Ranger 8 was a spacecraft designed to achieve a lunar impact trajectory and to transmit high-resolution photographs of the lunar surface during the final minutes of flight up to impact.

Why?

Ranger 8 took the first close up photos of Mare Tranquillitatis, the site of first manned landing.  Ranger close-ups showed for the first time that even areas on the Moon which looked smooth from Earth were peppered with small impact craters.