Encyclopedia Astronautica: Comprehensive resource providing detailed articles on most space technology subjects and space flight history

NASA History Office: Current events; index of sites covering history of major aeronautic and astronautic programs, key NASA and NACA (1915-1958) officials, policy documents, statistics, timeline of air and space achievements; publications; links to other resources

PBS Online: Lewis and Clark: Companion site to the Ken Burns film, 'Lewis and Clark: The Journey of the Corps of Discovery.' Information on the explorers, expedition journals, trip timeline and maps, interviews with historical experts, an overview of Native American tribes, and classroom lessons

Shoot for the Moon!: Outlines the highlights of the Mercury, Gemini and Apollo Space Programs from 1961 to 1972. Includes a brief bibliography