On ongoing theme. Any stamp that commemorates space exploration. This does not include sci-fi related stamps.
colnect.com
Letter Rate 4¢ Package Rate 4¢ Postcard Rate 3¢ Effective 8/1/1958 United States 1/12/1962 Operation Ranch Hand Begins The United States Air Force launched Operation Ranch Hand in Viet-Nam. This operation was designed to expose transportation routes by killing the vegetaion around them. The most commonly used herbicide during this operation was Agent Orange. American President John F Kennedy (1/20/1961-11/22/1963) British Prime Minister Harold Macmillan (1/10/1957-10/18/1963) German President Heinrich Lübke (9/13/1959-6/30/1969)