Space probes are unmanned spacecraft fitted with instruments to gather and transmit data and images from space.
Because the probes are self-sufficient, they can be sent where no person could survive: into orbit around the Sun, to the other planets, or even out beyond the solar system.
The downside of unmanned probes is that malfunctions need to be taken care of from Earth, or the space shuttle, which could be millions or billions of miles away.
Much of the information we have about the Sun and the planets came from space probes such as Pioneer, Mariner, and Voyager.
