Historical clue formulations

• Mars: Prefix — 2006-11-11
• Mars: Prefix — 2004-10-01
• Mars: Prefix — 2003-12-03
• Mars, in combinations — 1999-07-07
• Mars: Prefix — 1998-09-06
• Mars: Prefix — 1997-04-07
• Mars, in combinations — 1996-05-12