An Earth observation satellite or Earth remote sensing satellite is a satellite used or designed for Earth observation (EO) from orbit , including spy satellites and similar ones intended for non-military uses such as environmental monitoring , meteorology , cartography and others. The most common type are Earth imaging satellites , that take satellite images , analogous to aerial photographs ; some EO satellites may perform remote sensing without forming pictures, such as in GNSS radio occultation .
57-568: Envisat (" Environmental Satellite ") is a large Earth-observing satellite which has been inactive since 2012. It is still in orbit and considered space debris. Operated by the European Space Agency (ESA), it was the world's largest civilian Earth observation satellite. It was launched on 1 March 2002 aboard an Ariane 5 from the Guyana Space Centre in Kourou , French Guiana , into
114-471: A Sun synchronous polar orbit at an altitude of 790 ± 10 km. It orbits the Earth in about 101 minutes, with a repeat cycle of 35 days. After losing contact with the satellite on 8 April 2012, ESA formally announced the end of Envisat's mission on 9 May 2012. Envisat cost 2.3 billion Euro (including 300 million Euro for 5 years of operations) to develop and launch. The mission has been replaced by
171-543: A petabyte of data. ESA was expecting to turn off the spacecraft in 2014. Envisat poses a hazard because of the risk of collisions with space debris . Given its orbit and its area-to-mass ratio, it will take about 150 years for the satellite to be gradually pulled into the Earth's atmosphere. Envisat is currently orbiting in an environment where two catalogued space debris objects can be expected to pass within about 200 m (660 ft) of it every year, which would likely trigger
228-435: A correct description of the source of stratospheric ozone and its ability to generate heat within the stratosphere; he also wrote that ozone may be destroyed by reacting with atomic oxygen, making two molecules of molecular oxygen. We now know that there are additional ozone loss mechanisms and that these mechanisms are catalytic, meaning that a small amount of the catalyst can destroy a great number of ozone molecules. The first
285-496: A data link for ERS 1 and ERS 2 , providing numerous functions such as observations of different polarities of light or combining different polarities, angles of incidence and spatial resolutions. These different types of raw data can be given several levels of treatment (suffixed to the ID of the acquisition mode: IMP, APS, and so on): Data capture in WV mode is unusual in that they constitute
342-600: A mass of approximately 1.6 tonnes. Earth observation satellite The first occurrence of satellite remote sensing can be dated to the launch of the first artificial satellite, Sputnik 1 , by the Soviet Union on October 4, 1957. Sputnik 1 sent back radio signals, which scientists used to study the ionosphere . The United States Army Ballistic Missile Agency launched the first American satellite, Explorer 1 , for NASA's Jet Propulsion Laboratory on January 31, 1958. The information sent back from its radiation detector led to
399-484: A phenomenon called Rossby-wave pumping. An interesting feature of stratospheric circulation is the quasi-biennial oscillation (QBO) in the tropical latitudes, which is driven by gravity waves that are convectively generated in the troposphere . The QBO induces a secondary circulation that is important for the global stratospheric transport of tracers, such as ozone or water vapor . Another large-scale feature that significantly influences stratospheric circulation
456-588: A precision of 0.3 K (0.54 °F), for climate research . Among the secondary objectives of AATSR is the observation of environmental parameters such as water content, biomass, and vegetal health and growth. MIPAS (Michelson Interferometer for Passive Atmospheric Sounding ) is a Fourier transforming infrared spectrometer which provides pressure and temperature profiles, and profiles of trace gases nitrogen dioxide ( NO 2 ), nitrous oxide ( N 2 O ), methane ( CH 4 ), nitric acid ( HNO 3 ), ozone ( O 3 ), and water ( H 2 O ) in
513-440: A satellite to hover over a constant spot on the earth since the orbital period at this altitude is 24 hours. This allows uninterrupted coverage of more than 1/3 of the Earth per satellite, so three satellites, spaced 120° apart, can cover the whole Earth. This type of orbit is mainly used for meteorological satellites . Herman Potočnik explored the idea of using orbiting spacecraft for detailed peaceful and military observation of
570-458: A series of 5 km × 5 km spaced at 100 km. DORIS ( Doppler Orbitography and Radiopositioning Integrated by Satellite) determines the satellite's orbit to within 10 cm (4 in). GOMOS (Global Ozone Monitoring by Occultation of Stars ) looks at stars as they descend through the Earth's atmosphere and change colour, allowing measurement of gases such as ozone ( O 3 ), including their vertical distribution. GOMOS uses
627-467: A wide range of wavelengths can detect many trace gases even in tiny concentrations. The wavelengths captured also allow effective detection of aerosols and clouds. SCIAMACHY uses 3 different targeting modes: to the nadir (against the sun), to the limbus (through the atmospheric corona), and during solar or lunar eclipses. SCIAMACHY was built by Netherlands and Germany at TNO /TPD, SRON and Airbus Defence and Space Netherlands. RA-2 ( Radar Altimeter 2)
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#1733084508641684-496: Is exothermically photolyzed into oxygen in a cyclical fashion . This temperature inversion is in contrast to the troposphere, where temperature decreases with altitude, and between the troposphere and stratosphere is the tropopause border that demarcates the beginning of the temperature inversion. Near the equator , the lower edge of the stratosphere is as high as 20 km (66,000 ft; 12 mi), at mid-latitudes around 10 km (33,000 ft; 6.2 mi), and at
741-609: Is a dual- frequency Nadir pointing Radar operating in the K u band and S bands , it is used to define ocean topography , map/monitor sea ice and measure land heights. Mean sea level measurements from Envisat are continuously graphed at the Centre National d'Etudes Spatiales web site, on the Aviso page. ASAR (Advanced Synthetic Aperture Radar) operates in the C band in a wide variety of modes. It can detect changes in surface heights with sub- millimeter precision. It served as
798-480: Is a type of satellite that is primarily used to monitor the weather and climate of the Earth . These meteorological satellites, however, see more than clouds and cloud systems. City lights, fires , effects of pollution , auroras , sand and dust storms , snow cover, ice mapping, boundaries of ocean currents , energy flows, etc., are other types of environmental information collected using weather satellites. Weather satellite images helped in monitoring
855-401: Is caused by variations in the jet stream and other local wind shears, although areas of significant convective activity ( thunderstorms ) in the troposphere below may produce turbulence as a result of convective overshoot . On October 24, 2014, Alan Eustace became the record holder for reaching the altitude record for a manned balloon at 135,890 ft (41,419 m). Eustace also broke
912-510: Is classified in accordance with ITU Radio Regulations (article 1) as follows: Fixed service (article 1.20) The allocation of radio frequencies is provided according to Article 5 of the ITU Radio Regulations (edition 2012). In order to improve harmonisation in spectrum utilisation, the majority of service-allocations stipulated in this document were incorporated in national Tables of Frequency Allocations and Utilisations which
969-521: Is due to the reaction of hydroxyl radicals (•OH) with ozone. •OH is formed by the reaction of electrically excited oxygen atoms produced by ozone photolysis, with water vapor. While the stratosphere is dry, additional water vapor is produced in situ by the photochemical oxidation of methane (CH 4 ). The HO 2 radical produced by the reaction of OH with O 3 is recycled to OH by reaction with oxygen atoms or ozone. In addition, solar proton events can significantly affect ozone levels via radiolysis with
1026-577: Is the base of the lower stratosphere. This was based on temperature profiles from mostly unmanned and a few manned instrumented balloons. The mechanism describing the formation of the ozone layer was described by British mathematician and geophysicist Sydney Chapman in 1930, and is known as the Chapman cycle or ozone–oxygen cycle . Molecular oxygen absorbs high energy sunlight in the UV-C region, at wavelengths shorter than about 240 nm. Radicals produced from
1083-487: Is the breaking planetary waves resulting in intense quasi-horizontal mixing in the midlatitudes. This breaking is much more pronounced in the winter hemisphere where this region is called the surf zone. This breaking is caused due to a highly non-linear interaction between the vertically propagating planetary waves and the isolated high potential vorticity region known as the polar vortex . The resultant breaking causes large-scale mixing of air and other trace gases throughout
1140-432: Is with-in the responsibility of the appropriate national administration. The allocation might be primary, secondary, exclusive, and shared. However, military usage, in bands where there is civil usage, will be in accordance with the ITU Radio Regulations. Stratosphere The stratosphere ( / ˈ s t r æ t ə ˌ s f ɪər , - t oʊ -/ ) is the second-lowest layer of the atmosphere of Earth , located above
1197-571: The Cold War prompted the rapid development of Satellite launch systems and camera technology capable of sufficient Earth observation to garner intelligence on enemy military infrastructure and evaluate nuclear posture. Following the U-2 incident in 1960, which highlighted the risks of aerial spying, the U.S. accelerated surveillance satellite programs like CORONA . Satellites largely replaced aircraft overflights for surveillance after 1960. A weather satellite
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#17330845086411254-527: The MetOp spacecraft of EUMETSAT are all operated at altitudes of about 800 km (500 mi). The Proba-1 , Proba-2 and SMOS spacecraft of European Space Agency are observing the Earth from an altitude of about 700 km (430 mi). The Earth observation satellites of UAE, DubaiSat-1 & DubaiSat-2 are also placed in Low Earth orbits (LEO) orbits and providing satellite imagery of various parts of
1311-464: 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 . Its objective was to support the continuity of European Remote-Sensing Satellite missions, providing additional observations to improve environmental studies. To accomplish the global and regional objectives of
1368-401: The poles about 7 km (23,000 ft; 4.3 mi). Temperatures range from an average of −51 °C (−60 °F; 220 K) near the tropopause to an average of −15 °C (5.0 °F; 260 K) near the mesosphere. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly low temperatures in the polar night (winter). Winds in
1425-415: The stratosphere . The instrument functions with high spectral resolution in an extended spectral band, which allows coverage across the Earth in all seasons and at equal quality night and day. MIPAS has a vertical resolution of 3 to 5 km (2 to 3 mi) depending on altitude (the larger at the level of the upper stratosphere). MERIS (MEdium Resolution Imaging Spectrometer ) measures the reflectance of
1482-510: The troposphere and below the mesosphere . The stratosphere is composed of stratified temperature zones, with the warmer layers of air located higher (closer to outer space ) and the cooler layers lower (closer to the planetary surface of the Earth). The increase of temperature with altitude is a result of the absorption of the Sun 's ultraviolet (UV) radiation by the ozone layer , where ozone
1539-486: The Earth (surface and atmosphere) in the solar spectral range (390 to 1040 nm ) and transmits 15 spectral bands back to the ground segment . MERIS was built at the Cannes Mandelieu Space Center . SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) compares light coming from the sun to light reflected by the Earth, which provides information on the atmosphere through which
1596-550: The Earth-reflected light has passed. SCIAMACHY is an image spectrometer with the principal objective of mapping the concentration of trace gases and aerosols in the troposphere and stratosphere. Rays of sunlight that are reflected transmitted, backscattered and reflected by the atmosphere are captured at a high spectral resolution (0.2 to 0.5 nm) for wavelengths between 240 and 1700 nm, and in certain spectra between 2,000 and 2,400 nm. Its high spectral resolution over
1653-524: The Earth. To get global coverage with a low orbit, a polar orbit is used. A low orbit will have an orbital period of roughly 100 minutes and the Earth will rotate around its polar axis about 25° between successive orbits. The ground track moves towards the west 25° each orbit, allowing a different section of the globe to be scanned with each orbit. Most are in Sun-synchronous orbits . A geostationary orbit , at 36,000 km (22,000 mi), allows
1710-402: The altitudes of normal lightning and storm clouds. Upper-atmospheric lightning is believed to be electrically induced forms of luminous plasma . Lightning extending above the troposphere into the stratosphere is referred to as blue jet , and that reaching into the mesosphere as red sprite . Bacterial life survives in the stratosphere, making it a part of the biosphere . In 2001, dust
1767-485: The cold European winters of the 1960s. Stratospheric warming of the polar vortex results in its weakening. When the vortex is strong, it keeps the cold, high-pressure air masses contained in the Arctic ; when the vortex weakens, air masses move equatorward, and results in rapid changes of weather in the mid latitudes. Upper-atmospheric lightning is a family of short-lived electrical-breakdown phenomena that occur well above
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1824-575: The current vegetation state to its long term average. For example, the 2002 oil spill off the northwest coast of Spain was watched carefully by the European ENVISAT , which, though not a weather satellite, flies an instrument (ASAR) which can see changes in the sea surface. Anthropogenic emissions can be monitored by evaluating data of tropospheric NO 2 and SO 2 . These types of satellites are almost always in Sun-synchronous and "frozen" orbits. A Sun-synchronous orbit passes over each spot on
1881-495: The discovery of the Earth's Van Allen radiation belts . The TIROS-1 spacecraft, launched on April 1, 1960, as part of NASA's Television Infrared Observation Satellite (TIROS) program, sent back the first television footage of weather patterns to be taken from space. In 2008, more than 150 Earth observation satellites were in orbit, recording data with both passive and active sensors and acquiring more than 10 terabits of data daily. By 2021, that total had grown to over 950, with
1938-457: The ground at the same time of day, so that observations from each pass can be more easily compared, since the Sun is in the same spot in each observation. A "frozen" orbit is the closest possible orbit to a circular orbit that is undisturbed by the oblateness of the Earth , gravitational attraction from the Sun and Moon, solar radiation pressure , and air drag . Terrain can be mapped from space with
1995-488: The ground in his 1928 book, The Problem of Space Travel . He described how the special conditions of space could be useful for scientific experiments. The book described geostationary satellites (first put forward by Konstantin Tsiolkovsky ) and discussed communication between them and the ground using radio, but fell short of the idea of using satellites for mass broadcasting and as telecommunications relays. The onset of
2052-465: The homolytically split oxygen molecules combine with molecular oxygen to form ozone. Ozone in turn is photolysed much more rapidly than molecular oxygen as it has a stronger absorption that occurs at longer wavelengths, where the solar emission is more intense. Ozone (O 3 ) photolysis produces O and O 2 . The oxygen atom product combines with atmospheric molecular oxygen to reform O 3 , releasing heat. The rapid photolysis and reformation of ozone heat
2109-492: The initially planned life span by 5 years. The spacecraft was still in a stable orbit, but attempts to contact it were unsuccessful. Ground-based radar and the French Pleiades Earth probe were used to image the silent Envisat and look for damage. ESA formally announced the end of Envisat's mission on 9 May 2012. Envisat was launched in 2002 and it operated five years beyond its planned mission lifetime, delivering over
2166-487: The instruments were advanced versions of instruments that were flown on the earlier ERS-1 and ERS 2 missions and other satellites. MWR ( Microwave Radiometer) was designed for measuring water vapour in the atmosphere . AATSR (Advanced Along Track Scanning Radiometer ) can measure the sea surface temperature in the visible and infrared spectra . It is the successor of ATSR1 and ATSR2, payloads of ERS 1 and ERS 2 . AATSR can measure Earth's surface temperature to
2223-461: The largest number of satellites operated by US-based company Planet Labs . Most Earth observation satellites carry instruments that should be operated at a relatively low altitude. Most orbit at altitudes above 500 to 600 kilometers (310 to 370 mi). Lower orbits have significant air-drag , which makes frequent orbit reboost maneuvers necessary. The Earth observation satellites ERS-1, ERS-2 and Envisat of European Space Agency as well as
2280-562: The lift by the lift-to-drag ratio .) It also allows the airplane to stay above the turbulent weather of the troposphere. The Concorde aircraft cruised at Mach 2 at about 60,000 ft (18 km), and the SR-71 cruised at Mach 3 at 85,000 ft (26 km), all within the stratosphere. Because the temperature in the tropopause and lower stratosphere is largely constant with increasing altitude, very little convection and its resultant turbulence occurs there. Most turbulence at this altitude
2337-406: The lower reaches of the stratosphere in temperate latitudes. This optimizes fuel efficiency , mostly due to the low temperatures encountered near the tropopause and low air density, reducing parasitic drag on the airframe . Stated another way, it allows the airliner to fly faster while maintaining lift equal to the weight of the plane. (The fuel consumption depends on the drag, which is related to
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2394-492: The midlatitude surf zone. The timescale of this rapid mixing is much smaller than the much slower timescales of upwelling in the tropics and downwelling in the extratropics. During northern hemispheric winters, sudden stratospheric warmings , caused by the absorption of Rossby waves in the stratosphere, can be observed in approximately half of winters when easterly winds develop in the stratosphere. These events often precede unusual winter weather and may even be responsible for
2451-571: The mission, numerous scientific disciplines used the data acquired from the sensors on the satellite to study atmospheric chemistry , ozone depletion , biological oceanography , ocean temperature and colour, wind waves , hydrology ( humidity , floods ), agriculture and arboriculture , natural hazards, digital elevation modelling (using interferometry ), monitoring of maritime traffic, atmospheric dispersion modelling (pollution), cartography and snow and ice . 26 m (85 ft) × 10 m (33 ft) × 5 m (16 ft) in orbit with
2508-552: The need for a manoeuvre to avoid a possible collision. A collision between a satellite the size of Envisat and an object as small as 10 kg could produce a very large cloud of debris, initiating a self-sustaining chain-reaction of collisions and fragmentation with production of new debris, a phenomenon known as the Kessler Syndrome . Envisat was a candidate for a mission to remove it from orbit, called e.Deorbit . The spacecraft sent to bring down Envisat would itself need to have
2565-438: The ozone layer allows life to exist on the surface of the planet outside of the ocean. All air entering the stratosphere must pass through the tropopause , the temperature minimum that divides the troposphere and stratosphere. The rising air is literally freeze dried; the stratosphere is a very dry place. The top of the stratosphere is called the stratopause , above which the temperature decreases with height. Sydney Chapman gave
2622-520: The principle of occultation . Its sensors detect light from a star traversing the Earth's atmosphere and measures the depletion of that light by trace gases nitrogen dioxide ( NO 2 ), nitrogen trioxide, ( NO 3 ), OClO ), ozone ( O 3 ) and aerosols present between about 20 to 80 km (12 to 50 mi) altitude. It has a resolution of 3 km (1.9 mi). ESA announced on 12 April 2012 that they lost contact with Envisat on Sunday, 8 April 2012, after 10 years of service, exceeding
2679-468: The solar array deployed. 8,211 kg (18,102 lb), including 319 kg (703 lb) of fuel and a 2,118 kg (4,669 lb) instrument payload. Solar array with a total load of 3560 W . Envisat carries an array of nine Earth-observation instruments that gathered information about the Earth (land, water , ice , and atmosphere ) using a variety of measurement principles. A tenth instrument, DORIS, provided guidance and control . Several of
2736-456: The stratosphere can far exceed those in the troposphere, reaching near 60 m/s (220 km/h; 130 mph) in the Southern polar vortex . In 1902, Léon Teisserenc de Bort from France and Richard Assmann from Germany, in separate but coordinated publications and following years of observations, published the discovery of an isothermal layer at around 11–14 km (6.8-8.7 mi), which
2793-432: The stratosphere dynamically stable: there is no regular convection and associated turbulence in this part of the atmosphere. However, exceptionally energetic convection processes, such as volcanic eruption columns and overshooting tops in severe supercell thunderstorms , may carry convection into the stratosphere on a very local and temporary basis. Overall, the attenuation of solar UV at wavelengths that damage DNA by
2850-432: The stratosphere is termed as Brewer-Dobson circulation , which is a single-celled circulation, spanning from the tropics up to the poles, consisting of the tropical upwelling of air from the tropical troposphere and the extra-tropical downwelling of air. Stratospheric circulation is a predominantly wave-driven circulation in that the tropical upwelling is induced by the wave force by the westward propagating Rossby waves , in
2907-470: The stratosphere, resulting in a temperature inversion. This increase of temperature with altitude is characteristic of the stratosphere; its resistance to vertical mixing means that it is stratified. Within the stratosphere temperatures increase with altitude (see temperature inversion ) ; the top of the stratosphere has a temperature of about 270 K (−3 °C or 26.6 °F ). This vertical stratification , with warmer layers above and cooler layers below, makes
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#17330845086412964-424: The subsequent formation of OH. Nitrous oxide (N 2 O) is produced by biological activity at the surface and is oxidised to NO in the stratosphere; the so-called NO x radical cycles also deplete stratospheric ozone. Finally, chlorofluorocarbon molecules are photolysed in the stratosphere releasing chlorine atoms that react with ozone giving ClO and O 2 . The chlorine atoms are recycled when ClO reacts with O in
3021-557: The upper stratosphere, or when ClO reacts with itself in the chemistry of the Antarctic ozone hole. Paul J. Crutzen, Mario J. Molina and F. Sherwood Rowland were awarded the Nobel Prize in Chemistry in 1995 for their work describing the formation and decomposition of stratospheric ozone. Commercial airliners typically cruise at altitudes of 9–12 km (30,000–39,000 ft) which is in
3078-716: The use of satellites, such as Radarsat-1 and TerraSAR-X . According to the International Telecommunication Union (ITU), Earth exploration-satellite service (also: Earth exploration-satellite radiocommunication service ) is – according to Article 1.51 of the ITU Radio Regulations (RR) – defined as: A radiocommunication service between earth stations and one or more space stations , which may include links between space stations, in which: This service may also include feeder links necessary for its operation. This radiocommunication service
3135-478: The volcanic ash cloud from Mount St. Helens and activity from other volcanoes such as Mount Etna . Smoke from fires in the western United States such as Colorado and Utah have also been monitored. Other environmental satellites can assist environmental monitoring by detecting changes in the Earth's vegetation, atmospheric trace gas content, sea state, ocean color, and ice fields. By monitoring vegetation changes over time, droughts can be monitored by comparing
3192-456: The world records for vertical speed skydiving, reached with a peak velocity of 1,321 km/h (822 mph) and total freefall distance of 123,414 ft (37,617 m) – lasting four minutes and 27 seconds. The stratosphere is a region of intense interactions among radiative, dynamical , and chemical processes, in which the horizontal mixing of gaseous components proceeds much more rapidly than does vertical mixing. The overall circulation of
3249-544: Was collected at a height of 41 kilometres in a high-altitude balloon experiment and was found to contain bacterial material when examined later in the laboratory. Some bird species have been reported to fly at the upper levels of the troposphere. On November 29, 1973, a Rüppell's vulture ( Gyps rueppelli ) was ingested into a jet engine 11,278 m (37,000 ft) above the Ivory Coast . Bar-headed geese ( Anser indicus ) sometimes migrate over Mount Everest , whose summit
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