When I first saw the book, I was surprised by its size - it's so thick! It took me two weeks to finish the book, and I love it. I have read many books about space exploration, especially on human Mars exploration, but it is the one which I admire the most. Dr Zubrin is so creative for coming up with a plan called "Mars Direct". This plan is very different from the NASA's "90-Day Report", it involves no orbital assembly, no orbital infrastructure, no orbital rendezvous, and it doesn't need advanced propulsion or any other technology that we don't have, and basically what the approach takes is to explore Mars the way we explore the Earth, which is "travel light, and live off the land". Dr Zubrin explains that we can use this technology by using the resources that can be found on Mars rather than entirely Earth-supplied. I believe "Mars Direct" is the only way to get to Mars, because not only it is the cheapest, but also it is easier to accomplish. Dr Zubrin also explains why a moon base is not needed before the human Mars mission, which many people believe it is a necessary first step toward Mars. I agree, in fact I think his answer is quite convincing.
Later in the book Dr Zubrin explains that we will start colonizing Mars once a region is chosen. Things like carbon, nitrogen, hydrogen, and oxygen which are very useful for human colonization are very common on Mars. Also there are plenty of chemical substances in the soil of Mars which can be used to make metals, or even nuclear reactors for the energy supplies. Compare to the moon, Mars has more useful resources for human colonization, and that's one of the reason why we should go to Mars, not the moon.
Finally Dr Zubrin said in the far future we may "terraform" Mars. He said we can do this by putting a gigantic mirror in the orbit round Mars. When it reflects the sunlight onto the polar cap, the polar cap will melt and release carbon dioxide gas into the atmosphere, which will then warm the planet up. Or if we have a significant industrial capability on Mars we can produce artificial greenhouse gas like CFC. I don't think it is science fiction because I believe we can do this, and if we terraform Mars, it will become our second home.
The reason why our technology gets better is because we have plenty of resources on Earth, but once it becomes insufficient the result will be war and extinction of human being. The only way to avoid this is to search for other resources by exploring space, and of course, Mars is going to be a perfect place.
