D-Ration Bar

A D-Ration Bar is a compact, high-calorie emergency food originally developed by the U.S. military during World War II. It is a dense chocolate bar designed to provide a quick energy boost under survival conditions and withstand extreme temperatures without melting.

In the context of space missions, D-Ration Bars influenced the design of early astronaut rations by demonstrating how nutrient-dense, shelf-stable foods could be compactly packaged and preserved for harsh environments. Though not widely used in spaceflight, the concept of high-energy, durable bars informed the development of modern space snacks that support energy needs and storage constraints.