Space Nutrition, by Scott M. Smith, Janis Davis-Street, Lisa Neasbitt & Sara R. Zwart. Published by NASA Nutritional Biochemistry Laboratory. iPad (iBooks 2 and iOS5 required), free.

Reviewed by Veronique Greenwood

A couple of months ago, I attended a trade show for the processed food industry. There, wandering among booths hawking hydrolyzed vegetable protein, phosphate, and guar gum, I learned that despite its implication in the obesity epidemic, the processed food industry views itself as a direct descendant of Louis Pasteur and his pasteurization process—a provider of safe food for millions. This was profoundly unsettling, and I was relieved when I happened across a pair of NASA food scientists standing before a poster. In space, how food is preserved and packaged isn’t a matter of merchandizing. It is still, as in the days of Pasteur, a matter of survival.

This thesis and the science you need to know to understand it are presented in Space Nutrition, a free ebook put together by members of NASA’s Nutritional Biochemistry Laboratory. Though it makes extremely limited use of multimedia (warning: it only functions in the landscape orientation), Space Nutrition is a passable introduction to the special difficulties of getting a balanced diet in space, where bone loss is a given, nutrients are absorbed differently than on Earth, and everything must have a long shelf life. Perhaps more importantly, it's a window into the enthusiasms and curiosity of the scientists who wrote it.

The book, which is pitched at children grades 5-8, grew out of a long-running space nutrition newsletter [pdf], and this heritage may be responsible for its poor organization. There are sections, for example, called “Space Food” and “Space Flight Research” in the chapter called Nutrition, but the chapter called Space Flight Nutrition has only one section, entitled “Being Healthy is not Just About Nutrition (even though we like to think it is!)” (caps theirs). Frustratingly, the details of how space flight affects the human body and the nutrients in food are never enumerated in one place. This hampers its usefulness as a primer.

But for me, and I suspect for any kids reading it, the book's primary charm is in the photographs and asides that you can’t find in a Wikipedia article on the subject. One photogallery is full of snapshots taken by excited Nutritional Biochemistry Lab members as they drive to Kennedy Space Center to pick up astronaut blood samples from the ISS, which they use to determine the effects of space flight on nutrient absorption, bones, and muscles. The shots of the Experiment Payload truck that retrieves the samples and of the little blue NASA duffel bags they are carried home in give the process of space research a refreshing physicality.

And spaceflight seen from a food scientist's point of view is endearingly kooky. Crumbs are a big no-no for space foods—they fly around and clog the instruments. Tortillas that last almost a year, on the other hand, are a very exciting development, the authors write, because you would need three hands to make a traditional sandwich with two slices of bread and a slice of baloney in space. The book's history of manned spaceflight missions reads like no other you'll find. Gemini: Shrimp cocktail, chicken and vegetables, pudding, applesauce. Apollo: bread slices, cheddar cheese spread, frankfurters, fruit juice. Skylab: steak, vanilla ice cream.

These colorful details, at least for me, don't quite make up for the organizational problems. But the book is free, and if you or your kid are interested in space flight or astronaut food, it's certainly worth downloading.

The book also raises the hope, however faint, that perhaps someday we will seek to turn the considerable power of food science not towards making potato chips fly off the shelves, or devising yet more uses for soy protein, but towards getting humans on other planets.

Veronique Greenwood is a staff writer at DISCOVER Magazine. She writes about everything from caffeine chemistry to cold cures to Jelly Belly flavors, and her work has appeared in Scientific American, TIME.com, TheAtlantic.com, and others. Follow her on Twitter here.