I've been curious for some time about the history of the different moon logos on classic space figures. Is there any information about what sets the different types came in originally or if this was a switch made before/after some particular year?

Moon space logo qualities I have identified:

• Gold Logo - Bright and vibrant
• Gold Logo Faded - Clearly was originally gold
• Gold Logo Faded all the way to White - again, clearly originally gold
• Dark Gold Logo - Typically only seen on red figures but occasionally on blue.
• Red Logo - Only found on red figures Seen in the second photo
• White Logo - Everything is so crisp that it seems impossible that it was originally gold.

I'm pretty sure all of those were gold at one time.  My guess is that it's a combination of play wear along with the possibility of different paints being used.  I've been lucky and discerning as all of my classic space men have decent amounts of gold remaining.  

Here are the Classic Space men, if you click into the minifigs, you can check from which sets they came from.

One notable thing about the helmets. The original ones had a tendency to crack at the thin chinstrap, so they were replaced.

http://alpha.bricklink.com/pages/clone/searchproduct.page?q=classic%20space%20airtanks#T=M

I can see how play wear would rub the gold away leaving only the white background but the dark gold and red are a bit more of a mystery. Maybe finger oil?

Printed colors can often look different on different background colors because the background color can shine through a bit. So is it possible that the dark gold moon was printed directly on the red torso while later production runs had a full white moon printed on the red torso before the gold was printed on top of that? That could explain why some of the red figs have a red logo (there was never a white moon under the gold) while others have a white logo (there was a white moon under the gold). The yellow, blue and black figs were introduced later, so they would always have a white moon printed before the gold was printed on top of it.

That makes a lot of sense; the printing of gold either on the torso color or the white background.  Do you think there were figures printed just with the white without gold? Some of the white logo's look so good its hard to believe the gold faded from them. Looking at the dark gold pics above though, you can distinctly see a white ring around the gold logo.  I'm going to have to inspect those more closely to see if it is an actual ring or if the white does extend behind the gold.

I have a hard time believing some of the red logos were faded from gold printed directly onto a red torso, mostly because I don't see any middle-ground logos (faded gold partially to red).  They seem to just be solid red.  I'll have to look at them more closely though.

Thank you so much for your insight!