1. Important Missions for Solar System Exploration An overview from early ’50’s to today… Part I

2. Sputnik: 4/10/1957 Sputnik was the opening shot in the space race between the United States and the forme Soviet Union. The basketball-sized spacecraft was the world's first artificial satellite. It orbited the Earth sending back a beeping signal for 23 days. Sputnik was an amazing technical achievement followed only a month later by the stunning launch of Sputnik II, which carried the first living thing - Laika the dog - into space.

3. Explorer 1: 31/1/1958 Explorer 1 was the first spacecraft successfully launched by the U.S. It orbited Earth every 115 minutes, 358 kilometers (220 miles) above the surface at its closest point and 2550 kilometers (1580 miles) at its farthest. It carried instruments to measure cosmic rays, micrometeorites, and its own temperature, transmitting this data until February 28, 1958. Explorer 1 found a radiation belt around Earth, which came to be called the Van Allen radiation belt after the scientist who built the cosmic ray detector.

4. Pioneer (18 missions, started Aug. 1958) The early Pioneer missions marked the efforts to break the grip of Earth's gravity and make it to the Moon. While only Pioneer 4 achieved that goal, all eight Pioneer moon shots yielded valuable information. There were a total of 18 spacecraft in the series. After the lunar missions, spacecraft bearing the Pioneer name went on to explore the solar system. The most famous are Pioneers 10 and 11.

5. Pioneer 10 logged a series of firsts in the exploration of space, including first through the asteroid belt and first to Jupiter. NASA contacted Pioneer 10 as recently as December 2002. Pioneer 11 was the first spacecraft to fly past Saturn. Both spacecraft carry aluminum plaques with diagrams of the human race and are on a trajectory that will take them out of our solar system into interstellar space.

6. Luna Series (USSR): started 23/9/1958 Most of Russia's unmanned Moon exploration missions flew under the ambitious Luna program. The program was marked by historic successes and spectacular failures. Seventeen of the 45 Luna missions were successful. Luna spacecraft were the first to impact and make a survivable landing on the Moon, photograph the far side of the Moon (never before seen by humans) and orbit the Moon.