Humans are not native to the Earth. So posits astronautical engineer Bob Zubrin in the opening of Entering Space. We're native to just a small sliver of it, the spot where our species originated in tropical Kenya. We set out from that paradise about 50,000 years ago, north into "the teeth of the Ice Age," and all the ground we've gained since then has been thanks to our tenacity and our tools.
Zubrin reasons that it's time we cover a little more ground. Written with a boyish enthusiasm and formidable techie know-how, Entering Space urges us to realize "the feasibility, the necessity, and the promise" of becoming a space-faring civilization, of colonizing our own solar system and beyond. And Zubrin, author of the influential and widely acclaimed The Case for Mars, knows his stuff--NASA adapted his plans for near-term human exploration of Mars, and Carl Sagan gave the author no less credit: "Bob Zubrin really, nearly alone, changed our thinking on this issue." Entering Space plots the second and third phases of humanity's course--now that we've mastered our own planet, Zubrin says we must first look to settling our solar system (beginning with Mars) and then to the galaxy beyond.