This book can be considered a worthy update to Gerard K. O’Neill’s seminal The High Frontier (published in 1977), and authors Tom Marotta and Al Globus should be commended on making a major contribution to the subject. Gerard’s widow Tasha O’Neill even gave the authors permission to use the title.

O’Neill envisioned large orbital space settlements, built from non-terrestrial materials, which could eventually be located anywhere in the solar system and built in sufficient numbers that the total land area would greatly exceed the total land area of planetary surfaces, including Earth and Mars. But the problem has always been (and remains)—how do we get from here to there? There is an enormous gap between where we are now and the first orbital space settlements, and even after 40 years there are as yet no concrete plans to actually proceed with building any. This book provides new ideas on a stepby-step approach that can help bridge that gap.