Wait, so your saying that instead of going to the moon, our friendly, neighbourhood satellite, we are going to fly like, over 3 times the distance to land on an asteroid, which is way more dangerous than a moon landing (space rocks as damaging debris and such). That just is not a logical decision.
However, the unmanned idea is viable. An unmanned craft surely could get to the moon. They've gone way further. e.g Voyager which flew past Jupiter and Saturn.
I will see if i can find anything on it.
EDIT: I have researched the subject and came up with this. These are all the programs within the time period of when the first moon landing was;
LUNA program:
http://en.wikipedia.org/wiki/Luna_program
Did make it. Did return samples. However, these samples were not back on Earth until after the Apollo misions were.
RANGER program:
http://en.wikipedia.org/wiki/Ranger_program
This program was all about taking pictures of the moon. They never made back. actually, they never made it past hitting the ground.
SURVEYOR program:
http://en.wikipedia.org/wiki/Surveyor_program
This program tested soft-landings for space craft. So not only did they never return to the Earth, they didn't have any of the equipment required for a unmanned probe to take samples.
LUNAR program:
http://en.wikipedia.org/wiki/Lunar_Orbiter_program
This program never made to the surface of the moon, taking pictures from orbit.