NASA

National Aeronautics and Space Administration

Aircraft Picture - NASA insignia Motto: For the Benefit of All

Agency overview:
Formed: July 29, 1958 (1958-07-29) (53 years ago)
Preceding agency: NACA (1915-1958)
Jurisdiction: United States government
Headquarters: Washington, D.C.>br /> Employees: 18,800+
Annual budget: US$17.6 billion (FY 2009)
Agency executives: Charles Bolden, administrator Lori Garver, deputy administrator
Website:
: nasa.gov

For other uses, see NASA (disambiguation). For news about NASA or space, see Wikinews space portal

Coordinates: 38°52′59″N 77°0′59″W / 38.88306°N 77.01639°W / 38.88306; -77.01639

The National Aeronautics and Space Administration (NASA) is an executive branch agency of the United States government, responsible for the nation's civilian space program and aeronautics and aerospace research. Since February 2006, NASA's self-described mission statement is to "pioneer the future in space exploration, scientific discovery and aeronautics research." On September 14, 2011, NASA announced that it had selected the design of a new Space Launch System that it said would take the agency's astronauts farther into space than ever before and provide the cornerstone for future human space exploration efforts by the U.S.

NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for Aeronautics (NACA). The agency became operational on October 1, 1958. U.S. space exploration efforts have since been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is developing the manned Multi-Purpose Crew Vehicle. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs. NASA shares data with various national and international organizations such as from the Greenhouse Gases Observing Satellite.

Creation

From 1946, the NACA had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch an artificial satellite for the International Geophysical Year (1957-58). An effort for this was the American Project Vanguard. After the Soviet space program's launch of the world's first artificial satellite (Sputnik 1) on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts. The U.S. Congress, alarmed by the perceived threat to national security and technological leadership (known as the "Sputnik crisis"), urged immediate and swift action; President Dwight D. Eisenhower and his advisers counseled more deliberate measures. This led to an agreement that a new federal agency mainly based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency (ARPA) was also created at this time to develop space technology for military application.

On July 29, 1958, Eisenhower signed the National Aeronautics and Space Act, establishing NASA. When it began operations on October 1, 1958, NASA absorbed the 46-year-old NACA intact; its 8,000 employees, an annual budget of US$100 million, three major research laboratories (LaRC, ARC, and LFPL) and two small test facilities. A NASA seal was approved by President Eisenhower in 1959. Elements of the ABMA and the NRL were incorporated into NASA. A significant contributor to NASA's entry into the Space Race with the Soviet Union was the technology from the German rocket program (led by Werner von Braun, who was now working for ABMA) which in turn incorporated the technology of American scientist Robert Goddard's earlier works. Earlier research efforts within the U.S. Air Force and many of ARPA's early space programs were also transferred to NASA. In December 1958, NASA gained control of the JPL, a contractor facility operated by the Caltech.

NASA missions

The most important part of NASA's activities are its missions; they can be divided into manned and unmanned. The latter can be either independent, carrying scientific equipment, or supportive, testing equipment for manned flights. In the beginning, NASA’s missions focused on the spacerace with the Soviet Union, which won the first round, but later USA took the initiative and won the final race to the Moon. The unmanned missions have until now explored most of the solar system. They have also brought telescopes for deep space exploration into orbit around the Earth together with satellites for studying Earth itself.

Manned missions

The rocket planes experiments started by NACA was taken a step further by NASA which used them as support for spaceflights, the first of which was one-manned and launched by military rockets. When the attention turned to reaching the Moon, the solution chosen was complicated but also the most economical. Supportive projects, both manned and unmanned were introduced and bigger rockets together with spacecraft and moonlander developed. The Moon landing and end of the space race meant a reduction of NASA’s activities. Space stations of a more or less permanent nature, suggested already during the spacerace, were built and an international cooperation was introduced in an attempt to both bring nations together and at the same time share the high costs of space missions. In all, more than 100 manned missions have been made by NASA since 1958.

Airplane Picture - X-15A-2 leaving B-52, 1967

X-15 rocket plane (1959-1968)

The NACA XS-1 (Bell X-1) was followed by additional experimental vehicles, including the X-15 in cooperation with the US Air Force and US Navy. The design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems. When the spacerace began the main objective was to get a person into space as soon as possible, therefore the simplest spacecraft that could be launched by existing rockets was favored. This led to the choice of a small capsule spacecraft while rocket plane proposals like a modified X-15 were turned down. Instead X-15 was used for development of techniques and equipment of value for the space missions. This included jets for changing the orientation of a spacecraft, space suits for astronauts and horizon definition for navigation. Nearly 200 flights were made between 1959 and 1968 allowing NASA to collect data vital not only to the spacerace but also the design of the Space Shuttle. The altitude record for X-15 was 354,200 feet (107.96 km).

Project Mercury (1959-1963, manned missions from 1961)

Airplane Picture - Launch on May 5, 1961. The spacecraft is the black cone on top

Freedom 7, the first manned mission by NASA

Project Mercury was initiated in 1958 and started NASA down the path of human space exploration with missions designed to discover if man could survive in space. Representatives from the U.S. Army, Navy, and Air Force were selected to provide assistance to NASA. Pilot selections were facilitated through coordination with U.S. defense research, contracting, and military test pilot programs. On May 5, 1961, astronaut Alan Shepard became the first American in space when he piloted Mercury-Redstone 3, called Freedom 7, on a 15-minute suborbital flight. John Glenn became the first American to orbit the Earth on February 20, 1962 during the flight of Friendship 7.

At that time the Soviet Union had taken the lead in the space race. In April 1961, one month before Alan Shepard, cosmonaut Yuri Gagarin became the first person in space when he orbited the Earth once in Vostok 1. Further in August the same year, the follower Vostok 2 made a day long orbital flight which led to cancelling of additional American suborbital missions; they were no longer enough. Three more orbital flights were made by the Mercury project after Friendship 7, the last in 1963. Three additional orbital flights were cancelled since it was clear that the Mercury spacecraft had reached its limit of staying in space.

The defeat in the first round of the spacerace led to the introduction of the Moon race program, Apollo, in 1961 just after the flight of Freedom 7. However, it was estimated that this could not be done in one step and that further projects in Earth orbit were needed.

Project Gemini (1962-1966, manned missions from 1965)

Airplane Picture - Rendezvous of Gemini 6 and 7

Project Gemini focused on conducting experiments and developing and practicing techniques required for lunar missions. The first Gemini flight with astronauts on board, Gemini 3, was flown by Gus Grissom and John Young on March 23, 1965. Nine missions followed, showing that long-duration human space flight and rendezvous and docking with another vehicle in space were possible, and gathering medical data on the effects of weightlessness on humans. Together with that, Gemini missions also included the first American spacewalks.

Even though the Gemini project managed to make a docking a year before the Soviet space program, it was too early to call it a victory. The maneuvers practiced by Gemini could be used in two ways: a spacecraft could dock with a rocket stage in orbit around the Earth and use it for going to the Moon or a spacecraft together with a Moon lander could be sent to the Moon by a single rocket and then separate and dock again after the lander had been down on the surface. However, there was a third and more direct way of going to the Moon; the Soviet Union could just build a big rocket and land the top of it on the Moon. That again could take itself back to Earth without using rendezvous or docking. In that case the Gemini project would have been a waste of time.

Airplane Picture - Spacecraft and rocket comparison including Apollo (biggest), Gemini and Mercury. The Saturn IB and Mercury-Redstone rockets are left out

Apollo program (1961-1972, manned missions from 1968)

The Apollo (Moon) program was one of the most expensive American scientific programs ever. It is estimated to have cost $191 billion in present day US$. In comparison the Manhattan (atom bomb) project cost roughly today-US$24.4 billion. It used the Saturn rockets as launch vehicles, which were far bigger than the rockets build for previous projects. The spacecraft was also bigger as can be seen on the picture; it had two main parts: the combined command and service module (CSM) and the lunar landing module (LM). The LM was to be left on the Moon and only the command module (CM) containing the astronauts would eventually return to Earth. (For details see: Apollo 11 flight gallery)

Airplane Picture - Buzz Aldrin on the moon, 1969

The second manned mission, Apollo 8, brought astronauts for the first time in a flight around the Moon. This happened in December 1968. Shortly before, the Soviet had send an unmanned spacecraft around the Moon but they never managed to do more than that. On the next two missions docking maneuvers that were needed for the Moon landing were practiced and then finally the Moon landing was made on the Apollo 11 mission in July 1969. In 1961 President Kennedy had introduced the Apollo Program and set the deadline for a successful Moon landing at the end of the same decade. It was done by a narrow margin.

The first person to stand on the Moon was Neil Armstrong and after him Buzz Aldrin while Michael Collins orbited above. Five subsequent Apollo missions also landed astronauts on the Moon, the last in December 1972. In these six Apollo spaceflights twelve men walked on the Moon. These missions returned a wealth of scientific data and 381.7 kilograms (842 lb) of lunar samples. Experiments included soil mechanics, meteoroids, seismic, heat flow, lunar ranging, magnetic fields, and solar wind experiments. The Moon landing marked the end of the space race and as a gesture, Armstrong mentioned mankind when he stepped down on the Moon.

Apollo set major milestones in human spaceflight. It stands alone in sending manned missions beyond low Earth orbit, and landing humans on another celestial body. Apollo 8 was the first manned spacecraft to orbit another celestial body, while Apollo 17 marked the last moonwalk and the last manned mission beyond low Earth orbit. The program spurred advances in many areas of technology peripheral to rocketry and manned spaceflight, including avionics, telecommunications, and computers. Apollo sparked interest in many fields of engineering and left many physical facilities and machines developed for the program as landmarks. Many objects and artifacts from the program are on display at various locations throughout the world, notably at the Smithsonian's Air and Space Museums.

Skylab (1973-1979)

Airplane Picture - Skylab space station, 1974

Skylab was the only space station launched into orbit solely by the United States. The 100 short tons (91 t) station was in Earth orbit from 1973 to 1979, and was visited by crews three times, in 1973 and 1974. It included a laboratory for studying the effects of microgravity, and a solar observatory. A Space Shuttle was planned to dock with and elevate Skylab to a higher safe altitude, but Skylab reentered the atmosphere and was destroyed in 1979, before the first shuttle could be launched.

Apollo spacecrafts were used for bringing astronauts up to and down from Skylab. Inside it they could stay for three months. Skylab had a crew Size of 3, the same as the Apollo CSM, however its habitable volume was 361 m which was 60 times bigger than that of the CSM.

Apollo-Soyuz Test Project (1975-1981)

Airplane Picture - Apollo-Soyuz crews with model of spacecrafts, 1975

In the 1970s the cold war was thawing and as a consequence the Apollo-Soyuz Test Project (ASTP) was introduced. It was the first joint flight of the U.S. and Soviet space programs. The mission took place in July 1975. For the United States, it was the last Apollo flight, as well as the last manned space launch until the flight of the first Space Shuttle in April 1981. Manned Skylab and ASTP missions used the smaller Saturn IB with Apollo CSM, not the Saturn V.

The mission included both joint and separate scientific experiments, and provided useful engineering experience for future joint US-Russian space flights, such as the Shuttle-Mir Program and the International Space Station.

Space Shuttle program (1981-2011)

Airplane Picture - Discovery liftoff, 2008

Space Shuttle

The Space Shuttle became the major focus of NASA in the late 1970s and the 1980s. Planned as a frequently launchable and mostly reusable vehicle, four space shuttle orbiters were built by 1985. The first to launch, Columbia, did so on April 12, 1981, the 20th anniversary of the first space flight by Yuri Gagarin.

Its major components were a rocket plane orbiter with an external fuel tank and two solid fuel launch rockets at its side. The external tank, which was bigger than the spacecraft itself, was the only component that was not reused. The shuttle could orbit in altitudes of 185 - 643 km (115 - 400 miles) and carry a maximum payload (to low orbit) of 24,400 kg (54,000 lb). Missions could last from 5 to 17 days and crews could be from 2 to 8 astronauts.

On 20 missions 1983-1998 the Space Shuttle carried Spacelab a space laboratory designed in cooperation with ESA. It was never deployed into orbit but was mounted to the Space Shuttle and went up and down with it on each mission. Another famous line of missions were the launch and later successful repair of the Hubbles space telescope 1990 and 1993

In 1995 Russian-American interaction resumed with the Shuttle-Mir missions (1995-1998). Once more an American vehicle docked with a Russian craft, this time a full-fledged space station. This cooperation has continued to 2011, with Russia and the United States the two biggest partners in the largest space station ever built: the International Space Station (ISS). The strength of their cooperation on this project was even more evident when NASA began relying on Russian launch vehicles to service the ISS during the two-year grounding of the shuttle fleet following the 2003 Space Shuttle Columbia disaster.

The shuttle fleet lost two orbiters and 14 astronauts in two disasters: Challenger in 1986, and Columbia in 2003. While the 1986 loss was mitigated by building the Space Shuttle Endeavour from replacement parts, NASA did not build another orbiter to replace the second loss. NASA's Space Shuttle program had 135 successful missions when the program ended with the successful landing of the Space Shuttle Atlantis at the Kennedy Space Center on July 21, 2011. The program spanned 30 years with over 300 astronauts sent into space.

International Space Station (1998-)

Airplane Picture - The International Space Station, 2009

The ISS combines the Japanese Kib� laboratory with three space station projects, the Soviet/Russian Mir-2, the American Freedom, and the European Columbus. Budget constraints led to the merger of these projects into a single multi-national programme in the 1990s. The station consists of pressurised modules, external trusses, solar arrays and other components which have been launched by Russian Proton and Soyuz rockets together with space shuttles. It is currently being assembled in Low Earth Orbit. The construction began in 1998 and is scheduled to be completed by 2011, with operations continuing until at least 2015. The station can be seen from the Earth with the naked eye and, as of 2009, is the largest artificial satellite in Earth orbit with a mass larger than that of any previous space station.

As mentioned it is a joint project between the five participating space agencies, NASA, the Russian RKA, the Japanese JAXA, the European ESA, and the Canadian CSA. The ownership and use of the space station is established in intergovernmental treaties and agreements which divide the station into two areas and allow Russia to retain full ownership of the Russian Segment, with the US Segment allocated between the other international partners. The station is serviced by Soyuz and Progress spacecrafts together with the Automated Transfer Vehicle and the H-II Transfer Vehicle and has been visited by astronauts and cosmonauts from 15 different nations.

Unmanned missions (1958-)

Airplane Picture - Deep space mission deployed by shuttle, 1989

More than 1,000 unmanned missions have been designed to explore the earth and parts of the solar system. Apart from exploration also communication satellites have been launched by NASA. The missions have been launched directly from earth or by space shuttle, which again could launch the satellite itself or a vehicle containing the satellite.

The first mission was Explorer 1, which started as an ABMA/JPL project during the early space race. It was launched in January 1958, two month after Sputnik. At the creation of NASA it was transferred to this agency and still continues to this day (2011). Its missions have been focusing on the Earth and the Sun measuring among others magnetic fields and solar wind. A more recent Earth mission, not related to the Explorer program, was the Hubble telescope, which as mentioned above was brought into orbit in 1990.

The closest planets Mars, Venus and Mercury have been the goal of at least 4 programs. The first was Mariner in the 1960s and ‘70s, which visited all three of them. Mariner was also the first to make a planetary flyby, to take the first pictures from another planet, the first planetary orbiter, and the first to make a gravity assist maneuver. This is a technique where the satellite takes advantage of the gravity and velocity of planets to reach its destination.

The first successful landing on Mars was made by Viking I in 1976. 20 years later a rover was landed on Mars by Mars Pathfinder.

Outside Mars, Jupiter was first visited by Pioneer 10 in 1973. More than 20 years later Galileo sent a probe into the planets’ atmosphere. The first spacecraft to leave the solar system was Pioneer 10 in 1983. At a time it was the most distant spacecraft, but it is now passed by Voyager 2.

Both the Pioneer and the Voyager program carries messages from the Earth to extraterrestrial life. A problem with far space travel is communication. For instance, at present it takes about 3 hours for a radio signal to reach the New Horizon spacecraft at a point more than half way to Pluto. Contact with Pioneer 10 was lost in 2003.

Recent and planned activities

Airplane Picture - President Obama arrives at Kennedy Space Center in 2010 to present his space policy

NASA's ongoing investigations include in-depth surveys of Mars and Saturn and studies of the Earth and the Sun. Other active spacecraft missions are MESSENGER for Mercury, New Horizons (for Jupiter, Pluto, and beyond), and Dawn for the asteroid belt. NASA continued to support in situ exploration beyond the asteroid belt, including Pioneer and Voyager traverses into the unexplored trans-Pluto region, and Gas Giant orbiters Galileo (1989-2003), Cassini, and Juno (2011-).

The New Horizons mission to Pluto was launched in 2006 and aiming for Pluto flyby in 2015. The probe received a gravity assist from Jupiter in February 2007, examining some of Jupiter's inner moons and testing on-board instruments during the fly-by. On the horizon of NASA's plans is the MAVEN spacecraft as part of the Mars Scout Program to study the atmosphere of Mars. An improved and larger planetary rover, Mars Science Laboratory, is under construction and slated to launch in 2011.

On December 4, 2006, NASA announced it was planning a permanent moon base. The goal was to start building the moonbase by 2020, and by 2024, have a fully functional base that would allow for crew rotations and in-situ resource utilization. However, by 2010, President Barack Obama halted existing plans, including the Moon base, and directed a generic focus on manned missions to asteroids and Mars, as well as extending support for the International Space Station.

In September 2011, the Space Launch System, a planned launch vehicle was announced. The goal is a manned variant launching the Orion Multi-Purpose Crew Vehicle, and an even larger version after that. The Orion MPCV is planned for a test launch on a Delta IV Heavy rocket around 2013.

NASA science

Medicine in space

A variety of large scale medical studies are being conducted in space via the National Space Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity Study in which Astronauts (including former ISS Commanders Leroy Chiao and Gennady Padalka) perform ultrasound scans under the guidance of remote experts to diagnose and potentially treat hundreds of medical conditions in space. Usually, there is no physician onboard the International Space Station and diagnosis of medical conditions is challenging. In addition, Astronauts are susceptible to a variety of health risks including decompression sickness, barotrauma, immunodeficiencies, loss of bone and muscle, orthostatic intolerance due to volume loss, sleep disturbances, and radiation injury. Ultrasound offers a unique opportunity to monitor these conditions in space. This study's techniques are now being applied to cover professional and Olympic sports injuries as well as ultrasound performed by non-expert operators in populations such as medical and high school students. It is anticipated that remote guided ultrasound will have application on Earth in emergency and rural care situations, where access to a trained physician is often rare.

Ozone depletion

In the middle of the 20th century NASA augmented its mission of Earth’s observation and redirected it toward environmental quality. The result was the launch of Earth Observing System (EOS) in 1980s, which was able to monitor one of the global environmental problems-ozone depletion. The first comprehensive worldwide measurements were obtained in 1978 with the Nimbus-7 satellite and NASA scientists at the Goddard Institute for Space Studies.

Salt evaporation and energy management

In one of the nation's largest restoration projects, NASA technology helps state and federal government reclaim 15,100 acres (61 km) of salt evaporation ponds in South San Francisco Bay. Satellite sensors are used by scientists to study the effect of salt evaporation on local ecology.

NASA has started Energy Efficiency and Water Conservation Program as an agency-wide program directed to prevent pollution and reduce energy and water utilization. It helps to ensure that NASA meets its federal stewardship responsibilities for the environment.

Earth Science Enterprise

Understanding of natural and human-induced changes on the global environment is the main objective of NASA's Earth Science Enterprise. NASA currently has more than a dozen Earth science spacecraft/instruments in orbit studying all aspects of the Earth system (oceans, land, atmosphere, biosphere, cyrosphere), with several more planned for launch in the next few years.

NASA is working in cooperation with National Renewable Energy Laboratory (NREL). The goal is to obtain~to produce worldwide solar resource maps with great local detail. NASA was also one of the main participants in the evaluation innovative technologies for the clean up of the sources for dense non-aqueous phase liquids (DNAPLs). On April 6, 1999, the agency signed The Memorandum of Agreement (MOA) along with the United States Environmental Protection Agency, DOE, and USAF authorizing all the above organizations to conduct necessary tests at the John F. Kennedy Space center. The main purpose was to evaluate two innovative in-situ remediation technologies, thermal removal and oxidation destruction of DNAPLs. National Space Agency made a partnership with Military Services and Defense Contract Management Agency named the “Joint Group on Pollution Prevention�. The group is working on reduction or elimination of hazardous materials or processes.

On May 8, 2003, Environmental Protection Agency recognized NASA as the first federal agency to directly use landfill gas to produce energy at one of its facilities-the Goddard Space Flight Center, Greenbelt, Maryland.

Facilities

Airplane Picture - Jet Propulsion Laboratory complex in Pasadena, California

NASA facilities

NASA's facilities are research, construction and communication centers to help its missions. Some facilities serve more than one application for historic or administrative reasons. NASA also operates a short-line railroad at the Kennedy Space Center and own special aircrafts for instance two Boeing 747 which were used for transport of the Space Shuttle orbiter.

John F. Kennedy Space Center (KSC), is one of the best known NASA facilities. It has been the launch site for every United States human space flight since 1968. Although such flights are currently on pause, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program from three pads at the adjoining Cape Canaveral Air Force Station.

Another major facility is Marshall Space Flight Center in Huntsville, Alabama at which the Saturn 5 rocket and Skylab were developed. The JPL, mentioned above, was together with ABMA one of the agencies behind Explorer 1, the first American space mission.

Airplane Picture - Charles F. Bolden, Jr., Administrator

NASA leadership

Leadership

The administrator is the highest-ranking NASA official and serves as the senior space science adviser to the President of the United States. The administration is located at NASA Headquarters in Washington, DC and provides overall guidance and direction to the agency.

The first Administrator was Dr. T. Keith Glennan; during his term he brought together the disparate projects in space development research in the US.

Some administrators like Richard H. Truly (administrator 1989-1992) have been astronauts themselves. Among others he piloted Space Shuttle Columbia in 1981 on its second flight and later supervised the rebuilding of the shuttle program after the disaster of Challenger in 1986

Airplane Picture - NASA's budget 1962-2014 as % of federal budget peaking 1966

On May 24, 2009, President Obama announced the nomination of Charles Bolden as NASA administrator, and Lori Garver as deputy administrator. Bolden was confirmed by the US Senate on July 15, 2009 as the twelfth administrator of NASA. Lori Garver was confirmed as NASA's deputy administrator.

Budget

Public perception of the NASA budget may be very different from reality and has been the subject of controversy since the agency's creation.

A 1997 poll reported that Americans had an average estimate of 20% for NASA's share of the federal budget. In reality, NASA's budget has been between 0.5% and 1% from the late 1960s on.

NASA budget briefly peaked at over 4% of the federal budget in the mid-1960s during the build up to the Apollo program.

Aerospace Education Services Project
Astronomy Picture of the Day
Astrotech Corporation
Buran, Soviet space shuttle
Department of Defense Manned Space Flight Support Office
Federation of Earth Science Information Partners (ESIP Federation)
List of aerospace engineering topics
List of NASA aircraft
List of NASA missions
List of rockets used by NASA
NASA Acquisition Internet Service
NASA Advanced Space Transportation Program
NASA awards and decorations
NASAcast
NASA insignia
NASA RealWorld-InWorld Engineering Design Challenge
NASA Research Park
NASA spin-off
Project A119
Review of United States Human Space Flight Plans Committee
Robotic spacecraft
Saturn (rocket family)
Scientific research on the ISS
Small Explorer program
Space debris
Spacelab
Space policy of the Barack Obama administration
Space probe
Space race
Timeline of Solar System exploration
Unmanned spacecraft
Vision for Space Exploration

NASA Pictures

More airplane video.

Source: WikiPedia