space exploration Using spacecraft to investigate outer space and heavenly bodies. On October 4, 1957, the Soviet Union launched the first artificial satellite, Sputnik 1, into Earth orbit. Soviet cosmonauts, and their American equivalents, astronauts, orbited the Earth soon after. Unmanned space probes crash-landed on the Moon, sending back pictures to Earth during the descent. Then came soft landings, and probes orbiting the Moon showed its hidden side for the first time. By 1968, Soviet scientists developed techniques for returning a Moon orbiter safely to the Earth. In 1969, the US Apollo 11 mission became the first to place a man on the Moon. By that time, the Soviet Union had sent probes to explore Mars and Venus. CHRONOLOGY: First probe to land on the Moon: Lunik 2, launched September 12, 1959. First manned spaceflight: Yuri Gagarin, April 12, 1961. First close-up pictures of Mars: Mariner 4, received July 14, 1965. First person to walk on the Moon, Neil Armstrong, July 20, 1969. First pictures from surface of another planet: Venera 9, received from Venus on October 22, 1975. First probes to land on Mars, Viking 1 and 2, July 1976. Fly-bys of Voyager 2: Jupiter (1979), Saturn (1981), Uranus (1986), Neptune (1989). First space shuttle: Columbia, launched April 12, 1981. Giotto probe, launched 1985, flew within 600km (380mi) of Halley's Comet, sending back photographs and data. Galileo project, launched October 1989, photographed the asteroids Gaspra (1991) and Ida (1993), dropped a sub-probe (1995) into Jupiter's atmosphere and provided detailed data on Galilean satellites; Clementine probe (1994), discovered what are thought to be water-ice deposits in craters of the Moon; Solar and Heliospheric Observatory (SOHO) probe, launched 1995, provided data on the Sun's interior until 2000; Mars Pathfinder mission, launched December 1996, landed on Mars to deploy a ‘microrover’ (Sojourner) to explore and collect rock samples; Cassini space probe (launched 1997) on a seven-year journey towards Saturn.