1.
Deep Impact (spacecraft)
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Deep Impact was a NASA space probe launched from Cape Canaveral Air Force Station at 18,47 UTC on January 12,2005. It was designed to study the composition of the comet Tempel 1. At 05,52 UTC on July 4,2005, the impactor successfully collided with the comets nucleus, the impact excavated debris from the interior of the nucleus, forming an impact crater. Photographs taken by the spacecraft showed the comet to be more dusty, the impact generated an unexpectedly large and bright dust cloud, obscuring the view of the impact crater. Previous space missions to comets, such as Giotto and Stardust, were fly-by missions and these missions were able to photograph and examine only the surfaces of cometary nuclei, and even then from considerable distances. The Deep Impact mission was the first to eject material from a surface, and the mission garnered large publicity from the media, international scientists. Upon the completion of its mission, proposals were made to further utilize the spacecraft. Consequently, Deep Impact flew by Earth on December 31,2007 on its way to a mission, designated EPOXI, with a dual purpose to study extrasolar planets. By observing the composition of the comet, astronomers hoped to determine how comets form based on the differences between the interior and exterior makeup of the comet, observations of the impact and its aftermath would allow astronomers to attempt to determine the answers to these questions. The missions Principal Investigator was Michael AHearn, an astronomer at the University of Maryland, the Flyby spacecraft is about 3.2 meters long,1.7 meters wide and 2.3 meters high. It includes two panels, a debris shield, and several science instruments for imaging, infrared spectroscopy. The spacecraft also carried two cameras, the High Resolution Imager, and the Medium Resolution Imager.05 to 4.8 micrometres and it has been optimized for observing the comets nucleus. The MRI is the device, and was used primarily for navigation during the final 10-day approach. It also has a wheel, with a slightly different set of filters. The Impactor section of the spacecraft contains an instrument that is identical to the MRI, called the Impactor Targeting Sensor. Its dual purpose was to sense the Impactors trajectory, which could then be adjusted up to four times between release and impact, and to image the comet from close range, the final image taken by the impactor was snapped only 3.7 seconds before impact. The impactors payload, dubbed the Cratering Mass, was 100% copper, including this cratering mass, copper formed 49% of total mass of the impactor, this was to minimize interference with scientific measurements. Since copper was not expected to be found on a comet, instead of using explosives, it was also cheaper to use copper as the payload
2.
Comet nucleus
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The nucleus is the solid, central part of a comet, popularly termed a dirty snowball or an icy dirtball. A cometary nucleus is composed of rock, dust, and frozen gases, when heated by the Sun, the gases sublimate and produce an atmosphere surrounding the nucleus known as the coma. The force exerted on the coma by the Suns radiation pressure and solar wind cause an enormous tail to form, a typical comet nucleus has an albedo of 0.04. This is blacker than coal, and may be caused by a covering of dust, comets, or their precursors, formed in the outer Solar System, possibly millions of years before planet formation. How and when formed is debated, with distinct implications for Solar System formation, dynamics. Three-dimensional computer simulations indicate the structural features observed on cometary nuclei can be explained by pairwise low velocity accretion of weak cometesimals. The currently favored creation mechanism is that of the nebular hypothesis, astronomers think that comets originate in both the Oort cloud and the scattered disk. Most cometary nuclei are thought to be no more than about 10 miles across, the largest comets that have come inside the orbit of Saturn are C/2002 VQ94, Hale–Bopp, 29P, 109P/Swift–Tuttle, and 28P/Neujmin. The potato-shaped nucleus of Halleys comet contains equal amounts of ice, during a flyby in September 2001, the Deep Space 1 spacecraft observed the nucleus of Comet Borrelly and found it to be about half the size of the nucleus of Halleys Comet. Borrellys nucleus was also potato-shaped and had a black surface. Like Halleys Comet, Comet Borrelly only released gas from small areas where holes in the crust exposed the ice to sunlight, the nucleus of comet Hale–Bopp was estimated to be 60 ±20 km in diameter. Hale-Bopp appeared bright to the eye because its unusually large nucleus gave off a great deal of dust. The nucleus of P/2007 R5 is probably only 100–200 meters in diameter, the largest centaurs are estimated to be 250 km to 300 km in diameter. Three of the largest would include 10199 Chariklo,2060 Chiron, known comets have been estimated to have an average density of 0.6 g/cm3. Below is a list of comets that have had estimated sizes, densities, about 80% of the Halleys Comet nucleus is water ice, and frozen carbon monoxide makes up another 15%. Much of the remainder is carbon dioxide, methane. Scientists think that comets are chemically similar to Halleys Comet. The nucleus of Halleys Comet is also a dark black
3.
Comet
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A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to evolve gasses, a process called outgassing. This produces an atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of collections of ice, dust. The coma may be up to 15 times the Earths diameter, if sufficiently bright, a comet may be seen from the Earth without the aid of a telescope and may subtend an arc of 30° across the sky. Comets have been observed and recorded since ancient times by many cultures, Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star. Long-period comets are set in motion towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars, hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space. The appearance of a comet is called an apparition, Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma and the tail, however, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System, the discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets. As of November 2014 there are 5,253 known comets, however, this represents only a tiny fraction of the total potential comet population, as the reservoir of comet-like bodies in the outer Solar System is estimated to be one trillion. Roughly one comet per year is visible to the eye, though many of those are faint. Particularly bright examples are called Great Comets, the word comet derives from the Old English cometa from the Latin comēta or comētēs. That, in turn, is a latinisation of the Greek κομήτης, Κομήτης was derived from κομᾶν, which was itself derived from κόμη and was used to mean the tail of a comet. The astronomical symbol for comets is ☄, consisting of a disc with three hairlike extensions. The solid, core structure of a comet is known as the nucleus, cometary nuclei are composed of an amalgamation of rock, dust, water ice, and frozen gases such as carbon dioxide, carbon monoxide, methane, and ammonia. As such, they are described as dirty snowballs after Fred Whipples model
4.
Sun
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The Sun is the star at the center of the Solar System. It is a perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99. 86% of the total mass of the Solar System. About three quarters of the Suns mass consists of hydrogen, the rest is mostly helium, with smaller quantities of heavier elements, including oxygen, carbon, neon. The Sun is a G-type main-sequence star based on its spectral class and it formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into a disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core and it is thought that almost all stars form by this process. The Sun is roughly middle-aged, it has not changed dramatically for more than four billion years and it is calculated that the Sun will become sufficiently large enough to engulf the current orbits of Mercury, Venus, and probably Earth. The enormous effect of the Sun on Earth has been recognized since prehistoric times, the synodic rotation of Earth and its orbit around the Sun are the basis of the solar calendar, which is the predominant calendar in use today. The English proper name Sun developed from Old English sunne and may be related to south, all Germanic terms for the Sun stem from Proto-Germanic *sunnōn. The English weekday name Sunday stems from Old English and is ultimately a result of a Germanic interpretation of Latin dies solis, the Latin name for the Sun, Sol, is not common in general English language use, the adjectival form is the related word solar. The term sol is used by planetary astronomers to refer to the duration of a solar day on another planet. A mean Earth solar day is approximately 24 hours, whereas a mean Martian sol is 24 hours,39 minutes, and 35.244 seconds. From at least the 4th Dynasty of Ancient Egypt, the Sun was worshipped as the god Ra, portrayed as a falcon-headed divinity surmounted by the solar disk, and surrounded by a serpent. In the New Empire period, the Sun became identified with the dung beetle, in the form of the Sun disc Aten, the Sun had a brief resurgence during the Amarna Period when it again became the preeminent, if not only, divinity for the Pharaoh Akhenaton. The Sun is viewed as a goddess in Germanic paganism, Sól/Sunna, in ancient Roman culture, Sunday was the day of the Sun god. It was adopted as the Sabbath day by Christians who did not have a Jewish background, the symbol of light was a pagan device adopted by Christians, and perhaps the most important one that did not come from Jewish traditions
5.
Stardust (spacecraft)
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Stardust was a 300-kilogram robotic space probe launched by NASA on February 7,1999. Its primary mission was to collect dust samples from the coma of comet Wild 2, as well as samples of cosmic dust and it was the first sample return mission of its kind. En route to comet Wild 2, the craft also flew by, the primary mission was successfully completed on January 15,2006, when the sample return capsule returned to Earth. A mission extension codenamed NExT culminated in February 2011 with Stardust intercepting comet Tempel 1, Stardust ceased operations in March 2011. On August 14,2014, scientists announced the identification of possible interstellar dust particles from the Stardust capsule returned to Earth in 2006, beginning in the 1980s, scientists began seeking a dedicated mission to study a comet. During the early 1990s, several missions to study comet Halley became the first successful missions to return close-up data, however, the US cometary mission, Comet Rendezvous Asteroid Flyby, was canceled for budgetary reasons. In the mid-1990s, further support was given to a cheaper, Stardust was competitively selected in the fall of 1995 as a NASA Discovery Program mission of low-cost with highly focused science goals. Construction of Stardust began in 1996, and was subject to the maximum contamination restriction, Comet Wild 2 was selected as the primary target of the mission for the rare chance to observe a long-period comet that has ventured close to the Sun. The comet has since become a short period comet after an event in 1974, in planning the mission, it was expected that most of the original material from which the comet formed would still be preserved. Facilitating the intercept of significant numbers of interstellar dust particles using the collection medium. Returning as many high resolution images of the coma and nucleus as possible. The spacecraft was designed, built and operated by Lockheed Martin Astronautics as a Discovery-class mission in Denver, JPL provided mission management for the NASA division for mission operations. The principal investigator of the mission was Dr. Donald Brownlee from the University of Washington, the spacecraft bus measured 1.7 meters in length, and 0.66 meters in width, a design adapted from the SpaceProbe deep space bus developed by Lockheed Martin Astronautics. To maintain low costs, the spacecraft incorporated many designs and technologies used in past missions or previously developed for missions by the Small Spacecraft Technologies Initiative. The spacecraft featured five scientific instruments to collect data, including the Stardust Sample Collection tray, the spacecraft was launched with 80-kilograms of propellant. Information for spacecraft positioning was provided by a camera using FSW to determine attitude, an inertial measurement unit. The probe was powered by two arrays, providing an average of 330 watts of power. The arrays also included Whipple shields to protect the surfaces from the potentially damaging cometary dust while the spacecraft was in the coma of Wild 2
6.
Marseille
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Marseille, also known as Marseilles in English, is a city in France. Known to the ancient Greeks and Romans as Massalia, Marseille was the most important trading centre in the region, Marseille is now Frances largest city on the Mediterranean coast and the largest port for commerce, freight and cruise ships. The city was European Capital of Culture, together with Košice, Slovakia and it hosted the European Football Championship in 2016, and will be the European Capital of Sport in 2017. The city is home to campuses of Aix-Marseille University and part of one of the largest metropolitan conurbations in France. Marseille is the second largest city in France after Paris and the centre of the third largest metropolitan area in France after Paris, further east still are the Sainte-Baume, the city of Toulon and the French Riviera. To the north of Marseille, beyond the low Garlaban and Etoile mountain ranges, is the 1,011 m Mont Sainte Victoire. To the west of Marseille is the artists colony of lEstaque, further west are the Côte Bleue, the Gulf of Lion. The airport lies to the north west of the city at Marignane on the Étang de Berre, the citys main thoroughfare stretches eastward from the Old Port to the Réformés quarter. Two large forts flank the entrance to the Old Port—Fort Saint-Nicolas on the south side and Fort Saint-Jean on the north. Further out in the Bay of Marseille is the Frioul archipelago which comprises four islands, one of which, If, is the location of Château dIf, the main commercial centre of the city intersects with the Canebière at rue St Ferréol and the Centre Bourse. To the south east of central Marseille in the 6th arrondissement are the Prefecture and the fountain of Place Castellane. To the south west are the hills of the 7th arrondissement, the railway station—Gare de Marseille Saint-Charles—is north of the Centre Bourse in the 1st arrondissement, it is linked by the Boulevard dAthènes to the Canebière. Marseille has a Mediterranean climate with mild, humid winters and warm to hot, december, January, and February are the coldest months, averaging temperatures of around 12 °C during the day and 4 °C at night. Marseille is officially the sunniest major city in France with over 2,900 hours of sunshine while the average sunshine in France is around 1,950 hours, less frequent is the Sirocco, a hot, sand-bearing wind, coming from the Sahara Desert. Snowfalls are infrequent, over 50% of years do not experience a single snowfall, Massalia, whose name was probably adapted from an existing language related to Ligurian, was the first Greek settlement in France. It was established within modern Marseille around 600 BC by colonists coming from Phocaea on the Aegean coast of Asia Minor. The connection between Massalia and the Phoceans is mentioned in Thucydidess Peloponnesian War, he notes that the Phocaean project was opposed by the Carthaginians, the founding of Massalia has also been recorded as a legend. Protis was invited inland to a banquet held by the chief of the local Ligurian tribe for suitors seeking the hand of his daughter Gyptis in marriage, at the end of the banquet, Gyptis presented the ceremonial cup of wine to Protis, indicating her unequivocal choice
7.
Jupiter
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Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, Jupiter and Saturn are gas giants, the other two giant planets, Uranus and Neptune are ice giants. Jupiter has been known to astronomers since antiquity, the Romans named it after their god Jupiter. Jupiter is primarily composed of hydrogen with a quarter of its mass being helium and it may also have a rocky core of heavier elements, but like the other giant planets, Jupiter lacks a well-defined solid surface. Because of its rotation, the planets shape is that of an oblate spheroid. The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence, a prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere, Jupiter has at least 67 moons, including the four large Galilean moons discovered by Galileo Galilei in 1610. Ganymede, the largest of these, has a greater than that of the planet Mercury. Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. In late February 2007, Jupiter was visited by the New Horizons probe, the latest probe to visit the planet is Juno, which entered into orbit around Jupiter on July 4,2016. Future targets for exploration in the Jupiter system include the probable ice-covered liquid ocean of its moon Europa, Earth and its neighbor planets may have formed from fragments of planets after collisions with Jupiter destroyed those super-Earths near the Sun. Astronomers have discovered nearly 500 planetary systems with multiple planets, Jupiter moving out of the inner Solar System would have allowed the formation of inner planets, including Earth. Jupiter is composed primarily of gaseous and liquid matter and it is the largest of the four giant planets in the Solar System and hence its largest planet. It has a diameter of 142,984 km at its equator, the average density of Jupiter,1.326 g/cm3, is the second highest of the giant planets, but lower than those of the four terrestrial planets. Jupiters upper atmosphere is about 88–92% hydrogen and 8–12% helium by percent volume of gas molecules, a helium atom has about four times as much mass as a hydrogen atom, so the composition changes when described as the proportion of mass contributed by different atoms. Thus, Jupiters atmosphere is approximately 75% hydrogen and 24% helium by mass, the atmosphere contains trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, the outermost layer of the atmosphere contains crystals of frozen ammonia. The interior contains denser materials - by mass it is roughly 71% hydrogen, 24% helium, through infrared and ultraviolet measurements, trace amounts of benzene and other hydrocarbons have also been found
8.
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
9.
Chandra X-ray Observatory
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The Chandra X-ray Observatory, previously known as the Advanced X-ray Astrophysics Facility, is a Flagship-class space observatory launched on STS-93 by NASA on July 23,1999. Chandra is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, since the Earths atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes, therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2017, Chandra is one of the Great Observatories, along with the Hubble Space Telescope, Compton Gamma Ray Observatory, and the Spitzer Space Telescope. The telescope is named after astrophysicist Subrahmanyan Chandrasekhar, in 1976 the Chandra X-ray Observatory was proposed to NASA by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the year at Marshall Space Flight Center. In the meantime, in 1978, NASA launched the first imaging X-ray telescope, Einstein, work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned, four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAFs planned orbit was changed to a one, reaching one third of the way to the Moons at its farthest point. This eliminated the possibility of improvement or repair by the space shuttle, AXAF was assembled and tested by TRW in Redondo Beach, California. AXAF was renamed Chandra as part of a contest held by NASA in 1998, the contest winners, Jatila van der Veen and Tyrel Johnson, suggested the name in honor of Nobel Prize–winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. He is known for his work in determining the mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars. Originally scheduled to be launched in December 1998, the spacecraft was delayed several months, Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in Cambridge, Massachusetts, with assistance from MIT, the ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the focal plane during passages. Although Chandra was initially given a lifetime of 5 years. Physically Chandra could last much longer, a study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years. In July 2008, the International X-ray Observatory, a joint project between ESA, NASA and JAXA, was proposed as the next major X-ray observatory but was later cancelled, ESA later resurrected the project as the Advanced Telescope for High Energy Astrophysics with a proposed launch in 2028. The data gathered by Chandra has greatly advanced the field of X-ray astronomy, in the Crab Nebula, another supernova remnant, Chandra showed a never-before-seen ring around the central pulsar and jets that had only been partially seen by earlier telescopes
10.
Hubble Space Telescope
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The Hubble Space Telescope is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. Although not the first space telescope, Hubble is one of the largest and most versatile, with a 2. 4-meter mirror, Hubbles four main instruments observe in the near ultraviolet, visible, and near infrared spectra. Hubbles orbit outside the distortion of Earths atmosphere allows it to take extremely high-resolution images, Hubble has recorded some of the most detailed visible light images ever, allowing a deep view into space and time. Many Hubble observations have led to breakthroughs in astrophysics, such as determining the rate of expansion of the universe. The HST was built by the United States space agency NASA, the Space Telescope Science Institute selects Hubbles targets and processes the resulting data, while the Goddard Space Flight Center controls the spacecraft. Space telescopes were proposed as early as 1923, Hubble was funded in the 1970s, with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the Challenger disaster. When finally launched in 1990, Hubbles main mirror was found to have been ground incorrectly, the optics were corrected to their intended quality by a servicing mission in 1993. Hubble is the telescope designed to be serviced in space by astronauts. After launch by Space Shuttle Discovery in 1990, five subsequent Space Shuttle missions repaired, upgraded, the fifth mission was canceled on safety grounds following the Columbia disaster. However, after spirited public discussion, NASA administrator Mike Griffin approved the fifth servicing mission, the telescope is operating as of 2017, and could last until 2030–2040. Its scientific successor, the James Webb Space Telescope, is scheduled for launch in 2018, the history of the Hubble Space Telescope can be traced back as far as 1946, to the astronomer Lyman Spitzers paper Astronomical advantages of an extraterrestrial observatory. In it, he discussed the two advantages that a space-based observatory would have over ground-based telescopes. First, the resolution would be limited only by diffraction, rather than by the turbulence in the atmosphere. Second, a telescope could observe infrared and ultraviolet light. Spitzer devoted much of his career to pushing for the development of a space telescope, space-based astronomy had begun on a very small scale following World War II, as scientists made use of developments that had taken place in rocket technology. An orbiting solar telescope was launched in 1962 by the United Kingdom as part of the Ariel space program, oAO-1s battery failed after three days, terminating the mission. It was followed by OAO-2, which carried out observations of stars and galaxies from its launch in 1968 until 1972. The continuing success of the OAO program encouraged increasingly strong consensus within the community that the LST should be a major goal
