Written for engineers, scientists, and managers, this Tutorial Text provides an introduction to systems engineering principles, tools, and practices as applied to astronomical systems. Topics include interface control, the lifecycle model, the role of trade studies, and the flow and allocation of requirements. Particular attention is paid to deriving the law of error propagation because it is the basis for formal performance budgeting and estimating the probability of success. Several examples supplement this derivation. A case study for a space science mission is also included.

The discipline of systems engineering has been emerging since the 1940s. With the development of large ground-based telescopes, such as the Keck, Gemini, and the Very Large Telescope, and space telescopes, such as the Hubble Space Telescope, Chandra X-ray Observatory, and the Spitzer Infrared Telescope, the role of systems engineering for astronomical telescopes has come to the forefront. As we move forward into the next decade, there are numerous opportunities and a need for systems engineering to play a role for future observatories. The purpose of this book is to provide an overview of systems engineering as it applies to large astronomical telescopes, with an emphasis on space telescopes, and the tools for supporting the development and management of future programs. Examples from previous programs are used to illustrate the concepts and processes. The important personality and behavioral aspects of good systems engineers are mentioned. The book is intended for aspiring new systems engineers and as a refresher or reference for current practitioners. It is also useful for engineers in other disciplines to better understand and guide their participation in the larger system endeavor. To paraphrase an old bumper sticker from years ago: Think globally systems, act locally discipline.

The stimulus to develop this book has evolved over time. The initial impetus for Paul Lightsey was a suggestion from Phil Stahl following a briefing of the results of the pre-Phase-A architecture study for the Next-Generation Space Telescope (which later became the James Webb Space Telescope, or JWST). Stahl suggested that Lightsey offer a short course on systems engineering and architecture development for SPIE. The seed was planted but took time to germinate. In the interim, Lightsey was an adjunct lecturer for the Johns Hopkins Masters in Space Systems Engineering program offered at Ball Aerospace, and also developed and taught an internal training course at Ball on architectural concept development. A few years later, Stahl invited Jonathan Arenberg and Lightsey to collaborate on status updates on the progress of the JWST program at a Mirror Technologies Meeting. A few years later, Arenberg was invited to develop a short course on systems engineering for SPIE. He agreed on the condition that he and Lightsey could co-develop the course. The course relied on the combined experience of the authors having worked on the Great Observatories Hubble Space Telescope, Chandra X-ray Observatory, and the Spitzer Infrared Telescope Facility, along with diverse experience from a multitude of other aerospace programs. The course was first presented at the SPIE International Conference on Astronomical Telescopes and Instruments at Montreal in 2014. At that time, the authors were invited to develop a text based on the course. The progress was slow, with a preliminary draft ready at the time of the SPIE International Conference on Astronomical Telescopes and Instruments at Edinburgh in 2016. The SPIE editors solicited reviews, which have been used to update the book, from colleagues and feedback from the short-course students. So now as we approach the imminent launch of the JWST and the reports from the studies for missions to be presented for the 2020 Decadal survey, we offer this book and hope that readers find it useful.

We wish to thank the many colleagues and students, past and present, from whom we have learned much. We would like to dedicate this book to our wives, who tolerated the long hours we have put into our profession and into the preparation of this book.

Paul A. Lightsey
Greeley, Colorado

Jonathan W. Arenberg
Santa Monica, California