefits the growth of marine organisms. By contrast, generally poor conditions for growth prevail in most of the tropical ocean because strong layering isolates deep. Ocean currents are measured in sverdrup, where 1 sv is equivalent to a flow rate of 1,000,000 m3 per second. Surface currents are found on the surface of an ocean, and are driven by large scale wind currents and they are directly affected by the wind—the Coriolis effect plays a role in their behaviors. Horizontal and vertical currents also exist below the pycnocline in the deeper waters. The movement of water due to differences in density as a function of water temperature, ripple marks in sediments, scour lines, and the erosion of rocky outcrops on deep-ocean floors are evidence that relatively strong, localized bottom currents exist
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Ocean
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An ocean is a body of saline water that composes much of a planets hydrosphere. On Earth, an ocean is one of the major divisions of the World Ocean. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern, the word sea is often used interchangeably with ocean in American English but, strictly speaking, a sea is a body of saline water partly or fully enclosed by land. The ocean contains 97% of Earths water, and oceanographers have stated that less than 5% of the World Ocean has been explored, the total volume is approximately 1.35 billion cubic kilometers with an average depth of nearly 3,700 meters. As the world ocean is the component of Earths hydrosphere, it is integral to all known life, forms part of the carbon cycle. The world ocean is the habitat of 230,000 known species, but because much of it is unexplored, the origin of Earths oceans remains unknown, oceans are thought to have formed in the Hadean period and may have been the impetus for the emergence of life. Extraterrestrial oceans may be composed of water or other elements and compounds, the only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, compounds such as salts and ammonia dissolved in water lower its freezing point so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many planets and natural satellites, notably. The Solar Systems giant planets are thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of water within a circumstellar habitable zone. Ocean planets are a type of planet with a surface completely covered with liquid. The concept of Ōkeanós has an Indo-European connection, Greek Ōkeanós has been compared to the Vedic epithet ā-śáyāna-, predicated of the dragon Vṛtra-, who captured the cows/rivers. Related to this notion, the Okeanos is represented with a dragon-tail on some early Greek vases, though generally described as several separate oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean. This concept of a body of water with relatively free interchange among its parts is of fundamental importance to oceanography. The major oceanic divisions – listed below in descending order of area and volume – are defined in part by the continents, various archipelagos, Oceans are fringed by smaller, adjoining bodies of water such as seas, gulfs, bays, bights, and straits. The Mid-Oceanic Ridge of the World are connected and form the Ocean Ridge, the continuous mountain range is 65,000 km long, and the total length of the oceanic ridge system is 80,000 km long
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Atmosphere
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An atmosphere is a layer of gases surrounding a planet or other material body, that is held in place by the gravity of that body. An atmosphere is likely to be retained if the gravity it is subject to is high. The atmosphere of Earth is mostly composed of nitrogen, oxygen, argon with carbon dioxide, the atmosphere helps protect living organisms from genetic damage by solar ultraviolet radiation, solar wind and cosmic rays. Its current composition is the product of billions of years of modification of the paleoatmosphere by living organisms. The term stellar atmosphere describes the region of a star. Stars with sufficiently low temperatures may form compound molecules in their outer atmosphere, Atmospheric pressure is the force per unit area that is applied perpendicularly to a surface by the surrounding gas. It is determined by a gravitational force in combination with the total mass of a column of gas above a location. On Earth, units of air pressure are based on the recognized standard atmosphere. It is measured with a barometer, the pressure of an atmospheric gas decreases with altitude due to the diminishing mass of gas above. The height at which the pressure from an atmosphere declines by a factor of e is called the height and is denoted by H. For such an atmosphere, the pressure declines exponentially with increasing altitude. However, atmospheres are not uniform in temperature, so the determination of the atmospheric pressure at any particular altitude is more complex. Surface gravity, the force that holds down an atmosphere, differs significantly among the planets, for example, the large gravitational force of the giant planet Jupiter is able to retain light gases such as hydrogen and helium that escape from objects with lower gravity. Thus, the distant and cold Titan, Triton, and Pluto are able to retain their atmospheres despite their relatively low gravities, rogue planets, theoretically, may also retain thick atmospheres. Since a collection of gas molecules may be moving at a range of velocities. Lighter molecules move faster than ones with the same thermal kinetic energy. It is thought that Venus and Mars may have lost much of their water when, after being photo dissociated into hydrogen and oxygen by solar ultraviolet, Earths magnetic field helps to prevent this, as, normally, the solar wind would greatly enhance the escape of hydrogen. However, over the past 3 billion years Earth may have lost gases through the polar regions due to auroral activity
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Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
22.
Eddy (fluid dynamics)
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In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the side of the object. This phenomenon is naturally observed behind large emergent rocks in swift-flowing rivers, the propensity of a fluid to swirl is used to promote good fuel/air mixing in internal combustion engines. In fluid mechanics and transport phenomena, an eddy is not a property of the fluid, turbulent flow is defined as the flow in which the systems inertial forces are dominant over the viscous forces. This phenomena is described by Reynolds number, a number used to determine when turbulent flow will occur. Conceptually, the Reynolds number is the ratio between inertial forces and viscous forces, blood flow in straight sections of the arterial tree are typically laminar, but branches and curvatures in the system cause turbulent flow. Lift and drag properties of golf balls are customized by the manipulation of dimples along the surface of the ball, oceanic and atmospheric currents transfer particles, debris, and organisms all across the globe. Eddy formations circulate trash and other pollutants into concentrated areas which researchers are tracking to improve clean-up, mesoscale ocean eddies play crucial rolls in transferring heat poleward, as well as maintaining heat gradients at different depths. Eddies are common in the ocean, and range in diameter from centimeters to hundreds of kilometers, the smallest scale eddies may last for a matter of seconds, while the larger features may persist for months to years. Eddies which are between about 10 and 500 km in diameter and persist for periods of days to months are known in oceanography as mesoscale eddies. Mesoscale eddies can be split into two categories, static eddies, caused by flow around an obstacle, and transient eddies, when the ocean contains a sea surface height gradient this creates a jet or current, such as the Antarctic Circumpolar Current. This current as part of an unstable system meanders and creates eddies. Mesoscale ocean eddies are characterized by currents which flow in a circular motion around the center of the eddy. The sense of rotation of these currents may either be cyclonic or anticyclonic, oceanic eddies are also usually made of water masses that are different from those outside of the eddy. That is, the water within an eddy usually has different temperature, there is a direct link between the water mass properties of an eddy and its rotation. Warm eddies rotate anti-cyclonically, while cold eddies rotate cyclonically, because eddies may have a vigorous circulation associated with them, they are of concern to naval and commercial operations at sea. Further, because eddies transport anomalously warm or cold water as they move, they have an important influence on heat transport in certain parts of the ocean
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TOPEX/Poseidon
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Launched on August 10,1992, TOPEX/Poseidon was a joint satellite mission between NASA, the U. S. space agency, and CNES, the French space agency, to map ocean surface topography. The first major oceanographic research vessel to sail into space, TOPEX/Poseidon helped revolutionize oceanography by proving the value of satellite ocean observations, oceanographer Walter Munk described TOPEX/Poseidon as the most successful ocean experiment of all time. A malfunction ended normal satellite operations in January 2006, before TOPEX/Poseidon, scientists had only a brief glimpse of Earths ocean as a whole from the pioneering, but short-lived Seasat satellite. TOPEX/Poseidon radar altimeter provided the first continuous global coverage of the topography of the oceans. From orbit 1,330 kilometers above Earth, TOPEX/Poseidon provided measurements of the height of 95 percent of the ice-free ocean to an accuracy of 3.3 centimeters. The satellites measurements of the hills and valleys of the sea led to a fundamental new understanding of ocean circulation. The missions most important achievement was to determine the patterns of ocean circulation - how heat stored in the moves from one place to another. Since the ocean holds most of the Earths heat from the Sun, TOPEX/Poseidon made it possible for the first time to compare computer models of ocean circulation with actual global observations and use the data to improve climate predictions. While a three-year prime mission was planned, TOPEX/Poseidon delivered more than 10 years of data from orbit, lift-off from Kourou in French Guiana took place on 1992-08-10. At lift-off the mass of the satellite was 2,402 kilograms, the mission was named after the ocean TOPography EXperiment and the Greek god of the ocean Poseidon. In October 2005 after more than 62,000 orbits, TOPEX/Poseidon stopped providing science data after a momentum wheel malfunctioned, tOPEX/Poseidons follow-on mission, Jason-1, was launched in 2001 to continue the ongoing measurements of sea surface topography. The record of sea surface height begun by TOPEX/Poseidon and Jason-1 continues into the future with the Ocean Surface Topography Mission on the Jason-2 satellite. Planning for a Jason-3 mission is now underway, TOPEX/Poseidon flew two onboard altimeters sharing the same antenna, but only one altimeter was operated at any time, with TOPEX given preference. TOPEX, The NASA-built Nadir pointing Radar Altimeter using C band, Poseidon, The CNES-built solid state Nadir pointing Radar Altimeter using Ku band. In addition to the altimeters, the TOPEX Microwave Radiometer operating at 18,21, the satellite was also equipped with instruments to accurately pinpoint its location. Precise orbit determination is crucial because errors in locating the spacecraft would distort the sea level measurement calculated from the altimeter readings, three independent tracking systems determined the position of the spacecraft. The first, the NASA laser retroreflector array reflected laser beams from a network of 10 to 15 ground-based laser ranging stations under clear skies, the second, for all-weather, global tracking, was provided by the CNES Doppler Orbitography and Radiopositioning Integrated by Satellite tracking system receiver. This device uses microwave doppler techniques to track the spacecraft, DORIS consists of an on-board receiver and a global network of 40 to 50 ground-based transmitting stations. S Air Forces GPS constellation of Earth orbiting satellites
24.
Ocean surface topography
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The ocean surface has highs and lows, similar to the hills and valleys of Earths land surface depicted on a topographic map. These variations, called ocean surface topography, also dynamic topography, are mapped using measurements of sea surface height relative to Earths geoid. Earths geoid is a surface of equal gravitational potential energy. Topography is the arrangement of natural and artificial features of an area, Ocean surface topography is specifically the distance between the height of the ocean surface from the geoid. Ocean surface topography is caused by waves, tides, currents. The main purpose to measure ocean surface topography is to understand the large-scale circulation of the ocean, the height variations of ocean surface topography can be as much as two meters and are influenced by ocean circulation, ocean temperature, and salinity. Ocean surface topography is used to map ocean currents, which move around the oceans hills, a clockwise sense of rotation is found around hills in the northern hemisphere and valleys in the southern hemisphere. This is because of the Coriolis effect, conversely, a counterclockwise sense of rotation is found around valleys in the northern hemisphere and hills in the southern hemisphere. Ocean surface topography is used to understand how the ocean moves heat around the globe, a critical component of Earths climate. The satellites then measure the distance between their orbit altitude and the surface of the water, due to the differing depths of the ocean, an approximation is made. This is called the Arbitrary Reference Surface, Arbitrary Reference Surface is an estimated surface that is calculated to factor in the shape of the Earth. The general shape of the earth is spherical, but flattened out at the North and South Pole and this approximated surface is called the reference ellipsoid. This enables data to be taken due to the uniform surface level. The satellite’s altitude then has to be calculated with respect to the reference ellipsoid and it is calculated using the orbital parameters of the satellite and various positioning instruments. The sea surface height is then the difference between the altitude relative to the reference ellipsoid and the altimeter range. The satellite sends microwave pulses to the ocean surface, the travel time of the pulses ascending to the oceans surface and back provides data of the sea surface height. In the image below you can see the measurement system using by the satellite Jason-1, the collection of the data is useful for the long-term information about the ocean and its currents. According to NASA science this data can also be used to understanding of weather, climate, navigation, fisheries management
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United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
26.
France
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France, officially the French Republic, is a country with territory in western Europe and several overseas regions and territories. The European, or metropolitan, area of France extends from the Mediterranean Sea to the English Channel and the North Sea, Overseas France include French Guiana on the South American continent and several island territories in the Atlantic, Pacific and Indian oceans. France spans 643,801 square kilometres and had a population of almost 67 million people as of January 2017. It is a unitary republic with the capital in Paris. Other major urban centres include Marseille, Lyon, Lille, Nice, Toulouse, during the Iron Age, what is now metropolitan France was inhabited by the Gauls, a Celtic people. The area was annexed in 51 BC by Rome, which held Gaul until 486, France emerged as a major European power in the Late Middle Ages, with its victory in the Hundred Years War strengthening state-building and political centralisation. During the Renaissance, French culture flourished and a colonial empire was established. The 16th century was dominated by civil wars between Catholics and Protestants. France became Europes dominant cultural, political, and military power under Louis XIV, in the 19th century Napoleon took power and established the First French Empire, whose subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a succession of governments culminating with the establishment of the French Third Republic in 1870. Following liberation in 1944, a Fourth Republic was established and later dissolved in the course of the Algerian War, the Fifth Republic, led by Charles de Gaulle, was formed in 1958 and remains to this day. Algeria and nearly all the colonies became independent in the 1960s with minimal controversy and typically retained close economic. France has long been a centre of art, science. It hosts Europes fourth-largest number of cultural UNESCO World Heritage Sites and receives around 83 million foreign tourists annually, France is a developed country with the worlds sixth-largest economy by nominal GDP and ninth-largest by purchasing power parity. In terms of household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, France remains a great power in the world, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a member state of the European Union and the Eurozone. It is also a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, originally applied to the whole Frankish Empire, the name France comes from the Latin Francia, or country of the Franks
27.
Ocean Surface Topography Mission
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Like its two predecessors, OSTM/Jason-2 uses high-precision ocean altimetry to measure the distance between the satellite and the ocean surface to within a few centimeters. OSTM/Jason-2 was launched at 07,46 UTC on June 20,2008, from Space Launch Complex 2W at the Vandenberg Air Force Base in California, USA, the spacecraft separated from the rocket 55 minutes later. It is now in a 1,336 km circular, non-sun-synchronous orbit at an inclination of 66 degrees to Earths equator, Jason-1 has been moved to the opposite side of Earth and now flies over the same region of the ocean that Jason-2 flew over five days earlier. Jason-1s ground tracks fall midway between those of Jason-2, which are about 315 kilometers apart at the equator and this interleaved tandem mission provides twice the number of measurements of the oceans surface, bringing smaller features such as ocean eddies into view. The tandem mission also helps pave the way for a future ocean altimeter mission that would much more detailed data with its single instrument than the two Jason satellites now do together. With OSTM/Jason-2, ocean altimetry makes the transition from research into operational mode and these instruments send a microwave pulse to the ocean’s surface and time how long it takes to return. A microwave radiometer corrects any delay that may be caused by water vapor in the atmosphere, other corrections are also required to account for the influence of electrons in the ionosphere and the dry air mass of the atmosphere. Combining these data with the location of the spacecraft makes it possible to determine sea-surface height to within a few centimetres. The strength and shape of the signal also provides information on wind speed. These data are used in models to calculate the speed and direction of ocean currents and the amount and location of heat stored in the ocean. Another payload aboard Jason-2 is the T2L2 instrument, T2L2 is used to synchronize atomic clocks at ground stations, and to calibrate the on-board clock of the Jason-2 DORIS instrument. On 6 November 2008 CNES reported the T2L2 instrument was working well, OSTM/Jason-2 is a joint effort by four organizations. After completing the on-orbit commissioning of the spacecraft, CNES handed over operation, CNES will process, distribute and archive the research-quality data products that will become available in 2009. EUMETSAT will process and distribute operational data received by its station to users in Europe. NOAA will process and distribute operational data received by its stations to non-European users. NOAA and EUMETSAT will generate the products and distribute them to users. NASA will evaluate the performance of its instruments, the microwave radiometer, the Global Positioning System payload. In addition, NASA and CNES will validate scientific data products, NASAs Jet Propulsion Laboratory in Pasadena, California, manages the mission for NASAs Science Mission Directorate in Washington
28.
Ocean Surface Topography Mission/Jason-2
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Like its two predecessors, OSTM/Jason-2 uses high-precision ocean altimetry to measure the distance between the satellite and the ocean surface to within a few centimeters. OSTM/Jason-2 was launched at 07,46 UTC on June 20,2008, from Space Launch Complex 2W at the Vandenberg Air Force Base in California, USA, the spacecraft separated from the rocket 55 minutes later. It is now in a 1,336 km circular, non-sun-synchronous orbit at an inclination of 66 degrees to Earths equator, Jason-1 has been moved to the opposite side of Earth and now flies over the same region of the ocean that Jason-2 flew over five days earlier. Jason-1s ground tracks fall midway between those of Jason-2, which are about 315 kilometers apart at the equator and this interleaved tandem mission provides twice the number of measurements of the oceans surface, bringing smaller features such as ocean eddies into view. The tandem mission also helps pave the way for a future ocean altimeter mission that would much more detailed data with its single instrument than the two Jason satellites now do together. With OSTM/Jason-2, ocean altimetry makes the transition from research into operational mode and these instruments send a microwave pulse to the ocean’s surface and time how long it takes to return. A microwave radiometer corrects any delay that may be caused by water vapor in the atmosphere, other corrections are also required to account for the influence of electrons in the ionosphere and the dry air mass of the atmosphere. Combining these data with the location of the spacecraft makes it possible to determine sea-surface height to within a few centimetres. The strength and shape of the signal also provides information on wind speed. These data are used in models to calculate the speed and direction of ocean currents and the amount and location of heat stored in the ocean. Another payload aboard Jason-2 is the T2L2 instrument, T2L2 is used to synchronize atomic clocks at ground stations, and to calibrate the on-board clock of the Jason-2 DORIS instrument. On 6 November 2008 CNES reported the T2L2 instrument was working well, OSTM/Jason-2 is a joint effort by four organizations. After completing the on-orbit commissioning of the spacecraft, CNES handed over operation, CNES will process, distribute and archive the research-quality data products that will become available in 2009. EUMETSAT will process and distribute operational data received by its station to users in Europe. NOAA will process and distribute operational data received by its stations to non-European users. NOAA and EUMETSAT will generate the products and distribute them to users. NASA will evaluate the performance of its instruments, the microwave radiometer, the Global Positioning System payload. In addition, NASA and CNES will validate scientific data products, NASAs Jet Propulsion Laboratory in Pasadena, California, manages the mission for NASAs Science Mission Directorate in Washington
29.
Climate change
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Climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time. Climate change may refer to a change in weather conditions. Climate change is caused by such as biotic processes, variations in solar radiation received by Earth, plate tectonics. Certain human activities have also identified as significant causes of recent climate change. Scientists actively work to understand past and future climate by using observations, more recent data are provided by the instrumental record. The most general definition of change is a change in the statistical properties of the climate system when considered over long periods of time. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, the term climate change is often used to refer specifically to anthropogenic climate change. Anthropogenic climate change is caused by activity, as opposed to changes in climate that may have resulted as part of Earths natural processes. In this sense, especially in the context of environmental policy, within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect. A related term is climatic change, in 1966, the World Meteorological Organization proposed the term climatic change to encompass all forms of climatic variability on time-scales longer than 10 years, regardless of cause. Change was a given and climatic was used as an adjective to describe this kind of change, when it was realized that human activities had a potential to drastically alter the climate, the term climate change replaced climatic change as the dominant term to reflect an anthropogenic cause. Climate change was incorporated in the title of the Intergovernmental Panel on Climate Change, Climate change, used as a noun, became an issue rather than the technical description of changing weather. On the broadest scale, the rate at which energy is received from the Sun and this energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. Factors that can shape climate are called climate forcings or forcing mechanisms, there are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the system, such as the oceans and ice caps, respond more slowly in reaction to climate forcings. There are also key factors which when exceeded can produce rapid change. Forcing mechanisms can be internal or external. Internal forcing mechanisms are natural processes within the system itself
30.
Sea level rise
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Sea level rise refers to an increase in the volume of water in the world’s oceans, resulting in an increase in global mean sea level. Sea level rise is attributed to global climate change by thermal expansion of the water in the oceans and by melting of Ice sheets. Melting of floating ice shelves or icebergs at sea raises sea levels only slightly, Sea level rise at specific locations may be more or less than the global average. Local factors might include tectonic effects, subsidence of the land, tides, currents, storms, Sea level rise is expected to continue for centuries. IPCC Summary for Policymakers, AR5,2014, indicated that the mean sea level rise will continue during the 21st century, very likely at a faster rate than observed from 1971 to 2010. A January 2017 NOAA report suggests a range of GMSL rise of 0.3 –2.5 m possible during the 21st century, Sea level rises can considerably influence human populations in coastal and island regions and natural environments like marine ecosystems. On the timescale of centuries to millennia, the melting of ice sheets could result in even higher sea level rise, partial deglaciation of the Greenland ice sheet, and possibly the West Antarctic ice sheet, could contribute 4 to 6 m or more to sea level rise. Various factors affect the volume or mass of the ocean, leading to changes in eustatic sea level. The two primary influences are temperature, and the mass of water locked up on land and sea as water in rivers, lakes, glaciers. Over much longer timescales, changes in the shape of oceanic basins. Since the Last Glacial Maximum about 20,000 years ago, sea level has risen by more than 125 m, with rates varying from tenths of a mm/yr to 10+mm/year, as a result of melting of major ice sheets. During the rest of the early Holocene, the rate of sea level rise varied from a low of about 6.0 -9.9 mm/yr to as high as 30 -60 mm/yr during brief periods of accelerated sea level rise. In sharp contrast, the period between 14,300 and 11,100 calendar years ago, which includes the Younger Dryas interval, was an interval of reduced sea level rise at about 6.0 -9.9 mm/yr. Meltwater pulse 1C was centered at 8,000 calendar years, such rapid rates of sea level rising during meltwater events clearly implicate major ice-loss events related to ice sheet collapse. The primary source may have been meltwater from the Antarctic ice sheet, other studies suggest a Northern Hemisphere source for the meltwater in the Laurentide ice sheet. For example, this research included studies of Roman wells in Caesarea and these methods in combination suggest a mean eustatic component of 0.07 mm/yr for the last 2000 years. Since 1880, as the Industrial Revolution took center stage, the ocean began to rise briskly, climbing a total of 210 mm through 2009 causing extensive erosion worldwide, Sea level rose by 6 cm during the 19th century and 19 cm in the 20th century. Evidence for this includes geological observations, the longest instrumental records, for example, geological observations indicate that during the last 2,000 years, sea level change was small, with an average rate of only 0. 0–0.2 mm per year
31.
Altimeter
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An altimeter or an altitude meter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, altitude can be determined based on the measurement of atmospheric pressure. The greater the altitude, the lower the pressure, when a barometer is supplied with a nonlinear calibration so as to indicate altitude, the instrument is called a pressure altimeter or barometric altimeter. A pressure altimeter is the altimeter found in most aircraft, hikers and mountain climbers use wrist-mounted or hand-held altimeters, in addition to other navigational tools such as a map, magnetic compass, or GPS receiver. The calibration of an altimeter follows the equation z = c T log , where c is a constant, T is the temperature, P is the pressure at altitude z. The constant c depends on the acceleration of gravity and the mass of the air. A barometric altimeter, used along with a map, can help to verify ones location. An altimeter is the most important piece of skydiving equipment, after the parachute itself, altitude awareness is crucial at all times during the jump, and determines the appropriate response to maintain safety. This is the most basic and common type, and is used by all student skydivers. The common design has a face marked from 0 to 4000m, the face plate sports sections prominently marked with yellow and red respectively, signifying the recommended deployment altitude, as well as emergency procedure decision altitude. Some advanced electronic altimeters are also available which use of the familiar analogue display. Digital visual altimeters, mounted on the wrist or hand and this type always operates electronically, and conveys the altitude as a number, rather than a pointer on a dial. An electronic altimeter is turned on on the ground before jump, if the intended landing zone is at a different elevation than the takeoff point, the user needs to input the appropriate offset by using a designated function. These are inserted into ones helmet, and emit a warning tone at a predefined altitude, audibles are strictly auxiliary devices, and do not replace, but complement a visual altimeter which remains the primary tool for maintaining altitude awareness. Audibles are not recommended and often banned from use by student skydivers and these do not show the precise altitude, but rather help maintain a general indicator in ones peripheral vision. The exact choice of altimeters depends heavily on the individual preferences, experience level, primary disciplines. On one end of the spectrum, a demonstration jump with water landing and no free fall might waive the mandated use of altimeters. Another skydiver doing similar types of jumps might wear a digital altimeter for their primary visual one, in aircraft, an aneroid barometer measures the atmospheric pressure from a static port outside the aircraft
32.
Launch vehicle
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In spaceflight, a launch vehicle or carrier rocket is a rocket used to carry a payload from Earths surface into outer space. A launch system includes the launch vehicle, the launch pad, Earth orbital launch vehicles typically have at least two stages, and sometimes as many as four or more. Expendable launch vehicles are designed for one-time use and they usually separate from their payload and disintegrate during atmospheric reentry. In contrast, reusable vehicles are designed to be recovered intact. The Space Shuttle was a part of a vehicle with components used for multiple orbital spaceflights. SpaceX has developed a rocket launching system to successfully bring back a part—the first stage—of their Falcon 9 and launch it again. A fully reusable VTVL design is planned for all parts of the ITS launch vehicle, Launch vehicles are often classified by the amount of mass they can carry into orbit. For example, a Proton rocket can lift 22,000 kilograms into low Earth orbit, Launch vehicles are also characterized by their number of stages. Rockets with as many as five stages have been successfully launched, additionally, launch vehicles are very often supplied with boosters supplying high early thrust, normally burning with other engines. Boosters allow the engines to be smaller, reducing the burnout mass of later stages to allow larger payloads. Other frequently reported characteristics of vehicles are the launching nation or space agency. For example, the European Space Agency is responsible for the Ariane V, many launch vehicles are considered part of a historical line of vehicles of same or similar name, e. g. the Atlas V is the latest Atlas rocket. A small-lift launch vehicle is capable of lifting up to 2,000 kg of payload into low Earth orbit, a medium-lift launch vehicle is capable of lifting 2,000 to 20,000 kg of payload into LEO. A heavy-lift launch vehicle is capable of lifting 20,000 to 50,000 kg of payload into LEO, a super-heavy lift vehicle is capable of lifting more than 50,000 kg of payload into LEO. It refers to its 1,500 kg to LEO Vega launch vehicle as light lift, sounding rockets have long been used for brief, inexpensive unmanned space and microgravity experiments. Current human-rated suborbital launch vehicles include SpaceShipOne and the upcoming SpaceShipTwo, minimizing air drag requires a reasonably high ballistic coefficient, a ratio of length to diameter greater than ten. This generally results in a vehicle that is at least 20 m long. Leaving the atmosphere as early on in the flight as possible provides a velocity loss due to air drag of around 300 m/s, Launch vehicles of sufficient size are capable of launching payloads smaller than their orbital capability, to the Moon or beyond
33.
Ground track
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A ground track or ground trace is the path on the surface of the Earth directly below an aircraft or satellite. In the case of a satellite, it is the projection of the orbit onto the surface of the Earth. A satellite ground track may be thought of as a path along the Earths surface which traces the movement of a line between the satellite and the center of the Earth. In other words, the track is the set of points at which the satellite will pass directly overhead, or cross the zenith. In air navigation, ground tracks typically approximate an arc of a great circle, in order to follow a specified ground track, a pilot must adjust their heading in order to compensate for the effect of wind. Aircraft routes are planned to avoid restricted airspace and dangerous areas, typically, satellites have a roughly sinusoidal ground track. A satellite with an inclination between 90° and 180° is said to be in a retrograde orbit. A satellite in an orbit with an orbital period less than one day will tend to move from west to east along its ground track. This is called apparent direct motion, a satellite in a direct orbit with an orbital period greater than one day will tend to move from east to west along its ground track, in what is called apparent retrograde motion. This effect occurs because the satellite orbits more slowly than the speed at which the Earth rotates beneath it, any satellite in a true retrograde orbit will always move from east to west along its ground track, regardless of the length of its orbital period. Because a satellite in an orbit moves faster near perigee and slower near apogee, it is possible for a satellite to track eastward during part of its orbit. This phenomenon allows for ground tracks which cross over themselves, as in the geosynchronous, a satellite whose orbital period is an integer fraction of a day will follow roughly the same ground track every day. This ground track is shifted east or west depending on the longitude of the ascending node, which can vary over time due to perturbations of the orbit. If the period of the satellite is slightly longer than a fraction of a day, the ground track will shift west over time, if it is slightly shorter. For orbital periods longer than the Earths rotational period, an increase in orbital period corresponds to a stretching out of the ground track. A satellite whose orbital period is equal to the period of the Earth is said to be in a geosynchronous orbit. Its ground track will have a figure eight shape over a location on the Earth. It will track eastward when it is on the part of its orbit closest to perigee, a special case of the geosynchronous orbit, the geostationary orbit, has an eccentrity of zero, and an inclination of zero in the Earth-Centered, Earth-Fixed coordinate system
34.
Space debris
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As of December 2016 there were 5 satellite collisions with space waste. As of 5 July 2016, the United States Strategic Command tracked a total of 17,852 artificial objects in orbit about the Earth, including 1,419 operational satellites. For comparison, the International Space Station orbits in the 300–400 kilometres range, the ISS has Whipple shielding, however known debris with a collision chance over 1/10000 are avoided by maneuvering the station. The Kessler syndrome, a chain reaction of collisions exponentially increasing the amount of debris, has been hypothesized to ensue beyond a critical density. This could affect useful polar-orbiting bands, increases the cost of protection for spacecraft missions, whether it is already underway is debated. The measurement, mitigation and potential removal of debris are conducted by participants in the space industry. During the 1970s and 1980s, the Soviet Union launched a number of naval surveillance satellites as part of their RORSAT program, the satellites were equipped with a BES-5 nuclear reactor to power their radar systems. Although the satellites were normally boosted into a graveyard orbit at end of life. Satellites which were disposed of had an estimated eight-percent probability of puncture, the coolant freezes into droplets of solid sodium-potassium alloy, forming additional debris. As of 2009,19,000 debris over 5 cm were tracked, there are over 170 million pieces of debris smaller than 1 cm as of July 2013. There are approximately 670,000 pieces from one to ten cm, the current count of large debris is 29,000. The technical measurement cutoff is ~3 mm, over 98 percent of the 1,900 tons of debris in low Earth orbit was accounted for by about 1,500 objects, each over 100 kg. Total mass is mostly constant despite addition of smaller objects. Using a 2008 figure of 8,500 known items, it is estimated at 5,500 t, in LEO there are few universal orbits which keep spacecraft in particular rings. The closest are sun-synchronous orbits that keep a constant angle between the Sun and the plane, they are polar, meaning they cross over the polar regions. LEO satellites orbit in many planes, up to 15 times a day, orbits are further changed by perturbations, and collisions can occur from any direction. These can cross other orbits and lead to a cascade effect, a large-enough collision could make low Earth orbit impassable. Manned missions are mostly at 400 km and below, where air drag helps clear zones of fragments, atmospheric expansion as a result of space weather raises the critical altitude by increasing drag, in the 90s, it was a factor in reduced debris density
35.
Spectroscopy
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Spectroscopy /spɛkˈtrɒskəpi/ is the study of the interaction between matter and electromagnetic radiation. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, later the concept was expanded greatly to include any interaction with radiative energy as a function of its wavelength or frequency. Spectroscopic data is represented by an emission spectrum, a plot of the response of interest as a function of wavelength or frequency. Spectroscopy and spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are used to describe experimental spectroscopic methods. Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers, daily observations of color can be related to spectroscopy. Neon lighting is an application of atomic spectroscopy. Neon and other noble gases have characteristic emission frequencies, neon lamps use collision of electrons with the gas to excite these emissions. Inks, dyes and paints include chemical compounds selected for their characteristics in order to generate specific colors. A commonly encountered molecular spectrum is that of nitrogen dioxide, gaseous nitrogen dioxide has a characteristic red absorption feature, and this gives air polluted with nitrogen dioxide a reddish-brown color. Rayleigh scattering is a spectroscopic scattering phenomenon that accounts for the color of the sky, Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. As a result, these spectra can be used to detect, identify and quantify information about the atoms, Spectroscopy is also used in astronomy and remote sensing on earth. The measured spectra are used to determine the composition and physical properties of astronomical objects. One of the concepts in spectroscopy is a resonance and its corresponding resonant frequency. Resonances were first characterized in mechanical systems such as pendulums, mechanical systems that vibrate or oscillate will experience large amplitude oscillations when they are driven at their resonant frequency. A plot of amplitude vs. excitation frequency will have a peak centered at the resonance frequency and this plot is one type of spectrum, with the peak often referred to as a spectral line, and most spectral lines have a similar appearance. In quantum mechanical systems, the resonance is a coupling of two quantum mechanical stationary states of one system, such as an atom, via an oscillatory source of energy such as a photon. The coupling of the two states is strongest when the energy of the matches the energy difference between the two states. The energy of a photon is related to its frequency by E = h ν where h is Plancks constant, spectra of atoms and molecules often consist of a series of spectral lines, each one representing a resonance between two different quantum states
36.
Greece
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Greece, officially the Hellenic Republic, historically also known as Hellas, is a country in southeastern Europe, with a population of approximately 11 million as of 2015. Athens is the capital and largest city, followed by Thessaloniki. Greece is strategically located at the crossroads of Europe, Asia, situated on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, the Republic of Macedonia and Bulgaria to the north, and Turkey to the northeast. Greece consists of nine regions, Macedonia, Central Greece, the Peloponnese, Thessaly, Epirus, the Aegean Islands, Thrace, Crete. The Aegean Sea lies to the east of the mainland, the Ionian Sea to the west, the Cretan Sea and the Mediterranean Sea to the south. Greece has the longest coastline on the Mediterranean Basin and the 11th longest coastline in the world at 13,676 km in length, featuring a vast number of islands, eighty percent of Greece is mountainous, with Mount Olympus being the highest peak at 2,918 metres. From the eighth century BC, the Greeks were organised into various independent city-states, known as polis, which spanned the entire Mediterranean region and the Black Sea. Greece was annexed by Rome in the second century BC, becoming a part of the Roman Empire and its successor. The Greek Orthodox Church also shaped modern Greek identity and transmitted Greek traditions to the wider Orthodox World, falling under Ottoman dominion in the mid-15th century, the modern nation state of Greece emerged in 1830 following a war of independence. Greeces rich historical legacy is reflected by its 18 UNESCO World Heritage Sites, among the most in Europe, Greece is a democratic and developed country with an advanced high-income economy, a high quality of life, and a very high standard of living. A founding member of the United Nations, Greece was the member to join the European Communities and has been part of the Eurozone since 2001. Greeces unique cultural heritage, large industry, prominent shipping sector. It is the largest economy in the Balkans, where it is an important regional investor, the names for the nation of Greece and the Greek people differ from the names used in other languages, locations and cultures. The earliest evidence of the presence of human ancestors in the southern Balkans, dated to 270,000 BC, is to be found in the Petralona cave, all three stages of the stone age are represented in Greece, for example in the Franchthi Cave. Neolithic settlements in Greece, dating from the 7th millennium BC, are the oldest in Europe by several centuries and these civilizations possessed writing, the Minoans writing in an undeciphered script known as Linear A, and the Mycenaeans in Linear B, an early form of Greek. The Mycenaeans gradually absorbed the Minoans, but collapsed violently around 1200 BC and this ushered in a period known as the Greek Dark Ages, from which written records are absent. The end of the Dark Ages is traditionally dated to 776 BC, the Iliad and the Odyssey, the foundational texts of Western literature, are believed to have been composed by Homer in the 7th or 8th centuries BC. With the end of the Dark Ages, there emerged various kingdoms and city-states across the Greek peninsula, in 508 BC, Cleisthenes instituted the worlds first democratic system of government in Athens
37.
Jason
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Jason was an ancient Greek mythological hero who was famous for his role as the leader of the Argonauts and their quest for the Golden Fleece. He was the son of Aeson, the king of Iolcos. He was married to the sorceress Medea and he was also the great-grandson of the messenger god Hermes, through his mothers side. Jason appeared in literary works in the classical world of Greece and Rome, including the epic poem Argonautica. In the modern world, Jason has emerged as a character in various adaptations of his myths, such as the 1963 film Jason and the Argonauts, Jason has connections outside the classical world, being the mythical founder of the city of Ljubljana, the capital of Slovenia. Jasons father is invariably Aeson, but there is great variation as to his mothers name, Pelias was power-hungry and wished to gain dominion over all of Thessaly. Pelias was the product of a union between their mother, Tyro, the daughter of Salmoneus, and the sea god Poseidon. In a bitter feud, he overthrew Aeson, killing all the descendants of Aeson that he could and he spared his half-brother for unknown reasons. Alcimede I already had an infant son named Jason whom she saved from being killed by Pelias, by having women cluster around the newborn and cry as if he were still-born. Alcimede sent her son to the centaur Chiron for education, for fear that Pelias would kill him — she claimed that she had been having an affair with him all along. Pelias, still fearful that he would one day be overthrown, many years later, Pelias was holding games in honor of Poseidon, when Jason arrived in Iolcus and lost one of his sandals in the river Anauros, while helping an old woman to cross. She blessed him for she knew, as goddesses do, what Pelias had planned, when Jason entered Iolcus, he was announced as a man wearing one sandal. Jason, knowing that he was the king, told Pelias that and Pelias said, To take my throne. Jason assembled for his crew, a number of heroes, known as the Argonauts after their ship, the group of heroes included the Boreads who could fly, Heracles, Philoctetes, Peleus, Telamon, Orpheus, Castor and Pollux, Atalanta, Meleager and Euphemus. The isle of Lemnos is situated off the Western coast of Asia Minor, the island was inhabited by a race of women who had killed their husbands. The women had neglected their worship of Aphrodite, and as a punishment the goddess made the women so foul in stench that their husbands could not bear to be near them. The men then took concubines from the Thracian mainland opposite, the king, Thoas, was saved by Hypsipyle, his daughter, who put him out to sea sealed in a chest from which he was later rescued. The women of Lemnos lived for a while without men, with Hypsipyle as their queen, during the visit of the Argonauts the women mingled with the men creating a new race called Minyae
38.
Nadir
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The nadir, is the direction pointing directly below a particular location, that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there. Since the concept of being below is itself somewhat vague, scientists define the nadir in more rigorous terms. Specifically, in astronomy, geophysics and related sciences, the nadir at a point is the local vertical direction pointing in the direction of the force of gravity at that location. The direction opposite of the nadir is the zenith, the word is also used figuratively to mean the lowest point of a persons spirits, or the quality of an activity or profession. The term nadir can also be used to represent the lowest point reached by a body during its apparent orbit around a given point of observation. This can be used to describe the location of the Sun, the sun is said to be at the nadir at a location when it is at the zenith at the locations antipode and the sun is 90 degrees below the horizon. In oncology, the nadir is used to represent the lowest level of a blood cell count while a patient is undergoing chemotherapy. A diagnosis of neutropenic nadir after chemotherapy typically lasts 7–10 days
39.
Radar
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Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the objects location and speed. Radar was developed secretly for military use by several nations in the period before, the term RADAR was coined in 1940 by the United States Navy as an acronym for RAdio Detection And Ranging or RAdio Direction And Ranging. The term radar has since entered English and other languages as a common noun, high tech radar systems are associated with digital signal processing, machine learning and are capable of extracting useful information from very high noise levels. Other systems similar to make use of other parts of the electromagnetic spectrum. One example is lidar, which uses ultraviolet, visible, or near infrared light from lasers rather than radio waves, as early as 1886, German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. In 1895, Alexander Popov, an instructor at the Imperial Russian Navy school in Kronstadt. The next year, he added a spark-gap transmitter, in 1897, while testing this equipment for communicating between two ships in the Baltic Sea, he took note of an interference beat caused by the passage of a third vessel. In his report, Popov wrote that this phenomenon might be used for detecting objects, the German inventor Christian Hülsmeyer was the first to use radio waves to detect the presence of distant metallic objects. In 1904, he demonstrated the feasibility of detecting a ship in dense fog and he obtained a patent for his detection device in April 1904 and later a patent for a related amendment for estimating the distance to the ship. He also got a British patent on September 23,1904 for a radar system. It operated on a 50 cm wavelength and the radar signal was created via a spark-gap. In 1915, Robert Watson-Watt used radio technology to advance warning to airmen. Watson-Watt became an expert on the use of direction finding as part of his lightning experiments. As part of ongoing experiments, he asked the new boy, Arnold Frederic Wilkins, Wilkins made an extensive study of available units before selecting a receiver model from the General Post Office. Its instruction manual noted that there was fading when aircraft flew by, in 1922, A. Hoyt Taylor and Leo C. Taylor submitted a report, suggesting that this might be used to detect the presence of ships in low visibility, eight years later, Lawrence A. Australia, Canada, New Zealand, and South Africa followed prewar Great Britain, and Hungary had similar developments during the war. Hugon, began developing a radio apparatus, a part of which was installed on the liner Normandie in 1935
40.
C band (IEEE)
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The communications C-band was the first frequency band that was allocated for commercial telecommunications via satellites. The same frequencies were already in use for terrestrial microwave radio relay chains. Nearly all C-band communication satellites use the band of frequencies from 3.7 to 4.2 GHz for their downlinks, note that by using the band from 3.7 to 4.0 GHz, this C-band overlaps somewhat into the IEEE S-band for radars. The C-band communication satellites typically have 24 radio transponders spaced 20 MHz apart, hence, the transponders on the same polarization are always 40 MHz apart. Of this 40 MHz, each transponder utilizes about 36 MHz, the C-band is primarily used for open satellite communications, whether for full-time satellite television networks or raw satellite feeds, although subscription programming also exists. Typical antenna sizes on C-band capable systems ranges from 7.5 to 12 feet on consumer satellite dishes, rain fade – the collective name for the negative effects of adverse weather conditions on transmission – is mostly a consequence of precipitation and moisture in the air. Slight variations in the assignments of C-band frequencies have been approved for use in parts of the world. This latter region is the most populous one, since it includes the Peoples Republic of China, India, Pakistan, Japan and this is known as the 5-centimeter band by amateurs and the C-band by AMSAT. Particle accelerators may be powered by C-band RF sources, the frequencies are then standardized at 5.996 GHz or 5.712 GHz, which is the second harmonic of S-band
41.
Sea
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A sea is a large body of salt water that is surrounded in whole or in part by land. More broadly, the sea is the system of Earths salty. The sea moderates Earths climate and has important roles in the cycle, carbon cycle. Although the sea has been traveled and explored since prehistory, the scientific study of the sea—oceanography—dates broadly to the British Challenger expedition of the 1870s. Owing to the present state of continental drift, the Northern Hemisphere is now equally divided between land and sea but the South is overwhelmingly oceanic. Salinity in the ocean is generally in a narrow band around 3. 5% by mass, although this can vary in more landlocked waters, near the mouths of large rivers. About 85% of the solids in the sea are sodium chloride. Deep-sea currents are produced by differences in salinity and temperature, surface currents are formed by the friction of waves produced by the wind and by tides, the changes in local sea level produced by the gravity of the Moon and Sun. The direction of all of these is governed by surface and submarine land masses, former changes in sea levels have left continental shelves, shallow areas in the sea close to land. The most diverse areas surround great tropical coral reefs, whaling in the deep sea was once common but whales dwindling numbers prompted international conservation efforts and finally a moratorium on most commercial hunting. Life may have started there and aquatic microbial mats are generally credited with the oxygenation of Earths atmosphere, the sea is an essential aspect of human trade, travel, mineral extraction, and power generation. It is the scene of activities including swimming, diving, surfing. However, population growth, industrialization, and intensive farming have all contributed to marine pollution. Atmospheric carbon dioxide is being absorbed in increasing amounts, lowering its pH in a known as ocean acidification. The shared nature of the sea has made overfishing an increasing problem, both senses of sea date to Old English, the larger sense has required a definite article since Early Middle English. Seas are generally larger than lakes and contain salt water, while the defining elements of size and being bounded are generally used, there is no formally accepted technical definition of sea among oceanographers. In international law, the United Nations Convention on the Law of the Sea states that all the ocean is the sea. Earth is the known planet with seas of liquid water on its surface, although Mars possesses ice caps
42.
Microwave
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Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter, with frequencies between 300 MHz and 300 GHz. Different sources define different frequency ranges as microwaves, the broad definition includes both UHF and EHF bands. A more common definition in radio engineering is the range between 1 and 100 GHz, in all cases, microwaves include the entire SHF band at minimum. Frequencies in the range are often referred to by their IEEE radar band designations, S, C, X, Ku, K, or Ka band. The prefix micro- in microwave is not meant to suggest a wavelength in the micrometer range and it indicates that microwaves are small, compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. At the high end of the band they are absorbed by gases in the atmosphere, microwaves are extremely widely used in modern technology. Although at the low end of the band they can pass through building walls enough for useful reception, therefore on the surface of the Earth microwave communication links are limited by the visual horizon to about 30 -40 miles. Microwaves are absorbed by moisture in the atmosphere, and the attenuation increases with frequency, beginning at about 40 GHz, atmospheric gases also begin to absorb microwaves, so above this frequency microwave transmission is limited to a few kilometers. A spectral band structure causes absorption peaks at specific frequencies, in a microwave beam directed at an angle into the sky, a small amount of the power will be randomly scattered as the beam passes through the troposphere. A sensitive receiver beyond the horizon with a high gain antenna focused on that area of the troposphere can pick up the signal. This technique has been used at frequencies between 0.45 and 5 GHz in tropospheric scatter communication systems to communicate beyond the horizon and their short wavelength allows narrow beams of microwaves to be produced by conveniently small high gain antennas from a half meter to 5 meters in diameter. Therefore beams of microwaves are used for point-to-point communication links, an advantage of narrow beams is that they allow frequency reuse by nearby transmitters. Parabolic antennas are the most widely used directive antennas at microwave frequencies, flat microstrip antennas are being increasingly used in consumer devices. Where omnidirectional antennas are required, for example in wireless devices and Wifi routers for wireless LANs, small monopoles, dipole, or patch antennas are used. Due to the high cost and maintenance requirements of waveguide runs, the term microwave also has a more technical meaning in electromagnetics and circuit theory. As a consequence, practical microwave circuits tend to away from the discrete resistors, capacitors. Open-wire and coaxial transmission lines used at lower frequencies are replaced by waveguides and stripline, high-power microwave sources use specialized vacuum tubes to generate microwaves
43.
Radiometer
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A radiometer or roentgenometer is a device for measuring the radiant flux of electromagnetic radiation. Generally, a radiometer is a radiation detector or ultraviolet detector. The name Radiometer is frequently used to refer to a Crookes radiometer, a common myth is that the momentum of the absorbed light on the black faces makes the radiometer operate. If this were true however, the radiometer would spin away from the non-black faces, photons do exert radiation pressure on the faces, but those forces are dwarfed by other effects. The final explanation depends on having just the right degree of vacuum, the Nichols radiometer operates on a different principle and is more sensitive than the Crookes type. A microwave radiometer operates in the microwave wavelengths, the radiometer contains argon gas to enable it to rotate. The MEMS radiometer, invented by Patrick Jankowiak, can operate on the principles of Nichols or Crooke and can operate over a spectrum of wavelength
