This book covers the topic of On-orbit repair and servicing of spacecraft. Putting a communications satellite in synchronous orbit will set you back 100's of millions of dollars. Once on orbit, you hope it survived the launch environment, and operates correctly. You further hope it works at least for its design lifetime, and as long as possible. This approach, based on good engineering design practices, lessons learned, and hope, it the equivalent of buying a new Tesla with non-rechargeable batteries, and driving it until it stops. Then buying a new one.