Ranger 7 lunar impact crater...

Ranger 7 lunar impact crater...  If you're ancient enough, like me, you might remember this series of early robotic exploration missions.  Ranger 4, part of the series, was the first man-made object ever to strike another body in the solar system. 

Ranger 7 was the first to return high-quality photos.  The Ranger series wasn't intended to actually land safely on the moon – instead, they were aimed straight at the moon and intentionally slammed into it at very high velocities.  On their final approach, they took photos and other measurements and beamed them back to Earth in real time (these images were turned into the video at left).  Then the Rangers struck the moon, making small craters because of the kinetic energy of their impact – and of course there were no more pictures after that.  This was part of the preparatory work leading up to the Apollo landing missions.

The Ranger series were tremendously exciting for me as a kid.  I knew enough science and math to understand what was being attempted and just how difficult it was.  By today's standards, the technology employed in the Rangers was laughably primitive – but at that time, it was real bleeding-edge stuff.  The very idea of getting something made by mankind to another world sounded to us like something straight out of science fiction, an impossible feat.  Remember, this was less than 40 years after Lindbergh's pioneering trans-Atlantic flight!