Book excerpt: This second edition of Spacecraft Power Systems is a comprehensive coverage of the fundamentals, design trades, components, controls, and operations of spacecraft power systems based on the real-world design and operations of spacecraft that have successfully flown for decades. It also includes emerging high-voltage, high-power systems for in-space propulsion for interplanetary travel. With new and updated chapters, sections, and discussions, the second edition covers up-to-date high-voltage, MW-scale electric propulsion, updated PV and battery systems, spacecraft power components, power electronics, and their architectures and operations. This book also presents the latest in spacecraft design processes and trades, controls, operations, and protection. This book is intended for senior undergraduate and graduate students in mechanical, aerospace, and electrical engineering taking courses in Space Systems, Space Engineering, and Spacecraft Power Systems, as well as for practicing aerospace and power engineers and managers who are designing, developing, and operating spacecraft power systems.