Things we tend to like but not absolutely required:
the induction loop symbol, moons, radio waves, crescent moon, cosmos, three stars
The logo should feel modern and stand on it's own without the use of text or typeface text layouts. We'll use it on social media, so it would be ideal if it was purely graphical logo, where it'll be accompanied by text "PSW Science" and "Since 1871" in an accent color.
We are NOT looking for cheesy science clipart: beakers, atoms, chemistry kits, etc. This is a mature, established society, not a middle school science club. We are looking for an actual graphical logo, not just P, S, and W in different text layouts. See the planetary society example as something that looks awesome, represents the society, and stands on its own.