(From top to bottom) Sputnik 1, the first artificial satellite. Sputnik 1 ( "Спутник-1", "Satellite-1" ПС-1 ( PS-1, i This article is about artificial satellites For natural satellites also known as moons see Natural satellite. Cosmonaut Yuri Gagarin, the first person in space. This content has an uncertain copyright status and is pending deletion. You can comment on its removal. Astronaut Buzz Aldrin on the surface of the Moon. Buzz Aldrin (born Edwin Eugene Aldrin Jr, January 20, 1930 in Glen Ridge, New Jersey) is an American Aviator

Space exploration is the use of astronomy and space technology to explore outer space. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Space technology is Technology that is related to entering space, maintaining and using systems during Spaceflight and returning people and things Outer space, often simply called space, comprises the relatively empty regions of the Universe outside the escape velocities of Celestial bodies. ^[1] Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft. A human spaceflight is a Spaceflight with a human crew, and possibly passengers A robotic spacecraft is a Spacecraft with no humans on board that is usually under Telerobotic control

While the observation of objects in space—known as astronomy—pre-dates reliable recorded history, it was the development of large liquid-fueled rocket engines during the early 20th century that allowed physical space exploration to become a reality. Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Recorded history can be defined as History that has been written down or recorded by the use of Language, whereas History is a more general term referring A rocket engine is a Jet engine that uses only Propellant mass for forming its high speed propulsive jet. The twentieth century of the Common Era began on Common rationales for exploring space include advancing scientific research, uniting different nations, ensuring the future survival of humanity and developing military/strategic advantages against other countries. Various criticisms of Space Exploration are sometimes made, generally on cost or safety grounds.

Space exploration has often been used as a proxy competition for geopolitical rivalries such as the Cold War. Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the The early era of space exploration was driven by a "Space Race" between the Soviet Union and the United States; the launch of the first man-made object to orbit the Earth, the USSR's Sputnik 1, on October 4, 1957, and the first Moon landing by the American Apollo 11 craft on July 20, 1969 are often taken as the boundaries for this initial period. The Space Race was a competition of space exploration between the Soviet Union and the United States, which lasted roughly from 1957 to 1975 The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 The United States of America —commonly referred to as the Sputnik 1 ( "Спутник-1", "Satellite-1" ПС-1 ( PS-1, i Events 610 - Heraclius arrives by ship from Africa at Constantinople, overthrows Byzantine Emperor Phocas Year 1957 ( MCMLVII) was a Common year starting on Tuesday (link displays the 1957 Gregorian calendar) Events 1304 - Wars of Scottish Independence: Fall of Stirling Castle - King Edward I of England takes the last rebel stronghold Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. The Soviet space program achieved many of the first milestones under Sergey Korolyov and Kerim Kerimov, including the first human spaceflight (Yuri Gagarin aboard Vostok 1) in 1961, the first spacewalk (by Aleksei Leonov) in 1965, and the launch of the first space station (Salyut 1) in 1971. The Soviet space program consisted of initiatives within the Soviet Union by competing design groups Sergey Pavlovich Korolyov (often Transliterated as Sergei Korolev) (Серге́й Па́влович Королёв Сергій Павлович Корольов Kerim Aliyevich Kerimov (Kərim Əli oğlu Kərimov Керим Алиевич Керимов 1917 – 2003 was an Azerbaijani Soviet rocket scientist one of the founders A human spaceflight is a Spaceflight with a human crew, and possibly passengers Vostok 1 (Восток-1 meaning Orient -1 or East-1 was the first Human spaceflight. Extra-vehicular activity ( EVA) is work done by an Astronaut away from the Earth and outside of a Spacecraft. Alexey Arkhipovich Leonov (Алексе́й Архи́пович Лео́нов (born May 30, 1934 in Listvyanka Kemerovo Oblast, USSR A space station is an artificial structure designed for Humans to live in Outer space. Salyut 1 (DOS-1 ( Салют-1; English translation Salute 1) was the first space station of any kind and the first Soviet Space station

After the first 20 years of exploration, focus shifted from one-off flights to renewable hardware, such as the Space Shuttle program, and from competition to cooperation as with the International Space Station. NASA 's Space Shuttle, officially called Space Transportation System ( STS) is the United States government's current manned Launch From the 1990s onwards, private interests began promoting space tourism. Space tourism is the recent Phenomenon of tourists paying for flights into space pioneered by Russia Larger government programs have advocated manned missions to the Moon and possibly Mars sometime after 2010.

Contents 1 History 1.1 First orbital flights 1.2 First human flights 1.3 Key people in early space exploration 2 Targets of exploration 2.1 Astrobiology 2.2 Mercury 2.3 Venus 2.4 Earth 2.5 Earth's Moon 2.6 Mars 2.7 Jupiter 2.8 Saturn 2.9 Uranus 2.10 Neptune 2.11 Pluto 2.12 Asteroids 3 Rationale 3.1 In favor 3.2 Opposed 4 Related topics 4.1 Spaceflight 4.2 Space colonization 4.3 Space agencies 5 See also 6 References 7 External links

History

See also: Timeline of space exploration  and Astronomy#History

First orbital flights

The first successful orbital launch was of the Soviet unmanned Sputnik (Satellite I) mission on October 4, 1957. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Events 610 - Heraclius arrives by ship from Africa at Constantinople, overthrows Byzantine Emperor Phocas Year 1957 ( MCMLVII) was a Common year starting on Tuesday (link displays the 1957 Gregorian calendar) The satellite weighed about 83 kg (184 pounds), and is believed to have orbited Earth at a height of about 250 km (150 miles). It had two radio transmitters (20 and 40 MHz), which emitted "beeps" that could be heard by any radio around the globe. Analysis of the radio signals was used to gather information about the electron density of the ionosphere, while temperature and pressure data was encoded in the duration of radio beeps. The results indicated that the satellite was not punctured by a meteoroid. Sputnik 1 was launched by an R-7 rocket. The R-7 Semyorka (Р-7 "Семёрка" was the world's first true Intercontinental ballistic missile and was deployed by the Soviet Union during the It incinerated upon re-entry on January 3, 1958. Events 1431 - Joan of Arc is handed over to the Bishop Pierre Cauchon. Year 1958 ( MCMLVIII) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar.

This success led to an escalation of the American space program, which unsuccessfully attempted to launch Vanguard 1 into orbit two months later. This is a list of government agencies engaged in activities related to Outer space and Space exploration. Vanguard 1 was the fourth artificial Satellite launched and is the oldest still orbiting Earth though there is no longer any communication with it On January 31, 1958, the U. Events 1504 - France cedes Naples to Aragon. 1606 - Gunpowder Plot: Guy Fawkes Year 1958 ( MCMLVIII) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. S. successfully orbited Explorer 1 on a Juno rocket. Explorer 1 (officially titled at NASA as satellite 1958 Alpha) was the first Earth Satellite of the United States, launched on February 1 In the meantime, the Soviet dog Laika became the first animal in orbit on November 3, 1957. Laika (from the Лайка, a breed of dog, literally meaning "Barker" or "Howler" was a Soviet space dog (c Events 644 - Umar ibn al-Khattab, the second Muslim Caliph, is killed by a Persian slave in Medina. Year 1957 ( MCMLVII) was a Common year starting on Tuesday (link displays the 1957 Gregorian calendar)

First human flights

The first human spaceflight was Vostok 1 (East 1), carrying 27 year old cosmonaut Yuri Gagarin on April 12, 1961. Vostok 1 (Восток-1 meaning Orient -1 or East-1 was the first Human spaceflight. Events 467 - Anthemius is elevated to Emperor of the Western Roman Empire. Year 1961 ( MCMLXI) was a Common year starting on Sunday (link will display full calendar of the Gregorian calendar. The spacecraft completed one orbit around the globe, lasting about 1 hour and 48 minutes. Gagarin's flight resonated around the world; it was a demonstration of the advanced Soviet space program and it opened an entirely new era in space exploration — human spaceflight. The Soviet space program consisted of initiatives within the Soviet Union by competing design groups A human spaceflight is a Spaceflight with a human crew, and possibly passengers

The U. S. first launched a person into space within a month of Gagarin's flight with the first Mercury flight, by Alan Shepard. Alan Bartlett Shepard Jr (November 18 1923 &ndash July 21 1998 ( Rear Admiral, USN Ret Orbital flight was achieved by the United States when John Glenn's Mercury-Atlas 6 orbited the Earth on February 20, 1962. John Herschel Glenn Jr (born July 18 1921 in Cambridge Ohio) is a former United States Senator who first rose to fame as the first American to Orbit The Mercury-Atlas 6 mission was the first attempt by the US and Mercury program to place an astronaut in orbit Events 1472 - Orkney and Shetland are left by Norway to Scotland, due to a Dowry payment Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar.

Valentina Tereshkova, the first woman in space, orbited the Earth 48 times aboard Vostok 6 on June 16, 1963. Valentina Vladimirovna Tereshkova (Валенти́на Влади́мировна Терешко́ва born 6 March 1937) is a retired Soviet Vostok 6 was the first Human spaceflight mission to carry a woman cosmonaut Valentina Tereshkova, into space Events 1487 - Battle of Stoke Field, the last dying breath of the Wars of the Roses. Year 1963 ( MCMLXIII) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar.

China first launched a person into space 42 years after the launch of Vostok 1, on October 15, 2003, with the flight of Yang Liwei aboard the Shenzhou 5 (Spaceboat 5) spacecraft. Events 533 - Byzantine General Belisarius makes his formal entry into Carthage, having conquered it from the Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar. Yáng Lìwěi ( (born June 21, 1965) is a Chinese major general and military pilot and a CNSA Astronaut. Shenzhou 5 ( — was the first Human spaceflight mission of the People's Republic of China (PRC launched on October 15, 2003

Key people in early space exploration

The dream of stepping into the outer reaches of the Earth's atmosphere was driven by rocket technology. The German V2 was the first rocket to travel into space, overcoming the problems of thrust and material failure. See also Vergeltungswaffe The V-2 rocket ( Vergeltungswaffe 2 was the first Ballistic missile and first man-made object to achieve During the final days of World War II this technology was obtained by both the Americans and Soviets as were its designers. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including The initial driving force for further development of the technology was a weapons race for inter-continental ballistic missiles (ICBMs) to be used as long-range carriers for fast nuclear weapon delivery, but in 1961 when USSR launched the first man into space, the U. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 S. declared itself to be in a "Space Race" with Russia. The Space Race was a competition of space exploration between the Soviet Union and the United States, which lasted roughly from 1957 to 1975

• Konstantin Tsiolkovsky, Robert Goddard, Hermann Oberth and Reinhold Tilling laid the groundwork of rocketry in the early years of the 20th century. Robert Hutchings Goddard, PhD ( October 5, 1882 &ndash August 10 1945 U Hermann Julius Oberth ( June 25, 1894 &ndash December 28, 1989) was a Austro-Hungarian -born German ( Transylvanian Reinhold Tiling ( June 13 1893 &ndash October 11 1933) was a German Engineer, pilot and a Rocket
• Wernher von Braun was the lead rocket engineer for Nazi Germany's World War II V-2 rocket project. Wernher Magnus Maximilian Freiherr von Braun (March 23 1912 &ndash June 16 1977 a German rocket physicist and astronautics engineer became one of the leading figures in Nazism, which was a short name for National Socialism (Nationalsozialismus refers primarily to the Ideology and practices of the National Socialist German Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. See also Vergeltungswaffe The V-2 rocket ( Vergeltungswaffe 2 was the first Ballistic missile and first man-made object to achieve In the last days of the war he led a caravan of workers in the German rocket program to the American lines, where they surrendered and were brought to the USA to work on U. S. rocket development. He acquired American citizenship and led the team that developed and launched Explorer 1, the first American satellite. Explorer 1 (officially titled at NASA as satellite 1958 Alpha) was the first Earth Satellite of the United States, launched on February 1 Von Braun later led the team at NASA's Marshall Space Flight Center which developed the Saturn V moon rocket. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program George C Marshall Space Flight Center (MSFC the original home of NASA, is a lead center for propulsion, Space Shuttle propulsion Shuttle external fuel The Saturn V (pronounced 'Saturn Five' popularly known as the Moon Rocket was a multistage liquid-fuel expendable Rocket used by NASA 's
• Initially the race for space was often led by Sergey Korolyov, whose legacy includes both the R7 and Soyuz—which remain in service to this day. Sergey Pavlovich Korolyov (often Transliterated as Sergei Korolev) (Серге́й Па́влович Королёв Сергій Павлович Корольов The R-7 Semyorka (Р-7 "Семёрка" was the world's first true Intercontinental ballistic missile and was deployed by the Soviet Union during the Design A Soyuz spacecraft consists of three parts (from front to back A Spheroid Orbital module, which provides accommodation for the crew during Korolev was the mastermind behind the first satellite, first man (and first woman) in orbit and first spacewalk. Until his death his identity was a closely guarded state secret; not even his mother knew that he was responsible for creating the Russian space program.
• Kerim Kerimov was one of the founders of the Soviet space program and was one of the lead architects behind the first human spaceflight (Vostok 1) alongside Sergey Korolyov. Kerim Aliyevich Kerimov (Kərim Əli oğlu Kərimov Керим Алиевич Керимов 1917 – 2003 was an Azerbaijani Soviet rocket scientist one of the founders The Soviet space program consisted of initiatives within the Soviet Union by competing design groups A human spaceflight is a Spaceflight with a human crew, and possibly passengers Vostok 1 (Восток-1 meaning Orient -1 or East-1 was the first Human spaceflight. After Korolyov's death in 1966, Kerimov became the lead scientist of the Soviet space program and was responsible for the launch of the first space stations from from 1971 to 1991, including the Salyut and Mir series, and their precursors in 1967, the Cosmos 186 and Cosmos 188. A space station is an artificial structure designed for Humans to live in Outer space. The Salyut program (Салют lit  Salute or Fireworks) was the first Space station program undertaken by the Soviet Union, which consisted Mir (Мир which can mean both Peace and World, and was the name given to peasant communes in pre-revolutionary Russia was a Soviet (and Cosmos 186 and Cosmos 188 incorporated a Soyuz programme descent module for landing scientific instruments and test objects Cosmos 186 and Cosmos 188 incorporated a Soyuz programme descent module for landing scientific instruments and test objects ^[2][3]

Other key people included:

• Valentin Glushko held role of Chief Engine Designer for USSR. Glushko designed many of the engines used on the early Soviet rockets, but was constantly at odds with Korolyov.
• Vasily Mishin, Chief Designer working under Sergey Korolyov and one of first Soviets to inspect the captured German V2 design. Vasily Pavlovich Mishin ( January 18, 1917 – October 10 2001) was a Soviet engineer and a prominent Rocketry pioneer Following the death of Sergei Korolev, Mishin was held responsible for the Soviet failure to be first country to place a man on the moon.
• Bob Gilruth, was the NASA head of the Space Task Force and director of 25 manned space flights. Robert Rowe Gilruth ( October 18 1913 - August 17 2000) was an American aviation and space pioneer The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program Gilruth was the person who suggested to John F. Kennedy that the Americans take the bold step of reaching the Moon in an attempt to reclaim space superiority from the Soviets. John Fitzgerald "Jack" Kennedy (May 29 1917&ndashNovember 22 1963 often referred to by his initials JFK, was the thirty-fifth President of
• Christopher C. Kraft, Jr., was NASA's first flight director and oversaw development of Mission Control and associated technologies and procedures. Christopher Columbus Kraft Jr (born February 28 1924 is a retired NASA engineer and manager who was instrumental in establishing the agency's Mission Control Flight controllers are personnel who aid in the operations of a space flight working in Mission Control Centers such as NASA 's Mission Control Center, or Mission Control Center (MCC is a unit that manages aerospace flights

Targets of exploration

Astrobiology

Main article: Astrobiology

Astrobiology is the interdisciplinary study of life in the universe, combining aspects of astronomy, biology and geology. Astrobiology (from Greek grc ἄστρον astron, "constellation star" grc βίος bios, "life" and grc -λογία In Academia, Pedagogy, Physical sciences, Earth sciences, Human sciences and Social sciences Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study Foundations of modern biology There are five unifying principles Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit ^[4] It is focused primarily on the study of the origin, distribution and evolution of life. In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic eVolution is the third Album by eLDee, it was due to be released in 2008 It is also known as exobiology (from Greek: έξω, exo, "outside"). ^[5][6][7] The term "Xenobiology" has been used as well, but this is technically incorrect because its terminology means "biology of the foreigners". ^[8] Astrobiologists must also consider the possibility of life that is chemically entirely distinct from any life found on earth. ^[9]

Mercury

Main article: Exploration of Mercury

The exploration of Mercury has taken only a minor role in the space interests of the world. The MErcury Surface Space ENvironment GEochemistry and Ranging ( MESSENGER) probe is a NASA Spacecraft, launched August 3, 2004 The exploration of Mercury has taken only a minor role in the space interests of the world It is the least explored inner planet (JHU/APL, 2006). The Solar System consists of the Sun and those celestial objects bound to it by Gravity. As of January 2008, the Mariner 10 and MESSENGER missions have been the only missions that have made close observations of Mercury. Events in January Holidays New Year's Day - January 1 Coptic Christmas - January 7 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Mariner 10 was a robotic Space probe launched on November 3, 1973 to fly by the planets Mercury and Venus. The MErcury Surface Space ENvironment GEochemistry and Ranging ( MESSENGER) probe is a NASA Spacecraft, launched August 3, 2004 MESSENGER made a fly-by of Mercury on 14 January 2008, to further investigate the observations made by Mariner 10 in 1975 (Munsell, 2006b). The MErcury Surface Space ENvironment GEochemistry and Ranging ( MESSENGER) probe is a NASA Spacecraft, launched August 3, 2004 Events 1129 - Formal approval of the Order of the Templar at the Council of Troyes. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common A third mission to Mercury, BepiColombo, is to include two probes. BepiColombo is a joint Cornerstone mission of the European Space Agency (ESA and the Japan Aerospace Exploration Agency (JAXA to the planet Mercury A space probe is a scientific Space exploration mission in which a Robotic spacecraft leaves the Gravity well of Earth and approaches the BepiColombo is a joint mission between Japan and the European Space Agency. For a topic outline on this subject see List of basic Japan topics. The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member MESSENGER and BepiColombo are intended to gather complementary data to help scientists understand many of the mysteries discovered by Mariner 10's flybys. In Orbital mechanics and Aerospace engineering, a gravitational slingshot, gravity assist or swing-by is the use of the relative movement and

Flights to other planets within the Solar System are accomplished at a cost in energy, which is described by the net change in velocity of the spacecraft, or delta-v. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός In Astrodynamics, the term delta-v, literally "change in velocity" (see symbol delta) has a specific meaning it is a Scalar which takes Due to the relatively high delta-v to reach Mercury and its proximity to the Sun, it is difficult to explore and orbits around it are rather unstable.

Venus

Main article: Observations and explorations of Venus

Venus was the first target of interplanetary flyby and lander missions and, despite one of the most hostile surface environments in the solar system, has had more landers sent to it, nearly all from the Soviet Union, than any other planet in the solar system. Mariner 10 was a robotic Space probe launched on November 3, 1973 to fly by the planets Mercury and Venus. The observations and explorations of Venus started around 1600 BC The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University The first successful Venus flyby was the American Mariner 2 spacecraft, which flew past Venus in 1962. The United States of America —commonly referred to as the Mariner 2 (Mariner-Venus 1962 a space probe to Venus, was the first successful Spacecraft in the NASA Mariner program. Year 1962 ( MCMLXII) was a Common year starting on Monday (the link is to a full 1962 calendar of the Gregorian calendar. Mariner 2 has been followed by several other flybys by multiple space agencies often as part of missions using a Venus flyby to provide a gravitational assist en route to other celestial bodies. In Orbital mechanics and Aerospace engineering, a gravitational slingshot, gravity assist or swing-by is the use of the relative movement and In 1967 Venera 4 became the first probe to enter and directly examine the atmosphere of Venus. Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar. Venera 4 ( Russian:Венера-4 was a probe in the Soviet Venera program for the exploration of Venus. In 1970 Venera 7 became the first successful lander to reach the surface of Venus and by 1985 it had been followed by 8 additional successful Soviet Venus landers which provided images and other direct surface data. Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. The Venera 7 (Венера-7 was a Soviet Spacecraft part of the Venera series of probes to Venus. Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar) Starting in 1975 with the Soviet orbiter Venera 9 some 10 successful orbiter missions have been sent to Venus including later missions which were able map the surface of Venus using radar to pierce the obscuring atmosphere. Year 1975 ( MCMLXXV) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. Venera 9 (Венера-9 was a USSR Unmanned space mission to Venus. Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships

Earth

The Earth is by far the most explored object in the Solar System.

The Americans were the first to discover the existence of the Van Allen belts around the Earth. The Van Allen radiation belt is a Torus of energetic Charged particles ( plasma) around Earth, held in place by Earth's Magnetic These belts contain radiation trapped by the Earth's magnetic fields, which currently prevent habitable space stations from being placed above 1000km.

The Earth is explored and observed by Earth observation satellites. Earth observation satellites are Satellites specifically designed to observe Earth from Orbit, similar to Reconnaissance satellites but intended The hole in the ozone layer was found from an artificial satellite that was exploring Earth's atmosphere. Ozone depletion describes two distinct but related observations a slow steady decline of about 4 percent per decade in the total amount of Ozone in Earth's

Earth's Moon

Main article: Exploration of the Moon

The Russians were the first to take pictures of the far side of the moon; something that was never visible to humans. The Lunar Roving Vehicle (LRV or lunar rover was a type of surface exploration rover used on the Moon during the Apollo program. The physical exploration of the Moon began when Luna 2, a Space probe launched by the Soviet Union, impacted the surface of the Moon on Far Side of the Moon, in original French, La face cachée de la lune, is a 2003 film by Robert Lepage. It was discovered that the far side was more heavily cratered.

The American Apollo missions returned rocks from the moon that support the theory that the Moon was once part of the Earth.

Mars

Main article: Exploration of Mars

The exploration of Mars has been an important part of the space exploration programs of the Soviet Union (later Russia), the United States, Europe, and Japan. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into NASA 's Mars Exploration Rover ( MER) Mission is an ongoing robotic mission of exploring Mars, that began in 2003 with the sending of The exploration of Mars has been an important part of the Space exploration programs of the Soviet Union (later Russia) the United The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending The United States of America —commonly referred to as the For a topic outline on this subject see List of basic Japan topics. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s. A robotic spacecraft is a Spacecraft with no humans on board that is usually under Telerobotic control For other meanings see Orbiter (disambiguation. An orbiter is a Space probe that Orbits a Planet or Natural A lander is a Spacecraft which descends toward and comes to rest on the surface of an Astronomical body. A rover is a Space exploration vehicle designed to move across the surface of a Planet or other Astronomical body. These missions were aimed at gathering data about current conditions and answering questions about the history of Mars. The questions raised by the scientific community are expected to not only give a better appreciation of the red planet but also yield further insight into the past, and possible future of Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

The exploration of Mars has come at a considerable financial cost with roughly two-thirds of all spacecraft destined for Mars failing before completing their missions, with some failing before they even begin. Such a high failure rate can be attributed to the complexity and large number of variables involved in an interplanetary journey, and has led researchers to jokingly speak of The Great Galactic Ghoul ^[10] which subsists on a diet of Mars probes. This phenomenon is also informally known as the Mars Curse. ^[11]

Jupiter

Main article: Exploration of Jupiter

The exploration of Jupiter has consisted solely of a number of automated NASA spacecraft visiting the planet since 1973. The Voyager 1 spacecraft is a 722-kilogram robotic Space probe of the outer Solar system and beyond launched September 5, TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek Galileo was an Unmanned spacecraft sent by NASA to study the Planet Jupiter and its moons Named after the Astronomer The exploration of Jupiter has consisted of a few automated spacecraft visiting the planet since 1973 A large majority of the missions have been "flybys", in which detailed observations are taken without the probe landing or entering orbit; the Galileo spacecraft is only one to have orbited the planet. Galileo was an Unmanned spacecraft sent by NASA to study the Planet Jupiter and its moons Named after the Astronomer As Jupiter is projected to have only a relatively small rocky core and no real solid surface, a landing mission is impossible.

Reaching Jupiter from Earth requires a delta-v of 9. 2 km/s,^[12] which is comparable to the 9. 7 km/s delta-v needed to reach low Earth orbit. ^[13] Fortunately, gravity assists through planetary flybys can be used to reduce the energy required at launch to reach Jupiter, albeit at the cost of a significantly longer flight duration. In Orbital mechanics and Aerospace engineering, a gravitational slingshot, gravity assist or swing-by is the use of the relative movement and A space probe is a scientific Space exploration mission in which a Robotic spacecraft leaves the Gravity well of Earth and approaches the ^[12]

Jupiter has over 60 known moons many of which relatively little is known. Jupiter has 62 confirmed moons, giving it the largest retinue of moons with "reasonably secure" orbits of any planet in the Solar System

Saturn

Main article: Exploration of Saturn

The exploration of Saturn has been solely through unmanned spacecraft launched by NASA including one mission planned and executed in cooperation with other space agencies. The Huygens probe, supplied by the European Space Agency (ESA and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as The exploration of Saturn has been solely through unmanned spacecraft Like all gas giants, there is no solid surface for a probe to land on. A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large Planet that is not primarily Most missions therefore have been flybys with the exception of the joint NASA/ESA/ASI Cassini–Huygens spacecraft currently in orbit. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its

Saturn has at least 60 satellites, although the exact number is debatable since Saturn's rings are made up of vast numbers of independently orbiting objects of varying sizes. Saturn has 60 confirmed moons. These include 22 regular satellites, which all have Prograde orbits that are not greatly inclined with respect

Uranus

Main article: Exploration of Uranus

The exploration of Uranus has been solely through the Voyager 2 spacecraft, with no other visits currently planned. TemplateInfobox Planet.--> Miranda (mɨˈrændə) is the smallest The exploration of Uranus has been solely through the Voyager 2 spacecraft with no other visits currently planned Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. The closest approach to Uranus occurred on January 24, 1986. Events 41 - Gaius Caesar (Caligula, known for his eccentricity and cruel Despotism, is Assassinated by his disgruntled Year 1986 ( MCMLXXXVI) was a Common year starting on Wednesday (link displays 1986 Gregorian calendar) Voyager 2 discovered 10 previously unknown moons; studied the planet's unique atmosphere, caused by its axial tilt of 97. Uranus has twenty-seven named moons. Five of them are massive enough to have achieved Hydrostatic equilibrium and so would be considered Dwarf planets In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. 77°; and examined its ring system. The planet Uranus has a system of rings intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and

Neptune

Main article: Exploration of Neptune

The exploration of Neptune has only begun with one explorer, Voyager 2, which visited on August 25, 1989. Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek The exploration of Neptune has only begun with one explorer Voyager 2, which visited on August 25, 1989. Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. Events 1248 - The Dutch city of Ommen receives city rights and fortification rights from Otto III the Year 1989 ( MCMLXXXIX) was a Common year starting on Sunday (link displays 1989 Gregorian calendar) The possibility of a Neptune Orbiter is being discussed, yet other than that, no other missions have been given serious thought. Neptune Orbiter is a proposed NASA unmanned planetary spacecraft to explore the planet Neptune. As Neptune is a gas giant and has no solid surface, a surface mission such as a lander or rover is impossible. Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large Planet that is not primarily A lander is a Spacecraft which descends toward and comes to rest on the surface of an Astronomical body. A rover is a Space exploration vehicle designed to move across the surface of a Planet or other Astronomical body. Voyager 2 found that Neptune has the fastest winds of any planet in the solar system, measured as high as 2,100 km/h. ^[14] Neptunes largest moon Triton is thought to be a captured Kuiper belt object. TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek The Kuiper belt (ˈkaɪpɚ to rhyme with "viper" sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending ^[15]

Pluto

Main article: Exploration of Pluto

The dwarf planet Pluto (considered a planet until the IAU redefinition of "planet" in October 2006^[16]) presents significant challenges for spacecraft because of its great distance from Earth (requiring high velocity for reasonable trip times) and small mass (making capture into orbit very difficult at present). Charon (ˈʃærən; also, as in Χάρων) discovered in 1978 is either the largest Moon of Pluto or the smaller member of a double A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded Voyager 1 could have visited Pluto, but controllers opted instead for a close flyby of Saturn's moon Titan, resulting in a trajectory incompatible with a Pluto flyby. The Voyager 1 spacecraft is a 722-kilogram robotic Space probe of the outer Solar system and beyond launched September 5, Voyager 2 never had a plausible trajectory for reaching Pluto. Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. ^[17]

Despite its reclassification, as the lead and nearest member of a new and growing class of distant icy bodies of intermediate size, in mass between the remaining eight planets and the small rocky objects historically termed asteroids (and also the first member of the important subclass, defined by orbit and known as "Plutinos"), Pluto continues to be of great interest. In Astronomy, a plutino is a Trans-Neptunian object in 23 mean motion resonance with Neptune. After an intense political battle, a mission to Pluto dubbed New Horizons, was granted funding from the US government in 2003. New Horizons is a Robotic spacecraft mission by NASA currently underway ^[18] New Horizons was launched successfully on January 19, 2006. Events 1419 - Hundred Years' War: Rouen surrenders to Henry V of England completing his reconquest of Normandy. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar.

In early 2007 the craft made use of a gravity assist from Jupiter. In Orbital mechanics and Aerospace engineering, a gravitational slingshot, gravity assist or swing-by is the use of the relative movement and Its closest approach to Pluto will be on July 14, 2015; scientific observations of Pluto will begin 5 months prior to closest approach and will continue for at least a month after the encounter. Events 1223 - Louis VIII becomes King of France upon the death of his father Philip II of France. 2015 ( MMXV) will be a Common year starting on Thursday of the Gregorian calendar.

Asteroids

Main article: Exploration of the asteroids

Until the advent of space travel, objects in the asteroid belt were merely pinpricks of light in even the largest telescopes, their shapes and terrain remaining a mystery. TemplateInfobox Planet. --> 951 Gaspra (ˈɡæsprə is an S-type Asteroid that orbits very Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Spaceflight is the use of Space technology to fly a Spacecraft into and through Outer space. The asteroid belt is the region of the Solar System located roughly between the orbits of the Planets Mars and Jupiter. Several asteroids have now been visited by probes, the first of which was Galileo, which flew past two: 951 Gaspra in 1991, followed by 243 Ida in 1993. Galileo was an Unmanned spacecraft sent by NASA to study the Planet Jupiter and its moons Named after the Astronomer Gaspra (Гаспра Гаспра Gaspra is a Spa town in Crimea, Ukraine. Both of these lay near enough to Galileo's planned trajectory to Jupiter that they could be visited at acceptable cost. The first landing on an asteroid was performed by the NEAR Shoemaker probe in 2000, following an orbital survey of the object. The Near Earth Asteroid Rendezvous - Shoemaker (NEAR Shoemaker renamed after its launch in honor of planetary scientist Eugene M The dwarf planet Ceres and the asteroid 4 Vesta are targets of NASA's Dawn mission, launched in 2007 September. Ceres (ˈsɪəriːz TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt Dawn, launched on September 27 2007 is a Robotic spacecraft being sent by NASA on a Space exploration mission to the two most massive members

Rationale

See also: Space advocacy

In favor

The research that is conducted by national space exploration agencies, such as NASA and the RKA, is among the reasons supporters cite to justify government expenses. Space advocacy can be described as the general position supporting pleading or arguing forthe idea or cause of space exploration and settlements The Russian Federal Space Agency ( Russian: Федеральное космическое агентство России Federal'noe kosmicheskoe agentstvo Rossii Some even claim that space exploration is a necessity to mankind and that staying in our home planet will lead us to oblivion. Some of the reasons are lack of natural resources, comets, nuclear war, worldwide epidemic etc. Stephen Hawking, renowned British theoretical physicist, said that "I don't think the human race will survive the next thousand years, unless we spread into space. Stephen William Hawking CH, CBE, FRS, FRSA (born 8 January 1942 is a British theoretical physicist. There are too many accidents that can befall life on a single planet. But I'm an optimist. We will reach out to the stars. "^[19]

NASA has produced a series of Public Service Announcement videos supporting the concept of space exploration. ^[20]

Overall, the public remains largely supportive of both manned and unmanned space exploration. According to an Associated Press Poll conducted in July 2003, 71% of U. The Associated Press ( AP) is an American News agency. The AP is a Cooperative owned by its contributing Newspapers radio S. citizens agreed with the statement that the space program is "a good investment", compared to 21% who did not. ^[21]

Arthur C. Clarke (1950) presented a summary of motivations for the human exploration of space in his non-fiction semi-technical monograph Interplanetary Flight ^[22]. Sir Arthur Charles Clarke, CBE (16 December 1917–19 March 2008 was a British Science fiction Author, Inventor, and In it he argued that humanity's choice is essentially between expansion off the Earth into space, versus cultural (and eventually biological) stagnation and death.

Opposed

Critics, such as the late physicist and Nobel prize winner Richard Feynman have contended that space travel has never achieved any major scientific breakthroughs. A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature Richard Phillips Feynman (ˈfaɪnmən May 11 1918 – February 15 1988 was an American Physicist known for the Path integral formulation of quantum ^[23]

Related topics

Spaceflight

Main article: Spaceflight

Spaceflight is the use of space technology to fly a spacecraft into and through outer space. Spaceflight is the use of Space technology to fly a Spacecraft into and through Outer space. Space technology is Technology that is related to entering space, maintaining and using systems during Spaceflight and returning people and things A spacecraft is a Vehicle or machine designed for Spaceflight. Outer space, often simply called space, comprises the relatively empty regions of the Universe outside the escape velocities of Celestial bodies. Spaceflight is very typically a component of space exploration, but also supports commercial activities, satellite launches.

Space colonization

Main article: Space colonization

Space colonization, also called space settlement and space humanization, would be the permanent autonomous (self-sufficient) human habitation of locations outside Earth, especially of natural satellites or planets such as the Moon or Mars, using significant amounts of In-Situ Resource Utilization. Space colonization (also called space settlement, space humanization, Space habitation, etc A space habitat, also called space colony, orbital colony, space city, or space settlement is a Space station intended as a The colonization of the Moon is the proposed establishment of permanent human communities on the Moon. Mars is the focus of much speculation and serious study about possible human colonization which might be possible In Space exploration, In-Situ Resource Utilization (ISRU describes the proposed use of resources found or manufactured on other planetary bodies (the Moon Mars etc

Many past and current concepts for the continued exploration and colonization of space focus on a return to the moon as a "stepping stone" to the other planets, especially Mars. At the end of 2006 NASA announced they were planning to build a permanent moon base with continual presence by 2024. ^[24]

Space agencies

Main article: List of space agencies

While only the space programs of the United States, Soviet Union/Russia, and China have launched humans into orbit, a number of other countries have space agencies which design and launch satellites, conduct space research, and coordinate national astronaut programs. This is a list of government agencies engaged in activities related to Outer space and Space exploration.

See also

Main list: List of basic space exploration topics

References

External links

• Space related news
• Nasa's website on human space travel
• "America's Space Program: Exploring a New Frontier", a National Park Service Teaching with Historic Places (TwHP) lesson plan

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