Unmanned Space Vehicles

Unmanned missions (1958–)

Over 1,000 unmanned missions have been sent into space to explore our solar system. NASA has launched both exploration and communication satellites into orbit. The missions have been both directly launched into space from earth and launched from a space shuttle once it was already in space. The first unmanned mission was Explorer 1. This project was launched in January 1958, two month's after Sputnik. This was early on in the space race. A more recent unmanned mission was the Hubble Telescope, which was launched in 1990. The closest planets to earth, Mars, Venus, and Mercury, have been the goals of more than four programs. The first was the Mariner in the sixties and seventies which visited all three of the planets. The Mariner was also the first to make a planetary flyby and a gravity assist maneuver. A gravity assist maneuver is where a satellite uses the gravity and velocity of a planet to reach its destination while simultaneously getting the opportunity for close up pictures of a planet. The Viking 1, was the first successful landing on Mars, and landed in 1976.

    Twenty years later, NASA also launched rovers to mars on the Mars Pathfinder. This was also a very successful mission and got a lot of useful data from Mars. The Pioneer 10  visited Jupiter in 1973. Pioneer 10 was also the first spacecraft to leave the solar system in 1983. However, Voyager 2 had passed it in distance from our solar system. Both the Pioneer and Voyager program carried messages to earth. A problem with space travel going out this far is the communication. For instance, it takes about 3 hours for a radio signal to reach the New Horizon space craft which is only half-way to Pluto. Contact with Pioneer 10 was lost in 2003. On 26 November, 2011, NASA launched a mission to mars with the robotic "Curiosity" rover. This new rover will look for evidence of past or present life on Mars.