Robots in Space
Whether orbiting other planets or moons, landing on them, or just flying by, small but sturdy unmanned spacecraft--basically robots-- have provided Earth-bound scientists with images of every planet in the solar system and even beyond, inspiring and informing future missions--both manned and unmanned.
LANDING ON VENUS
1970: Venera 7
Venera 7, a Soviet spacecraft, landed on Venus, the first unmanned probe to touch down on another planet and transmit data back to Earth.
TO THE OUTER SOLAR SYSTEM
1972: Pioneer 10 & 11
Pioneer 10 & 11American missions headed for Jupiter and Saturn, respectively, were the first objects to cross the asteroid belt between Mars and Jupiter. Both spacecraft eventually left the solar system, and though they no longer send back signals to Earth, they continue to travel deeper into space.
Bolted to the Pioneer spacecraft, plaques sporting the design here--including two Earthlings--rode into space. Designed by Carl Sagan and others, the plaques were meant as a greeting from humans to potential intelligent, extraterrestrial life.
Twin American spacecraftVoyager 1 & 2 headed first to Jupiter and Saturn. Voyager 2 then visited Uranus and Neptune, the only spacecraft to have done so. The two craft are now travelling literally billions of miles from the Sun, measuring the particle and magnetic properties of interstellar space.
VOYAGER GOLD RECORD
A two-sided, gold-plated record travelled aboard each Voyager craft, carrying sounds of Earth like surf, wind, thunder and birds, as well as spoken greetings in 55 languages from Earthlings to potential extraterrestrial life.
MARS EXPLORATION ROVER
Mars is a hard planet to visit: since the 1970s, only a few spacecraft have successfully reached it. In 2004, however, two identical NASA rovers landed on Mars. Equipped with cameras, computers and specialized scientific devices, the rovers Spirit and Opportunity revolutionized our understanding of Mars, in particular by confirming that the planet was once home to much liquid water. The rovers were only expected to remain active for a year or so but Spiritcontinued transmitting data until 2010.Opportunity, meanwhile, is still going strong; in 2011, it discovered a rock that contains zinc and bromine. On Earth, such elements suggest that heated water once flowed through the rock. So this finding may prove to be more evidence that Mars had a watery past.