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Venus is one of the best-explored bodies in all the solar system. The first fruitful observation of Venus as a celestial body, rather than as a mythical entity, was by [[Galileo Galilei]]. He first documented the phases of Venus, something that requires a 75-meter telescope to observe. Other astronomers readily discerned that Venus had an atmosphere, though some incorrectly surmised that the solar day on Venus was comparable to that on Earth.

Venus is one of the best-explored bodies in all the solar system. The first fruitful observation of Venus as a celestial body, rather than as a mythical entity, was by [[Galileo Galilei]]. He first documented the phases of Venus, something that requires a 75-meter telescope to observe. Other astronomers readily discerned that Venus had an atmosphere, though some incorrectly surmised that the solar day on Venus was comparable to that on Earth.

The [[United States]] and the [[Union of Soviet Socialist Republics]] both sent multiple rocket probes to Venus. The Soviet [[Project Venera]] was the first to attempt landings on Venus, but the first several Venera landers were crushed by the 92-bar atmosphere before they could even reach the surface. But eventually the Soviets did succeed in launching probes that descended to Venus's surface by parachute and transmitted data and even images.

The [[United States]] and the [[Union of Soviet Socialist Republics]] both sent multiple rocket probes to Venus. The Soviet Union holds the present record for attempted missions (successful or failed) to Venus, including [[Project Sputnik]] and the highly prolific [[Project Venera]]. The first several Venera landers were crushed by the 92-bar atmosphere before they could even reach the surface. But eventually the Soviets did succeed in launching probes that descended to Venus's surface by parachute and transmitted data and even images.

The American [[Project Mariner]] achieved some success, mainly with orbiters that either traveled to Venus directly or (in the case of [[Mariner 10]] made brief rendez-vous with Venus on the way to Mercury. The USA also launched the [[Pioneer Venus]] series of missions, including one orbiter and a total of five atmospheric descenders.

The American [[Project Mariner]] achieved some success, mainly with orbiters that either traveled to Venus directly or (in the case of [[Mariner 10]] made brief rendez-vous with Venus on the way to Mercury. The USA also launched the [[Pioneer Venus]] series of missions, including one orbiter and a total of five atmospheric descenders.<ref name=timeline>Williams, David R. "[http://nssdc.gsfc.nasa.gov/planetary/chronology_venus.html Chronology of Venus Exploration]." National Space Science Data Center, [[National Aeronautics and Space Administration|NASA]], November 20, 2007. Accessed May 22, 2008.</ref>

NASA had intended to send an [[Project Apollo|Apollo]]-style rocket with a three-man crew to make rendez-vous with Venus in 1974 and also fly close to Mercury and the Sun. The mission was projected to last a year.

In 1967, a NASA contractor developed plans for sending an [[Project Apollo|Apollo]]-style rocket with a three-man crew to make rendez-vous with Venus in 1974 and also fly close to Mercury and the Sun. The mission was projected to last a year by carrying an extra life-support module, using the spent S-IVB stage as expanded living quarters, and mounting a solar cell array system on the S-IVB.<ref name=Feldman>Feldman, M. S., ''et al.'' ''[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790072165_1979072165.pdf Manned Venus Flyby].'' Bellcomm, Inc., Contract No. NASw-417, February 1, 1967. Accessed May 22, 2008.</ref>

[[Project Magellan]] achieved a major research breakthrough with the arrival of the Magellan orbiter at Venus on August 10, 1990. Over four and a half years, the craft successfully mapped 98% of the planet's surface and 95% of its gravity field. Magellan determined that the planet's geography is largely volcanic, with many lava domes, plains and channels.

[[Project Magellan]] achieved a major research breakthrough with the arrival of the Magellan orbiter at Venus on August 10, 1990. Over four and a half years, the craft successfully mapped 98% of the planet's surface and 95% of its gravity field. Magellan determined that the planet's geography is largely volcanic, with many lava domes, plains and channels.