After reading a science fiction book centered around the concept of a ramjet ship that could travel close to light speed (Tau Zero), I decided to go back to another favorite subject: generation ships. About three years ago to the day, I read Lungfish by John Brunner. This time I went back to one of the all-time classic authors: Robert Heinlein and his tale Orphans of the Sky.

The story takes place on a starship that has been en route so long, for so many generations, that Earth is a distant legend, the crew has forgotten why they are there and the entire universe they know about is the inside of the ship. Legends have developed around their mission, and religions have formed based on the old legends.

The ship is very old, and many sections have long been abandoned. Radiation damage has caused many births with deformities. The crew has realized that they can’t allow the mutants to live. However, over the centuries, mutants have escaped and reproduced on their own. They are called the “muties” and they live in the upper reaches of the ship, while the crew lives in the lower decks, and the two don’t really mix. If they do, it usually ends up in death for one or the other side.

One of the young crew members, Hugh, is adventurous and makes friends with the muties. Eventually he finds out more and more about the truth of the ship, its mission, and the reality of what the universe really is – not just a ship. He meets severe resistance from the ship’s political establishment and leadership. But eventually he sets in motion events that impact the entire ship.

Heinlein, true to his style, builds the story and the characters, and immerses the reader in the little universe that is the ship. Unfortunately, it all falls apart in the last 10% of the book. The ending, the solution, is completely inconsistent with the beginning and main body of the story and seems more of a deus ex machina solution to the plot than a real possibility. Orphans of the Sky is only 209 pages long, but could easily have been twice as long. The author could have built out the ending to a point where it made sense. The last 10 pages are completely unsatisfactory and unrealistic – and unfortunately they leave the lasting impression for the whole book – a good, fascinating concept, done haphazardly. It’s like Heinlein lost interest in the end and tried to wrap it up as quickly as he could.

If you like generation ship stories, this is still a must-read.