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A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots. Rovers usually arrive at the planetary surface on a lander-style spacecraft.

Contents 1 History 1.1 Lunokhod 1 1.2 Apollo Lunar Roving Vehicle 1.3 Lunokhod 2 1.4 Prop-M Rover 1.5 Sojourner 2 Active rover missions 2.1 Mars Exploration Rovers 3 Planned rover missions 3.1 Mars Science Laboratory 3.2 Chandrayaan-II 4 Autonomy 4.1 Distances and lag times 5 References

Main article: Lunokhod 1

The Lunokhod 1 rover landed on the Moon in 1970. It was the first roving remote-controlled robot to land on any celestial body. The Soviet Union launched Lunokhod 1 aboard the Luna 17 spacecraft on November 10, 1970, and it entered lunar orbit on November 15. The spacecraft soft-landed in the Sea of Rains region on November 17. The lander had dual ramps from which Lunokhod 1 could descend to the lunar surface, which it did at 06:28 UT. From November 17, 1970 to November 22, 1970 the rover drove 197 m, and during 10 communication sessions returned 14 close up pictures of the Moon and 12 panoramic views. It also conducted analysis of the lunar soil. The last successful communications session with Lunokhod 1 was on September 14, 1971. At the end of its mission Lunokhod had driven over 10 kilometers on the surface of the Moon.

Main article: Lunar rover

Main article: Lunokhod 2

Main articles: Mars 3 and Prop-M Rover

Mars 3 lander had a small 4.5 kg Mars rover on board, which would move across the surface on skis while connected to the lander with a 15-meter umbilical. Two small metal rods were used for autonomous obstacle avoidance, as radio signals from Earth would take too long to drive the rovers using remote control. The rover was planned to be placed on the surface after landing by a manipulator arm and to move in the field of view of the television cameras and stop to make measurements every 1.5 meters. The traces of movement in the Martian soil would also be recorded to determine material properties. Because of the demise of the lander, the rover never saw action.

Main article: Sojourner (rover)

The Mars Pathfinder mission included Sojourner, the first rover to successfully reach another planet. The U.S. National Aeronautics and Space Administration (NASA) launched Mars Pathfinder on December 4, 1996; it landed on Mars in a region called Chryse Planitia on 4 July 1997. From its landing until the final data transmission on September 27, 1997, Mars Pathfinder returned 16,500 images from the lander and 550 images from Sojourner, as well as more than 15 chemical analysis of rocks and soil and extensive data on winds and other weather factors.

Main article: Spirit rover

Main article: Opportunity rover

Two rovers -- Spirit and Opportunity -- were landed on Mars as part of the Mars Exploration Rover mission. Both Spirit and Opportunity have been operating on Mars for more than three years. By February 6, 2007, Opportunity had traversed 10 kilometers on the Martian surface.^[1]

Main article: Mars Science Laboratory

The Mars Science Laboratory is a NASA rover scheduled to launch in December 2009 and perform a precision landing on Mars in October 2010. This rover will be three times as heavy and twice the width of the Mars Exploration Rovers that landed in 2004.

Main articles: Chandrayaan#Chandrayaan-II and Chandrayaan-II

Rovers which land on celestial bodies far from the Earth - such as the Mars Exploration Rovers - cannot be remotely controlled since the speed of light (the speed at which radio signals travel) is far to slow for real time or near-real time communication, and therefore must be capable of operating autonomously which little assistance from ground control.

1. ^ Opportunity Passes 10-Kilometer Mark. nasa.gov. Retrieved on February 8, 2007.

v • d • e Lunar Rovers
Succeeded	Lunar rover (Apollo 15, Apollo 16, and Apollo 17), Lunokhod programme (Lunokhod 1, Lunokhod 2)
Proposed	Chang'e Rover, Chandrayaan-II