The study of astronautics and space missions can appear difficult at times, but our goal with Understanding Space is to bring space down to Earth and de-mystify it, so each reader understands the big picture with confidence. It contains historical background and a discussion of space missions, space environment, orbits, atmospheric entry, spacecraft design, spacecraft subsystems, and space operations. This is a truly user-friendly, full-color text focused on understanding concepts and practical applications but written in a down-to-earth, engaging manner that painlessly helps the reader understand complex topics. It is laid out with multi-color highlights for key terms and ideas, reinforced with detailed example problems, and supported by detailed section reviews summarizing key concepts, terms, and equations.