Barely visible against the blackness of space was a tiny speck of light 3.7 million miles away. Although the speck seemed insignificant, it contained oceans, land, mountains, clouds, and even life forms. Speeding into deep space at 37, 000 mph, the Voyager 1 spacecraft turned its cameras to face Earth for the last time.
In reality, humans have only traveled as far as the moon. All exploration beyond that has been performed by robotic space probes (or spacecraft). These space probes are sent into the solar system with scientific instruments to take pictures and measure important properties of planets and their moons.
The obvious advantage of robotic spacecraft is that you don't need to take humans [forget humans!]. This means that the mission designers do not need to worry about living quarters, food, hygiene, crew morale, etc. There is also the fact that all missions have a risk of going terribly wrong and no lives would be lost. On the other hand a robotic spacecraft is unable to make onboard repairs as well as being unable to make certain descriptive observations.
Space probes have traveled far and wide through our Solar System. Some flew by while others landed on planets. Probes have even plunged into the tail of Halley's Comet. These sophisticated robotic craft have greatly assisted humans in the exploration of the Universe and will continue to do so for years to come.
