Courtesy of Henry Throop The "Chasing New Horizons" authors, mission director Alan Stern (left) and planetary scientist David Grinspoon.

mountains, polar caps and a heart-shaped patch that is now the dwarf planet's signature. But some thought the New Horizons mission, which was run out of Boulder, was impossible. Across the 26 years of development, there were many times the historic flyby almost didn't happen.

The inside story of the mission is now chronicled in a book, "Chasing New Horizons," by mission director Alan Stern and planetary scientist David Grinspoon. Stern and Grinspoon told Colorado Matters about all the close calls along the decades-long journey to Pluto, and how they fit the whole story into the book.

Read an excerpt from "Chasing New Horizons":