The Ranger probes were instruments designed by the NASA Jet Propulsion Laboratory and were basicly kamikaze missions. The probe had to take pictures until it crashed on the Moon surface.
This way scientists could take a good look at the smoothness of the Moon's surface. The information obtained by the Rangers was valuable to discover how difficult a Moon landing would be. The question to be answered was how many craters were present on the Moon surface and if man could land on the Moon.
Rangers 1-5 missed the Moon and the projectmanager was fired. The new boss simplified the Ranger design and Ranger 6 crashed succesfully into the Moon. But because of a malfunction no images were sent back to Earth.
Ranger 7 completed the task and the images were a thousand times more detailled than what could be seen by telescopes on Earth. On 24 March 1965 images from Ranger 9 were broadcasted live on television and the world watched the probe crash into the Moon.