1989 July President George H Bush's Space Exploration Initiative speech.

1989 November NASA 90-day study of Moon and Mars exploration.

1990 December Report of the Advisory Committee On the Future of the US Space Programme.

1991 July Exploring the Moon and Mars: Choices for the Nation report.

1993 President William Clinton agrees International Space Station with Russians.

2003 Space Shuttle Columbia disaster.

2003 Columbia Accident Investigation Board.

2004 January President George W Bush's Vision for Space Exploration (VSE).

2004 March Norman Augustine gives Congress-ional VSE testimony.

2005 NASA Exploration Systems Architecture Study.

2006 National Academy of Sciences reviews NASA's International Space Station plans.

2009 May Norman Augustine is chairman of President Barack Obama's US human spaceflight plans review.

Source: Flight International