Unmanned space mission

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Unmanned space missions are those using remote-controlled spacecraft. The first unmanned space mission was Sputnik I, launched October 4, 1957 to orbit the Earth. While the terms 'manned' and 'unmanned' are gender-neutral[1], some people prefer other terms such as unpiloted or uncrewed space missions. Space missions where animals but no humans are on-board are considered unmanned missions. Space missions with a mixed human and other animal crew are considered manned missions.

Many space missions are more suited to unmanned missions rather than manned space missions, due to lower cost and lower risk factors. In addition, some planetary destinations such as Venus or the vicinity of Jupiter are too hostile for human survival, given current technology. Outer planets such as Saturn, Uranus and Neptune are too distant to reach with current manned spaceflight technology, so unmanned probes are the only way to explore them.

Unmanned space probes use telemetry to radio back to earth acquired data and vehicle status information. Most probes have command systems to allow remote control from the ground. However increased autonomy is important for distant probes where the light travel time prevents rapid decision and control from earth. Newer probes such as Cassini-Huygens and Mars Exploration Rover are highly autonomous and can operate independently for periods of time using on-board computers.

Unmanned space missions have been flown by many countries. Most American unmanned missions have been coordinated by the Jet Propulsion Laboratory, and European missions by the European Space Operations Centre, part of ESA (the European Space Agency). The ESA has conducted relatively few space exploration missions (one example is the Giotto mission, which encountered comet Halley). ESA has, however, launched various spacecraft to carry out astronomy, and is a collaborator with NASA on the Hubble Space Telescope. There have been many successful Russian space missions. There have also been a few Japanese, Chinese and Indian missions.

Unmanned space missions may be divided into two classes: artificial satellites, which orbit the Earth, and space probes, which leave Earth's orbit to explore other worlds. See the relevant articles for more information.

Although generally referred to as remote controlled, some unmanned vehicles have not been. The earliest orbital probes such as Sputnik I and Explorer I transmitted one way data to earth; they were not remote controlled. Soon after the first probes, command systems were developed to allow remote control.

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