European Space Agency
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 worldwide staff of about 2,200 in 2018 and an annual budget of about €5.72 billion in 2019. ESA's space flight programme includes human spaceflight; the main European launch vehicle Ariane 5 is operated through Arianespace with ESA sharing in the costs of launching and further developing this launch vehicle. The agency is working with NASA to manufacture the Orion Spacecraft service module, that will fly on the Space Launch System; the agency's facilities are distributed among the following centres: ESA science missions are based at ESTEC in Noordwijk, Netherlands. After World War II, many European scientists left Western Europe in order to work with the United States. Although the 1950s boom made it possible for Western European countries to invest in research and in space-related activities, Western European scientists realised national projects would not be able to compete with the two main superpowers.
In 1958, only months after the Sputnik shock, Edoardo Amaldi and Pierre Auger, two prominent members of the Western European scientific community, met to discuss the foundation of a common Western European space agency. The meeting was attended by scientific representatives from eight countries, including Harrie Massey; the Western European nations decided to have two agencies: one concerned with developing a launch system, ELDO, the other the precursor of the European Space Agency, ESRO. 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, when ESRO was merged with ELDO. ESA had ten founding member states: Belgium, France, West Germany, the Netherlands, Sweden and the United Kingdom; these signed the ESA Convention in 1975 and deposited the instruments of ratification by 1980, when the convention came into force. During this interval the agency functioned in a de facto fashion.
ESA launched its first major scientific mission in 1975, Cos-B, a space probe monitoring gamma-ray emissions in the universe, first worked on by ESRO. The ESA collaborated with NASA on the International Ultraviolet Explorer, the world's first high-orbit telescope, launched in 1978 and operated for 18 years. A number of successful Earth-orbit projects followed, in 1986 ESA began Giotto, its first deep-space mission, to study the comets Halley and Grigg–Skjellerup. Hipparcos, a star-mapping mission, was launched in 1989 and in the 1990s SOHO, Ulysses and the Hubble Space Telescope were all jointly carried out with NASA. Scientific missions in cooperation with NASA include the Cassini–Huygens space probe, to which ESA contributed by building the Titan landing module Huygens; as the successor of ELDO, ESA has constructed rockets for scientific and commercial payloads. Ariane 1, launched in 1979, carried commercial payloads into orbit from 1984 onward; the next two versions of the Ariane rocket were intermediate stages in the development of a more advanced launch system, the Ariane 4, which operated between 1988 and 2003 and established ESA as the world leader in commercial space launches in the 1990s.
Although the succeeding Ariane 5 experienced a failure on its first flight, it has since established itself within the competitive commercial space launch market with 82 successful launches until 2018. The successor launch vehicle of Ariane 5, the Ariane 6, is under development 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 the 1990s, changed circumstances led to decisions to rely more on itself and on co-operation with Russia. A 2011 press issue thus stated: Russia is ESA's first partner in its efforts to ensure long-term access to space. There is a framework agreement between ESA and the government of the Russian Federation on cooperation and partnership in the exploration and use of outer space for peaceful purposes, cooperation is underway in two different areas of launcher activity that will bring benefits to both partners.
Notable outcomes are ESA's include SMART-1, a probe testing cutting-edge new space propulsion technology, the Mars Express and Venus Express missions, as well as the development of the Ariane 5 rocket and its role in the ISS partnership. ESA maintain
The Ghadr-110 is a medium-range ballistic missile designed and developed by Iran. The missile has a range of 1,800 km to 2,000 km; the Iranian Armed Forces first displayed the missile to the public at an annual military parade to mark the Iran–Iraq War. The Ghadr-110 is an improved version of the Shahab-3A known as the Ghadr-101, it is believed to have a liquid-fuel first stage and a solid-fuel second stage, which allows it to have a range of 1,500 km. The Ghadr-110 has a higher maneuverability and a shorter set-up time than the Shahab-3; the missile has been manufactured in Iran at the top-secret Hemmat Missile Industries Complex. On November 21, 2015 and January 29, 2017, Iran carried out launches of the Ghadr 110; the United States viewed this as a violation of United Nations Security Council Resolution 2231 which "calls upon" Iran to not work on any ballistic missiles capable of carrying nuclear warheads, including launching them. Russia's ambassador to the UN disputed this, saying "a call is different from a ban, so you cannot violate a call, you can comply with a call or you can ignore the call, but you cannot violate a call".
Iran's foreign minister, Javad Zarif, responded by saying that since Iran does not possess nuclear weapons nor does it intend to have one, it does not design its missiles to be capable of carrying nuclear warheads, a statement, questioned in light of the Iranian nuclear archive discovery. However, Senior Fellow for Missile Defence at the IISS Michael Elleman noted that bomb design presented by Benjamin Netanyahu would fit in Iran's pre-2004 Nodong/Shahab-3 nosecone, but not any of the post-2004 missiles, including Ghadr-110 missile. Military of Iran Aerospace Force of the Army of the Guardians of the Islamic Revolution – controls Iran's missile forces Iranian military industry
NCube was a series of two Norwegian satellites, built by students at several Norwegian universities and university colleges. Due to problems during launch and deployment into orbit, neither of the satellites became operational. Both satellites were built to the CubeSat pico-satellite standard, which defined their mass and size; this standard allows one or more cube satellites to be launched by'piggybacking' with a larger satellite. In this way the smaller satellites get a cheap ride into orbit; the goal of the nCube satellites was to stimulate interest in science and increase competence in space technology among students and educational institutions. Moreover, enhance co-operation between educational institutions and industry and exchange of knowledge between educational institutions in north and south of Norway; the second goal was to communicate with amateur radio ground stations, to test a space-born AIS receiver for tracking ships and reindeer. As of 2013 NTNU is developing a 2U CubeSat called NUTS-1.
List of CubeSats http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1791&context=smallsat More information and project documents
The term apsis refers to an extreme point in the orbit of an object. It denotes either the respective distance of the bodies; the word comes via Latin from Greek, there denoting a whole orbit, is cognate with apse. Except for the theoretical possibility of one common circular orbit for two bodies of equal mass at diametral positions, there are two apsides for any elliptic orbit, named with the prefixes peri- and ap-/apo-, added in reference to the body being orbited. All periodic orbits are, according to Newton's Laws of motion, ellipses: either the two individual ellipses of both bodies, with the center of mass of this two-body system at the one common focus of the ellipses, or the orbital ellipses, with one body taken as fixed at one focus, the other body orbiting this focus. All these ellipses share a straight line, the line of apsides, that contains their major axes, the foci, the vertices, thus the periapsis and the apoapsis; the major axis of the orbital ellipse is the distance of the apsides, when taken as points on the orbit, or their sum, when taken as distances.
The major axes of the individual ellipses around the barycenter the contributions to the major axis of the orbital ellipses are inverse proportional to the masses of the bodies, i.e. a bigger mass implies a smaller axis/contribution. Only when one mass is sufficiently larger than the other, the individual ellipse of the smaller body around the barycenter comprises the individual ellipse of the larger body as shown in the second figure. For remarkable asymmetry, the barycenter of the two bodies may lie well within the bigger body, e.g. the Earth–Moon barycenter is about 75% of the way from Earth's center to its surface. If the smaller mass is negligible compared to the larger the orbital parameters are independent of the smaller mass. For general orbits, the terms periapsis and apoapsis are used. Pericenter and apocenter are equivalent alternatives, referring explicitly to the respective points on the orbits, whereas periapsis and apoapsis may refer to the smallest and largest distances of the orbiter and its host.
For a body orbiting the Sun, the point of least distance is the perihelion, the point of greatest distance is the aphelion. The terms become apastron when discussing orbits around other stars. For any satellite of Earth, including the Moon, the point of least distance is the perigee and greatest distance the apogee, from Ancient Greek Γῆ, "land" or "earth". For objects in lunar orbit, the point of least distance is sometimes called the pericynthion and the greatest distance the apocynthion. Perilune and apolune are used. In orbital mechanics, the apsides technically refer to the distance measured between the barycenters of the central body and orbiting body. However, in the case of a spacecraft, the terms are used to refer to the orbital altitude of the spacecraft above the surface of the central body; these formulae characterize the pericenter and apocenter of an orbit: Pericenter Maximum speed, v per = μ a, at minimum distance, r per = a. Apocenter Minimum speed, v ap = μ a, at maximum distance, r ap = a.
While, in accordance with Kepler's laws of planetary motion and the conservation of energy, these two quantities are constant for a given orbit: Specific relative angular momentum h = μ a Specific orbital energy ε = − μ 2 a where: a is the semi-major axis: a = r per + r ap 2 μ is the standard gravitational parameter e is the eccentricity, defined as e = r ap − r per r ap + r per = 1 − 2 r ap r per + 1 Note t
Angular resolution or spatial resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution. In physics and geosciences, the term spatial resolution refers to the precision of a measurement with respect to space. Resolving power is the ability of an imaging device to separate points of an object that are located at a small angular distance or it is the power of an optical instrument to separate far away objects, that are close together, into individual images; the term resolution or minimum resolvable distance is the minimum distance between distinguishable objects in an image, although the term is loosely used by many users of microscopes and telescopes to describe resolving power. In scientific analysis, in general, the term "resolution" is used to describe the precision with which any instrument measures and records any variable in the specimen or sample under study.
The imaging system's resolution can be limited either by aberration or by diffraction causing blurring of the image. These two phenomena are unrelated. Aberrations can be explained by geometrical optics and can in principle be solved by increasing the optical quality — and the cost — of the system. On the other hand, diffraction comes from the wave nature of light and is determined by the finite aperture of the optical elements; the lens' circular aperture is analogous to a two-dimensional version of the single-slit experiment. Light passing through the lens interferes with itself creating a ring-shape diffraction pattern, known as the Airy pattern, if the wavefront of the transmitted light is taken to be spherical or plane over the exit aperture; the interplay between diffraction and aberration can be characterised by the point spread function. The narrower the aperture of a lens the more the PSF is dominated by diffraction. In that case, the angular resolution of an optical system can be estimated by the Rayleigh criterion defined by Lord Rayleigh: two point sources are regarded as just resolved when the principal diffraction maximum of one image coincides with the first minimum of the other.
If the distance is greater, the two points are well resolved and if it is smaller, they are regarded as not resolved. Rayleigh defended this criteria on sources of equal strength. Considering diffraction through a circular aperture, this translates into: θ = 1.220 λ D where θ is the angular resolution, λ is the wavelength of light, D is the diameter of the lens' aperture. The factor 1.220 is derived from a calculation of the position of the first dark circular ring surrounding the central Airy disc of the diffraction pattern. This number is more 1.21966989... the first zero of the order-one Bessel function of the first kind J 1 divided by π. The formal Rayleigh criterion is close to the empirical resolution limit found earlier by the English astronomer W. R. Dawes who tested human observers on close binary stars of equal brightness; the result, θ = 4.56/D, with D in inches and θ in arcseconds is narrower than calculated with the Rayleigh criterion: A calculation using Airy discs as point spread function shows that at Dawes' limit there is a 5% dip between the two maxima, whereas at Rayleigh's criterion there is a 26.3% dip.
Modern image processing techniques including deconvolution of the point spread function allow resolution of binaries with less angular separation. The angular resolution may be converted into a spatial resolution, Δℓ, by multiplication of the angle with the distance to the object. For a microscope, that distance is close to the focal length f of the objective. For this case, the Rayleigh criterion reads: Δ ℓ = 1.220 f λ D. This is the size, in the imaging plane, of smallest object that the lens can resolve, the radius of the smallest spot to which a collimated beam of light can be focused; the size is proportional to wavelength, λ, thus, for example, blue light can be focused to a smaller spot than red light. If the lens is focusing a beam of light with a finite extent, the value of D corresponds to the diameter of the light beam, not the lens. Since the spatial resolution is inversely proportional to D, this leads to the surprising result that a wide beam of light may be focused to a smaller spot than a narrow one.
This result is related to the Fourier properties of a lens. A similar result holds for a small sensor imaging a subject at infinity: The angular resolution can be converted to a spatial resolution on the sensor by using f as the distance to the image sensor. Since this is the radius of the Airy disk, the resolution is better estimated by the diameter, 2.44 λ ⋅ Point-like sources separated by an angle smaller than the angular resolution cannot be resolved. A single opt
The United Kingdom the United Kingdom of Great Britain and Northern Ireland, sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world; the Irish Sea lies between Great Ireland. With an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world, it is the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017. The UK is constitutional monarchy; the current monarch is Queen Elizabeth II, who has reigned since 1952, making her the longest-serving current head of state.
The United Kingdom's capital and largest city is London, a global city and financial centre with an urban area population of 10.3 million. Other major urban areas in the UK include Greater Manchester, the West Midlands and West Yorkshire conurbations, Greater Glasgow and the Liverpool Built-up Area; the United Kingdom consists of four constituent countries: England, Scotland and Northern Ireland. Their capitals are London, Edinburgh and Belfast, respectively. Apart from England, the countries have their own devolved governments, each with varying powers, but such power is delegated by the Parliament of the United Kingdom, which may enact laws unilaterally altering or abolishing devolution; the nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the UK, being Crown dependencies with the British Government responsible for defence and international representation. The medieval conquest and subsequent annexation of Wales by the Kingdom of England, followed by the union between England and Scotland in 1707 to form the Kingdom of Great Britain, the union in 1801 of Great Britain with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland.
Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain and Northern Ireland. There are fourteen British Overseas Territories, the remnants of the British Empire which, at its height in the 1920s, encompassed a quarter of the world's land mass and was the largest empire in history. British influence can be observed in the language and political systems of many of its former colonies; the United Kingdom is a developed country and has the world's fifth-largest economy by nominal GDP and ninth-largest economy by purchasing power parity. It has a high-income economy and has a high Human Development Index rating, ranking 14th in the world, it was the world's first industrialised country and the world's foremost power during the 19th and early 20th centuries. The UK remains a great power, with considerable economic, military and political influence internationally, it is sixth in military expenditure in the world. It has been a permanent member of the United Nations Security Council since its first session in 1946.
It has been a leading member state of the European Union and its predecessor, the European Economic Community, since 1973. The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the G20, NATO, the Organisation for Economic Co-operation and Development and the World Trade Organization; the 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain". The term "United Kingdom" has been used as a description for the former kingdom of Great Britain, although its official name from 1707 to 1800 was "Great Britain"; the Acts of Union 1800 united the kingdom of Great Britain and the kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland. Following the partition of Ireland and the independence of the Irish Free State in 1922, which left Northern Ireland as the only part of the island of Ireland within the United Kingdom, the name was changed to the "United Kingdom of Great Britain and Northern Ireland".
Although the United Kingdom is a sovereign country, Scotland and Northern Ireland are widely referred to as countries. The UK Prime Minister's website has used the phrase "countries within a country" to describe the United Kingdom; some statistical summaries, such as those for the twelve NUTS 1 regions of the United Kingdom refer to Scotland and Northern Ireland as "regions". Northern Ireland is referred to as a "province". With regard to Northern Ireland, the descriptive name used "can be controversial, with the choice revealing one's political preferences"; the term "Great Britain" conventionally refers to the island of Great Britain, or politically to England and Wales in combination. However, it is sometimes used as a loose synonym for the United Kingdom as a whole; the term "Britain" is used both as a synonym for Great Britain, as a synonym for the United Kingdom. Usage is mixed, with the BBC preferring to use Britain as shorthand only for Great Britain and the UK Government, while accepting that both terms refer to the United K
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period of any planet in the Solar System and rotates in the opposite direction to most other planets, it does not have any natural satellites. It is named after the Roman goddess of beauty, it is the second-brightest natural object in the night sky after the Moon, reaching an apparent magnitude of −4.6 – bright enough to cast shadows at night and visible to the naked eye in broad daylight. Orbiting within Earth's orbit, Venus is an inferior planet and never appears to venture far from the Sun. Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, proximity to the Sun, bulk composition, it is radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide; the atmospheric pressure at the planet's surface is 92 times that of Earth, or the pressure found 900 m underwater on Earth.
Venus is by far the hottest planet in the Solar System, with a mean surface temperature of 735 K though Mercury is closer to the Sun. Venus is shrouded by an opaque layer of reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light, it may have had water oceans in the past, but these would have vaporized as the temperature rose due to a runaway greenhouse effect. The water has photodissociated, the free hydrogen has been swept into interplanetary space by the solar wind because of the lack of a planetary magnetic field. Venus's surface is a dry desertscape interspersed with slab-like rocks and is periodically resurfaced by volcanism; as one of the brightest objects in the sky, Venus has been a major fixture in human culture for as long as records have existed. It has been made sacred to gods of many cultures, has been a prime inspiration for writers and poets as the morning star and evening star. Venus was the first planet to have its motions plotted across the sky, as early as the second millennium BC.
As the planet with the closest approach to Earth, Venus has been a prime target for early interplanetary exploration. It was the first planet beyond Earth visited by a spacecraft, the first to be landed on. Venus's thick clouds render observation of its surface impossible in visible light, the first detailed maps did not emerge until the arrival of the Magellan orbiter in 1991. Plans have been proposed for rovers or more complex missions, but they are hindered by Venus's hostile surface conditions. Venus is one of the four terrestrial planets in the Solar System, meaning that it is a rocky body like Earth, it is similar to Earth in size and mass, is described as Earth's "sister" or "twin". The diameter of Venus is 12,103.6 km —only 638.4 km less than Earth's—and its mass is 81.5% of Earth's. Conditions on the Venusian surface differ radically from those on Earth because its dense atmosphere is 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen. The Venusian surface was a subject of speculation until some of its secrets were revealed by planetary science in the 20th century.
Venera landers in 1975 and 1982 returned images of a surface covered in sediment and angular rocks. The surface was mapped in detail by Magellan in 1990–91; the ground shows evidence of extensive volcanism, the sulfur in the atmosphere may indicate that there have been recent eruptions. About 80% of the Venusian surface is covered by smooth, volcanic plains, consisting of 70% plains with wrinkle ridges and 10% smooth or lobate plains. Two highland "continents" make up the rest of its surface area, one lying in the planet's northern hemisphere and the other just south of the equator; the northern continent is called Ishtar Terra after Ishtar, the Babylonian goddess of love, is about the size of Australia. Maxwell Montes, the highest mountain on Venus, lies on Ishtar Terra, its peak is 11 km above the Venusian average surface elevation. The southern continent is called Aphrodite Terra, after the Greek goddess of love, is the larger of the two highland regions at the size of South America. A network of fractures and faults covers much of this area.
The absence of evidence of lava flow accompanying any of the visible calderas remains an enigma. The planet has few impact craters, demonstrating that the surface is young 300–600 million years old. Venus has some unique surface features in addition to the impact craters and valleys found on rocky planets. Among these are flat-topped volcanic features called "farra", which look somewhat like pancakes and range in size from 20 to 50 km across, from 100 to 1,000 m high; these features are volcanic in origin. Most Venusian surface features are named after mythological women. Exceptions are Maxwell Montes, named after James Clerk Maxwell, highland regions Alpha Regio, Beta Regio, Ovda Regio; the latter three features were named before the current system was adopted by the International Astronomical Union, the body which oversees planetary nomenclature. The longitudes of physical features on Venus are expressed relative to its prime meridian; the original prime meridian passed through the radar-bright spot at the centre o