1.
A-train (satellite constellation)
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The A-train is a satellite constellation of six Earth observation satellites of varied nationality in sun-synchronous orbit at an altitude of 705 km above the Earth. The orbit, at an inclination of 98 and they are spaced a few minutes apart from each other so their collective observations may be used to build high-definition three-dimensional images of the Earths atmosphere and surface. The train, as of July 2014, consists of six satellites, OCO-2, lead spacecraft in formation. GCOM-W1 SHIZUKU, follows OCO-2 by 11 minutes, launched by JAXA on May 18,2012, Aqua, runs 4 minutes behind GCOM-W1, launched for NASA on May 4,2002. CloudSat, an effort between NASA and the Canadian Space Agency, runs 2 minutes and 30 seconds behind Aqua. CALIPSO, a joint effort of CNES and NASA, follows CloudSat by no more than 15 seconds, launched on April 28,2006. Aura, a satellite, lags Aqua by 15 minutes, crossing the equator 8 minutes behind due to different orbital track to allow for synergy with Aqua. PARASOL, launched by CNES on December 18,2004 and moved to orbit on December 2,2009. OCO, destroyed by a vehicle failure on February 24,2009. Glory, failed during launch on a Taurus XL rocket on March 4,2011, NASA A-Train Portal NASA satellite program impacted NASA Program Page Orbital Sciences Program Page LEcuyer, T. S. Jiang, J. H. Touring the atmosphere aboard the A-Train
2.
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
3.
Orbit
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In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet about a star or a natural satellite around a planet. Normally, orbit refers to a regularly repeating path around a body, to a close approximation, planets and satellites follow elliptical orbits, with the central mass being orbited at a focal point of the ellipse, as described by Keplers laws of planetary motion. For ease of calculation, in most situations orbital motion is adequately approximated by Newtonian Mechanics, historically, the apparent motions of the planets were described by European and Arabic philosophers using the idea of celestial spheres. This model posited the existence of perfect moving spheres or rings to which the stars and it assumed the heavens were fixed apart from the motion of the spheres, and was developed without any understanding of gravity. After the planets motions were accurately measured, theoretical mechanisms such as deferent. Originally geocentric it was modified by Copernicus to place the sun at the centre to help simplify the model, the model was further challenged during the 16th century, as comets were observed traversing the spheres. The basis for the understanding of orbits was first formulated by Johannes Kepler whose results are summarised in his three laws of planetary motion. Second, he found that the speed of each planet is not constant, as had previously been thought. Third, Kepler found a relationship between the orbital properties of all the planets orbiting the Sun. For the planets, the cubes of their distances from the Sun are proportional to the squares of their orbital periods. Jupiter and Venus, for example, are respectively about 5.2 and 0.723 AU distant from the Sun, their orbital periods respectively about 11.86 and 0.615 years. The proportionality is seen by the fact that the ratio for Jupiter,5. 23/11.862, is equal to that for Venus,0. 7233/0.6152. Idealised orbits meeting these rules are known as Kepler orbits, isaac Newton demonstrated that Keplers laws were derivable from his theory of gravitation and that, in general, the orbits of bodies subject to gravity were conic sections. Newton showed that, for a pair of bodies, the sizes are in inverse proportion to their masses. Where one body is more massive than the other, it is a convenient approximation to take the center of mass as coinciding with the center of the more massive body. Lagrange developed a new approach to Newtonian mechanics emphasizing energy more than force, in a dramatic vindication of classical mechanics, in 1846 le Verrier was able to predict the position of Neptune based on unexplained perturbations in the orbit of Uranus. This led astronomers to recognize that Newtonian mechanics did not provide the highest accuracy in understanding orbits, in relativity theory, orbits follow geodesic trajectories which are usually approximated very well by the Newtonian predictions but the differences are measurable. Essentially all the evidence that can distinguish between the theories agrees with relativity theory to within experimental measurement accuracy
4.
Reconnaissance satellite
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A reconnaissance satellite is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The first generation type took photographs, then ejected canisters of photographic film which would descend to earth, corona capsules were retrieved in mid-air as they floated down on parachutes. Later, spacecraft had digital imaging systems and downloaded the images via encrypted radio links, in the United States, most information available is on programs that existed up to 1972, as this information has been declassified due to its age. Some information about prior to that time is still classified. A few up-to-date reconnaissance satellite images have been declassified on occasion, or leaked, there are several major types of reconnaissance satellite. Missile Early warning Provides warning of an attack by detecting ballistic missile launches, earliest known are Missile Defense Alarm System. Nuclear explosion detection Identifies and characterizes nuclear explosions in space, photo surveillance Provides imaging of earth from space. Images can be a survey or close-look telephoto, electronic-reconnaissance Signals intelligence, intercepts stray radio waves. Radar imaging Most space-based radars use synthetic aperture radar, can be used at night or through cloud cover. On 17 February 2014, a Russian Kosmos-1220 originally launched in 1980 and used for naval missile targeting until 1982, reconnaissance satellites have been used to enforce human rights, through the Satellite Sentinel Project, which monitors atrocities in Sudan and South Sudan. Additionally, companies such as GeoEye and DigitalGlobe have provided commercial satellite imagery in support of disaster response. During the 1950s, a Soviet hoax had led to American fears of a bomber gap, president Lyndon B. Johnson told a gathering in 1967, I wouldnt want to be quoted on this. Weve spent $35 or $40 billion on the space program, and if nothing else had come out of it except the knowledge that we gained from space photography, it would be worth ten times what the whole program has cost. Because tonight we know how many missiles the enemy has and, it turned out and we were doing things we didnt need to do. We were building things we didnt need to build and we were harboring fears we didnt need to harbor. Spy satellites are commonly seen in spy fiction and military fiction, americas Secret Eyes in Space, the U. S. Spies in the Sky, Surveillance Satellites in War and Peace, berlin, New York, Springer, Chichester, UK, In association with Praxis Publishing
5.
Natural environment
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The natural environment encompasses all living and non-living things occurring naturally. The term is most often applied to the Earth or some part of Earth and this environment encompasses the interaction of all living species, climate, weather, and natural resources that affect human survival and economic activity. Even acts which seem less extreme, such as building a mud hut or a system in the desert. Though many animals build things to provide an environment for themselves, they are not human, hence beaver dams. People seldom find absolutely natural environments on Earth, and naturalness usually varies in a continuum, more precisely, we can consider the different aspects or components of an environment, and see that their degree of naturalness is not uniform. If, for instance, in a field, the mineralogic composition and the structure of its soil are similar to those of an undisturbed forest soil. Natural environment is used as a synonym for habitat. For instance, when we say that the environment of giraffes is the savanna. Earth science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere as correspondent to rocks, water, air, and life respectively. Some scientists include, as part of the spheres of the Earth, Earth science, is an all-embracing term for the sciences related to the planet Earth. There are four major disciplines in sciences, namely geography, geology, geophysics. These major disciplines use physics, chemistry, biology, chronology, the Earths crust, or lithosphere, is the outermost solid surface of the planet and is chemically and mechanically different from underlying mantle. It has been generated greatly by igneous processes in which magma cools, beneath the lithosphere lies the mantle which is heated by the decay of radioactive elements. The mantle though solid is in a state of rheic convection and this convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics, volcanoes result primarily from the melting of subducted crust material or of rising mantle at mid-ocean ridges and mantle plumes. An ocean is a body of saline water, and a component of the hydrosphere. Approximately 71% of the Earths surface is covered by ocean, a body of water that is customarily divided into several principal oceans. More than half of area is over 3,000 meters deep
6.
Meteorology
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Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not occur until the 18th century, the 19th century saw modest progress in the field after weather observation networks were formed across broad regions. Prior attempts at prediction of weather depended on historical data, Meteorological phenomena are observable weather events that are explained by the science of meteorology. Different spatial scales are used to describe and predict weather on local, regional, Meteorology, climatology, atmospheric physics, and atmospheric chemistry are sub-disciplines of the atmospheric sciences. Meteorology and hydrology compose the interdisciplinary field of hydrometeorology, the interactions between Earths atmosphere and its oceans are part of a coupled ocean-atmosphere system. Meteorology has application in diverse fields such as the military, energy production, transport, agriculture. The word meteorology is from Greek μετέωρος metéōros lofty, high and -λογία -logia -logy, varāhamihiras classical work Brihatsamhita, written about 500 AD, provides clear evidence that a deep knowledge of atmospheric processes existed even in those times. In 350 BC, Aristotle wrote Meteorology, Aristotle is considered the founder of meteorology. One of the most impressive achievements described in the Meteorology is the description of what is now known as the hydrologic cycle and they are all called swooping bolts because they swoop down upon the Earth. Lightning is sometimes smoky, and is then called smoldering lightning, sometimes it darts quickly along, at other times, it travels in crooked lines, and is called forked lightning. When it swoops down upon some object it is called swooping lightning, the Greek scientist Theophrastus compiled a book on weather forecasting, called the Book of Signs. The work of Theophrastus remained a dominant influence in the study of weather, in 25 AD, Pomponius Mela, a geographer for the Roman Empire, formalized the climatic zone system. According to Toufic Fahd, around the 9th century, Al-Dinawari wrote the Kitab al-Nabat, ptolemy wrote on the atmospheric refraction of light in the context of astronomical observations. St. Roger Bacon was the first to calculate the size of the rainbow. He stated that a rainbow summit can not appear higher than 42 degrees above the horizon, in the late 13th century and early 14th century, Kamāl al-Dīn al-Fārisī and Theodoric of Freiberg were the first to give the correct explanations for the primary rainbow phenomenon. Theoderic went further and also explained the secondary rainbow, in 1716, Edmund Halley suggested that aurorae are caused by magnetic effluvia moving along the Earths magnetic field lines. In 1441, King Sejongs son, Prince Munjong, invented the first standardized rain gauge and these were sent throughout the Joseon Dynasty of Korea as an official tool to assess land taxes based upon a farmers potential harvest. In 1450, Leone Battista Alberti developed a swinging-plate anemometer, and was known as the first anemometer, in 1607, Galileo Galilei constructed a thermoscope
7.
Cartography
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Cartography is the study and practice of making maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively, the fundamental problems of traditional cartography are to, Set the maps agenda and select traits of the object to be mapped. This is the concern of map editing, traits may be physical, such as roads or land masses, or may be abstract, such as toponyms or political boundaries. Represent the terrain of the object on flat media. This is the concern of map projections, eliminate characteristics of the mapped object that are not relevant to the maps purpose. This is the concern of generalization, reduce the complexity of the characteristics that will be mapped. This is also the concern of generalization, orchestrate the elements of the map to best convey its message to its audience. This is the concern of map design, modern cartography constitutes many theoretical and practical foundations of geographic information systems. The earliest known map is a matter of debate, both because the term map isnt well-defined and because some artifacts that might be maps might actually be something else. A wall painting that might depict the ancient Anatolian city of Çatalhöyük has been dated to the late 7th millennium BCE, the oldest surviving world maps are from 9th century BCE Babylonia. One shows Babylon on the Euphrates, surrounded by Assyria, Urartu and several cities, all, in turn, another depicts Babylon as being north of the world center. The ancient Greeks and Romans created maps since Anaximander in the 6th century BCE, in the 2nd century AD, Ptolemy wrote his treatise on cartography, Geographia. This contained Ptolemys world map – the world known to Western society. As early as the 8th century, Arab scholars were translating the works of the Greek geographers into Arabic, in ancient China, geographical literature dates to the 5th century BCE. The oldest extant Chinese maps come from the State of Qin, dated back to the 4th century BCE, in the book of the Xin Yi Xiang Fa Yao, published in 1092 by the Chinese scientist Su Song, a star map on the equidistant cylindrical projection. Early forms of cartography of India included depictions of the pole star and these charts may have been used for navigation. Mappa mundi are the Medieval European maps of the world, approximately 1,100 mappae mundi are known to have survived from the Middle Ages. Of these, some 900 are found illustrating manuscripts and the remainder exist as stand-alone documents, the Arab geographer Muhammad al-Idrisi produced his medieval atlas Tabula Rogeriana in 1154
8.
Sputnik 1
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Sputnik 1 was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957 and it was a 58 cm diameter polished metal sphere, with four external radio antennas to broadcast radio pulses. It was visible all around the Earth and its radio pulses were detectable and this surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the larger Cold War. The launch ushered in new political, military, technological, tracking and studying Sputnik 1 from Earth provided scientists with valuable information, even though the satellite itself wasnt equipped with sensors. The density of the atmosphere could be deduced from its drag on the orbit. Sputnik 1 was launched during the International Geophysical Year from Site No. 1/5, at the 5th Tyuratam range, the satellite travelled at about 29,000 kilometres per hour, taking 96.2 minutes to complete each orbit. It transmitted on 20.005 and 40.002 MHz, the signals continued for 21 days until the transmitter batteries ran out on 26 October 1957. Sputnik burned up on 4 January 1958 while reentering Earths atmosphere, after travelling about 70 million km, on 17 December 1954, chief Soviet rocket scientist Sergei Korolev addressed Dimitri Ustinov and proposed a developmental plan for an artificial satellite. Korolev forwarded a report by Mikhail Tikhonravov with an overview of similar projects abroad, Tikhonravov had emphasized that the launch of an orbital satellite was an inevitable stage in the development of rocket technology. On 29 July 1955, U. S. President Dwight D. Eisenhower announced through his press secretary that the United States would launch an artificial satellite during the International Geophysical Year. A week later, on 8 August, the Politburo of the Communist Party of the Soviet Union approved the proposal to create an artificial satellite. On 30 August Vasily Ryabikov – the head of the State Commission on R-7 rocket test launches – held a meeting where Korolev presented calculation data for a trajectory to the Moon. They decided to develop a version of the R-7 rocket for satellite launches. On 30 January 1956 the Council of Ministers approved practical work on an artificial Earth-orbiting satellite. This satellite, named Object D, was planned to be completed in 1957–58, it would have a mass of 1,000 to 1,400 kg, the first test launch of Object D was scheduled for 1957. These included measuring the density of the atmosphere and its ion composition, the wind, magnetic fields. These data would be valuable in the creation of artificial satellites. A system of stations was to be developed to collect data transmitted by the satellite, observe the satellites orbit
9.
Ionosphere
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The ionosphere is a region of Earths upper atmosphere, from about 60 km to 1,000 km altitude, and includes the thermosphere and parts of the mesosphere and exosphere. It is ionized by radiation, plays an important part in atmospheric electricity. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth and it owes its existence primarily to ultraviolet radiation from the Sun. The lowest part of the Earths atmosphere, the troposphere extends from the surface to about 10 km, above 10 km is the stratosphere, followed by the mesosphere. In the stratosphere incoming solar radiation creates the ozone layer, at heights of above 80 km, in the thermosphere, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The number of free electrons is sufficient to affect radio propagation. This portion of the atmosphere is ionized and contains a plasma which is referred to as the ionosphere, in this process the light electron obtains a high velocity so that the temperature of the created electronic gas is much higher than the one of ions and neutrals. The reverse process to ionization is recombination, in which an electron is captured by a positive ion. Recombination occurs spontaneously, and causes the emission of a photon carrying away the energy produced upon recombination, as gas density increases at lower altitudes, the recombination process prevails, since the gas molecules and ions are closer together. The balance between two processes determines the quantity of ionization present. Ionization depends primarily on the Sun and its activity, the amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. Thus there is an effect and a seasonal effect. The local winter hemisphere is tipped away from the Sun, thus there is less received solar radiation, the activity of the Sun is associated with the sunspot cycle, with more radiation occurring with more sunspots. Radiation received also varies with geographical location, there are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as flares and the associated release of charged particles into the solar wind which reaches the Earth. At night the F layer is the layer of significant ionization present. During the day, the D and E layers become more heavily ionized, as does the F layer
10.
Explorer 1
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Explorer 1 was the first satellite of the United States, launched as part of its participation in the International Geophysical Year. The mission followed the first two satellites the previous year, the Soviet Unions Sputnik 1 and 2, beginning the Cold War Space Race between the two nations. Explorer 1 was launched on January 31,1958 at 22,48 Eastern Time atop the first Juno booster from LC-26 at the Cape Canaveral Missile Annex, Florida. It was the first spacecraft to detect the Van Allen radiation belt and it remained in orbit until 1970, and has been followed by more than 90 scientific spacecraft in the Explorer series. Explorer 1 was given Satellite Catalog Number 4, and the Harvard designation 1958 Alpha 1, the forerunner to the modern International Designator. Earth satellite program began in 1954 as a joint U. S. Army and U. S. Navy proposal, called Project Orbiter, to put a scientific satellite into orbit during the International Geophysical Year. The proposal, using a military Redstone missile, was rejected in 1955 by the Eisenhower administration in favor of the Navys Project Vanguard, using a booster advertised as more civilian in nature. Following the launch of the Soviet satellite Sputnik 1 on October 4,1957, the Jupiter-C design used for the launch had already been flight-tested in nose cone reentry tests for the Jupiter IRBM, and was modified into Juno I. Working closely together, ABMA and JPL completed the job of modifying the Jupiter-C, however, before work was completed, the Soviet Union launched a second satellite, Sputnik 2, on November 3,1957. The U. S. Navys attempt to put the first U. S. satellite into orbit failed with the launch of the Vanguard TV3 on December 6,1957. Explorer 1 was designed and built by the California Institute of Technologys JPL under the direction of Dr. William H. Pickering and it was the second satellite to carry a mission payload. The total weight of the satellite was 13.37 kilograms, in comparison, the first Soviet satellite Sputnik 1 weighed 83.6 kg. The instrument section at the front end of the satellite and the empty scaled-down fourth-stage rocket casing orbited as a single unit, data from the scientific instruments was transmitted to the ground by two antennas. This was an early time frame in the development of transistor technology. A total of 29 transistors were used in Explorer 1, plus additional ones in the Armys micrometeorite amplifier, electrical power was provided by mercury chemical batteries that made up approximately 40 percent of the payload weight. The external skin of the instrument section was sandblasted stainless steel with white stripes, the final coloration was determined by studies of shadow–sunlight intervals based on firing time, trajectory, orbit, and inclination. The Explorer 1 payload consisted of the Iowa Cosmic Ray Instrument without a data recorder which was not modified in time to make it onto the spacecraft. The real-time data received on the ground was very sparse and puzzling showing normal counting rates
11.
Van Allen radiation belt
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A radiation belt is a zone of energetic charged particles, most of which originate from the solar wind that is captured by and held around a planet by that planets magnetic field. The Earth has two belts and sometimes others may be temporarily created. The discovery of the belts is credited to James Van Allen, Earths two main belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region radiation levels vary. Most of the particles form the belts are thought to come from solar wind. By trapping the solar wind, the magnetic field deflects those energetic particles, the belts are located in the inner region of the Earths magnetosphere. The belts trap energetic electrons and protons, other nuclei, such as alpha particles, are less prevalent. The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend significant time in that zone, kristian Birkeland, Carl Størmer, and Nicholas Christofilos had investigated the possibility of trapped charged particles before the Space Age. Explorer 1 and Explorer 3 confirmed the existence of the belt in early 1958 under James Van Allen at the University of Iowa, the trapped radiation was first mapped by Explorer 4, Pioneer 3 and Luna 1. The term Van Allen belts refers specifically to the radiation belts surrounding Earth, however, the Sun does not support long-term radiation belts, as it lacks a stable, global, dipole field. The Earths atmosphere limits the belts particles to regions above 200–1,000 km, the belts are confined to a volume which extends about 65° on either side of the celestial equator. The NASA Van Allen Probes mission aims at understanding how populations of relativistic electrons and ions in space form or change in response to changes in solar activity, the Van Allen Probes mission successfully launched on August 30,2012. The primary mission is scheduled to last two years with expendables expected to last four, NASAs Goddard Space Flight Center manages the Living With a Star program of which the Van Allen Probes is a project, along with Solar Dynamics Observatory. The Applied Physics Laboratory is responsible for the implementation and instrument management for the Van Allen Probes, Radiation belts exist around other planets and moons in the solar system that have magnetic fields powerful enough to sustain them. To date, most of these belts have been poorly mapped. The Voyager Program only nominally confirmed the existence of similar belts around Uranus, the inner Van Allen Belt extends typically from an altitude of 0.2 to 2 Earth radii or 1,000 km to 6,000 km above the Earth. In certain cases when solar activity is stronger or in areas such as the South Atlantic Anomaly. The inner belt contains high concentrations of electrons in the range of hundreds of keV and energetic protons with energies exceeding 100 MeV, the source of lower energy protons is believed to be proton diffusion due to changes in the magnetic field during geomagnetic storms. Due to the offset of the belts from Earths geometric center
12.
TIROS-1
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TIROS I was the first successful low-Earth orbital weather satellite, and the first of a series of Television Infrared Observation Satellites. The TIROS-1 spacecraft was launched by NASA and partners at 6,40 AM EST on April 1,1960, from Cape Canaveral, Florida, in the United States. Mission partners were NASA, the U. S. Army Signal Research and Development Laboratory, RCA, the U. S. Weather Bureau, the TIROS Program was NASAs first experimental step to determine if satellites could be useful in the study of the Earth. At that time, the effectiveness of satellite observations was still unproven, since satellites were a new technology, the TIROS Program also tested various design issues for spacecraft, instruments, data and operational parameters. The goal was to improve satellite applications for Earth-bound decisions, such as should we evacuate the coast because of the hurricane, the TIROS Programs first priority was the development of a meteorological satellite information system. Weather forecasting was deemed the most promising application of space-based observations, TIROS proved extremely successful, providing the first accurate weather forecasts based on data gathered from space. TIROS began continuous coverage of the Earths weather in 1962, and was used by meteorologists worldwide, the programs success with many instrument types and orbital configurations lead to the development of more sophisticated meteorological observation satellites
13.
Television Infrared Observation Satellite
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TIROS, or Television Infrared Observation Satellite, is a series of early weather satellites launched by the United States, beginning with TIROS-1 in 1960. TIROS was the first satellite that was capable of remote sensing of the Earth, enabling scientists to view the Earth from a new perspective, space. The program, promoted by Harry Wexler, proved the usefulness of satellite weather observation, TIROS demonstrated at that time that the key to genius is often simplicity. The 270 lb satellite was launched into a circular low earth orbit by a Thor Able rocket. Drum-shaped with a 42-inch diameter, and height of 19 inches, one of the cameras had a wide-angle lens with an f /1.6 aperture that could view an 800-mile-wide area of the Earth. The other camera had a lens with an f /1.8 aperture. The satellite itself was stabilized in its orbit by spinning like a gyroscope, when it first separated from the rockets third stage, it was spinning at about 136 revolutions per minute. To take unblurred photographs, a de-spin mechanism slowed the satellite down to 12 rpm after the orbit was accomplished. The camera shutters made possible the series of pictures which were stored and transmitted back to earth via 2-watt FM transmitters as the satellite approached one of its ground command points. After transmission, the tape was erased or cleaned and readied for more recording, nOAA-N Prime is the last in the TIROS series of NOAA satellites that observe Earth’s weather and the environment. First Tiros satellite in near-polar orbit TIROS-10, launched July 2,1965, deactivated July 31,1966 As of June 2009, nOAA-6 Launched 27 June 1979 into a 450-nmi orbit. The HIRS, a primary sensor, failed 19 September 1983. The satellite exceeded its designed lifetime by almost six years when deactivated on 31 March 1987. It failed to achieve an orbit because of a booster engine anomaly. NOAA-7 Launched 23 June 1981 into a 470-nmi orbit, deactivated June 1986, NOAA-12 Launched 14 May 1991 into a 450-nmi AM orbit, out of sequence. Placed in standby mode on 14 December 1998, when NOAA-15 became operational and deactivated on 10 August 2007, the Advanced TIROS-N spacecraft were similar to the NOAA-A through -D satellites, apart from an enlarged Equipment Support Module to allow integration of additional payloads. The search and rescue system became independent, utilizing a special frequency for transmission of data to the ground, nOAA-8 Launched 28 March 1983 into a 450-nautical-mile orbit, out of sequence to get the first SAR system on a US satellite operational. Deactivated 29 December 1985, following a thermal runaway which destroyed a battery, nOAA-9 Launched 12 December 1984 into 470 nmi afternoon orbit and was the first satellite to carry an SBUV/2 instrument
14.
Drag (physics)
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In fluid dynamics, drag is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two layers or a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are independent of velocity. Drag force is proportional to the velocity for a laminar flow, even though the ultimate cause of a drag is viscous friction, the turbulent drag is independent of viscosity. Drag forces always decrease fluid velocity relative to the object in the fluids path. In the case of viscous drag of fluid in a pipe, in physics of sports, the drag force is necessary to explain the performance of runners, particularly of sprinters. Types of drag are generally divided into the categories, parasitic drag, consisting of form drag, skin friction, interference drag, lift-induced drag. The phrase parasitic drag is used in aerodynamics, since for lifting wings drag it is in general small compared to lift. For flow around bluff bodies, form and interference drags often dominate, further, lift-induced drag is only relevant when wings or a lifting body are present, and is therefore usually discussed either in aviation or in the design of semi-planing or planing hulls. Wave drag occurs either when an object is moving through a fluid at or near the speed of sound or when a solid object is moving along a fluid boundary. Drag depends on the properties of the fluid and on the size, shape, at low R e, C D is asymptotically proportional to R e −1, which means that the drag is linearly proportional to the speed. At high R e, C D is more or less constant, the graph to the right shows how C D varies with R e for the case of a sphere. As mentioned, the equation with a constant drag coefficient gives the force experienced by an object moving through a fluid at relatively large velocity. This is also called quadratic drag, the equation is attributed to Lord Rayleigh, who originally used L2 in place of A. Sometimes a body is a composite of different parts, each with a different reference areas, in the case of a wing the reference areas are the same and the drag force is in the same ratio to the lift force as the ratio of drag coefficient to lift coefficient. Therefore, the reference for a wing is often the area rather than the frontal area. For an object with a surface, and non-fixed separation points—like a sphere or circular cylinder—the drag coefficient may vary with Reynolds number Re. For an object with well-defined fixed separation points, like a disk with its plane normal to the flow direction
15.
European Remote-Sensing Satellite
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European remote sensing satellite was the European Space Agencys first Earth-observing satellite programme using a polar orbit. The first satellite was launched on 17 July 1991 into a Sun-synchronous polar orbit at an altitude of 782–785 km, ERS-1 carried an array of earth-observation instruments that gathered information about the Earth using a variety of measurement principles. These included, RA is a single frequency nadir-pointing radar altimeter operating in the Ku band, aTSR-1 is a 4 channel infrared radiometer and microwave sounder for measuring temperatures at the sea-surface and the top of clouds. SAR operating in C band can detect changes in surface heights with sub-millimeter precision, Wind Scatterometer used to calculate information on wind speed and direction. MWR is a Microwave Radiometer used in measuring atmospheric water, as well as providing a correction for the water for the altimeter. To accurately determine its orbit, the satellite included the PRARE, the PRARE became non-operational shortly after launch. The Retroreflector was used for calibrating the Radar Altimeter to within 10 cm, ERS-1 had various mission phases using 3-day, 35-day and a 336-day repeat cycle. The 336-day mission allowed for mapping of the Earths bathymetry. ERS-1 failed on 10 March 2000, far exceeding its expected lifespan and its successor, ERS-2, was launched on 21 April 1995, on an Ariane 4, from ESAs Guiana Space Centre near Kourou, French Guiana. Largely identical to ERS-1, it added additional instruments and included improvements to existing instruments including, GOME is a nadir scanning ultraviolet, aTSR-2 included 3 visible spectrum bands specialized for Chlorophyll and Vegetation When ERS-2 was launched, ERS-1 shared the same orbital plane. This allowed a tandem mission, with ERS-2 passing the point on the ground 1 day later than ERS-1. ERS-2 has a cycle of 35 days. ERS-2 has been operating without gyroscopes since February 2001, resulting in degradation of the data provided by the instruments. The tape drive aboard failed on 22 June 2003, leaving the instruments operating only within visibility of a ground station, since the tape drive failure additional ground stations have been brought online to increase the data gathering abilities of the satellite. The Wind Scatterometer and GOME were the instruments of their kind until the launches of MetOp-A and Envisat. The successor to ERS-2 is Envisat containing improved versions of many of the instruments onboard ERS-2, however, over a series of burns in July, August and September, ERS-2 was finally depleted of all fuel on 5 September 2011. In the final stages of emptying the fuel tanks, it was estimated that they would be empty after a 40-minute burn on 2 September 2011, however, the spacecraft survived both this maneuver and a second 40-minute burn on 3 September. On 5 September a third burn was initiated and the tanks were finally drained
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Envisat
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Envisat is a large inactive Earth-observing satellite which is still in orbit. Operated by the European Space Agency, it was the worlds largest civilian Earth observation satellite and it was launched on 1 March 2002 aboard an Ariane 5 from the Guyana Space Centre in Kourou, French Guiana, into a Sun synchronous polar orbit at an altitude of 790 km. It orbits the Earth in about 101 minutes, with a cycle of 35 days. After losing contact with the satellite on 8 April 2012, ESA formally announced the end of Envisats mission on 9 May 2012, Envisat cost €2.3 billion to develop and launch. The mission is due to be replaced by the Sentinel series of satellites, the first of these, Sentinel 1, has taken over the radar duties of Envisat since its launch in 2014. Envisat was launched as an Earth observation satellite and its objective was to service the continuity of European Remote-Sensing Satellite missions, providing additional observational parameters to improve environmental studies. Dimensions 26 m ×10 m ×5 m Mass 8,211 kg, including 319 kg of fuel and a 2,118 kg instrument payload. Power Solar array with a load of 3560 W. Envisat carries an array of nine Earth-observation instruments that gathered information about the Earth using a variety of measurement principles. A tenth instrument, DORIS, provided guidance and control, several of the instruments were advanced versions of instruments that were flown on the earlier ERS1 and ERS2 missions and other satellites. MERIS measures the reflectance of the Earth in the spectral range. MERIS was built at the Cannes Mandelieu Space Center, AATSR can measure the sea surface temperature in the visible and infrared spectra. Because of its wide angle lens it is possible to very precise measurements of atmospheric effects on how emissions from the Earths surface propagate. AATSR is the successor of ATSR1 and ATSR2, payloads of ERS1, AATSR can measure Earths surface temperature to a precision of 0.3 K, for climate research. Among the secondary objectives of AATSR is the observation of environmental parameters such as content, biomass. SCIAMACHY compares light coming from the sun to light reflected by the Earth, SCIAMACHY is an image spectrometer with the principal objective of mapping the concentration of trace gases and aerosols in the troposphere and stratosphere. Its high spectral resolution over a range of wavelengths can detect many trace gases even in tiny concentrations. The wavelengths captured also allow detection of aerosols and clouds. SCIAMACHY uses 3 different targeting modes, to the nadir, to the limbus, rA-2 is a dual-frequency Nadir pointing Radar operating in the Ku band and S bands, it is used to define ocean topography, map/monitor sea ice and measure land heights
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European Space Agency
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The European Space Agency is an intergovernmental organisation of 22 member states, dedicated to the exploration of space. Established in 1975 and headquartered in Paris, France, ESA has a staff of about 2,000. The main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching, after World War II, many European scientists left Western Europe in order to work with the United States. The meeting was attended by representatives from eight countries, including Harrie Massey. The Western European nations decided to have two different agencies, one concerned with developing a system, ELDO, and the precursor of the European Space Agency. The latter was established on 20 March 1964 by an agreement signed on 14 June 1962, from 1968 to 1972, ESRO launched seven research satellites. ESA in its current form was founded with the ESA Convention in 1975, ESA has 10 founding member states, Belgium, Denmark, France, Germany, Italy, the Netherlands, Spain, Sweden, Switzerland and the United Kingdom. These signed the ESA Convention in 1975 and deposited the instruments of ratification by 1980, during this interval the agency functioned in a de facto fashion. ESA launched its first major scientific mission in 1975, Cos-B, ESA joined NASA in the IUE, the worlds first high-orbit telescope, which was launched in 1978 and operated very successfully for 18 years. A number of successful Earth-orbit projects followed, and in 1986 ESA began Giotto, its first deep-space mission, to study the comets Halley and Grigg–Skjellerup. Hipparcos, a mission, was launched in 1989 and in the 1990s SOHO, Ulysses. Recent scientific missions in co-operation with NASA include the Cassini–Huygens space probe, as the successor of ELDO, ESA has also constructed rockets for scientific and commercial payloads. Ariane 1, launched in 1979, brought mostly commercial payloads into orbit from 1984 onward, the successor launch vehicle of Ariane 5, the Ariane 6 is already in the definition stage and is envisioned to enter service in the 2020s. The beginning of the new millennium saw ESA become, along with agencies like NASA, JAXA, ISRO, CSA and Roscosmos, one of the major participants in scientific space research. Although ESA had relied on co-operation with NASA in previous decades, especially the 1990s, changed circumstances led to decisions to rely more on itself, a 2011 press issue thus stated, Russia is ESAs first partner in its efforts to ensure long-term access to space. ESA maintains its scientific and research projects mainly for astronomy-space missions such as Corot, launched on 27 December 2006 and this is the reason space exploration is an integral part of overall space activities. It has always been so, and it will be more important in the future. ESA describes its work in two overlapping ways, For the general public the various fields of work are described as Activities, Member states participate to varying degrees in the mandatory and optional space programmes
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MetOp
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MetOp is a series of three polar orbiting meteorological satellites developed by the European Space Agency and operated by the European Organization for the Exploitation of Meteorological Satellites. The satellites form the space segment component of the overall EUMETSAT Polar System, the satellites carry a payload comprising 11 scientific instruments and two which support Search and Rescue services. In order to provide continuity between MetOp and NOAA Polar Operational Satellites, several instruments are carried on both fleets of satellites. MetOp-A, launched on October 19,2006, is Europes first polar orbiting satellite used for operational meteorology, subsequent satellites in the series are provisionally planned for launch at 5 year intervals to match the 5-year design life and provide continuity of services. However, in case of extended mission lifetime, a period of operations is expected as well as an extension to the overall programme. In 2021 a second generation of MetOp satellites will be deployed, called MetOp-SG, MetOp has been developed as a joint undertaking between the European Space Agency and European Organisation for the Exploitation of Meteorological Satellites. Data from MetOp are additionally used for chemistry and provision of long term data sets for climate records. The MetOp satellites have a construction, comprising a Service Module, a Payload Module. A SPOT heritage service module provides power, attitude and orbit control, thermal regulation and Tracking, Telemetry, an Envisat heritage payload module provides common command and control and power buses for the instruments along with science data acquisition and transmission. The main Command and Data Acquisition head is located at Svalbard Satellite Station in Norway, the high latitude of this station allows the global data stored in the solid state recorder of each satellite to be dumped via X-Band once per orbit. Each MetOp satellite produces approximately 2 GB of raw data per orbit, additionally, in order to improve timeliness of products, one of the operational satellites dumps the data from the descending part of the orbit over the McMurdo groundstation in Antarctica. HRPT is used to provide a direct readout local mission via a network of receivers on ground provided by cooperating organisations. Data from these stations is also transmitted to EUMETSAT and redistributed to provide a service with approximately 30 minutes latency. Due to radiation sensitivity of the HRPT hardware, the MetOp-A HRPT does not operate over the regions or South Atlantic Anomaly. Command and Control of MetOp is performed from the EPS Control Room at EUMETSAT Headquarters in Darmstadt, the control center is connected to the CDA in Svalbard which is used for S-Band ranging and doppler measurements, acquisition of real-time house keeping telemetry and uplink of telecommands. The CDA at Svalbard, located at approximately 78 degrees North, commands for routine operations are generally uplinked at each CDA contact, approximately 36 hours in advance of on-board execution. Orbit determination can also be performed using data from the GNSS Receiver for Atmospheric Sounding instrument, an independent back-up control center is also located at Instituto Nacional de Técnica Aeroespacial, near Madrid, Spain. The MetOp and NOAA satellites both carry a set of core instruments
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EUMETSAT
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These States fund the EUMETSAT programs and are the principal users of the systems. EUMETSAT also has 1 Cooperating State, cooperation agreements with Serbia have entered into force. The convention establishing EUMETSAT was opened for signature in 1983 and entered force on 19 June 1986. EUMETSATs primary objective is to establish, maintain and exploit European systems of meteorological satellites. The activities of EUMETSAT contribute to a meteorological satellite observing system coordinated with other space-faring nations. Satellite observations are an essential input to numerical weather prediction systems, of growing importance is the capacity of weather satellites to gather long-term measurements from space in support of climate change studies. EUMETSAT is not part of the European Union, but became a signatory to the International Charter on Space and Major Disasters in 2012, the national mandatory contributions of member states are proportional to their gross national income. However, the cooperating countries contribute only half of the fee they would pay for full membership, two generations of active Meteosat geostationary satellites, Meteosat First Generation and Meteosat Second Generation, provide images of the full Earth disc, and data for weather forecasts. More detail can be found on the Meteosat wiki, EUMETSAT Polar System Metop mission consists of three polar orbiting Metop satellites, to be flown successively for more than 14 years. The first, Metop-A, was launched by a Russian Soyuz-2. 1a rocket from Baikonur on October 19,2006, Metop-A was initially controlled by ESOC for the LEOP phase immediately following launch, with control handed over to EUMETSAT72 hours after lift-off. EUMETSATs first commands to the satellite were sent at 14,04 UTC on October 22,2006, the second EPS satellite, Metop-B, was launched from Baikonur on 17 September 2012, with the third, Metop-C, scheduled for launch in 2017. The satellites also ensure that the remote regions of the globe. The EPS programme is also the European half of a joint program with NOAA, NOAA has operated a continuous series of low earth orbiting meteorological satellite since April 1960. Many of the instruments on Metop are also operated on NOAA/POES satellites, Jason-2 was launched successfully from Vandenberg Air Force Base aboard a Delta-II rocket on 20 June 2008,7,46 UTC. Jason Satellites Jason-2 reliably delivers detailed oceanographic data vital to our understanding of weather forecasting, Jason-2 provides data on the decadal oscillations in large ocean basins, such as the Atlantic Ocean, mesoscale variability, and surface wind and wave conditions. Jason-2 measurements contribute to the European Centre for Medium-Range Weather Forecasts satellite data assimilation, helping improve global atmosphere, the next step is the Jason-3 Programme, which has been approved. News, Europe’s next weather satellite passes final checks Press release, MetOp to be launched in October
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Soil Moisture and Ocean Salinity
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Soil Moisture and Ocean Salinity, or SMOS, is a satellite which forms part of ESAs Living Planet Programme. It is intended to provide new insights into Earths water cycle, in addition, it is intended to provide improved weather forecasting and monitoring of snow and ice accumulation. The project was proposed in November 1998, in 2004 the project passed ESA-phase C/D and, after several delays, the first data from the MIRAS instrument was received on 20 November 2009. The SMOS programme cost is about €315 million and it is led by ESA but with significant input from French and Spanish interests. The satellite is part of ESAs Earth Explorer programme – eight spacecraft that will do innovative science in obtaining data on issues of pressing environmental concern. The first is already in orbit – a mission called GOCE, SMOS is the second Explorer to launch, and a third spacecraft, known as CryoSat-2, was launched on 8 April 2010. CryoSat will assess the state of the ice cover. The SMOS satellite was launched together with the Proba-2, a demonstration satellite. The goal of the SMOS mission is to surface soil moisture with an accuracy of 4%. This aspect is managed by the HYDROS project, project Aquarius will attempt to monitor sea surface salinity with an accuracy of 0.1 psu. Soil moisture is an important aspect of climate, and therefore forecasting, Ocean salinity is crucial to the understanding of the role of the ocean in climate through the global water cycle. Salinity in combination with temperature determine ocean circulation by defining its density, additionally, ocean salinity is one of the variables that regulate CO2 uptake and release and therefore has an effect on the oceanic carbon cycle. Information from SMOS is expected to help improve short and medium-term weather forecasts, in addition, climate models should benefit from having a more precise picture of the scale and speed of movement of water in the different components of the hydrological cycle. The SMOS satellite carries a new type of instrument called Microwave Imaging Radiometer with Aperture Synthesis, some eight metres across, it has the look of helicopter rotor blades, the instrument creates images of radiation emitted in the microwave L-band. MIRAS will measure changes in the wetness of the land and in the salinity of seawater by observing variations in the microwave emission coming up off the surface of the planet. The CNES Satellite Operations Ground Segment will operate the spacecraft with telecommunications from ESAs S-band facility located in Kiruna, the Data Processing Ground Segment will process SMOS data through the X-band. Higher level processing of information will be done by scientists globally
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DubaiSat-1
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The earth observation satellite was designed and developed by Satrec Initiative, with participation from EIAST engineers. DubaiSat-1 observes the earth at a Low Earth orbit and generates high-resolution optical images at 2. 5m in panchromatic, DubaiSat-1 images are also useful for promoting geosciences and remote sensing research in the region, and for supporting different scientific disciplines in private and academic sectors. For example, DubaiSat-1 images have been used, to progress on the Dubai World Megaproject, Palm Islands. The United Nations also used DubaiSat-1 images to monitor relief efforts following the 2011 Tōhoku earthquake, the satellite accommodates two main payloads. The primary payload is the Dubai Medium Aperture Camera, and the secondary and experimental payload, the DMAC system is pushbroom imaging system with one panchromatic and four multi-spectral imaging channels. It also consists of an Electro-Optical Subsystem and the Payload Management Subsystem, the Electro-Optical Subsystem has a telescope, a focal plane assembly, and a Signal Processing Module. The Payload Management Subsystem consists of the Thermal & Power Module, the Space Radiation Monitor, the secondary and experimental payload, is capable of measuring the total ionizing dose from the charged particles at the orbits of satellites. The instrument utilizes four p-type Metal-Oxide-Semiconductor Field Effects Transistors and these devices measure the current-voltage characteristics of the satellite. Subsequent analysis will allow measurements of the amount of cumulative ionizing dose, DubaiSat-1 has a hexagonal body with three deployable solar panels. The frame includes spacecraft adaptors, six longerons, rails, a ring that provides rigidity and stability of the satellites camera, inner rods. Three spacecraft adaptors connect with shear brackets and mechanically couple the satellite and separation adaptor of the launch vehicle, each one of the spacecraft adaptors has separation sensors to monitor the separation condition between the satellite and the launch vehicle. The umbilical connector attaches on the surface of the bottom deck with its mounting support bracket. EIASTs Ground Station is located in Dubai, and is the ground system supporting the DubaiSat-1 mission. The RF equipment, including transmitting and receiving antennas, are used to communicate with the satellite, the Antenna & RF subsystem receives X-band RF signals and performs RF processing. It also produces a demodulated and bit-synchronized data stream from X-band signals, from the Mission Control Station, EIAST staff plan and operate the entire space mission, including the configuration and scheduling of resources for both space and ground elements. It also monitors and commands the satellite, the third component of the ground system is the Image Receiving and Processing Station. The IRPS receives and processes the X-band downlink data in real-time, the IRPS is located at EIAST’s ground station in Dubai, UAE. It has an interface with the main mission control station and it generates schedule requests which includes imaging
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DubaiSat-2
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EIAST also intends to continue manpower training for the UAE’s space program. 16 UAE engineers have been working on the design, development, the space segment consists of a spacecraft bus and an electro-optical payload. The electro-optical payload is a camera with Time Delay Integration sensors. DubaiSat-2 is designed for an orbit of 600 km, with a spatial resolution of 1m PAN and 4m Multispectral. The modules in the use two CAN Bus networks to communicate with each other and it has the capacity to store approximately 17,000 km2 of image data. It also includes an experimental system for orbit correction and maintenance. The satellite’s expected lifetime is at least five years, the mechanical bus consists of 2 decks and an upper sun shield to protect the cold propellants from solar and Earth radiation. The electronics are distributed on the decks and on the side panels, four solar panels are attached to the sides of the satellite. Longerons and rails make up the bus structure frame, on the top, carbon-fiber-reinforced polymer struts hold the Sun shield at the baffle of the High Resolution Advanced Imaging System. The High-Resolution Imaging System is attached to the bus at the internal deck, the mechanical configuration of the satellite is less than 2000 mm in height and less than 1500 mm in diameter. The total mass of the satellite is less than 300 kg, the power system supplies and controls the required voltage levels and current essential for satellite operation during its mission. The power system uses a rechargeable Li-ion battery to power for the satellite’s payload. The system is divided into two stages, first is the stage and the second is the discharging stage. The charging stage is made of a power generator and power regulator. DubaiSat-2 generates more than 450W of power using four solar panels, each solar panel contains 6 arrays and each array consists of 26 cells. The solar panels charge the batteries, the battery charging process is handled and regulated by the Battery Charging Regulators modules. DubaiSat-2 has three battery charging regulators with hot redundancy configuration which seamlessly take over if the battery charging regulator fails. The spacecraft can function normally with two battery charging regulators
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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
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Satellite imagery
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Satellite imagery consists of images of Earth or other planets collected by satellites. Imaging satellites are operated by governments and businesses around the world, Satellite imaging companies sell images under licence. Images are licensed to governments and businesses such as Apple Maps, the first images from space were taken on sub-orbital flights. The U. S-launched V-2 flight on October 24,1946 took one image every 1.5 seconds. With an apogee of 65 miles, these photos were from five times higher than the previous record, the first satellite photographs of Earth were made on August 14,1959 by the U. S. The first satellite photographs of the Moon might have made on October 6,1959 by the Soviet satellite Luna 3. The Blue Marble photograph was taken from space in 1972, and has very popular in the media. Also in 1972 the United States started the Landsat program, the largest program for acquisition of imagery of Earth from space, Landsat Data Continuity Mission, the most recent Landsat satellite, was launched on 11 February 2013. In 1977, the first real time satellite imagery was acquired by the United Statess KH-11 satellite system, all satellite images produced by NASA are published by NASA Earth Observatory and are freely available to the public. Several other countries have satellite imaging programs, and a collaborative European effort launched the ERS, there are also private companies that provide commercial satellite imagery. Images can be in visible colours and in other spectra, there are also elevation maps, usually made by radar images. Interpretation and analysis of imagery is conducted using specialized remote sensing applications. There are four types of resolution when discussing satellite imagery in remote sensing, spatial, spectral, temporal, and radiometric. GSD is a term containing the optical and systemic noise sources and is useful for comparing how well one sensor can see an object on the ground within a single pixel. For example, the GSD of Landsat is ~30m, which means the smallest unit that maps to a single pixel within an image is ~30m x 30m, the latest commercial satellite has a GSD of 0.41 m. This compares to a 0.3 m resolution obtained by some early military film based Reconnaissance satellite such as Corona, the resolution of satellite images varies depending on the instrument used and the altitude of the satellites orbit. For example, the Landsat archive offers repeated imagery at 30 meter resolution for the planet, Landsat 7 has an average return period of 16 days. For many smaller areas, images with resolution as high as 41 cm can be available, Satellite imagery is sometimes supplemented with aerial photography, which has higher resolution, but is more expensive per square meter
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Polar orbit
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A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the equator, a satellite in a polar orbit will pass over the equator at a different longitude on each of its orbits. Polar orbits are used for earth-mapping, earth observation, capturing the earth as time passes from one point, reconnaissance satellites. The Iridium satellite constellation also uses a polar orbit to provide telecommunications services, the disadvantage to this orbit is that no one spot on the Earths surface can be sensed continuously from a satellite in a polar orbit. Near-polar orbiting satellites commonly choose a Sun-synchronous orbit, meaning each successive orbital pass occurs at the same local time of day. To keep the local time on a given pass, the time period of the orbit must be kept as short as possible. However, very low orbits of a few hundred kilometers rapidly decay due to drag from the atmosphere, commonly used altitudes are between 700 km and 800 km, producing an orbital period of about 100 minutes. The half-orbit on the Sun side then takes only 50 minutes, list of orbits Molniya orbit Vandenberg Air Force Base, a major United States launch location for polar orbits Orbital Mechanics
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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
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Sun-synchronous orbit
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A Sun-synchronous orbit is a geocentric orbit that combines altitude and inclination in such a way that the satellite passes over any given point of the planets surface at the same local solar time. Such an orbit can place a satellite in constant sunlight and is useful for imaging, spy, more technically, it is an orbit arranged in such a way that it precesses once a year. The surface illumination angle will be nearly the same time that the satellite is overhead. This consistent lighting is a characteristic for satellites that image the Earths surface in visible or infrared wavelengths. For example, a satellite in sun-synchronous orbit might ascend across the twelve times a day each time at approximately 15,00 mean local time. This is achieved by having the orbital plane precess approximately one degree each day with respect to the celestial sphere, eastward. Typical sun-synchronous orbits are about 600–800 km in altitude, with periods in the 96–100 minute range, riding the terminator is useful for active radar satellites as the satellites solar panels can always see the Sun, without being shadowed by the Earth. The dawn/dusk orbit has been used for solar observing scientific satellites such as Yohkoh, TRACE, Hinode and PROBA2, Sun-synchronous orbits can happen around other oblate planets, such as Mars. A satellite around the almost spherical Venus, for example, will need an outside push to be in a sun-synchronous orbit.696 deg. Note that according to this approximation cos i equals −1 when the semi-major axis equals 12352 km, the period can be in the range from 88 minutes for a very low orbit to 3.8 hours. If one wants a satellite to fly over some given spot on Earth every day at the same hour, it can do between 7 and 16 orbits per day, as shown in the following table. When one says that a Sun-synchronous orbit goes over a spot on the earth at the local time each time. The Sun will not be in exactly the same position in the sky during the course of the year, very often a frozen orbit is therefore selected that is slightly higher over the Southern hemisphere than over the Northern hemisphere. ERS-1, ERS-2 and Envisat of European Space Agency as well as the MetOp spacecraft of EUMETSAT are all operated in Sun-synchronous, orbital perturbation analysis Analemma Geosynchronous orbit Geostationary orbit List of orbits Polar orbit World Geodetic System Sandwell, David T. The Gravity Field of the Earth - Part 1 Sun-Synchronous Orbit dictionary entry, centennial of Flight Commission NASA Q&A Boain, Ronald J. The A-B-Cs of Sun Synchronous Orbit Design, List of satellites in Sun-synchronous orbit
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Geostationary orbit
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A geostationary orbit, geostationary Earth orbit or geosynchronous equatorial orbit is a circular orbit 35,786 kilometres above the Earths equator and following the direction of the Earths rotation. An object in such an orbit has a period equal to the Earths rotational period and thus appears motionless, at a fixed position in the sky. Using this characteristic, ocean color satellites with visible and near-infrared light sensors can also be operated in geostationary orbit in order to monitor sensitive changes of ocean environments, the notion of a geostationary space station equipped with radio communication was published in 1928 by Herman Potočnik. The first appearance of an orbit in popular literature was in the first Venus Equilateral story by George O. Smith. Clarke acknowledged the connection in his introduction to The Complete Venus Equilateral, the orbit, which Clarke first described as useful for broadcast and relay communications satellites, is sometimes called the Clarke Orbit. Similarly, the Clarke Belt is the part of space about 35,786 km above sea level, in the plane of the equator, the Clarke Orbit is about 265,000 km in circumference. Most commercial communications satellites, broadcast satellites and SBAS satellites operate in geostationary orbits, a geostationary transfer orbit is used to move a satellite from low Earth orbit into a geostationary orbit. The first satellite placed into an orbit was the Syncom-3. A worldwide network of operational geostationary meteorological satellites is used to provide visible and infrared images of Earths surface, a geostationary orbit can only be achieved at an altitude very close to 35,786 km and directly above the equator. This equates to a velocity of 3.07 km/s and an orbital period of 1,436 minutes. This ensures that the satellite will match the Earths rotational period and has a footprint on the ground. All geostationary satellites have to be located on this ring. 85° per year, to correct for this orbital perturbation, regular orbital stationkeeping manoeuvres are necessary, amounting to a delta-v of approximately 50 m/s per year. A second effect to be taken into account is the longitude drift, there are two stable and two unstable equilibrium points. Any geostationary object placed between the points would be slowly accelerated towards the stable equilibrium position, causing a periodic longitude variation. The correction of this effect requires station-keeping maneuvers with a maximal delta-v of about 2 m/s per year, solar wind and radiation pressure also exert small forces on satellites, over time, these cause them to slowly drift away from their prescribed orbits. In the absence of servicing missions from the Earth or a renewable propulsion method, hall-effect thrusters, which are currently in use, have the potential to prolong the service life of a satellite by providing high-efficiency electric propulsion. This delay presents problems for latency-sensitive applications such as voice communication, geostationary satellites are directly overhead at the equator and become lower in the sky the further north or south one travels. At latitudes above about 81°, geostationary satellites are below the horizon, because of this, some Russian communication satellites have used elliptical Molniya and Tundra orbits, which have excellent visibility at high latitudes
29.
Weather satellite
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The weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting, covering the entire Earth asynchronously, or geostationary, Meteorological satellites see more than clouds and cloud systems. City lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of currents, energy flows. Other types of information are collected using weather satellites. Weather satellite images helped in monitoring the volcanic ash cloud from Mount St. Helens, smoke from fires in the western United States such as Colorado and Utah have also been monitored. Other environmental satellites can detect changes in the Earths vegetation, sea state, ocean color, El Niño and its effects on weather are monitored daily from satellite images. The Antarctic ozone hole is mapped from weather satellite data, collectively, weather satellites flown by the U. S. Europe, India, China, Russia, and Japan provide nearly continuous observations for a global weather watch. As early as 1946, the idea of cameras in orbit to observe the weather was being developed and this was due to sparse data observation coverage and the expense of using cloud cameras on rockets. By 1958, the prototypes for TIROS and Vanguard were created. The first weather satellite, Vanguard 2, was launched on February 17,1959 and it was designed to measure cloud cover and resistance, but a poor axis of rotation and its elliptical orbit kept it from collecting a notable amount of useful data. The Explorer VI and VII satellites also contained weather-related experiments, the first weather satellite to be considered a success was TIROS-1, launched by NASA on April 1,1960. TIROS operated for 78 days and proved to be more successful than Vanguard 2. TIROS paved the way for the Nimbus program, whose technology and findings are the heritage of most of the Earth-observing satellites NASA, the ESSA and NOAA polar orbiting satellites followed suit from the late 1960s onward. Geostationary satellites followed, beginning with the ATS and SMS series in the late 1960s and early 1970s, observation is typically made via different channels of the electromagnetic spectrum, in particular, the visible and infrared portions. Some of these channels include Visible and Near Infrared,0.6 μm –1.6 μm – For recording cloud cover during the day Infrared,3.9 μm –7.3 μm,8.7 μm, –13. Even wind can be determined by cloud patterns, alignments and movement from successive photos, Infrared pictures depict ocean eddies or vortices and map currents such as the Gulf Stream which are valuable to the shipping industry. Fishermen and farmers are interested in knowing land and water temperatures to protect their crops against frost or increase their catch from the sea, even El Niño phenomena can be spotted. Using color-digitized techniques, the gray shaded thermal images can be converted to color for easier identification of desired information, each meteorological satellite is designed to use one of two different classes of orbit, geostationary and polar orbiting
30.
Konstantin Tsiolkovsky
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Konstantin Eduardovich Tsiolkovsky was a Russian and Soviet rocket scientist and pioneer of the astronautic theory. Along with the French Robert Esnault-Pelterie, the German Hermann Oberth and his works later inspired leading Soviet rocket engineers such as Sergei Korolev and Valentin Glushko and contributed to the success of the Soviet space program. Tsiolkovsky spent most of his life in a log house on the outskirts of Kaluga, a recluse by nature, he appeared strange and bizarre to his fellow townsfolk. He was born in Izhevskoye, in the Russian Empire, to a middle-class family and his father, Edward Tsiolkovsky, was a Polish-born Russian Orthodox, his mother, Maria Ivanovna Yumasheva belonged to Russian nobility of Volga Tatar origin. His father was successively a forester, teacher, and minor government official, at the age of 10, Konstantin caught scarlet fever and became hard of hearing. When he was 13, his mother died and he was not admitted to elementary schools because of his hearing problem, so he was self-taught. As a reclusive home-schooled child, he passed much of his time by reading books, as a teenager, he began to contemplate the possibility of space travel. After falling behind in his studies, Tsiolkovsky spent three years attending a Moscow library where Russian cosmism proponent Nikolai Fyodorov worked and he later came to believe that colonizing space would lead to the perfection of the human race, with immortality and a carefree existence. Additionally, inspired by the fiction of Jules Verne, Tsiolkovsky theorized many aspects of space travel and he is considered the father of spaceflight and the first person to conceive the space elevator, becoming inspired in 1895 by the newly constructed Eiffel Tower in Paris. Afterwards, Tsiolkovsky passed the exam and went to work at a school in Borovsk near Moscow. He also met and married his wife Varvara Sokolovaya during this time, despite being stuck in Kaluga, a small town far from major learning centers, Tsiolkovsky managed to make scientific discoveries on his own. The first two decades of the 20th century were marred by personal tragedy, Tsiolkovskys son Ignaty committed suicide in 1902, and in 1908 many of his accumulated papers were lost in a flood. In 1911, his daughter Lyubov was arrested for engaging in revolutionary activities and this section has recently been partly machine translated from the Russian article. Please supply an improved translation if possible, Tsiolkovsky stated that he developed the theory of rocketry only as a supplement to philosophical research on the subject. He wrote more than 400 works including approximately 90 published pieces on space travel, Tsiolkovskys first scientific study dates back to 1880–1881. Undaunted, he pressed ahead with his work, The Mechanics of the Animal Organism. It received favorable feedback, and Tsiolkovsky was made a member of the Society, in 1892, he was transferred to a new teaching post in Kaluga where he continued to experiment. Tsiolkovsky developed the first aerodynamics laboratory in Russia in his apartment, in 1897, he built the first Russian wind tunnel with an open test section and developed a method of experimentation using it
31.
Satellite temperature measurements
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The temperature of the atmosphere at various altitudes as well as sea and land surface temperatures can be inferred from satellite measurements. Wildfires, volcanos, and industrial hot spots can also be found via thermal imaging from weather satellites, weather satellites do not measure temperature directly. They measure radiances in various wavelength bands, measurements of infrared radiation pertaining to sea surface temperature have been collected since 1967. Satellite datasets show that over the past four decades the troposphere has warmed, both of these trends are consistent with the influence of increasing atmospheric concentrations of greenhouse gases. They measure radiances in various bands, which must then be mathematically inverted to obtain indirect inferences of temperature. The resulting temperature profiles depend on details of the methods that are used to obtain temperatures from radiances, as a result, different groups that have analyzed the satellite data have produced differing temperature datasets. Among these are the UAH dataset prepared at the University of Alabama in Huntsville, the satellite time series is not homogeneous. It is constructed from a series of satellites with similar but not identical sensors, the sensors also deteriorate over time, and corrections are necessary for orbital drift and decay. Particularly large differences between reconstructed temperature series occur at the few times there is little temporal overlap between successive satellites, making intercalibration difficult. Satellites may also be used to surface temperatures in cloud-free conditions. Weather satellites have been available to infer sea surface temperature information since 1967, since 1982, satellites have been increasingly utilized to measure SST and have allowed its spatial and temporal variation to be viewed more fully. For example, changes in SST monitored via satellite have been used to document the progression of the El Niño-Southern Oscillation since the 1970s, over the land the retrieval of temperature from radiances is harder, because of the inhomogeneities in the surface. Studies have been conducted on the heat island effect via satellite imagery. Use of advanced very high resolution infrared satellite imagery can be used, in the absence of cloudiness, along Track Scanning Radiometers aboard weather satellites are able to detect wildfires, which show up at night as pixels with a greater temperature than 308 K. The Moderate-Resolution Imaging Spectroradiometer aboard the Terra satellite can detect thermal hot spots associated with wildfires, volcanoes, the intensity is proportional to the temperature of broad vertical layers of the atmosphere, as demonstrated by theory and direct comparisons with atmospheric temperatures from radiosonde profiles. Upwelling radiance is measured at different frequencies, these different frequency bands sample a different weighted range of the atmosphere, channel 2 or TMT is broadly representative of the troposphere, albeit with a significant overlap with the lower stratosphere. However, this noise, increases inter-satellite calibration biases and enhances surface contamination. The 2LT product has gone through numerous versions as various corrections have been applied, the T4 or TLS channel in representative of the temperature in the lower stratosphere with a peak weighting function at around 17 km above the earth surface
32.
GOES 8
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It was launched in 1994, and operated until 2004 when it was retired and boosted to a graveyard orbit. At launch, the satellite had a mass of 2,105 kilograms, and it was built by Space Systems/Loral, based on the LS-1300 satellite bus, and was the first of five GOES-I series satellites to be launched. GOES8 was also featured in the 1996 film Twister, GOES-I was launched aboard a Martin Marietta Atlas I rocket, flying from Launch Complex 36B at the Cape Canaveral Air Force Station. The launch occurred at 06,04 GMT on 13 April 1994 and it was then raised into geostationary orbit by means of an R-4D-11 apogee motor. During the third burn, a malfunction of the controlling the attitude control system caused several manoeuvring thrusters to fire. This resulted in the burn being aborted, GOES8 was eventually raised to the correct orbit, and positioned at a longitude of 75° West. Following on-orbit testing, it was activated as the GOES-EAST satellite, allowing GOES7, GOES8 suffered from a design fault with the motor windings in its imager and sounder, with one of two sets failing within a few years of it becoming operational. If the other set had failed, it would have made the system inoperable and this fault also occurred on the GOES9 satellite, which was launched in 1995. It was corrected before GOES10 was launched, in 1997, one of its momentum wheels failed, however unlike with GOES9, the other wheel was not affected, and the satellite was able to continue operations. GOES8 was retired from GOES-EAST operations in 2003, when it was replaced by GOES12, following this it remained in storage for a year as a backup, before being boosted to a graveyard orbit between 4 and 5 May 2004. 1994 in spaceflight List of GOES satellites
33.
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
34.
Weather
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Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the lowest level of the atmosphere, Weather refers to day-to-day temperature and precipitation activity, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, weather is understood to mean the weather of Earth. Weather is driven by air pressure, temperature and moisture differences between one place and another and these differences can occur due to the suns angle at any particular spot, which varies with latitude. The strong temperature contrast between polar and tropical air gives rise to the largest scale atmospheric circulations, the Hadley Cell, the Ferrel Cell, the Polar Cell, Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow. Because the Earths axis is tilted relative to its orbital plane, on Earths surface, temperatures usually range ±40 °C annually. Over thousands of years, changes in Earths orbit can affect the amount and distribution of energy received by the Earth, thus influencing long-term climate. Surface temperature differences in turn cause pressure differences, higher altitudes are cooler than lower altitudes as most atmospheric heating is due to contact with the Earths surface while radiative losses to space are mostly constant. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The Earths weather system is a system, as a result. Human attempts to control the weather have occurred throughout history, and there is evidence that human activities such as agriculture, studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the Solar System, Jupiters Great Red Spot, is a storm known to have existed for at least 300 years. However, weather is not limited to planetary bodies, a stars corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind, on Earth, the common weather phenomena include wind, cloud, rain, snow, fog and dust storms. Less common events include natural disasters such as tornadoes, hurricanes, typhoons, almost all familiar weather phenomena occur in the troposphere. Weather does occur in the stratosphere and can affect weather lower down in the troposphere, Weather occurs primarily due to air pressure, temperature and moisture differences between one place to another. These differences can occur due to the sun angle at any particular spot, in other words, the farther from the tropics one lies, the lower the sun angle is, which causes those locations to be cooler due the spread of the sunlight over a greater surface. The strong temperature contrast between polar and tropical air gives rise to the large scale atmospheric circulation cells and the jet stream, Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow
35.
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
36.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
37.
Fire
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Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition, at a certain point in the combustion reaction, called the ignition point, flames are produced. The flame is the portion of the fire. Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen, if hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame, Fire in its most common form can result in conflagration, which has the potential to cause physical damage through burning. Fire is an important process that affects ecological systems around the globe, the positive effects of fire include stimulating growth and maintaining various ecological systems. The negative effects of fire hazard to life and property, atmospheric pollution. If fire removes protective vegetation, heavy rainfall may lead to an increase in soil erosion by water and this is commonly called the fire tetrahedron. Fire cannot exist without all of elements in place and in the right proportions. For example, a liquid will start burning only if the fuel. Some fuel-oxygen mixes may require a catalyst, a substance that is not consumed, when added, in any chemical reaction during combustion, but which enables the reactants to combust more readily. Without gravity, a fire rapidly surrounds itself with its own products and non-oxidizing gases from the air. Because of this, the risk of fire in a spacecraft is small when it is coasting in inertial flight, of course, this does not apply if oxygen is supplied to the fire by some process other than thermal convection. Fire can be extinguished by removing any one of the elements of the fire tetrahedron, consider a natural gas flame, such as from a stovetop burner. In contrast, fire is intensified by increasing the rate of combustion. In many cases, such as the burning of organic matter, for wood, or the incomplete combustion of gas. This light has a continuous spectrum, complete combustion of gas has a dim blue color due to the emission of single-wavelength radiation from various electron transitions in the excited molecules formed in the flame. Usually oxygen is involved, but hydrogen burning in chlorine produces a flame
38.
Pollution
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Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution, Air pollution has always accompanied civilizations. Pollution started from prehistoric times when man created the first fires, metal forging appears to be a key turning point in the creation of significant air pollution levels outside the home. The burning of coal and wood, and the presence of horses in concentrated areas made the cities the cesspools of pollution. The Industrial Revolution brought an infusion of untreated chemicals and wastes into local streams that served as the water supply, king Edward I of England banned the burning of sea-coal by proclamation in London in 1272, after its smoke became a problem. But the fuel was so common in England that this earliest of names for it was acquired because it could be carted away from some shores by the wheelbarrow and it was the industrial revolution that gave birth to environmental pollution as we know it today. London also recorded one of the extreme cases of water quality problems with the Great Stink on the Thames of 1858. Pollution issues escalated as population growth far exceeded view ability of neighborhoods to handle their waste problem, reformers began to demand sewer systems, and clean water. In 1870, the conditions in Berlin were among the worst in Europe. There were no toilets in the streets or squares. Visitors, especially women, often became desperate when nature called, in the public buildings the sanitary facilities were unbelievably primitive. As a metropolis, Berlin did not emerge from a state of barbarism into civilization until after 1870. Chicago and Cincinnati were the first two American cities to enact laws ensuring cleaner air in 1881, as historian Martin Melosi notes, The generation that first saw automobiles replacing the horses saw cars as miracles of cleanliness. By the 1940s, however, automobile-caused smog was an issue in Los Angeles. Other cities followed around the country early in the 20th century. Extreme smog events were experienced by the cities of Los Angeles and Donora, Pennsylvania in the late 1940s, Air pollution would continue to be a problem in England, especially later during the industrial revolution, and extending into the recent past with the Great Smog of 1952. Awareness of atmospheric pollution spread widely after World War II, with fears triggered by reports of fallout from atomic warfare. Then a non-nuclear event, The Great Smog of 1952 in London and this prompted some of the first major modern environmental legislation, The Clean Air Act of 1956
39.
Aurora
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An aurora, sometimes referred to as a polar lights or northern lights, is a natural light display in the sky, predominantly seen in the high latitude regions. The resulting ionization and excitation of atmospheric constituents emits light of varying colour, the form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere, proton auroras are usually observed at lower latitudes. A region that currently displays an aurora is called the auroral oval, early evidence for a geomagnetic connection comes from the statistics of auroral observations. Elias Loomis, and later Hermann Fritz and S. Tromholt in more detail, day-to-day positions of the auroral ovals are posted on the internet. In northern latitudes, the effect is known as the Aurora Borealis or the Northern Lights, the former term was coined by Galileo in 1619, from the Roman goddess of the dawn and the Greek name for the north wind. The Aurora Australis is visible from southern latitudes in Antarctica, Chile, Argentina, New Zealand. A geomagnetic storm causes the auroral ovals to expand, and bring the aurora to lower latitudes and it was hardly ever seen near the geographic pole, which is about 2000 km away from the magnetic pole. The aurora can be seen best at this time, which is called magnetic midnight, Auroras also occur poleward of the auroral zone as either diffuse patches or arcs, which can be sub-visual. Auroras are occasionally seen in latitudes below the zone, when a geomagnetic storm temporarily enlarges the auroral oval. Large geomagnetic storms are most common during the peak of the sunspot cycle or during the three years after the peak. An aurora may appear overhead as a corona of rays, radiating from a distant and apparent central location, an electron spirals about a field line at an angle that is determined by its velocity vectors, parallel and perpendicular, respectively, to the local geomagnetic field vector B. This angle is known as the “pitch angle” of the particle, the distance, or radius, of the electron from the field line at any time is known as its Larmor radius. The pitch angle increases as the travels to a region of greater field strength nearer to the atmosphere. Thus it is possible for particles to return, or mirror. Other particles that do not mirror enter the atmosphere and contribute to the display over a range of altitudes. Other types of auroras have been observed from space, e. g. poleward arcs stretching sunward across the cap, the related theta aurora. These are relatively infrequent and poorly understood, there are other interesting effects such as flickering aurora, black aurora and sub-visual red arcs
40.
Snow
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Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime. As snow accumulates into a snowpack, it may blow into drifts, over time, accumulated snow metamorphoses, by sintering, sublimation and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form, otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging groundwater. Major snow-prone areas include the regions, the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture. In the Southern Hemisphere, snow is confined primarily to mountainous areas, Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Snow develops in clouds that themselves are part of a weather system. The physics of snow crystal development in clouds results from a set of variables that include moisture content. The resulting shapes of the falling and fallen crystals can be classified into a number of shapes and combinations. Occasionally, some plate-like, dendritic and stellar-shaped snowflakes can form under clear sky with a cold temperature inversion present. Two additional and locally productive sources of snow are lake-effect storms and elevation effects, miid-latitude cyclones are low pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards. During a hemispheres fall, winter, and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall, in the Northern Hemisphere, the northern side of the low pressure area produces the most snow. For the southern mid-latitudes, the side of a cyclone that produces the most snow is the southern side, a cold front, the leading edge of a cooler mass of air, can produce frontal snowsqualls—an intense frontal convective line, when temperature is near freezing at the surface. The strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall generally lasts less than 30 minutes at any point along its path, in cases where there is a large amount of vertical growth and mixing the squall may develop embedded cumulonimbus clouds resulting in lightning and thunder which is dubbed thundersnow. A warm front can produce snow for a period, as warm, moist air overrides below-freezing air, often, snow transitions to rain in the warm sector behind the front. The same effect occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the air mass is uplifted by the orographic influence of higher elevations on the downwind shores
41.
Ice
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Ice is water frozen into a solid state. Depending on the presence of such as particles of soil or bubbles of air. In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far as away the Oort cloud objects, beyond the Solar System, it occurs as interstellar ice. It falls as snowflakes and hail or occurs as frost, icicles or ice spikes, Ice molecules can exhibit up to sixteen different phases that depend on temperature and pressure. When water is cooled rapidly, up to three different types of ice can form depending on the history of its pressure and temperature. When cooled slowly correlated proton tunneling occurs below 20 K giving rise to macroscopic quantum phenomena, virtually all the ice on Earths surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice Ih with minute traces of cubic ice denoted as ice Ic. The most common phase transition to ice Ih occurs when water is cooled below 0°C at standard atmospheric pressure. It may also be deposited directly by water vapor, as happens in the formation of frost, the transition from ice to water is melting and from ice directly to water vapor is sublimation. Ice is used in a variety of ways, including cooling, winter sports, as a naturally occurring crystalline inorganic solid with an ordered structure, ice is considered a mineral. It possesses a regular crystalline structure based on the molecule of water, an unusual property of ice frozen at atmospheric pressure is that the solid is approximately 8. 3% less dense than liquid water. The density of ice is 0.9167 g/cm3 at 0 °C, liquid water is densest, essentially 1.00 g/cm³, at 4 °C and becomes less dense as the water molecules begin to form the hexagonal crystals of ice as the freezing point is reached. This is due to hydrogen bonding dominating the intermolecular forces, which results in a packing of molecules less compact in the solid, density of ice increases slightly with decreasing temperature and has a value of 0.9340 g/cm³ at −180 °C. When water freezes, it increases in volume and it is also a common cause of the flooding of houses when water pipes burst due to the pressure of expanding water when it freezes. The result of this process is that ice floats on liquid water, sufficiently thin ice sheets allow light to pass through while protecting the underside from short-term weather extremes such as wind chill. This creates an environment for bacterial and algal colonies. When ice melts, it absorbs as much energy as it would take to heat an equivalent mass of water by 80 °C, during the melting process, the temperature remains constant at 0 °C. While melting, any energy added breaks the bonds between ice molecules. Energy becomes available to increase the thermal energy only after enough hydrogen bonds are broken that the ice can be considered liquid water, the amount of energy consumed in breaking hydrogen bonds in the transition from ice to water is known as the heat of fusion
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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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Energy
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In physics, energy is the property that must be transferred to an object in order to perform work on – or to heat – the object, and can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton. Mass and energy are closely related, for example, with a sensitive enough scale, one could measure an increase in mass after heating an object. Living organisms require available energy to stay alive, such as the humans get from food. Civilisation gets the energy it needs from energy resources such as fuels, nuclear fuel. The processes of Earths climate and ecosystem are driven by the radiant energy Earth receives from the sun, the total energy of a system can be subdivided and classified in various ways. It may also be convenient to distinguish gravitational energy, thermal energy, several types of energy, electric energy. Many of these overlap, for instance, thermal energy usually consists partly of kinetic. Some types of energy are a mix of both potential and kinetic energy. An example is energy which is the sum of kinetic. Whenever physical scientists discover that a phenomenon appears to violate the law of energy conservation. Heat and work are special cases in that they are not properties of systems, in general we cannot measure how much heat or work are present in an object, but rather only how much energy is transferred among objects in certain ways during the occurrence of a given process. Heat and work are measured as positive or negative depending on which side of the transfer we view them from, the distinctions between different kinds of energy is not always clear-cut. In contrast to the definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness. The modern analog of this property, kinetic energy, differs from vis viva only by a factor of two, in 1807, Thomas Young was possibly the first to use the term energy instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described kinetic energy in 1829 in its modern sense, the law of conservation of energy was also first postulated in the early 19th century, and applies to any isolated system. It was argued for years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat and these developments led to the theory of conservation of energy, formalized largely by William Thomson as the field of thermodynamics
44.
Mount St. Helens
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Mount St. Helens or Louwala-Clough is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is 96 miles south of Seattle, Washington, and 50 miles northeast of Portland, Mount St. Helens takes its English name from the British diplomat Lord St Helens, a friend of explorer George Vancouver who made a survey of the area in the late 18th century. The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc and this volcano is well known for its ash explosions and pyroclastic flows. Mount St. Helens is most notorious for its major 1980 eruption, fifty-seven people were killed,250 homes,47 bridges,15 miles of railways, and 185 miles of highway were destroyed. The debris avalanche was up to 0.7 cubic miles in volume, the Mount St. Helens National Volcanic Monument was created to preserve the volcano and allow for its aftermath to be scientifically studied. As with most other volcanoes in the Cascade Range, Mount St. Helens is a large eruptive cone consisting of lava rock interlayered with ash, pumice, the mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the domes formed the previous summit. Both were destroyed in the 1980 eruption, Mount St. Helens is 34 miles west of Mount Adams, in the western part of the Cascade Range. These sister and brother volcanic mountains are approximately 50 miles from Mount Rainier, Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles southeast of Mount St. Helens. Mount St. Helens is geologically young compared with the other major Cascade volcanoes and it formed only within the past 40,000 years, and the pre-1980 summit cone began rising about 2,200 years ago. The volcano is considered the most active in the Cascades within the Holocene epoch, prior to the 1980 eruption, Mount St. Helens was the fifth-highest peak in Washington. It stood out prominently from surrounding hills because of the symmetry and extensive snow and ice cover of the summit cone. The peak rose more than 5,000 feet above its base, the mountain is 6 miles across at its base, which is at an elevation of 4,400 feet on the northeastern side and 4,000 feet elsewhere. At the pre-eruption tree line, the width of the cone was 4 miles. Streams that originate on the volcano enter three main systems, the Toutle River on the north and northwest, the Kalama River on the west. The streams are fed by abundant rain and snow, the average annual rainfall is 140 inches, and the snow pack on the mountains upper slopes can reach 16 feet. The Lewis River is impounded by three dams for power generation. The southern and eastern sides of the drain into an upstream impoundment, the Swift Reservoir
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