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Irregular moons

Irregular moons are small satellites with large-radii, inclined, and frequently retrograde orbits, believed to have been acquired by the parent planet through a capture process. They often occur as collisional families or groups.HP Pavilion DV7-1290EO Battery

The precise size as well as albedo of the irregular moons are not known for sure because the moons are very small to be resolved by a telescope, although the latter is usually assumed to be quite low—around 6% (albedo of Phoebe) or less. The irregulars generally have featureless visible and near infrared spectra dominated by water absorption bands.Apple A1281 Battery

They are neutral or moderately red in color—similar to C-type, P-type, or D-type asteroids,though they are much less red than Kuiper Belt objects.

Inuit group

The Inuit group includes five prograde outer moons that are similar enough in their distances from the planet (186–297 radii of Saturn), their orbital inclinations (45–50°) and their colors that they can be considered a group.Apple A1280 Battery

The moons are Ijiraq, Kiviuq, Paaliaq, Siarnaq, and Tarqeq. The largest among them is Siarnaq with an estimated size of about 40 km.

Gallic group

The Gallic group are four prograde outer moons that are similar enough in their distance from the planet (207–302 radii of Saturn), their orbital inclination (35–40°) and their color that they can be considered a group.Dell LATITUDE D800 Battery

They are Albiorix, Bebhionn, Erriapus, and Tarvos.[26] Tarvos, as of 2009, is the most distant of Saturn's moons with a prograde orbit. The largest among these moons is Albiorix with an estimated size of about 32 km.

Norse group

The Norse (or Phoebe) group consists of 29 retrograde outer moons.Dell Inspiron 6400 AC Adapter

They are Aegir, Bergelmir, Bestla, Farbauti, Fenrir, Fornjot, Greip, Hati, Hyrrokkin, Jarnsaxa, Kari, Loge, Mundilfari, Narvi,

Phoebe, Skathi, Skoll, Surtur, Suttungr, Thrymr, Ymir, S/2004 S 7, S/2004 S 12, S/2004 S 13, S/2004 S 17, S/2006 S 1, S/2006 S 3, S/2007 S 2, and S/2007 S 3.Sony Vaio VGN-CR190E/L Battery

After Phoebe, Ymir is the largest of the known retrograde irregular moons, with an estimated diameter of only 18 km. The Norse group may itself consist of several smaller subgroups.[26]

  • Phoebe, at 214 km in diameter, is by far the largest of Saturn's irregular satellites.HP 448007-001 Battery
  • It has a retrograde orbit and rotates on its axis every 9.3 hours.[60] Phoebe was the first moon of Saturn to be studied in detail by Cassini, in June 2004; during this encounter Cassini was able to map nearly 90% of the moon's surface. Phoebe has a nearly spherical shape and a relatively high density of about 1.6 g/cm3.Sony VGP-BPS11 Battery
  • Cassini images revealed a dark surface scarred by numerous impacts—there are about 130 craters with diameters exceeding 10 km. Spectroscopic measurement showed that the surface is made of water ice, carbon dioxide, phyllosilicates, organics and possibly iron bearing minerals.HP Pavilion DV6-1223EO Battery
  • Phoebe is believed to be a captured Kuiper Belt object or centaur.[19] It also serves as a source of material for the largest known ring of Saturn, which darkens the leading hemisphere of Iapetus (see above).

The Saturnian moons are listed here by orbital period (or semi-major axis), from shortest to longest.Compaq CQ35-100 Battery

Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in bold, while the irregular moons are listed in red, orange and gray background.

Space exploration is the use of astronomy and space technology to explore outer space.HP DV9700 Battery

Physical exploration of space is conducted both byhuman spaceflights and by robotic spacecraft. While the observation of objects in space, known as astronomy, predates reliable recorded history, it was the development of large and relatively efficient rockets during the early 20th century that allowed physical space exploration to become a reality.Sony VGP-BPS13 Battery

Common rationales for exploring space include advancing scientific research, uniting different nations, ensuring the future survival of humanity and developing military and strategic advantages against other countries. Various criticisms of space exploration are sometimes made.HP Pavilion DV8 Battery

Space exploration has often been used as a proxy competition for geopolitical rivalries such as the Cold War. 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'sSputnik 1, on October 4, 1957,Compaq CQ50 Battery

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 Soviet space program achieved many of the first milestones, including the first living being in orbit in 1957, the first human spaceflight(Yuri Gagarin aboard Vostok 1) in 1961,HP PP2200 Battery

the first spacewalk (by Aleksei Leonov) in 1965, the first automatic landing on another celestial body in 1966, and the launch of the first space station (Salyut 1) in 1971.

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 (ISS).HP Pavilion DV7-1290EO  Battery

With the substantial completion of the ISS[2] following STS-133 in March 2011, plans for space exploration by the USA remain in flux.HP Compaq Business  6830S  Battery

Constellation, a Bush Administration program for a return to the Moon by 2020[3] was judged inadequately funded and unrealistic by an expert review panel reporting in 2009.[4] The Obama Administration proposed a revision of Constellation in 2010 to focus on the development of the capability for crewed missions beyond low earth orbit (LEO),HP Pavilion DV7-2185DX  Battery

envisioning extending the operation of the ISS beyond 2020, transferring the development of launch vehicles for human crews from NASA to the private sector, and developing technology to enable missions to beyond LEO, such as Earth/Moon L1, the Moon, Earth/Sun L2, near-earth asteroids, and Phobos or Mars orbit.HP HSTNN-OB51  Battery 

 As of March 2011, the US Senate and House of Representatives are still working towards a compromise NASA funding bill, which will probably terminate Constellation and fund development of a heavy lift launch vehicle (HLLV).

In the 2000s, the People's Republic of China initiated a successful manned spaceflight program, while the European Union, Japan, and India have also planned future manned space missions. HP Pavilion DV6203TX Battery

China, Russia, Japan, and India have advocated manned missions to the Moon during the 21st century, while the European Union has advocated manned missions to both the Moon and Mars during the 21st century. From the 1990s onwards, private interests began promoting space tourism and then private space exploration of the Moon (see Google Lunar X Prize).HP Pavilion DV9565EA  Battery

History of exploration in the 20th Century

The first steps of putting a man-made object into space were taken by German scientists during World War II while testing theV2 rocket which became the first human-made object in space on October 3, 1942 with the launching of V-4. After the war, the U.S. used German scientists and their captured rockets in programs for both military and civilian research.Compaq Presario CQ71  Battery

The first scientific exploration from space was the cosmic radiation experiment launched by the U.S. on a V2 rocket on May 10, 1946. The first images of Earth taken from space followed the same year while the first animal experiment saw fruit flies lifted into space in 1947, both also on modified V2s launched by Americans.HP Compaq 464119-143  Battery

Starting in 1947, the Soviets, also with the help of German teams, launched sub-orbital V2 rockets and their own variant, the R-1, including radiation and animal experiments on some flights. These suborbital experiments only allowed a very short time in space which limited their usefulness.HP Pavilion DV2166EA  Battery

First flights
The first successful orbital launch was of the Soviet unmanned Sputnik ("Satellite I") mission on October 4, 1957. 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 radios around the globe.HP Compaq 451086-661  Battery
 


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. It burned up upon re-entry on January 3, 1958.HP G6000  Battery


This success led to an escalation of the American space program, which unsuccessfully attempted to launch a Vanguard satellite into orbit two months later. On January 31, 1958, the U.S. successfully orbited Explorer 1 on a Juno rocket. In the meantime, the Soviet dog Laika became the first animal in orbit on November 3, 1957.Compaq Presario 1245  Battery

First human flights
The first successful human spaceflight was Vostok 1 ("East 1"), carrying 27 year old Russian cosmonaut Yuri Gagarin on April 12, 1961. The spacecraft completed one orbit around the globe, lasting about 1 hour and 48 minutes. Gagarin's flight resonated around the world; HP Pavilion DM3-1050EO Battery
it was a demonstration of the advanced Soviet space program and it opened an entirely new era in space exploration: human spaceflight.
The U.S. first launched a person into space within a month of Vostok 1 with Alan Shepard's suborbital flight in Mercury-Redstone 3.Compaq Evo N610C  Battery
 


Orbital flight was achieved by the United States when John Glenn's Mercury-Atlas 6 orbited the Earth on February 20, 1962.


Valentina Tereshkova, the first woman in space, orbited the Earth 48 times aboard Vostok 6 on June 16, 1963.HP Pavilion DV9500  Battery


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.

First planetary explorations

The first artificial object to reach another celestial body was Luna 2 in 1959.HP EliteBook 6930P Battery

The first automatic landing on another celestial body was performed by Luna 9[8] in 1966. Luna 10 became the first artificial satellite of another celestial body.[9]

The first manned landing on another celestial body was performed by Apollo 11 in its lunar landing on July 20, 1969.HP Pavilion DV6-1211AX  Battery

The first successful interplanetary flyby was the 1962 Mariner 2 flyby of Venus (closest approach 34,773 kilometers). Flybys for the other planets were first achieved in 1965 for Mars by Mariner 4, 1973 for Jupiter by Pioneer 10, 1974 forMercury by Mariner 10, 1979 for Saturn by Pioneer 11, 1986 for Uranus by Voyager 2, and 1989 for Neptune by Voyager 2.HP G62-100EB  Battery

The first interplanetary surface mission to return at least limited surface data from another planet was the 1970 landing ofVenera 7 on Venus which returned data to earth for 23 minutes. In 1971 the Mars 3 mission achieved the first soft landing on Mars returning data for almost 20 seconds. HP Pavilion ZE4500  Battery

Later much longer duration surface missions were achieved, including over 6 years of Mars surface operation by Viking 1 from 1975 to 1982 and over 2 hours of transmission from the surface of Venus by Venera 13 in 1982 (the longest ever Soviet planetary surface mission).HP Compaq HSTNN-LB51  Battery

Key people in early space exploration

The dream of stepping into the outer reaches of the Earth's atmosphere was driven by the fiction of Jules Verne and H.G.Wells, and rocket technology was developed to try and realise this vision. The German V2 was the first rocket to travel into space, overcoming the problems of thrust and material failure.Compaq Presario CQ35-100 Battery

During the final days of World War II this technology was obtained by both the Americans and Soviets as were its designers. The initial driving force for further development of the technology was a weapons race for intercontinental ballistic missiles (ICBMs) to be used as long-range carriers for fast nuclear weapon delivery, HP Compaq 490306-001  Battery

but in 1961 when USSR launched the first man into space, the U.S. declared itself to be in a "Space Race" with Russia.

  • Konstantin Tsiolkovsky, Robert Goddard, Hermann Oberth, and Reinhold Tilling laid the groundwork of rocketry in the early years of the 20th century.HP Pavilion DV6-1223EO  Battery
  • Wernher von Braun was the lead rocket engineer for Nazi Germany's World War II V-2 rocket project. 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 ("Operation Paperclip"). Compaq Presario CQ50  Battery
  • He acquired American citizenship and led the team that developed and launched Explorer 1, the first American satellite. Von Braun later led the team at NASA's Marshall Space Flight Center which developed the Saturn V moon rocket.HP Compaq 490306-001  Battery
  • Initially the race for space was often led by Sergei Korolyov, whose legacy includes both the R7 and Soyuz—which remain in service to this day. Korolev was the mastermind behind the first satellite, first man (and first woman) in orbit and first spacewalk. HP Pavilion DV6-1215SA  Battery
  • 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. HP Pavilion DV8  Battery
  • 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 1971 to 1991, including the Salyut and Mir series, and their precursors in 1967, the Cosmos 186 and Cosmos 188.HP Pavilion DV3-2008TX  Battery

The Sun

While the Sun will probably not be physically explored in the close future, one of the reasons for going into space includes knowing more about the Sun. Once above the atmosphere in particular and the Earth's magnetic field, this gives access to the Solar wind and infrared and ultraviolet radiations that cannot reach the surface of the Earth. HP Pavilion DV6-1234TX Battery

The Sun generates most space weather, which can affect power generation and transmission systems on Earth and interfere with, and even damage, satellites and space probes.

Mercury

Mercury remains the least explored of the inner planets. As of May 2011, the Mariner 10 and MESSENGER missions have been the only missions that have made close observations of Mercury. HP Pavilion DV5-1111EA Battery

MESSENGER entered orbit around Mercury in March, 2011, to further investigate the observations made by Mariner 10 in 1975 (Munsell, 2006b). A third mission to Mercury, scheduled to arrive in 2020, BepiColombo is to include two probes. BepiColombo is a joint mission between Japan and the European Space Agency. HP Pavilion DV4-1125BR  Battery

MESSENGER and BepiColombo are intended to gather complementary data to help scientists understand many of the mysteries discovered by Mariner 10's flybys.

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. HP Pavilion DV9500  Battery

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

Venus was the first target of interplanetary flyby and lander missions and, despite one of the most hostile surface environments in the solar system, HP Pavilion ZD8181EA  Battery

has had more landers sent to it (nearly all from the Soviet Union) than any other planet in the solar system. The first successful Venus flyby was the American Mariner 2 spacecraft, which flew past Venus in 1962. 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 assisten route to other celestial bodies.HP Pavilion DV6-1230SB Battery

In 1967 Venera 4 became the first probe to enter and directly examine the atmosphere 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 eight additional successful Soviet Venus landers which provided images and other direct surface data.HP Pavilion DV5-1015EA  Battery

Starting in 1975 with the Soviet orbiter Venera 9 some ten successful orbiter missions have been sent to Venus, including later missions which were able to map the surface of Venus using radar to pierce the obscuring atmosphere.HP Compaq Business  6530B  Battery

Earth

Space exploration has been used as a tool to understand the Earth as a celestial object in its own right. Orbital missions can provide data for the Earth that can be difficult or impossible to obtain from a purely ground-based point of reference.HP 448007-001 Battery

For example, the existence of the Van Allen belts was unknown until their discovery by the United States' first artificial satellite, Explorer 1. These belts contain radiation trapped by the Earth's magnetic fields, which currently renders construction of habitable space stations above 1000 km impractical. HP Pavilion DV6-1210SA  Battery

Following this early unexpected discovery, a large number of Earth observation satellites have been deployed specifically to explore the Earth from a space based perspective. These satellites have significantly contributed to the understanding of a variety of earth based phenomena. HP Pavilion TX1000 Battery

For instance, the hole in the ozone layer was found by an artificial satellite that was exploring Earth's atmosphere, and satellites have allowed for the discovery of archeological sites or geological formations that were difficult or impossible to otherwise identify.HP Pavilion DV3-4000  Battery

Earth's Moon

Earth's Moon was the first celestial body to be the object of space exploration. It holds the distinctions of being the first remote celestial object to be flown by, orbited, and landed upon by spacecraft, and the only remote celestial object ever to be visited by humans.HP HSTNN-LB31 Battery

In 1959 the Soviets obtained the first images of the far side of the Moon, never previously visible to humans. The U.S. exploration of the Moon began with the Ranger 4 impactor in 1962. Starting in 1966 the Soviets successfully deployed a number of landers to the Moon which were able to obtain data directly from the Moon's surface; HP Compaq 491278-001 Battery

just four months later, Surveyor 1 marked the debut of a successful series of U.S. landers. The Soviet unmanned missions culminated in the Lunokhod program in the early '70s which included the first unmanned rovers and also successfully returned lunar soil samples to the Earth for study. HP Compaq Business  TC4400 Battery

This marked the first (and to date the only) automated return of extraterrestrial soil samples to the Earth. Unmanned exploration of the Moon continues with various nations periodically deploying lunar orbiters, and in 2008 the Indian Moon Impact Probe.HP Compaq Business NW9440 Battery

Manned exploration of the Moon began in 1968 with the Apollo 8 mission that successfully orbited the Moon, the first time any extraterrestrial object was orbited by humans. In 1969 the Apollo 11mission marked the first time humans set foot upon another world. Manned exploration of the Moon did not continue for long, however. HP 540 Battery

The Apollo 17 mission in 1972 marked the most recent human visit to another world, and there is no further planned human exploration of an extraterrestrial body, though robotic missions are still pursued vigorously.HP Compaq Business 6735S Battery

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. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s. HP Pavilion DV7-1290EO Battery

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.HP Pavilion DV7 Battery

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 began. HP Pavilion DV9000 Battery

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[16] which subsists on a diet of Mars probes. This phenomenon is also informally known as the Mars Curse.HP EliteBook 2730P Battery

Phobos

The Russian space mission Phobos-Grunt, Scheduled to launch in 2011,[18] will begin exploration of the Phobos and Martian circumterrestrial orbit, and study whether the moons of Mars, or at least Phobos, could be a "trans-shipment point" for spaceships travelling to Mars.[HP Pavilion DV6100 Battery

Asteroids and comets

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. 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.HP Compaq HSTNN-IB62 Battery

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.HP Pavilion DV6-3013SL Battery

The dwarf planet Ceres and the asteroid 4 Vesta, two of the three largest asteroids, are targets of NASA's Dawn mission, launched in 2007.

While many comets have been closely studied from Earth sometimes with centuries-worth of observations, only a few comets have been closely visited. HP HDX X18-1005EA Battery

A few long-period comets are currently the furthest known objects in the solar system. In 1985, the International Cometary Explorer conducted the first comet fly-by (21P/Giacobini-Zinner) before joining the Halley Armada studying the famous comet. HP G6000 Battery

The Deep Impact probe smashed into 9P/Tempel to learn more about its structure and composition while the Stardust mission returned samples of another comet's tail. The Philae lander will attempt to land on a comet in 2014.HP Pavilion DV7-1290EO Battery

Hayabusa was an unmanned spacecraft developed by the Japan Aerospace Exploration Agency to return a sample of material from a small near-Earth asteroid named 25143 Itokawa to Earth for further analysis. Hayabusa was launched on 9 May 2003 and rendezvoused with Itokawa in mid-September 2005.Compaq Presario CQ71 Battery

After arriving at Itokawa, Hayabusa studied the asteroid's shape, spin, topography, colour, composition, density, and history. In November 2005, it landed on the asteroid to collect samples. The spacecraft returned to Earth on 13 June 2010.

The exploration of Jupiter has consisted solely of a number of automated NASA spacecraft visiting the planet since 1973. HP Pavilion DV6-1210SA Battery

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 the only one to have orbited the planet. As Jupiter is believed to have only a relatively small rocky core and no real solid surface, a landing mission is nearly impossible.HP EliteBook 6930P Battery

Reaching Jupiter from Earth requires a delta-v of 9.2 km/s,[20] which is comparable to the 9.7 km/s delta-v needed to reach low Earth orbit.[21]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.HP Pavilion DV6-1220SO Battery

Jupiter has over 60 known moons, many of which have relatively little known information about them.

Saturn

Saturn has been explored only through unmanned spacecraft launched by NASA, including one mission (Cassini–Huygens) planned and executed in cooperation with other space agencies. HP Pavilion DV6-1211AX Battery

These missions consist of flybys in 1979 by Pioneer 11, in 1980 by Voyager 1, in 1982 by Voyager 2 and an orbital mission by the Cassini spacecraft which entered orbit in 2004 and is expected to continue its mission well into 2010.HP G62-100EB Battery

Saturn has at least 62 satellites, although the exact number is debatable since Saturn's rings are made up of vast numbers of independently orbiting objects of varying sizes. The largest of the moons is Titan. Titan holds the distinction of being the only moon in the solar system with an atmosphere denser and thicker than that of the Earth. HP Pavilion ZE4500 Battery

As a result of the deployment from the Cassini spacecraft of the Huygens probe and its successful landing on Titan, Titan also holds the distinction of being the only moon (apart from Earth's own Moon) to be successfully explored with a lander.HP Compaq HSTNN-LB51 Battery

Uranus

The exploration of Uranus has been entirely through the Voyager 2 spacecraft, with no other visits currently planned. Given its axial tilt of 97.77°, with its polar regions exposed to sunlight or darkness for long periods, scientists were not sure what to expect at Uranus. The closest approach to Uranusoccurred on January 24, 1986. Compaq Presario CQ35-100 Battery

Voyager 2 studied the planet's unique atmosphere and magnetosphere. Voyager 2 also examined its ring systemand the moons of Uranus including all five of the previously known moons, while discovering an additional ten previously unknown moons.HP Compaq 490306-001 Battery

Images of Uranus proved to have a very uniform appearance, with no evidence of the dramatic storms or atmospheric banding evident on Jupiter and Saturn. Great effort was required to even identify a few clouds in the images of the planet.HP Compaq Business NC6400 Battery

The magnetosphere of Uranus, however, proved to be completely unique and proved to be profoundly affected by the planet's unusual axial tilt. In contrast to the bland appearance of Uranus itself, striking images were obtained of the moons of Uranus, including evidence that Miranda had been unusually geologically active.HP Pavilion dv5 Adapter

Neptune

The exploration of Neptune began with the August 25, 1989 Voyager 2 flyby, the sole visit to the system as of 2009. The possibility of a Neptune Orbiter has been discussed, but no other missions have been given serious thought.Dell Studio PP39L Battery

Although the extremely uniform appearance of Uranus during Voyager 2's visit in 1986 had led to expectations that Neptune would also have few visible atmospheric phenomena, Voyager 2 found that Neptune had obvious banding, visible clouds, auroras, and even a conspicuous anticyclone storm system rivaled in size only by Jupiter's small Spot.Ibm Thinkpad T30 Battery

Neptune also proved to have the fastest winds of any planet in the solar system, measured as high as 2,100 km/h.[22] Voyager 2 also examined Neptune's ring and moon system. It discovered 900 complete rings and additional partial ring "arcs" around Neptune. In addition to examining Neptune's three previously known moons, HP Pavilion dv6000 Battery

Voyager 2 also discovered five previously known moons, one of which, Proteus, proved to be the last largest moon in the system. Data from Voyager further reinforced the view that Neptune's largest moon, Triton, is a captured Kuiper belt object.Asus S1 Adapter

Pluto

The dwarf planet Pluto (considered a planet until the IAU redefinition of "planet" in October 2006 ) 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).Acer Aspire 5920G Adapter

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. Voyager 2 never had a plausible trajectory for reaching Pluto.

Pluto continues to be of great interest, despite its reclassification as the lead and nearest member of a new and growing class of distant icy bodies of intermediate size,Acer PA-1650-02 Adapter

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"). After an intense political battle, a mission to Pluto dubbed New Horizons was granted funding from the US government in 2003.Dell T117C Battery

New Horizons was launched successfully on January 19, 2006. In early 2007 the craft made use of a gravity assist from Jupiter. Its closest approach to Pluto will be on July 14, 2015; scientific observations of Pluto will begin five months prior to closest approach and will continue for at least a month after the encounter.HP Pavilion DV6500 Adapter

Future of space exploration

In the 2000s, several plans for space exploration were announced; both government entities and the private sector have space exploration objectives. TheNASA Authorization Act of 2010 provides objectives for American space exploration.HP Compaq nx7400 Adapter

Technical avenues for US space exploration beyond low earth orbit (LEO) are being investigated by a NASA multi-center Technology Applications Assessment Team led from the Johnson Spaceflight Center. This study has as of January 2011 outlined "Nautilus-X",Dell Studio XPS 16 Battery

a concept for a multi-mission space exploration vehicle useful for missions beyond LEO, of up to 24 months duration for a crew of up to six. Although adaptable to a variety of mission-specific propulsion units of various low-thrust, high specific impulse (Isp) designs, nuclear ion-electric drive is shown for illustrative purposes. Nikon COOLPIX 5700  Battery

It is intended for integration and checkout at the International Space Station (ISS), and would be suitable for deep-space missions from the ISS to and beyond the Moon, including Earth/Moon L1, Sun/Earth L2, near-Earth asteroidal, and Mars orbital destinations.Dell Studio PP39L Battery

It incorporates a reduced-g centrifuge providing artificial gravity for crew health to ameliorate the effects of long-term 0g exposure, and the capability to mitigate the space radiation environment.

Rationales

The research that is conducted by national space exploration agencies, such as NASA and Roscosmos, HP Compaq 2510p Adapter

is one of the reasons supporters cite to justify government expenses. Economic analyses of the NASA programs often showed ongoing economic benefits (from things such as spin-offs), generating many times the revenue of the cost of the program.HP Compaq nx7300 Adapter

Another claim is that space exploration is a necessity to mankind and that staying on Earth will lead to extinction. Some of the reasons are lack of natural resources, comets, nuclear war, and worldwide epidemic. Stephen Hawking, renowned British theoretical physicist, Sony VGP-BPS13 Battery

said that "I don't think the human race will survive the next thousand years, unless we spread into space. 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."[31]

NASA has produced a series of public service announcement videos supporting the concept of space exploration.Sony VGP-BPS9 Battery

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.S. citizens agreed with the statement that the space program is "a good investment", compared to 21% who did not.HP Compaq Business NC6220 Battery

Arthur C. Clarke (1950) presented a summary of motivations for the human exploration of space in his non-fiction semi-technical monograph Interplanetary Flight.[34] He argued that humanity's choice is essentially between expansion off the Earth into space, versus cultural (and eventually biological) stagnation and death.Dell Inspiron 6400 Battery

Opposition

Critics such as the late physicist and Nobel prize winner Richard Feynman have contended that human space travel (as distinguished from space exploration in general, such as robotic missions) has never achieved any major scientific breakthroughs.Asus Eee PC 901 Battery

Spaceflight

Spaceflight is the use of space technology to achieve the flight of spacecraft into and through outer space.

Spaceflight is used in space exploration, and also in commercial activities like space tourism and satellite telecommunications.Asus M50 Battery

Additional non-commercial uses of spaceflight include space observatories, reconnaissance satellites and other earth observation satellites.

A spaceflight typically begins with a rocket launch, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Toshiba PA3534U-1BRS Battery

Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study calledastrodynamics. Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry, and others reach a planetary or lunar surface for landing or impact.Dell Vostro 1510 Battery

Satellites

Satellites are used for a large number of purposes. Common types include military (spy) and civilian Earth observation satellites, communication satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites.HP Compaq nx7300 Adapter

Commercialization of space

Current examples of the commercial use of space include satellite navigation systems, satellite television and satellite radio. Space tourism is the recent phenomenon of space travel by individuals for the purpose of personal pleasure.Dell Mini 1011v Battery

Militarization of space

While military activities have taken place in space and space is an operating location for many military spacecraft (such as imaging & communications satellites) or a temporary transit medium for weapons (such as ballistic missiles), permanent placement of large-scale operational weapons in space has never been conducted.Acer Aspire 5052ANWXMi Battery

Astrobiology

Astrobiology is the interdisciplinary study of life in the universe, combining aspects of astronomy, biology and geology.[36] It is focused primarily on the study of the origin, distribution and evolution of life. It is also known as exobiology (from Greek: ???, exo, "outside").Toshiba Equium A110-252 Battery

The term "Xenobiology" has been used as well, but this is technically incorrect because its terminology means "biology of the foreigners".[40] Astrobiologists must also consider the possibility of life that is chemically entirely distinct from any life found on earth.[Acer Aspire 5720 Adapter

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.HP Compaq nx6325 Adapter

To date, the longest human occupation of space was the space station Mir, which was continuously inhabited for almost ten years, including Valeri Polyakov's record single spaceflight of almost 438 days. Long-term stays in space reveal issues with bone and muscle loss in low gravity, immune system suppression, and radiation exposure.HP Compaq 6710b Adapter

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.toshiba pa3332u-1brs Battery,Dell Mini 1011 Battery,Dell 451-10617 battery

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