Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Commands 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in Brevard County, Florida, CCAFS is the primary head of Americas Eastern Range with three launch pads currently active. The Cape Canaveral Air Force Station Skid Strip provides a 10, 000-foot runway close to the launch complexes for military airlift aircraft delivering heavy, a number of American space exploration firsts were launched from CCAFS, including the first U. S. Earth satellite, first U. S. astronaut, first U. S. astronaut in orbit, first two-man U. S. spacecraft, first U. S. unmanned lunar landing, and first three-man U. S. spacecraft. The CCAFS area had used by the United States government to test missiles since 1949. On June 1,1948, the U. S. Navy transferred the former Banana River Naval Air Station to the U. S. Air Force, with USAF renaming the facility the Joint Long Range Proving Ground Base on June 10,1949.
On October 1,1949, the Joint Long Range Proving Ground Base was transferred from the Air Materiel Command to the Air Force Division of the Joint Long Range Proving Ground. On May 17,1950, the base was renamed the Long Range Proving Ground Base, in 1951, the Air Force established the Air Force Missile Test Center. Early American sub-orbital rocket flights were achieved at Cape Canaveral in 1956 and these flights occurred shortly after sub-orbital flights launched from White Sands Missile Range, such as the Viking 12 sounding rocket on February 4,1955. Following the Soviet Unions successful Sputnik 1, the US attempted its first launch of a satellite from Cape Canaveral on December 6,1957. However, the rocket carrying Vanguard TV3 blew up on the launch pad, NASA was founded in 1958, and Air Force crews launched missiles for NASA from the Cape, known as Cape Canaveral Missile Annex. The row of Titan and Atlas launch pads along the coast came to be known as Missile Row in the 1960s, nASAs first manned spaceflight program was prepared for launch from Canaveral by U. S.
Air Force crews. Mercurys objectives were to place a spacecraft in Earth orbit, investigate human performance and ability to function in space. Suborbital flights were launched by derivatives of the Armys Redstone missile from LC-5, Orbital flights were launched by derivatives of the Air Forces larger Atlas D missile from LC-14. The first American in orbit was John Glenn on February 20,1962, three more orbital flights followed through May 1963. Flight control for all Mercury missions was provided at the Mercury Control Center located at Canaveral near LC-14 and he had convinced Gov. C. Farris Bryant to change the name of Cape Canaveral to Cape Kennedy and this resulted in some confusion in public perception, which conflated the two. This name was used through the Gemini and early Apollo programs, the geographical name change proved to be unpopular, owing to the historical longevity of Cape Canaveral
Mariner program
The program included a number of firsts, including the first planetary flyby, the first planetary orbiter, and the first gravity assist maneuver. Of the ten vehicles in the Mariner series, seven were successful, other Mariner-based spacecraft, launched since Voyager, included the Magellan probe to Venus, and the Galileo probe to Jupiter. A second-generation Mariner spacecraft, called the Mariner Mark II series, eventually evolved into the Cassini–Huygens probe, the total cost of the Mariner program was approximately $554 million. Mariner 2 was based on the Ranger Lunar probe, all of the Mariners launched after Mariner 2 had four solar panels for power, except for Mariner 10, which had two. Additionally, all except Mariner 1, Mariner 2 and Mariner 5 had TV cameras, the first five Mariners were launched on Atlas-Agena rockets, while the last five used the Atlas-Centaur. All Mariner-based probes after Mariner 10 used the Titan IIIE, Titan IV unmanned rockets or the Space Shuttle with a solid-fueled Inertial Upper Stage and multiple planetary flybys.
Mariners, Mariner 1 Mariner 2 Mariner 3 Mariner 4 Mariner 5 Mariner 6 Mariner 7 Mariner 8 Mariner 9 Mariner 10 Mariner 1, a secondary objective was to make interplanetary magnetic field and/or particle measurements on the way to, and in the vicinity of, Venus. Mariner 1 was launched on July 22,1962, but was destroyed approximately 5 minutes after liftoff by the Air Force Range Safety Officer when its malfunctioning Atlas-Agena rocket went off course. Mariner 2 was launched on August 27,1962, sending it on a 3½-month flight to Venus, the mission was a success, and Mariner 2 became the first spacecraft to have flown by another planet. Mariner 2 – Defunct after successful mission, occupies a heliocentric orbit, sisterships Mariner 3 and Mariner 4 were Mars flyby missions. Mariner 3 was lost when the vehicles nose fairing failed to jettison. Mariner 4, launched on November 28,1964, was the first successful flyby of the planet Mars, Mariner 4 – Communications lost after bombardment by micrometeoroids.
The Mariner 5 spacecraft was launched to Venus on June 14,1967, Mariners 6 and 7 were identical teammates in a two-spacecraft mission to Mars. Mariner 6 was launched on February 24,1969, followed by Mariner 7 on March 21,1969 and they flew over the equator and southern hemisphere of the planet Mars. Mariner 8 and Mariner 9 were identical sister craft designed to map the Martian surface simultaneously and its identical sister craft, Mariner 9, was launched in May 1971 and became the first artificial satellite of Mars. It entered Martian orbit in November 1971 and began photographing the surface and analyzing the atmosphere with its infrared, in Areocentric orbit until at least 2022 when it is projected to fall out of orbit and into the Martian atmosphere. It was the first spacecraft to encounter two planets at close range, and for 33 years the spacecraft to photograph Mercury in closeup. Mission, charged particles, magnetic fields, radio occultation and celestial mechanics Status, Mariner Jupiter-Saturn was approved in 1972 after the cancellation of the Grand Tour program, which proposed visiting all the outer planets with multiple spacecraft
Atmosphere
An atmosphere is a layer of gases surrounding a planet or other material body, that is held in place by the gravity of that body. An atmosphere is likely to be retained if the gravity it is subject to is high. The atmosphere of Earth is mostly composed of nitrogen, argon with carbon dioxide, the atmosphere helps protect living organisms from genetic damage by solar ultraviolet radiation, solar wind and cosmic rays. Its current composition is the product of billions of years of modification of the paleoatmosphere by living organisms. The term stellar atmosphere describes the region of a star. Stars with sufficiently low temperatures may form compound molecules in their outer atmosphere, Atmospheric pressure is the force per unit area that is applied perpendicularly to a surface by the surrounding gas. It is determined by a gravitational force in combination with the total mass of a column of gas above a location. On Earth, units of air pressure are based on the recognized standard atmosphere. It is measured with a barometer, the pressure of an atmospheric gas decreases with altitude due to the diminishing mass of gas above.
The height at which the pressure from an atmosphere declines by a factor of e is called the height and is denoted by H. For such an atmosphere, the pressure declines exponentially with increasing altitude. However, atmospheres are not uniform in temperature, so the determination of the atmospheric pressure at any particular altitude is more complex. Surface gravity, the force that holds down an atmosphere, differs significantly among the planets, for example, the large gravitational force of the giant planet Jupiter is able to retain light gases such as hydrogen and helium that escape from objects with lower gravity. Thus, the distant and cold Titan and Pluto are able to retain their atmospheres despite their relatively low gravities, rogue planets, may retain thick atmospheres. Since a collection of gas molecules may be moving at a range of velocities. Lighter molecules move faster than ones with the same thermal kinetic energy. It is thought that Venus and Mars may have lost much of their water when, after being photo dissociated into hydrogen and oxygen by solar ultraviolet, Earths magnetic field helps to prevent this, as, the solar wind would greatly enhance the escape of hydrogen.
However, over the past 3 billion years Earth may have lost gases through the polar regions due to auroral activity
Atlas-Centaur
The Atlas-Centaur was an American expendable launch system derived from the SM-65 Atlas D missile. Launches were conducted from Launch Complex 36 at Cape Canaveral Air Force Station, the manufacturer of the Atlas, developed the Centaur upper stage specifically for that booster, sharing its inflated balloon skin. It was the first production rocket stage to liquid hydrogen. Despite high performance, LH2 nonetheless had problems because it had to be chilled at extremely low temperatures, the progress made during the aborted venture was picked up by Convair and others for rocket stage use. Although originally under ARPA supervision, Centaur was transferred to NASA in July 1959, the Air Force retained ultimate supervision in part because they intended to use Centaur for an ambitious network of military communications satellites known as ADVENT. A constellation of ten satellites would provide round-the-clock instant communications for the three branches of the US military. The first three would be launched on an Atlas-Agena, the remainder on Centaur, ADVENT never got off the drawing board, but Centaur quickly found a use for several NASA planetary probe projects, namely Mariner and Surveyor.
Centaur development was somewhat difficult by the insistence on modifying Atlas components rather than develop totally new ones. This was done for time and budget reasons and because it allowed the Centaur to be manufactured on the existing Atlas assembly line at Convair, the engines were manufactured by Pratt and Whitney. He preferred the use of a Saturn-Agena combo for planetary probes and this and lack of funds caused the project to drag on far longer than intended. Under original timetables, Centaur was to make its first flight in January 1961, in April, NASA Lunar and Planetary Programs director Oran Nicks suggested that it might be necessary to use Atlas-Agena for Mariner instead. By September, there was no launch date anywhere in sight while program costs rose higher and higher, the first Atlas-Centaur, Vehicle F-1, arrived at Cape Canaveral in October 1961 and was erected at the newly completed LC-36A, a pad built specifically for A/C flights. Flight plans amounted to more than a single burn with a partially fueled Centaur.
The mission at last got under way on 8 May 1962, all went well until about T+53 seconds when the Centaur stage ruptured and disintegrated, taking the Atlas with it in a matter of seconds. It was unclear what had caused the failure at first, as tracking camera footage showed a large white cloud enveloping the booster followed by explosion of the entire launch vehicle. Scott Carpenters Mercury flight was only days away, and if the failure were caused by the Atlas, it could mean significant delays for that mission, which used a similar Atlas D derived booster. However, analysis of data and closer examination of the launch films quickly confirmed the Centaur as the source of trouble. The failure was determined to be caused by a panel that ripped off the Centaur during ascent, causing the LH2 to overheat
Atmosphere of Mars
The atmosphere of Mars is the layer of gases surrounding Mars. It is composed mostly of carbon dioxide, the atmospheric pressure on the Martian surface averages 600 pascals, about 0. 6% of Earths mean sea level pressure of 101.3 kilopascals. It ranges from a low of 30 pascals on Olympus Monss peak to over 1,155 pascals in the depths of Hellas Planitia and this pressure is well below the Armstrong limit for the unprotected human body. Marss atmospheric mass of 25 teratonnes compares to Earths 5148 teratonnes with a height of about 11 kilometres versus Earths 7 kilometres. On 16 December 2014, NASA reported detecting an increase, decrease. Organic chemicals have been detected in powder drilled from a rock by the Curiosity rover, on 18 March 2015, NASA reported the detection of an aurora that is not fully understood and an unexplained dust cloud in the atmosphere of Mars. On 4 April 2015, NASA reported studies, based on measurements by the Sample Analysis at Mars instrument on the Curiosity rover, of the Martian atmosphere using xenon and argon isotopes.
This was further supported by results from the MAVEN orbiter circling Mars, Marss atmosphere is composed of the following layers, Typically stated to start at 200 km and higher, this region is where the last wisps of atmosphere merge into the vacuum of space. There is no boundary where the atmosphere ends, it just tapers away. Upper atmosphere, or thermosphere, A region with high temperatures. Atmospheric gases start to separate from each other at these altitudes, middle atmosphere, The region in which Marss jetstream flows. Lower atmosphere, A relatively warm region affected by heat from airborne dust, there is a complicated ionosphere, and a seasonal ozone layer over the south pole. The MAVEN spacecraft determined in 2015 that there is a layered structure present in both neutral gases and ion densities. Spectroscopic observations in the 1860s and 1870s led many to think the atmosphere of Mars is similar to Earths, in 1894, spectral analysis and other qualitative observations by William Wallace Campbell suggested Mars resembles the Moon, which has no appreciable atmosphere, in many respects.
In 1926, photographic observations by William Hammond Wright at the Lick Observatory allowed Donald Howard Menzel to discover evidence of Marss atmosphere. The main component of the atmosphere of Mars is carbon dioxide at 95. 9%, each pole is in continual darkness during its hemispheres winter, and the surface gets so cold that as much as 25% of the atmospheric CO2 condenses at the polar caps into solid CO2 ice. When the pole is exposed to sunlight during summer, the CO2 ice sublimes back into the atmosphere. This process leads to a significant annual variation in the atmospheric pressure and it has been suggested that Mars had a much thicker and wetter atmosphere early in its history
Nitrogen
Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772, although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. Nitrogen is the lightest member of group 15 of the periodic table, the name comes from the Greek πνίγειν to choke, directly referencing nitrogens asphyxiating properties. It is an element in the universe, estimated at about seventh in total abundance in the Milky Way. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2, dinitrogen forms about 78% of Earths atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids, in the nucleic acids, the human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen and hydrogen.
The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, many industrially important compounds, such as ammonia, nitric acid, organic nitrates, and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen, the second strongest bond in any diatomic molecule. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Apart from its use in fertilisers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric, Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many notable nitrogen-containing drugs, such as the caffeine and morphine or the synthetic amphetamines. Nitrogen compounds have a long history, ammonium chloride having been known to Herodotus. They were well known by the Middle Ages, alchemists knew nitric acid as aqua fortis, as well as other nitrogen compounds such as ammonium salts and nitrate salts.
The mixture of nitric and hydrochloric acids was known as aqua regia, celebrated for its ability to dissolve gold, the discovery of nitrogen is attributed to the Scottish physician Daniel Rutherford in 1772, who called it noxious air. Though he did not recognise it as a different chemical substance, he clearly distinguished it from Joseph Blacks fixed air. The fact that there was a component of air that does not support combustion was clear to Rutherford, Nitrogen was studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as air or azote, from the Greek word άζωτικός. In an atmosphere of nitrogen, animals died and flames were extinguished
Valles Marineris
Valles Marineris is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 4,000 km long,200 km wide and up to 7 km deep, Valles Marineris is one of the largest canyons of the Solar System, surpassed in length only by the rift valleys of Earth. Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge and it has been recently suggested that Valles Marineris is a large tectonic crack in the Martian crust. Most researchers agree that this formed as the crust thickened in the Tharsis region to the west, near the eastern flanks of the rift, there appear to be channels that may have been formed by water or carbon dioxide. It has proposed that Valles Marineris is a large channel formed by the erosion of lava flowing from the flank of Pavonis Mons. There have been many different theories about the formation of Valles Marineris that have changed over the years, ideas in the 1970s were erosion by water or thermokarst activity, which is the melting of permafrost in glacial climes.
Many scientists agree that there was liquid water flowing on the Martian surface in the past, Valles Marineris may have been enlarged by flowing water at this time. Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma, around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. The most agreed upon theory today is that Valles Marineris was formed by rift faults like the East African Rift, made bigger by erosion and it has been proposed that Valles Marineris was formed by flowing lava. The formation of Valles Marineris is thought to be tied with the formation of the Tharsis Bulge. The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, stage two consisted of more volcanism and a loss of isostatic equilibrium, the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures formed, stage three mainly consisted of more volcanism and asteroid impacts.
The crust, having reached its failure point, just stayed in place. Landslides have left numerous deposits on the floor of Valles Marineris, possible triggers of landslides are quakes caused by tectonic activity or impact events. Both types of events release seismic waves that accelerate the ground at, Mars is much less tectonically active than Earth, and Mars-quakes are unlikely to have provided seismic waves of the required magnitude. Most sizable craters on Mars date to the Late Heavy Bombardment,4.1 to 3.8 billion years ago, and are older than the landslide deposits in Valles Marineris. However, three craters have been identified, on the basis of their proximity and dates, as ones whose formation may have caused some of the landslides, it contains canyons that run in different directions surrounding large blocks of older terrain. Most of the parts of the blocks are composed of younger fractured material thought to be of volcanic origin associated with the Tharsis bulge
International Standard Book Number
The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay.
The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces.
Separating the parts of a 10-digit ISBN is done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
Jet Propulsion Laboratory
The Jet Propulsion Laboratory is a federally funded research and development center and NASA field center in La Cañada Flintridge and Pasadena, United States. The JPL is managed by the nearby California Institute of Technology for NASA, the laboratorys primary function is the construction and operation of planetary robotic spacecraft, though it conducts Earth-orbit and astronomy missions. It is responsible for operating NASAs Deep Space Network and they are responsible for managing the JPL Small-Body Database, and provides physical data and lists of publications for all known small Solar System bodies. The JPLs Space Flight Operations Facility and Twenty-Five-Foot Space Simulator are designated National Historic Landmarks, JPL traces its beginnings to 1936 in the Guggenheim Aeronautical Laboratory at the California Institute of Technology when the first set of rocket experiments were carried out in the Arroyo Seco. Malinas thesis advisor was engineer/aerodynamicist Theodore von Kármán, who arranged for U. S.
Army financial support for this GALCIT Rocket Project in 1939. In 1941, Parsons, Martin Summerfield, in 1943, von Kármán, Malina and Forman established the Aerojet Corporation to manufacture JATO motors. The project took on the name Jet Propulsion Laboratory in November 1943, during JPLs Army years, the laboratory developed two deployed weapon systems, the MGM-5 Corporal and MGM-29 Sergeant intermediate range ballistic missiles. These missiles were the first US ballistic missiles developed at JPL and it developed a number of other weapons system prototypes, such as the Loki anti-aircraft missile system, and the forerunner of the Aerobee sounding rocket. At various times, it carried out testing at the White Sands Proving Ground, Edwards Air Force Base. A lunar lander was developed in 1938-39 which influenced design of the Apollo Lunar Module in the 1960s. The team lost that proposal to Project Vanguard, and instead embarked on a project to demonstrate ablative re-entry technology using a Jupiter-C rocket.
They carried out three successful flights in 1956 and 1957. Using a spare Juno I, the two organizations launched the United States first satellite, Explorer 1, on February 1,1958, JPL was transferred to NASA in December 1958, becoming the agencys primary planetary spacecraft center. JPL engineers designed and operated Ranger and Surveyor missions to the Moon that prepared the way for Apollo, JPL led the way in interplanetary exploration with the Mariner missions to Venus and Mercury. In 1998, JPL opened the Near-Earth Object Program Office for NASA, as of 2013, it has found 95% of asteroids that are a kilometer or more in diameter that cross Earths orbit. JPL was early to employ women mathematicians, in the 1940s and 1950s, using mechanical calculators, women in an all-female computations group performed trajectory calculations. In 1961, JPL hired Dana Ulery as their first woman engineer to work alongside male engineers as part of the Ranger and Mariner mission tracking teams, when founded, JPLs site was a rocky flood-plain just outside the city limits of Pasadena.
Almost all of the 177 acres of the U. S, the city of La Cañada Flintridge, California was incorporated in 1976, well after JPL attained international recognition with a Pasadena address
Water on Mars
Almost all water on Mars today exists as ice, though it exists in small quantities as vapor in the atmosphere and occasionally as low-volume liquid brines in shallow Martian soil. The only place where water ice is visible at the surface is at the polar ice cap. Abundant water ice is present beneath the permanent carbon dioxide ice cap at the Martian south pole. More than five million kilometers of ice have been identified at or near the surface of modern Mars. Even more ice is likely to be locked away in the deep subsurface, some liquid water may occur transiently on the Martian surface today, but only under certain conditions. Water has apparently flowed across the surface for short periods at various intervals more recently in Mars history, Many lines of evidence indicate that water is abundant on Mars and has played a significant role in the planets geologic history. The present-day inventory of water on Mars can be estimated from spacecraft imagery, remote sensing techniques, numerous geomorphic features suggest the presence of ground ice and the movement of ice in glaciers, both in the recent past and present.
Gullies and slope lineae along cliffs and crater walls suggest that flowing water continues to shape the surface of Mars, in addition, Mars lacks a thick atmosphere, ozone layer, and magnetic field, allowing solar and cosmic radiation to strike the surface unimpeded. The damaging effects of ionizing radiation on cellular structure is one of the prime limiting factors on the survival of life on the surface. Therefore, the best potential locations for discovering life on Mars may be in subsurface environments. On November 22,2016, NASA reported finding a large amount of ice on the planet Mars – the volume of water detected is equivalent to the volume of water in Lake Superior. Understanding water on Mars is vital to assess the potential for harboring life. For this reason, Follow the Water was the theme of NASAs Mars Exploration Program in the first decade of the 21st century. The ESAs Mars Express orbiter has provided data in this quest. The Mars Odyssey, Mars Express, MER Opportunity rover, MRO, and Mars Science Lander Curiosity rover are still sending back data from Mars, the notion of water on Mars preceded the space age by hundreds of years.
Early telescopic observers correctly assumed that the polar caps and clouds were indications of waters presence. By the start of the 20th century, most astronomers recognized that Mars was far colder and drier than Earth, the presence of oceans was no longer accepted, so the paradigm changed to an image of Mars as a dying planet with only a meager amount of water. The dark areas, which could be seen to change seasonally, were now thought to be tracts of vegetation, although generating tremendous public enthusiasm, Lowells ideas were rejected by most astronomers
Equator
The Equator usually refers to an imaginary line on the Earths surface equidistant from the North Pole and South Pole, dividing the Earth into the Northern Hemisphere and Southern Hemisphere. The Equator is about 40,075 kilometres long, some 78. 7% lies across water and 21. 3% over land, other planets and astronomical bodies have equators similarly defined. Generally, an equator is the intersection of the surface of a sphere with the plane that is perpendicular to the spheres axis of rotation. The latitude of the Earths equator is by definition 0° of arc, the equator is the only line of latitude which is a great circle — that is, one whose plane passes through the center of the globe. The plane of Earths equator when projected outwards to the celestial sphere defines the celestial equator, in the cycle of Earths seasons, the plane of the equator passes through the Sun twice per year, at the March and September equinoxes. To an observer on the Earth, the Sun appears to travel North or South over the equator at these times, light rays from the center of the Sun are perpendicular to the surface of the Earth at the point of solar noon on the Equator.
Locations on the Equator experience the quickest sunrises and sunsets because the sun moves nearly perpendicular to the horizon for most of the year. The Earth bulges slightly at the Equator, the diameter of the Earth is 12,750 kilometres. Because the Earth spins to the east, spacecraft must launch to the east to take advantage of this Earth-boost of speed, seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earths axis relative to the plane of revolution. During the year the northern and southern hemispheres are inclined toward or away from the sun according to Earths position in its orbit, the hemisphere inclined toward the sun receives more sunlight and is in summer, while the other hemisphere receives less sun and is in winter. At the equinoxes, the Earths axis is not tilted toward the sun, instead it is perpendicular to the sun meaning that the day is about 12 hours long, as is the night, across the whole of the Earth. Near the Equator there is distinction between summer, autumn, or spring.
The temperatures are usually high year-round—with the exception of high mountains in South America, the temperature at the Equator can plummet during rainstorms. In many tropical regions people identify two seasons, the wet season and the dry season, but many places close to the Equator are on the oceans or rainy throughout the year, the seasons can vary depending on elevation and proximity to an ocean. The Equator lies mostly on the three largest oceans, the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean. The highest point on the Equator is at the elevation of 4,690 metres, at 0°0′0″N 77°59′31″W and this is slightly above the snow line, and is the only place on the Equator where snow lies on the ground. At the Equator the snow line is around 1,000 metres lower than on Mount Everest, the Equator traverses the land of 11 countries, it passes through two island nations, though without making a landfall in either. Starting at the Prime Meridian and heading eastwards, the Equator passes through, Despite its name, its island of Annobón is 155 km south of the Equator, and the rest of the country lies to the north
Photovoltaic system
A photovoltaic system, PV system or solar power system, is a power system designed to supply usable solar power by means of photovoltaics. It may use a tracking system to improve the systems overall performance and include an integrated battery solution. Strictly speaking, a solar array only encompasses the ensemble of solar panels, the part of the PV system. Moreover, PV systems convert light directly into electricity and shouldnt be confused with other technologies, such as concentrated solar power or solar thermal, used for heating and cooling. PV systems range from small, rooftop-mounted or building-integrated systems with capacities from a few to tens of kilowatts. Nowadays, most PV systems are grid-connected, while off-grid or stand-alone systems only account for a portion of the market. A rooftop system recoups the energy for its manufacturing and installation within 0.7 to 2 years. Due to the growth of photovoltaics, prices for PV systems have rapidly declined in recent years. However, they vary by market and the size of the system, a photovoltaic system converts the suns radiation into usable electricity.
It comprises the solar array and the balance of system components, other distinctions may include, systems with microinverters vs. central inverter, systems using crystalline silicon vs. thin-film technology, and systems with modules from Chinese vs. About 99 percent of all European and 90 percent of all U. S. solar power systems are connected to the grid, while off-grid systems are somewhat more common in Australia. PV systems rarely use battery storage and this may change soon, as government incentives for distributed energy storage are being implemented and investments in storage solutions are gradually becoming economically viable for small systems. A solar array of a typical residential PV system is rack-mounted on the roof, rather than integrated into the roof or facade of the building, utility-scale solar power stations are ground-mounted, with fixed tilted solar panels rather than using expensive tracking devices. Crystalline silicon is the predominant material used in 90 percent of worldwide produced solar modules, about 70 percent of all solar cells and modules are produced in China and Taiwan, leaving only 5 percent to European and US-manufacturers. S.
Which are less opposed to ground-mounted solar farms and cost-effectiveness is more emphasized by investors, driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics is declining continuously. There are several million PV systems distributed all over the world, mostly in Europe, in exceptionally irradiated locations, or when thin-film technology is used, the so-called energy payback time decreases to one year or less. Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have greatly supported installations of PV systems in many countries. As of 2015, the fast-growing global PV market is approaching the 200 GW mark – about 40 times the installed capacity of 2006
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