There's a large number of acronyms and initialisms in this book, drawn primarily from usage in space, science and engineering, plus a few from IT and military, and some have been newly invented for the purpose of this document. Unfortunately this is the nature of the topic, and acronyms are a preferable shorthand to the expanded version in most cases. Each is expanded on first use, and can also be looked up in the Abbreviations section towards the end of the book. Abbreviations for chemical formulae are also provided in the same section.