Settling on Mars would involve building bases, generating power to use on the planet and terraforming the landscape to make it habitable for humans.Pat Rawlings, SAIC / NASA

To say Robert Zubrin is passionate about Mars is a bit of an understatement. The 66-year-old aerospace engineer has devoted the better part of his life to thinking about and encouraging the exploration of Mars.

In 1998, Zubrin co-founded The Mars Society, a Lakewood, Colorado-based nonprofit, and in the years since has become an outspoken advocate for the establishment of a permanent settlement on Mars — and a harsh critic of what he considers NASA’s stagnant human spaceflight program.

Recently, NBC News MACH spoke with Zubrin about why he feels so strongly that humans should colonize Mars and that NASA shouldn’t build a lunar “spaceport” — and why Mars exploration is so deeply personal to him.