The Wikipedia article for Alexandr Wolszczan (the astronomer who first discovered an extrasolar planet) says that he admitted to being a paid spy from 1974 from 1988. The cited article is this:
No. The second paragraph says that he cooperated with the (Służba Bezpieczeństwa (SB)) internal intelligence agency [my bit: of the Polish People’s Republic]… So no… not a spy, but I guess working for a communist intelligence agency may hint of this, as usually people who worked for the SB, gave information about others who went or acted against the communist ideology.
… Kind of like the Hitler Youth… You see anything suspicious, report it. Then a whole bunch of goons come over and and at best take them away, beat them up (read - interigate), and release them, and at worst, they’re killed by torture.
To add, not at one point in the article does it mention SPY (“szpieg” in polish).