知
=
口
+
矢
:
Mnemonic symbol: Francis Bacon is attributed to have stated "scientia potentia est", "knowledge is power". I'll thus represent 知 by Francis Bacon. Francis Bacon (知) and James II of England (zh) are playing darts (矢) in front of the space station (Ø1). Because they lack a dart board they just use a mandarin (口).
识
=
只
+
讠
:
Sherlock Holmes (sh) is inspecting the new arrival at the entrance of the space station (Ø2). It's a big advertising column (讠) with a cuttlefish (只) on it, to broaden the space station's inhabitant's knowledge (识).
俭
=
亻
+
佥
:
General Fu Qian (佥) is a very rich and respected general, but he still lives very frugal (俭). To amuse himself he merely visits the anthill's bar (an3) and puts one arm around Joan of Arc (ji) and Rosa Luxemburg (亻) respectively.