Landed spacecraft can make detailed observations of a planet's surface. However, these observations are restricted to a small area. To obtain coverage over a wider area, spacecraft can carry robots that are able to rove over the surface. Crewed missions or robotic rovers provide not only mobility but also the capability to do complex tasks and make intelligent and selective observations.
Two Soviet mobile vehicles, the Lunokhods, have landed on the Moon, one in November 1970 and the other in January, 1973. The Lunokhods were remotely controlled roving vehicles that carried television cameras and instruments to measure the physical and chemical properties of the lunar soil.
The six Apollo lunar landing missions demonstrated the value of manned exploration of planetary surfaces. The astronauts were able to set up scientific instruments, choose the most interesting samples for collection, and study the geology of the lunar surface.
Since the first Mars rover Sojourner traversed the rocky plain of Ares Valles, increasingly sophisticated vehicles have explored the hills and plains of Mars.
Marie Curie is the flight spare, or backup vehicle, for the Sojourner rover that operated on Mars in 1997. Nearly identical to Sojourner, Marie Curie was used for testing on a simulated Mars terrain at the Jet Propulsion Laboratory. Sojourner traveled about 100 meters (330 feet) across the Martian surface with a top speed of 1 centimeter (0.4 inch) per second. It was the first to test a "rocker bogie" mobility system, designed to prevent rovers from tipping over in their exploration of the rocky surface of Mars. During its 83 Martian days of operation, it provided over 500 images and collected chemical data from 16 locations.
Transferred from NASA/JPL-CalTech
Two Mars Exploration Rovers (Spirit and Opportunity) arrived on Mars in 2004. Operating long past their design lifetimes, they have explored Gusev Crater and Meridiani Planum, two locations on opposite sides of the planet.
Lent by Cornell University; rover design by JPL-Caltech
Using an innovative "sky crane" landing system, the Mars Science Laboratory rover, named Curiosity, set down in Gale Crater in August 2012. Gale Crater is 150 kilometers (about 90 miles) in diameter and contains a large central mound 5 kilometers (3 miles) high. The mound is made up of many different rock layers that record the geologic history of the area and may tell the story of environmental change over millions of years of Mars' history. Early in its mission, the rover found signs of a past lake at Gale Crater, and evidence that the ancient environment in the area could have supported life.
Transferred from NASA/JPL-Caltech