Historical clue formulations

• Government investigation — 2024-12-01
• NASA project — 2023-09-13
• Get personal, say — 2023-07-14
• Voyager 1, for one — 2022-03-17
• Really dig — 2020-11-28
• Investigation — 2019-08-11
• Do some digging — 2019-02-27
• Dig for answers — 2017-09-17
• Nonhuman explorer — 2016-04-08
• See circled letters — 2014-06-04
• Certain NASA launch — 2014-02-09
• Certain NASA launch — 2013-05-19
• Government investigation — 2012-08-20
• Look into — 2012-05-01
• Exploratory spacecraft — 2011-03-21
• Exploratory spacecraft — 2004-06-09
• Space explorer — 2003-07-22
• Grand jury's activity — 1998-12-21
• Investigation — 1998-09-06
• Deep-space mission — 1998-04-14
• Explore — 1997-05-06
• Investigation — 1996-02-01
• Perscrutation — 1994-06-25