Aerospace Technology

Space Exploration

Three men were the first scientists to conceive pragmatically of spaceflight: the Russian Kon-stantin Tsiolkovsky, the American Robert God-dard, and the German Hermann Oberth. Technology in the early 20th century, however, was a long way from the level required for rocket-powered flight. Nonetheless, the theory and dynamics of such flights were rigorously studied. By the end of World War II, the German development of rocket propulsion for aircraft and guided missiles (notably the V-2) had reached a high level. With the German surrender in 1945, the US and its Allies fell heir to the technical knowledge of rocket power developed by the Germans. The technical director of the German missile effort, Wernher von Braun, and some 150 of his top aides surrendered to US troops. Most emigrated to the US, where they assembled and launched V-2 missiles that had been captured and shipped there. The USSR carried out an unpublicized but extensive and likely similar program; Britain and France conducted smaller programs.

In both the US and the USSR the development of military missile technology was essential to the achievement of satellite flight. Preparations for the International Geophysical Year (IGY, 1957-58) stimulated discussion of the possibility of launching artificial Earth satellites for scientific investigations. Both the US and the USSR became determined to prepare scientific satellites for launching during the IGY. While the US was still developing a space launch vehicle, the USSR startled the world by placing Sputnik 1 in orbit on 4 Oct 1957. This was followed a month later by Sputnik 2 carrying a live dog. The failure by the US to launch its small payload on 6 Dec 1957 heightened that nation’s political discomfiture in view of its supposed advanced status in science. Following debates on the necessity of achieving parity, the US government established the National Aeronautics and Space Administration (NASA) in 1958. Since that time, NASA has conducted virtually all major aspects of the US space program.

The first successful US satellite, Explorer 1, was launched about 4 months after Sputnik 1. During the next decades the two nations participated in a space race, conducting thousands of successful launches of spacecraft of all varieties including scientific-research, Significant space programs and missions: Sputnik (Russian for “fellow traveler”)

Years launched: 1957-58. Country or space agency: USSR. Designation: 1 through 3 (first series). Not manned. Events of note: Sputnik 1 was the first satellite to be successfully launched into space; Sputnik 2 carried a small dog named Laika (“Barker”); Sputnik 3 became the first multipurpose space-science satellite.

Communications, meteorological, remote-sensing, mili tary-reconnaissance, early-warning, and navigatior satellites, lunar and planetary probes, and manned craft. The USSR launched the first human, Yurj Gagarin, into orbit around Earth on 12 Apr 1961. On 20 July 1969, the US landed two men, Neil Armstrong and Edwin (“Buzz”) Aldrin, on the surface of the Moon as part of the Apollo 11 mission. On 12 Apr 1981, the 20th anniversary of manned space flight, the US launched the first reusable manned space transporta tion system, the space shuttle. From the 1960s the Eu ropean nations, Japan, India, and other countries have formed their own agencies for space exploration anc development. The European Space Agency (ESA) con sists of 15 member nations. Private corporations, too offer space launches for communications and remote-sensing satellites.

In the post-Apollo decades, while the US focused much of its manned space program on the shuttle, the USSR concentrated on launching a series of increasingly sophisticated Earth-orbiting space stations, beginning with the world’s first in 1971. Station crews, who were carried up in two- and three-person spacecraft carried out mostly scientific missions while gaining experience in living and working for long periods in the space environment. After the USSR was dissolved in 1991, its space program was continued by Russia on e much smaller scale owing to economic constraints. The US launched a space station in 1973 using surplus Apollo hardware and conducted shuttle missions to e Russian station, Mir, in the 1990s. In 1998, at the head of a 16-nation consortium and with Russia as a majoi partner, it began in-orbit assembly of the Internationa Space Station (ISS), using the shuttle and Russian ex pendable launch vehicles to ferry the facility’s modular components and crews into space. In addition to manned and unmanned lunar exploration, space explo ration programs have included deep-space robotic missions to the planets, their moons, and smaller bodies such as comets and asteroids. Also important has been the development of unmanned space-based astronomical observatories, which allow observation of near and distant cosmic objects above the filtering and distorting effects of Earth’s atmosphere.


Years launched: 1958-59. Country or space agency: US. Designation: 1 through 3. Not manned. Events of note: The first attempted Vanguard launch, hastily mounted in December 1957 after the USSR’s Sputnik successes, failed with the launch vehicle’s explosion.


Years launched: 1958-75. Country or space agency: US. Designation: 1 through 55. Not manned. Events of note: Explorer 1, the first successful US satellite, discovered Earth’s inner radiation belt. Other Explorers in this long series conducted pioneering studies over a broad spectrum of Earth and space sciences.


Years launched: 1958-78. Country or space agency: US. Designation: 1 through 13. Not manned. Events of note: Pioneer 10 was the first spacecraft to travel through the asteroid belt, to fly by Jupiter, and to escape the solar system; Pioneer 11 was the first to visit Saturn. Complementary Pioneer 12 and 13 spacecraft (also called Pioneer Venus) explored Venus, one conducting radar mapping of the planet’s cloud-shrouded surface from orbitwhile the other dropped atmospheric probes.

Luna (Russian for “Moon”)_

Years launched: 1959-76. Country or space agency: USSR. Designation: 1 through 24. Not manned. Events of note: Luna 2 was the first spacecaft to crash-land on the lunar surface; Luna 3 took the first photographs of the Moon’s far side; three Lunas (16, 20, and 24) returned with samples of lunar soil.


Years launched: 1961-63 (manned missions). Country or space agency: US. Designation: Mercury spacecraft had program designations, but they were better known by the individual names bestowed on them, such as Freedom 7, to honor the seven NASA astronauts chosen for the program. Events of note: Some 20 preliminary unmanned Mercury missions took place between 1959 and 1961. Of the six manned missions, Freedom 7 was launched in 1961 with Alan Shepard (the first American in space) aboard; Liberty Bell 7 in 1961 with Virgil “Gus” Grissom; Friendship 7 in 1962 with John Glenn (the first American to orbit Earth); Aurora 7 in 1962 with Scott Carpenter; Sigma 7 in 1962 with Walter Schirra; and Faith 7 in 1963 with Gordon Cooper.

Vostok (Russian for “east”)

Years launched: 1961-63. Country or space agency: USSR. Designation: 1 through 6. Manned. Events of note: The first man in space and to orbit Earth was Soviet cosmonaut Yury Gagarin in Vostok 1, launched on 12 April 1961. Vostok 2 was launched with Gherman Titov in 1961, Vostok 3 with Andriyan Nikolayev in 1962, Vostok 4 with Pavel Popovich in 1962, Vostok 5 with Valery Bykovsky in 1963, and Vostok 6 with Valentina Tereshkova, the first woman in space, in 1963.

Venera (Russian for “Venus”)

Years launched: 1961-83. Country or space agency: USSR. Designation: 1 through 16. Not manned. Events of note: Venera 1 carried out the first Venus flyby. Venera 3 was the first spacecraft to impact on another planet, and Venera 7 was the first to soft-land on another planet. Venera 9 and 10 sent back the first close-up pictures of Venus’s surface.


Years launched: 1961-65. Country or space agency: US. Designation: 1 through 9. Not manned. Events of note: Ranger 4 was the first US spacecraft to crash-land on the Moon; the last three Rangers returned thousands of images of the lunar surface before crashing on the lunar surface as planned.


Years launched: 1962-73. Country or space agency: US. Designation: 1 through 10. Not manned. Events of note: Various Mariners in the program flew by Venus, Mercury, and Mars. Mariner 9 mapped Mars in detail from orbit, becoming the first spacecraft to orbit another planet. Mariner 10 is the only spacecraft to have visited the vicinity of Mercury.

Voskhod (Russian for “sunrise” or “ascent”)_

Years launched: 1964-65. Country or space agency: USSR. Designation: 1 and 2. Manned. Events of note: Voskhod 1 was the first spacecraft to carry more than one person; Aleksey Leonov performed the first space walk, from the Voskhod 2 spacecraft, on 18 Mar 1965.


Years launched: 1965-66. Country or space agency: US. Designation: 1 through 12. Manned. Events of note: Ten two-person manned missions followed two unmanned test flights. Gemini 8 was the first spacecraft to dock with another craft, an unmanned launcher stage. The Gemini program showed that astronauts could carry out rendezvous and docking maneuvers and could live and work in space for the time needed for a round-trip to the Moon.

Lunar Orbiter

Years launched: 1966-67. Country or space agency: US. Designation: 1 through 5. Not manned. Events of note: Five consecutive spacecraft made detailed photographic surveys of most of the Moon’s surface, providing the mapping essential for choosing landing sites for the manned Apollo missions.

Soyuz (Russian for “union”)

Years launched: 1967-present. Country or space agency: USSR. Designation: 1 through 40 (first series). Three subsequent series of upgraded spacecraft received the additional suffix letters T, TM, or TMA and were renumbered from 1. Manned. Events of note: On 24 Apr 1967 cosmonaut Vladimir Komarov conducted the inaugural test flight (Soyuz 1) of this multiperson transport craft but died returning to Earth after the parachute system failed, becoming the first fatality during a spaceflight. Soyuz 11 ferried the crew of the first space station, Salyut 1. Soyuz TM-2 made the inaugural manned flight of this TM upgrade while transporting the second crew of the Mir space station. Soyuz TM-31 carried up the International Space Station’s first three-man crew. An automated unmanned cargo ferry, called Progress, was derived from the Soyuz design. High-resolution remote observations of Earth were made possible in 2006 with the launch of the Resurs-DK1 satellite.


Years launched: 1968-72. Country or space agency: US. Designation: 7 through 17. Manned. Events of note: Several unmanned test flights preceded 11 manned Apollo missions, including two in Earth orbit (7 and 9), two in lunar orbit (8 and 10), one lunar flyby (13), and six lunar landings (11, 12, and 14-17) in which a total of 12 astronauts walked on the Moon. Apollo 11, crewed by Neil Armstrong, Michael Collins, and Buzz Aldrin, was the first mission to land humans on the Moon, on 20 Jul 1969. Apollo 13, planned as a lunar landing mission, experienced an onboard explosion en route to the Moon; after a swing around the Moon, the crippled spacecraft made a harrowing but safe return journey to Earth with its crew, James Lovell, John Swigert, and Fred Haise. The six landing missions collectively returned almost 382 kg (842 lb) of lunar rocks and soil for study on Earth.

Salyut (Russian for “salute”)

Years launched: 1971-82. Country or space agency: USSR. Designation: 1 through 7 (two designs). Manned. Events of note: Salyut 1, launched 19 Apr 1971, was the world’s first space station; its crew, cosmonauts Georgy Dobrovolsky, Vladislav Volkov, and Viktor Patsayev, died returning to Earth when their Soyuz spacecraft depressurized. Salyut 6, the first of an improved design, operated as a highly successful scientific space platform, supporting a series of crews and international visitors over a four-year period.


Year launched: 1973. Country or space agency: US. Manned. Events of note: Skylab, based on the outfitted and pressurized upper stage of a Saturn V Moon rocket, was the first US space station. Three successive astronaut crews carried out solar astronomy studies, materials-sciences research, and biomedical experiments on the effects of weightlessness.


Year launched: 1975. Countries or space agencies: US and USSR. Manned. Events of note: As a sign of improved US-Soviet relations, an Apollo spacecraft carrying three astronauts docked in Earth orbit with a Soyuz vehicle carrying two cosmonauts. It was the first cooperative multinational space mission and the last use of an Apollo craft.


Year launched: 1975. Country or space agency: US. Designation: 1 and 2. Not manned. Events of note:

Both space probes traveled to Mars, released landers, and took photographs of large expanses of Mars from orbit. The Viking 1 lander transmitted the first pictures from the Martian surface; both landers carried experiments designed to detect living organisms or life processes but found no convincing signs of life.


Year launched: 1977. Country or space agency: US. Designation: 1 and 2. Not manned. Events of note: Both Voyager spacecraft flew past Jupiter and Saturn, transmitting measurements and photographs; Voyager 2 went on to Uranus in 1986 and then to Neptune. Both craft continued out of the solar system, with Voyager 1 overtaking Pioneer 10 in 1998 to become the most distant human-made object in space.

Space shuttle (Space Transportation System, or STS) Years launched: 1981-present. Country or space agency: US. Designation: Individual missions were designated STS with a number (and sometimes letter) suffix, although the orbiter spacecraft themselves were reused. Manned. Events of note: The first flight of a manned space shuttle, STS-1, was on 12 Apr 1981 with the orbiter Columbia. Other original operational orbiters included Challenger, Discovery, and Atlantis. During shuttle mission STS-51-L, Challenger exploded after liftoff on 28 Jan 1986, killing all seven astronauts aboard, including a private citizen, Christa McAuliffe; the orbiter Endeavour was built as a replacement vehicle. Space shuttle missions were used to deploy satellites, space observatories, and planetary probes; to carry out in-space repairs of orbiting spacecraft; and to take US astronauts to the Russian space station Mir. Beginning in 1998 a series of shuttle missions ferried components, supplies, and crews to the International Space Station during its assembly and operation. In 2003 the orbiter Columbia disintegrated while returning from a space mission, claiming the lives of its seven-person crew, including Ilan Ramon, the first Israeli astronaut to go into space.


Year launched: 1985. Countries or space agency: ESA. Not manned. Events of note: This first deep-space probe launched by ESA made a close flyby of Halley’s Comet, collecting data and transmitting images of the icy nucleus. It was then redirected to a second comet, using a gravity-assist flyby of Earth, the first time that a spacecraft coming back from deep space had made such a maneuver.

Mir (Russian for “peace” and “world”)

Years launched: 1986-96. Country or space agency: USSR/Russia. Manned. Events of note: The core of this modular space station was launched on 20 Feb 1986; five additional modules were added over the next decade to create a large, versatile space laboratory. Although intended for a five-year life, it supported human habitation between 1986 and 2000, including an uninterrupted stretch of occupancy of almost 10 years, and it hosted a series of US astronauts as part of a Mir-space shuttle cooperative endeavor. In 1995 Mir cosmonaut Valery Polyakov set a space endurance record of nearly 438 days.


Year launched: 1989. Country or space agency: US. Not manned. Events of note: Magellan was the first deep-space probe deployed by the space shuttle. During four years in orbit above Venus, it mapped some 98% of the surface of the cloud-covered planet with radar at high resolution. At the end of its mission, it was sent on a gradual dive into the Venusian atmosphere, where it measured various properties before burning up.


Year launched: 1989. Country or space agency: US. Not manned. Events of note: En route to Jupiter, Galileo took the first detailed pictures of two asteroids and returned unique images of a comet as it impacted Jupiter’s atmosphere. Near the Jovian system, it released an atmospheric probe and then went into orbit around Jupiter for an extended study of the giant planet and its Galilean moons. Among many discoveries, Galileo found evidence of a liquid-water ocean belowthe moon Europa’s icy surface.


Year launched: 1990. Countries or space agency: US and ESA. Not manned. Events of note: Ulysses traveled first to Jupiter in order to use the giant planet’s gravity to sling the probe out of the plane of the planets. Ulysses successively passed over the Sun’s south and north poles, studying properties of the corona, solar wind, and interplanetary space at high solar latitudes.


Year launched: 1994. Country or space agency: US. Not manned. Events of note: This probe was designed to test new imaging sensors in space for defense applications. It mapped the Moon in various wavelengths from lunar orbit, determining mineral content of the surface and producing tantalizing hints of the existence of frozen water in permanently shadowed craters near the Moon’s south pole.

NEAR Shoemaker (Near Earth Asteroid Rendezvous Shoemaker)

Year launched: 1996. Country or space agency: US. Not manned. Events of note: This spacecraft was the first to orbit a small body (the Earth-approaching asteroid Eros) to touch down on its surface. It studied Eros for a year with cameras and instruments and then made a slow descent and a soft landing and transmitted gamma-ray data from the surface for more than two weeks.

Mars Global Surveyor (MGS)

Year launched: 1996. Country or space agency: US. Not manned. Events of note: MGS conducted long-term mapping from Martian orbit of the planet’s entire surface and studies of its magnetic, atmospheric, and internal properties. Close-up images suggested, controversially, that liquid water may have flowed on or near the planet’s surface in geologically recent times and still may exist in protected areas. They also showed that the “face on Mars” formation first photographed by Viking 1 was of natural origin and not a product of alien intelligence, as some had purported.

Mars Pathfinder

Year launched: 1996. Country or space agency: US. Not manned. Events of note: The first spacecraft to land on Mars since the 1976 Viking missions, Pathfinder descended to the Martian surface using a novel combination of parachutes, rockets, and air bags. The lander and its robotic surface rover, Sojourner, which together successfully collected 17,000 images and other data, added to evidence that ancient Mars was much more Earth-like than it is today.


Year launched: 1997. Country or space agency: US, ESA, and Italy. Not manned. Events of note: Consisting of an orbiter (Cassini) and a descent probe (Huygens), thespacecraft traveled sevenyears to theSat-urnian system. En route it flew by Jupiter and returned detailed images. At Saturn, Cassini established an orbit around the planetforseveral years of studies, while the Huygens probe parachuted through the atmosphere of the moon Titan, transmitting pictures and other data for about three hours during its descent and once on the moon’s surface.

Lunar Prospector

Year launched: 1998. Country or space agency: US. Not manned. Events of note: Equipped with radiation-and particle-measuring equipment to assay the geochemistry of the Moon’s surface from orbit, the probe strengthened the evidence for water (first found by Clementine) in the south polar region. It later was deliberately crashed into a permanently shadowed crater at the south pole in an unsuccessful attempt to liberate water vapor, which could be detected from Earth.

International Space Station (ISS)

Years launched: 1998-present. Countries or space agencies: US, Russia, ESA, Canada, Japan, and Brazil. Manned. Events of note: A large modular complex of habitat modules and laboratories powered by solar arrays, the ISS continued to be assembled in Earth orbit by means of space-shuttle and Proton and Soyuz rocket flights that ferried components, crews, and supplies between Earth and the station. The first component, a US-funded, Russian-built module called Zarya, was launched on 20 Nov 1998. The ISS received its first resident crew on 2 Nov 2000.

Chandra X-Ray Observatory_

Year launched: 1999. Country or space agency: US. Not manned. Events of note: The world’s most powerful X-ray telescope, it revolves in an elliptical orbit around Earth, delivering roughly 1,000 observations annually of the universe. To scientists, the stunning images of the universe’s outer limits (including images of black holes and distant galaxies) help clarify its origin and evolution.

2001 Mars Odyssey

Year launched: 2001. Country or space agency: US. Not manned. Events of note: This spacecraft was launched to study Mars from orbit and serve as a communications relay for future US and multinational landers. Its instruments mapped the distribution of various elements on or near the surface; some of its data suggested the presence of huge subsurface reservoirs of frozen water in both polar regions.

Mars Express

Year launched: 2003. Country or space agency: ESA. Not manned. Events of note: Carrying instruments to study the atmosphere, surface, and subsurface from Mars orbit, the spacecraft detected vast fields of water ice as well as carbon-dioxide ice at the planet’s south pole. Its lander, Beagle 2, which was designed to examine the rocks and soil for signs of past or present life, failed to establish radio contact after presumably reaching the Martian surface.

Mars Exploration Rovers

Year launched: 2003. Country or space agency: US. Designation: Spirit and Opportunity. Not manned. Events of note: Twin six-wheeled robotic rovers, each equipped with cameras, a microscopic imager, a rock-grinding tool, and other instruments, landed on opposite sides of Mars. Both rovers found evidence of past water; particularly dramatic was the discovery by Opportunity of rocks that appeared to have been laid down at the shoreline of an ancient body of salty water.

Deep Impact

Year launched: 2005. Country or space agency: US. Not manned. Events of note: Deep Impact was the first spacecraft designed to study the interior composition of a comet. As it traveled past Comet Tempel 1, it released a 370-kg (820-lb) instrumented impactor into the path of the comet’s icy nucleus. A high-resolution camera and other apparatuses on the flyby portion of the probe studied the impact and the resulting crater and excavated debris. The collision occurred at a relative speed of about 37,000 km/hr (23,000 mi/hr).

Mars Reconnaissance Orbiter

Year launched: 2005. Country or space agency: US. Not manned. Events of note: It carries the most powerful camera ever flown on a space mission. The Orbiter is expected to be an important communications link between other spacecraft, Mars,and Earth.


Year launched: 2007. Country or space agency: US. Not manned. Events of note: Phoenix was the first spacecraft designed to measure water (ice) on a planet other than Earth. It is equipped with robotic arms and sophisticated sensors to dig under the surface of Mars, collect soil samples, and analyze them. It landed on the surface of Mars on 25 May 2008 and quickly established communications with Earth.








earliest known person to write

Lucian, in True History, which


2nd century ad

about spaceflight

includes a visit to the Moon



earliest appearance of rocket

recorded use of gunpowder-


by 13th century

propulsion technology

propelled arrows in battle



first person to study in detail the

Konstantin Tsiolkovsky


late 19th-early

use of rockets for spaceflight


20th centuries

first launch of a liquid-fueled rocket

Robert Goddard


16 Mar 1926

first launch of the V-2 ballistic missile,

Wernher von Braun


3 Oct 1942

the forerunner of modern space rockets



first artificial Earth satellite

Sputnik 1


4 Oct 1957

first animal launched into space

dog Laika aboard Sputnik 2


3 Nov 1957

first spacecraft to hard-land on another

Luna 2


14 Sep 1959

celestial object (the Moon)



first pictures of the far side of the Moon

Luna 3


7 Oct 1959

first applications satellite launched

TIROS 1 (weather observation)


1 Apr 1960

first recovery of a payload from Earth orbit

Discoverer 13 (part of Corona


11 Aug 1960

reconnaissance satellite program)


first piloted spacecraft to orbit Earth

Yury Gagarin on Vostok 1


12 Apr 1961

first US citizen in space

Alan Shepard on Freedom 7


5 May 1961

first piloted US spacecraft to orbit Earth

John Glenn on Friendship 7


20 Feb 1962

first active communications satellite

Telstar 1


10 July 1962

first data transmitted to Earth from vicinity

Mariner 2


14 Dec 1962

of another planet (Venus)



first woman in space

Valentina Tereshkova on Vostok 6


16 Jun 1963

first satellite to operate in geostationary

Syncom 2 (telecommunications


26 Jul 1963





first space walk

Aleksey Leonov on Voskhod 2


18 Mar 1965

first spacecraft pictures of Mars

Mariner 4


14 Jul 1965

first spacecraft to soft-land on the Moon

Luna 9


3 Feb 1966

first death during a space mission

Vladimir Komarov on Soyuz 1


24 Apr 1967

first humans to orbit the Moon

Frank Borman, James Lovell, and


24 Dec 1968

William Anders on Apollo 8



first human to walk on the Moon

Neil Armstrong on Apollo 11


20 Jul 1969

first unmanned spacecraft to carry lunar

Luna 16


24 Sep 1970

samples back to Earth



first soft landing on another planet (Venus)

Venera 7


15 Dec 1970

first space station launched

Salyut 1


19 Apr 1971

first spacecraft to orbitanother planet (Mars)

Mariner 9


13 Nov 1971

first spacecraft to soft-land on Mars

Mars 3


2 Dec 1971

first spacecraft to fly by Jupiter

Pioneer 10


3 Dec 1973

first international docking in space

Apollo and Soyuz spacecraft


17 Jul 1975


during Apollo-Soyuz Test Project



first pictures transmitted from the

Viking 1


20 Jul 1976

surface of Mars



first spacecraft to fly by Saturn

Pioneer 11


1 Sep 1979

first reusable spacecraft launched and

space shuttle Columbia


12-14 Apr 1981

returned from space



first spacecraft to fly by Uranus

Voyager 2


24 Jan 1986

first spacecraft to make a close flyby of

Giotto at Halley’s Comet


13 Mar 1986

a comet’s nucleus

Space Agency (ESA)


first spacecraft to fly by Neptune

Voyager 2


24 Aug 1989

first large optical space telescope launched

Hubble Space Telescope


25 Apr 1990

first spacecraft to orbit Jupiter



7 Dec 1995

first confirmed case of a large black hole

Chandra X-Ray Observatory

US September1999-

outside of the nucleus of a galaxy


12 Jun 2000

first resident crew to occupy the

William Shepherd, Yury Gidzenko,


2 Nov 2000

International Space Station

and Sergey Krikalev



first spacecraft to orbit and land on

NEAR Shoemaker at the asteroid Eros US

14 Feb 2000-

an asteroid


12 Feb 2001

first piloted Chinese spacecraft to orbit Earth

Shenzhou 5, piloted by Yang Liwei


15 Oct 2003

first privately funded human spaceflight

SpaceShipOne, piloted by


21 Jun 2004

(to 100 km [62 mi])

Michael W. Melvill (private venture)


first spacecraft to strike a comet’s nucleus

Deep Impact at Comet Tempel 1


4 Jul 2005

and study its interior composition



first spacecraft designed to measure water (ice) on a planet other than Earth



5 Jun 2008

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