Any idea what these postcards were from?

Factual Questions
1

When I was a kid, I remember taking a bunch of postcards to my 2nd grade show and tell. From what I remember, it was some sort of (maybe) NASA promotional material - a connected series of 6-10 postcards, all featuring some space-related photograph. There was the famous shot from the Viking lander, one with Jupiter’s rings clearly visible, and some other shots that I can’t quite remember. Any idea what this might have been? I know it’s a longshot, and pretty vague. Thanks.