On ongoing theme. Any stamp that commemorates space exploration. This does not include sci-fi related stamps.
Colnect.com
Letter Rate 29¢ Package Rate 29¢ Postcard Rate 19¢ Comments F Stamp American President George H W Bush (1/20/1989-1/20/1993) British Prime Minister John Major (11/28/1990-5/2/1997) German President Richard von Weizsäcker (7/1/1984-6/30/1994)