1.
A-train (satellite constellation)
–
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
–
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
–
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
–
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
–
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
–
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
–
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
–
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
–
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
.
