Britannica Educational Publishing 
Pioneers in Astronomy and Space Exploration [PDF ebook] 

The pioneers of astronomy and space exploration have advanced humankind’s understanding of the universe. These individuals include earthbound theorists such as Aristotle, Ptolemy, and Galileo, as well as those who put their lives on the line travelling into the great unknown. Readers chronicle the lives of individuals positioned at the vanguard of astronomical discovery, laying the groundwork for space exploration past, present, and yet to come.