Unmanned space exploration began with Sputnik 1 being launched on October 4, 1957, by the USSR. It has developed from this to probes that took several photographs before they collided with the surface of the Moon, to probes that reached Venus and Mars (our closest neighbours) to such well known interstellar probes as Pioneer 1 and 2 and Voyager 1 and 2 to the Mars lander Viking. Furthermore, these came in all shapes and sizes, some that took up orbits around other planets and surveyed the surface, others took photographs on fly-by passes, while others landed and small remotely controlled rovers explored the surface and analysed soil samples.
Important Space Probes |
