A series of NASA Moon probes, originally intended to photograph the Moon as they approached and then to eject an instrument package on to the surface. After a sequence of failures the Rangers were changed into photographic-only missions. Three probes were successful, sending back increasingly detailed pictures before they crashed into the Moon. The Ranger pictures of the lunar surface assisted the design of the later Surveyor soft landers.

http://nssdc.gsfc.nasa.gov/planetary/lunar/ranger.html NASA information page.